Article

Myth, Marula, and Elephant: An Assessment of Voluntary Ethanol Intoxication of the African Elephant ( Loxodonta africana ) Following Feeding on the Fruit of the Marula Tree ( Sclerocarya birrea )

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Abstract

Africa can stir wild and fanciful notions in the casual visitor; one of these is the tale of inebriated wild elephants. The suggestion that the African elephant (Loxodonta africana) becomes intoxicated from eating the fruit of the marula tree (Sclerocarya birrea) is an attractive, established, and persistent tale. This idea now permeates the African tourist industry, historical travelogues, the popular press, and even scholastic works. Accounts of ethanol inebriation in animals under natural conditions appear mired in folklore. Elephants are attracted to alcohol, but there is no clear evidence of inebriation in the field. Extrapolating from human physiology, a 3,000-kg elephant would require the ingestion of between 10 and 27 L of 7% ethanol in a short period to overtly affect behavior, which is unlikely in the wild. Interpolating from ecological circumstances and assuming rather unrealistically that marula fruit contain 3% ethanol, an elephant feeding normally might attain an ethanol dose of 0.3 g kg(-1), about half that required. Physiological issues to resolve include alcohol dehydrogenase activity and ethanol clearance rates in elephants, as well as values for marula fruit alcohol content. These models were highly biased in favor of inebriation but even so failed to show that elephants can ordinarily become drunk. Such tales, it seems, may result from "humanizing" elephant behavior.

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... Video footage, although anthropomorphized, shows elephants inebriated after consuming marula. (5) Certain ethologists contend that the alcohol content produced through these nonhuman assemblages is not sufficient to lead to intoxication (Morris et al, 2006). They suggest that overt effects are generated not by alcohol, but by nicotinic acid and poisonous beetle pupae present in the fruit (Morris et al, 2006). ...
... (5) Certain ethologists contend that the alcohol content produced through these nonhuman assemblages is not sufficient to lead to intoxication (Morris et al, 2006). They suggest that overt effects are generated not by alcohol, but by nicotinic acid and poisonous beetle pupae present in the fruit (Morris et al, 2006). Debates aside, there is consensus that elephants like the taste of alcohol. ...
... Debates aside, there is consensus that elephants like the taste of alcohol. Frugivory amongst elephants may be the evolutionary outcome of a predilection for ethanol in overripe fruit (Fowler, 2006; Morris et al, 2006). However, alcohol stored in distilleries is produced through a different assemblage. ...
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Political ecology has had a long connection with materials, going back to some of its canonical concerns. Yet materials are rendered inert with no capacity to mobilize political action. Further, the influence of matter in wider ecologies of human-animal cohabitation is poorly acknowledged. This paper examines the role of materials in mediating people's relationships with elephants in rural northeast India. Drawing upon ethnographic research and ethological studies of elephants, the paper shows that human-elephant conflict is not simply a linear outcome of interactions between elephants and people. Materials, in this case alcohol, play a vital role. Alcohol binds people and elephants in unforeseen ways. The sociopolitical outcomes alcohol generates have deep impacts on the livelihoods of the rural poor and the well-being of elephants. This examination of social and political life through concerted interactions between humans, animals, and materials ecologizes politics, making it more attuned to the more-than-human collectivities within which material lives are lived. The paper strives towards a political ecology that is symmetrical and challenges the discipline's humanist focus. It concludes with a discussion of the future implications and potential of this approach.
... Possibly the most iconic is the story of African elephants (Loxodonta africana) and marula fruit. According to this widespread lore, elephants across Africa preferentially feed on the fallen, fermenting fruit of the marula tree (Sclerocarya birrea), becoming intoxicated [21][22][23]. Such accounts have been criticized, however. ...
... Such accounts have been criticized, however. Researchers have suggested that tales of drunk elephants may be a result of 'humanizing elephant behavior' [23]. Yet, this argument is based on calculations drawing on human ethanol metabolism, which may be a critical flaw. ...
... While it is possible that any of the five lineages in which we identified pseudogenized ADH7 possess alternative mechanisms for ethanol metabolism, it is unlikely that these species approach human-level efficiencies in the absence of diets rich in fermentable sugars. Morris et al. [23] reject the possibility of inebriation in elephants on the basis of extrapolations from modern human physiology. In their calculations they suggest that, based on elephants' large body size and the amount of fruit consumed, elephants could not possibly experience intoxicating effects from the naturally occurring ethanol in fermented marula. ...
Article
Humans have a long evolutionary relationship with ethanol, pre-dating anthropogenic sources, and possess unusually efficient ethanol metabolism, through a mutation that evolved in our last common ancestor with African great apes. Increased exposure to dietary ethanol through fermenting fruits and nectars is hypothesized to have selected for this in our lineage. Yet, other mammals have frugivorous and nectarivorous diets, raising the possibility of natural ethanol exposure and adaptation in other taxa. We conduct a comparative genetic analysis of alcohol dehydrogenase class IV (ADH IV) across mammals to provide insight into their evolutionary history with ethanol. We find genetic variation and multiple pseudogenization events in ADH IV, indicating the ability to metabolize ethanol is variable. We suggest that ADH enzymes are evolutionarily plastic and show promise for revealing dietary adaptation. We further highlight the derived condition of humans and draw attention to problems with modelling the physiological responses of other mammals on them, a practice that has led to potentially erroneous conclusions about the likelihood of natural intoxication in wild animals. It is a fallacy to assume that other animals share our metabolic adaptations, rather than taking into consideration each species' unique physiology.
... It also provides valuable shade that produces large areas with cool subcanopy environments that are good habitats for other plant and animal species. Marula is also a favorite food of numerous birds, mammals and insects [15,22,25,42]. Therefore, removal of this large dominant species can threaten biodiversity and result in loss of many important subcanopy species such as mistletoes which grow on marula branches and wood roses that are often used by rural curio traders [10]. ...
... These trees are also host to various insect species such as buterlies and moths. The larvae of the edible kinds of these insects such as the mopane worm (Imbrasia belina) and the African moon moth (Argema mimosa) are used as food by many tribes in southern Africa [16,21,42,55,76]. The Swazis and Zulus also traditionally use the tough silk pupa cases of the moon moth for anklet ratles used in tribal dances such as the annual reed dance and Buganu ceremonies practiced in Swaziland. ...
... Dies spiegelt sich auch in den, von allen untersuchten Proben, höchsten Werten des Zuckergehaltes wider. [12]. ...
... Letzteres wurde von der Distell-Gruppe bei der Vermarktung des "Amarula"-Likörs erkannt und wird dementsprechend ausgiebig genutzt. Allerdings ist Alkohol aus Marula nach Ansicht der Wissenschaftler [12] eine unwahrscheinliche Quelle ("drunken elephants seem highly improbable."), es gibt alternative Erklärungen. ...
... Conversely, the oft repeated tale that African elephants (Loxodonta africana) get voluntarily uncontrollably drunk by eating the fruit of the Marula tree has been debunked as a myth for tourists. 8 Perhaps the recent finding that there is genetic evidence of widespread variation in ethanol metabolism among mammals (Fig. 5), 6 including elephants, may suggest that the conclusions about the quantity of fruit ingestion needed and the amount of ethanol required to produce inebriation in African elephants, were likely erroneous and the myth of inebriation may well be substantiated. It is in this genetic context that the mysteries of human alcohol use disorders 9 are being disentangled. ...
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... final paper of this collection (Morris et al. 2006, in this issue). Many of the important insights (as well as some huge misconceptions ) for " ordinary " people lie within the confines of comparative physiology and biochemistry and, as several of the authors emphasize, with this accrue social responsibilities. ...
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The articles in this volume are a product of the enthusiasm shown by delegates to meet in a remote corner of southern Africa and to discuss comparative physiology and biochemistry in their wider interpretation and future course. This collection reflects a small but long-standing commitment to fostering the engagement of biological research with African issues and colleagues. Comparative physiology and biochemistry are evolving, but in this we must guard against fractionation of effort and purpose. Increasingly available molecular methods are seductive in encouraging work on model species and in employing these species in place of more appropriate comparative models. Concomitantly, the comparative approach is reaching out beyond the individual organism and organism-organism interactions to establish underlying principles at ecosystem and landscape levels. The integration of molecular methods into comparative studies will require judicious selection and use of such skills if it is to be achieved without abandoning nonmodel species. The physiological and metabolic bases of ecosystem and evolutionary approaches must be underpinned by relevant data, requiring comparative researchers to accommodate colleagues contributing this specialist knowledge. These articles report distinct symposia, prefaced by a plenary paper. While each paper is itself a review of an entire symposium, they all exhibit a common theme, that comparative physiology and biochemistry are about interactions. It is our hope that the Comparative Physiology and Biology in Africa meetings will continue to facilitate special interactions between the people who make this happen.
... Work on the consumption of ethanol-rich foods by Old World fruit bats (Pteropodidae) has assumed ethanol kinetics similar to those of humans [32] so we administered ethanol in proportion to total blood volume [40]. Thus, a 16 g bat should require 1.03 ml of ethanol sugar water to achieve a BAC of 0.11 g 100 ml 21 [32,41], which we expected would produce overt effects of intoxication. We weighed each bat and orally fed it enough sugar water with ethanol to attain a BAC of 0.11 g 100 ml 21 , or the equivalent volume of ethanol-free sugar water as a control. ...
Article
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In the wild, frugivorous and nectarivorous bats often eat fermenting fruits and nectar, and thus may consume levels of ethanol that could induce inebriation. To understand if consumption of ethanol by bats alters their access to food and general survival requires examination of behavioural responses to its ingestion, as well as assessment of interspecific variation in those responses. We predicted that bats fed ethanol would show impaired flight and echolocation behaviour compared to bats fed control sugar water, and that there would be behavioural differences among species. We fed wild caught Artibeus jamaicensis, A. lituratus, A. phaeotis, Carollia sowelli, Glossophaga soricina, and Sturnira lilium (Chiroptera, Phyllostomidae) sugar water (44 g of table sugar in 500 ml of water) or sugar water with ethanol before challenging them to fly through an obstacle course while we simultaneously recorded their echolocation calls. We used bat saliva, a non-invasive proxy, to measure blood ethanol concentrations ranging from 0 to >0.3% immediately before flight trials. Flight performance and echolocation behaviour were not significantly affected by consumption of ethanol, but species differed in their blood alcohol concentrations after consuming it. The bats we studied display a tolerance for ethanol that could have ramifications for the adaptive radiation of frugivorous and nectarivorous bats by allowing them to use ephemeral food resources over a wide span of time. By sampling across phyllostomid genera, we show that patterns of apparent ethanol tolerance in New World bats are broad, and thus may have been an important early step in the evolution of frugivory and nectarivory in these animals.
... To the best of our knowledge, there is no information on ethanol metabolism in Egyptian fruit bats, therefore we also assumed that the kinetics of ethanol absorption immediately after administration in the bats is similar to that in humans. Thus, if to increase blood alcohol content to a level of intoxication (∼0.15 g·100 ml −1 ), a 70 kg human with a 5 l blood volume needs to imbibe 9 l of a 1% mixture of ethanol in water (Morris et al., 2006), then a 0.14 kg fruit bat would require 18.5 ml of the same mixture to achieve a similar blood alcohol content. ...
Article
Ethanol, a potential toxin for vertebrates, is present in all fleshy fruits and its content increases as the fruit ripens. Previously, we found that the marginal value of food for Egyptian fruit bats, Rousettus aegyptiacus, decreases when its ethanol content exceeds 1%. Therefore, we hypothesized that, if ingested, food containing >1% ethanol is toxic to these bats, probably causing inebriation that will affect flight and echolocation skills. We tested this hypothesis by flying Egyptian fruit bats in an indoor corridor and found that after ingesting ethanol-rich food bats flew significantly slower than when fed ethanol-free food. Also, the ingestion of ethanol significantly affected several variables of the bats' echolocation calls and behavior. We concluded that ethanol can be toxic to fruit bats; not only does it reduce the marginal value of food, but it also has negative physiological effects on their ability to fly competently and on their calling ability.
... In dealing with such a group of often entertaining and always stimulating delegates, it became apparent to us that comparative physiology and biochemistry have a great advantage-they're fun, and they're fun to communicate. With this in mind and in respect of some of the conversation that we overheard during the week in the African bush, we included the final paper of this collection (Morris et al. 2006, in this issue). Many of the important insights (as well as some huge misconceptions) for "ordinary" people lie within the confines of comparative physiology and biochemistry and, as several of the authors emphasize, with this accrue social responsibilities. ...
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The highly successful Fourth International Conference in Africa for Comparative Physiology and Biochemistry (ICA-CPB) was held in the Maasai Mara National Reserve in July 2008. The theme of the meeting was "Molecules to Migration: Pressures of Life." To enhance the theme, the venue and timing of the meeting were chosen to coincide with the arrival of approximately 1.4 million wildebeest on their annual migration from the Serengeti National Park in Tanzania. Like the three previous ICA-CPB meetings, the discussion topics and the resulting collection of synthesia presented here were very diverse. The articles in this special collection reflect the authors' interest in broadening our understanding of the field of comparative physiology and biochemistry and their commitment to engaging in global research with international colleagues. These articles are brief, synthetic reviews integrating information presented at and inspired by the meeting. From seasonal migration and reproduction in birds, to cardiovascular system development in vertebrates, to strategies for hypoxia survival, papers range from specific to broad interactions. What they all have in common: they increase our understanding of how animals are affected by and respond to the pressures of life.
... Both natural sources of ethanol availability contrast with manmade fermented beverages; ethanol concentrations in ripe fruits are extremely low in comparison to levels experienced by people who consume alcoholic beverages: one or two orders of magnitude below typical concentrations in beer and wine (3-6% and 8-12%, respectively, or 522-1043 mM and 1391-2086 mM). Therefore, reports of mammals inebriated with alcohol under natural conditions are only folk tales [18], and even frequent consumption of ethanol-rich fruits does not allow excessive ethanol consumption under human standards. Availability of ethanol at concentrations higher than those attained by yeast fermentation is a very recent event in evolutionary history. ...
... Furthermore, particular vegetation communities are associated with higher or lower elevations, for example, along a catena sequence (Venter et al. 2003) or with respect to a riparian zone (Rogers and O'Keefe 2003). Independent of vegetation productivity or leaf area, plants along such gradients might vary with respect to presence of key forage resources (e.g., marula, S. birrea; Morris et al. 2006) or overall palatability as a consequence of plant defences (Scholes and Walker 1993). Elephants favour Acacia-marula woodlands in the wet season (Shannon et al., 2006), and some elephants change their seasonal movements in response to the availability of fruits (White 1994). ...
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Foraging behaviour and habitat selection occur as hierarchical processes. Understanding the factors that govern foraging and habitat selection thus requires investigation of those processes over the scales at which they occur. We investigated patterns of habitat use by African elephants (Loxodonta africana) in relation to vegetation greenness to investigate the scale at which that landscape attribute was most closely related to distribution of elephant locations. We analysed Global Positioning System radio-collar locations for 15 individuals, using the Normalized Difference Vegetation Index as a representation of vegetation greenness in a Geographic Information Systems framework. We compared the importance of vegetation greenness at three spatial scales: the total home range, the seasonal home range and the 16-day home range. During the wet season, seasonal home ranges for both sexes were associated with intermediate greenness within the total home range; there was no evidence of selection based on greenness at finer scales. During the dry season, the strongest associations were within the 16-day home range: individual locations for males tended to be in areas of intermediate greenness, and those for females were in areas of intermediate and high greenness. Our findings suggest that the role of vegetation greenness varies with the scale of analysis, likely reflecting the hierarchical processes involved in habitat selection by elephants. KeywordsAfrican elephant–Habitat selection– Loxodonta africana –Normalized Difference Vegetation Index (NDVI)–Scale
... Another important factor that leads to house damage is alcohol. Elephants are fond of alcoholic liquor (Morris et al., 2006;Sukumar, 1993), and raid village distilleries where alcohol is brewed and stored (Sukumar, 2003). Popular reports of elephants raiding village breweries are widespread (Barua, 2010). ...
... Unfortunately, to our knowledge, there is no information on ethanol metabolism in fruit bats; thus, we also assumed that ethanol kinetics in humans and Egyptian fruit bats was similar when estimating the intoxicating dose for each bat. For example, for a 70·kg human with a 5·l blood volume, 9000·ml of a 1% mixture of ethanol in water is necessary to increase blood alcohol content to a level of intoxication, ~0.15·g 100·ml -1 (Morris et al., 2006); thus a 0.14·kg F. Sánchez and others ...
... Unfortunately, to our knowledge, there is no information on ethanol metabolism in fruit bats; thus, we also assumed that ethanol kinetics in humans and Egyptian fruit bats was similar when estimating the intoxicating dose for each bat. For example, for a 70·kg human with a 5·l blood volume, 9000·ml of a 1% mixture of ethanol in water is necessary to increase blood alcohol content to a level of intoxication, ~0.15·g 100·ml –1 (Morris et al., 2006); thus a 0.14·kg ...
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Food resources are complementary for a forager if their contribution to fitness is higher when consumed together than when consumed independently, e.g. ingesting one may reduce the toxic effects of another. The concentration of potentially toxic ethanol, [EtOH], in fleshy fruit increases during ripening and affects food choices by Egyptian fruit bats, becoming deterrent at high concentrations (>/=1%). However, ethanol toxicity is apparently reduced when ingested along with some sugars; more with fructose than with sucrose or glucose. We predicted (1) that ingested ethanol is eliminated faster by bats eating fructose than by bats eating sucrose or glucose, (2) that the marginal value of fructose-containing food (food+fructose) increases with increasing [EtOH] more than the marginal value of sucrose- or glucose-containing food (food+sucrose, food+glucose), and (3) that by increasing [EtOH] the marginal value of food+sucose is incremented more than that of food+glucose. Ethanol in bat breath declined faster after they ate fructose than after eating sucrose or glucose. When food [EtOH] increased, the marginal value of food+fructose increased relative to food+glucose. However, the marginal value of food+sucrose increased with increasing [EtOH] more than food+fructose or food+glucose. Although fructose enhanced the rate at which ethanol declined in Egyptian fruit bat breath more than the other sugars, the bats treated both fructose and sucrose as complementary to ethanol. This suggests that in the wild, the amount of ethanol-containing fruit consumed or rejected by Egyptian fruit bats may be related to the fruit's own sugar content and composition, and/or the near-by availability of other sucrose- and fructose-containing fruits.
... The selection of marula fruits could be due to the energy-providing sugars and their high vitamin C content. Fresh marula fruits contain up to 180 mg per 100 g of vitamin C (Shackleton et al. 2002), attracting not only the greater kudu (Hooimeijer et al. 2005), but also other browsers such as Loxodonta africana (Morris et al. 2006), Giraffa camelopardalis, Kobus ellipsiprymnus and Taurotragus oryx (Venter & Venter 1996). During the wet season the greater kudu mainly browses the leaves (Table 11.2), probably because other plant parts such as pods and seeds are still unripe. ...
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Colophospermum mopane (Benth.) J. Léonard, commonly known as mopane, is a dominant tree or shrub in the mopane woodland. It is distributed in the low-lying areas of southern Africa’s savannas. Mopane maintains its foliage well into the dry season, and thus provides nutritional forage for browsers such as Tragelaphus strepsiceros, commonly known as the greater kudu. Despite its wide distribution and value as a source of forage for browsers, especially during the dry season, knowledge of the effect of browsers on mopane leaf quality is limited. There is also inadequate knowledge of the diet composition of the greater kudu during different seasons in the mopane woodland. Such information is important for proper management of browsers in the mopane woodland. As a result, a field experiment was conducted at Musina Nature Reserve, Limpopo Province, South Africa to determine the effect of pruning on mopane leaf phenology, production, macronutrients, trace elements and secondary metabolites. Pruning was conducted to simulate the effect of browsing by large herbivores such as the greater kudu on mopane leaf quality. In addition, rumen content analysis of greater kudu was conducted in order to quantify the amount of mopane and other plants browsed during the dry and wet seasons. Collected datasets were analysed using descriptive and inferential statistics. A two-tailed Mann-Whitney U-test was used to test the effect of pruning on mopane leaf phenology and production. The effect of pruning on the monthly concentration of macronutrients, trace elements and secondary metabolites was tested using a two-tailed t-Test: Two-Sample Assuming Equal Variance. The seasonal and annual effect of pruning on the concentration of macronutrients, trace elements and secondary metabolites was tested using One-Way Anova. Rumen datasets were analysed using the Pearson Correlation Coefficient. This study found that the rate of leaf phenology and production, including the concentration of certain macronutrients (Ca, K, N, P, S, Cl, Na, protein and fibre), trace elements (Fe, Mn, Mo, Cu, Zn and Se) and secondary metabolites (TP, CT and PPT) increased during leaf flush in October and then declined as the leaves matured and aged. However, the concentration of selected macronutrients (Mg and NO3) and trace elements (B, Co and F) increased when the leaves reached maturity in June, particularly during the leaf senescence stage, and declined thereafter. The concentration of macronutrients, trace elements and secondary metabolites between the control and pruned trees was statistically insignificant at P>0.05 for most samples. This study further showed that C. mopane contributed most (47%) to the diet of the greater kudu during the dry season. Other important dry season browse plants were Dichrostachys cinerea (30%), Commiphora edulis (12%), Grewia bicolor (6%) and Combretum apiculatum (5%). However, when gender was considered, the diet of the female greater kudu during the dry season consisted mainly of C. mopane (71%) and D. cinerea (22%). The diet of the male greater kudu contained less C. mopane (33%), but similar proportions of D. cinerea (31%) and other browse species. However, during the wet season, the diet of the greater kudu was mainly composed of C. apiculatum (43%). Other wet season browse plant species were Sclerocarya birrea (24%), C. mopane (12%) and Senegalia nigrescens (8%), with the contribution of the remaining species to the diet being insignificant. The diet of the female greater kudu in the wet season consisted mainly of C. apiculatum (44%) and C. mopane (20%), while the diet of the male mostly contained S. birrea (38%) and C. apiculatum (34%). It is concluded that the concentration of macronutrients, trace elements and secondary metabolites in mopane leaves is not dependent on <10% pruning, but seems to be associated with leaf growth stages. It is further concluded that the concentration of nutrients and chemical compound in mopane leaves has implications on the diet composition of browsers such as the greater kudu in the mopane woodland. The dependency of the greater kudu on species such as C. mopane and C. apiculatum as main sources of browse indicates the importance of these species to the diet of the greater kudu in the mopane woodland.
... The artificial nature of the conditions that are used to ferment wine and other alcoholic drinks is emphasized by the need for humans to produce alcohol themselves, rather than to collect it from some natural source. Whilst anecdotal reports of animals getting drunk on naturally occurring alcohol are common, well-known examples such as elephants (Morris, Humphreys and Reynolds 2006) and waxwings (Eriksson and Nummi 1983) have been debunked. In addition, although low levels of ethanol can occur in fruits (Eriksson and Nummi 1983) and nectar (Wiens et al. 2008), there is no evidence that Saccharomyces is the primary microorganism responsible. ...
Article
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Different species are usually thought to have specific adaptations, which allow them to occupy different ecological niches. But recent neutral ecology theory suggests that species diversity can simply be the result of random sampling, due to finite population sizes and limited dispersal. Neutral models predict that species are not necessarily adapted to specific niches, but are functionally equivalent across a range of habitats. Here we evaluate the ecology of S. cerevisiae, one of the most important microbial species in human history. The artificial collection, concentration, and fermentation of large volumes of fruit for alcohol production produces an environment in which S. cerevisiae thrives, and therefore it is assumed that fruit is the ecological niche that S. cerevisiae inhabits and has adapted to. We find very little direct evidence that S. cerevisiae is adapted to fruit, or indeed to any other specific niche. We propose instead a neutral nomad model for S. cerevisiae, which we believe should be used as the starting hypothesis in attempting to unravel the ecology of this important microbe. © FEMS 2015. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
... In relation to respiratory physiology portable devices to detect volatile molecules in exhaled air date back to the 1960s with the development of the first breathalyzer to detect alcohol in exhaled air samples (Borkenstein and Smith, 1961). Their use is marginally relevant to the comparative physiologist unless one wanted to empirically examine the myth of elephant intoxication on the fruits of the marula tree (Morris et al., 2006). The development of the breathalyzer, however, paved the way for the monitoring of other non-respiratory gases in exhaled breath such as carbon monoxide (CO) or nitric oxide (NO). ...
Article
Point-of-care (POC) devices provide quick diagnostic results that increase the efficiency of patient care. Many POC devices are currently available to measure metabolites, blood gases, hormones, disease biomarkers or pathogens in samples as diverse as blood, urine, feces or exhaled breath. This diversity is potentially very useful for the comparative physiologist in field studies if proper validation studies are carried out to justify the accuracy of the devices in non-human species under different conditions. Our review presents an account of physiological parameters that can be monitored with POC devices and surveys the literature for suitable quantitative and statistical procedures for comparing POC measurements with reference “gold standard” procedures. We provide a set of quantitative tools and report on different correlation coefficients (Lin's Concordance Correlation Coefficient or the more widespread Pearson correlation coefficient), describe the graphical assessment of variation using Bland–Altman plots and discuss the difference between Model I and Model II regression procedures. We also report on three validation datasets for lactate, glucose and hemoglobin measurements in birds using the newly proposed procedures. We conclude the review with a haphazard account of future developments in the field, emphasizing the interest in lab-on-a-chip devices to carry out more complex experimental measurements than the ones currently available in POC devices.
... The selection of marula fruits could be due to energy-providing sugars and their high vitamin C content. Fresh marula fruits contain up to 180 mg per 100 g of vitamin C (Shackleton et al., 2002), attracting not only the greater kudu (Hooimeijer et al., 2005), but also other browsers such as Loxodonta africana (Morris et al., 2006), Giraffa camelopardalis, Kobus ellipsiprymnus, and Taurotragus oryx (Venter and Venter, 1996). ...
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Tragelaphus strepsiceros (greater kudu) has adapted to the harsh conditions of southern Africa’s mopani woodland. However, there is still limited information on the diet composition and selection of browse by greater kudu, particularly during the wet season. This poses a challenge to manage these ungulates effectively within their habitat. The study used rumen content to quantify the diet composition of greater kudu during the wet season. The study was conducted at the Sandown GameFarm, Limpopo Province, South Africa. Rumen samples were collected from four adult female and four adult male greater kudu culled in March 2015 and statistically analyzed using the t-test: paired two sample for means and Pearson’s correlation coefficient analysis. Findings show that Combretum apiculatum contributed most (43%) to the diet of greater kudu during the wet season. Other browse plant species were Sclerocarya birrea (24%), Colophospermum mopane (12%), and Acacia nigrescens (8%), with the contribution of the remaining species to the diet being insignificant. Leaves were the plant parts browsed most often and contributed 81% to the diet during this season. The remaining 19% of the diet consisted mainly of S. birrea fruit. Gender differences in diet selectionwere observed. The diet of female greater kudu consisted mainly of C. apiculatum (44%) and C. mopane (20%), while the diet of male greater kudu mostly contained S. birrea (38%) and C. apiculatum (34%). Implications for the management and conservation of greater kudu in mopani veld are discussed.
... For example, the sometimes unusual behaviour of African elephants (Loxodonta africana) after consuming the marula fruit (Sclerocarya birrea) has often been attributed to ethanol intoxication (e.g. Siegel and Brodie 1984), but Morris et al. (2006) suggested that a more likely explanation is that elephants are intoxicated by beetle pupae that live in the bark of the marula tree and other chemicals such as nicotinic acid, found on the fruit of the marula tree. Nevertheless, laboratory studies show that at high concentrations, ethanol may have significant physiological effects leading to changes in the behaviour of organisms (e.g. ...
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Ethanol is a natural by-product of the fermentation process of fruit sugars. Its production started with the advent of fleshy fruits, which suggests a long-term association between ethanol and frugivores. Consequently, one suggestion is that because frugivores could use its odour to locate fruiting plants, they should show a preference for fruit with high ethanol concentrations. The aim of this study was to test this hypothesis by determining whether frugivorous birds show a preference for fruit laden with alcohol at levels equivalent to those of overripe fruits. Three species of frugivorous bird species were used for this study: the Cape White-eye (Zosterops virens), Speckled Mousebird (Colius striatus) and Red-winged Starling (Onychognathus morio). Birds were provided with two artificial fruit diets in pairwise choice tests: an experimental diet containing 1% ethanol and a control diet with no ethanol. For all species, no significant differences were observed in the amount of artificial fruit consumed between the food types. Given that the concentration of ethanol used in the study is assumed to represent that of overripe fruit, these results, in conjunction with previous studies, suggest that birds do not show a preference for fruits with high ethanol concentrations.
... Marula fruit are part of the local human diet and also play an important role in the economy turned into jam, beer, wine and the popular liquor Amarula. The marula trees are also lore for safaris, as travellers are promised to see drunk elephants feasting on fermenting marula fruit (though this is actually unlikely [15]). The use of marula in the local diet likely traces back thousands of years, as archaeological excavations found seeds of marula in caves where the ancestors of the San people, historically indigenous hunter-gatherer groups, once lived [16]. ...
Article
Drosophila melanogaster is a human commensal and dietary generalist. A new study in its ancestral range in Africa finds that wild Drosophila melanogaster are specialists on marula fruit — fruits cached in caves by Pleistocene humans. Drosophila melanogaster is a human commensal and dietary generalist. A new study in its ancestral range in Africa finds that wild Drosophila melanogaster are specialists on marula fruit — fruits cached in caves by Pleistocene humans.
... The precise reasons for the choice of the elephant logo are somewhat opaque, but there are all sorts of associations between elephants and alcohol. Elephants in the wild supposedly get drunk on rotting fruit, although this has more recently been called into question (Morris, Humphreys, & Reynolds, 2006). There is a long running idea that people experiencing drunken hallucinations see pink elephants, something famously played on in the 1941 Disney film, Dumbo (Brown, 2014). ...
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This article explores the contentious definition and communication of alcohol consumption limits and their relationship to ideas about risk through an analysis of the development of health education materials during the 1980s. It argues that changing ideas about alcohol and risk, and their communication to the public, were a reflection of both specific developments in thinking about alcohol and the harm it could pose as well as broader shifts within public health policy, practice and outlook. Risk was understood as something experienced by individuals and populations, a conceptual framing that suggested different approaches. To get to grips with these issues, the article focuses on: (1) the definition of alcohol consumption limits; (2) the communication of these limits; and (3) the limits to limits. The problems experienced in defining and communicating limits suggests not only a ‘limit to limits’ but also to the entire notion of risk-based ‘sensible’ drinking as a strategy for health education.
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Tragelaphus strepsiceros (greater kudu) has adapted to the harsh conditions of southern Africa’s mopani woodland. However, there is still limited information on the diet composition and selection of browse by greater kudu, particularly during the wet season. This poses a challenge to manage these ungulates effectively within their habitat. The study used rumen content to quantify the diet composition of greater kudu during the wet season. The study was conducted at the Sandown Game Farm, Limpopo Province, South Africa. Rumen samples were collected from four adult female and four adult male greater kudu culled in March 2015 and statistically analyzed using the t-test: paired two sample for means and Pearson’s correlation coefficient analysis. Findings show that Combretum apiculatum contributed most (43%) to the diet of greater kudu during the wet season. Other browse plant species were Sclerocarya birrea (24%), Colophospermum mopane (12%), and Acacia nigrescens (8%), with the contribution of the remaining species to the diet being insignificant. Leaves were the plant parts browsed most often and contributed 81% to the diet during this season. The remaining 19% of the diet consisted mainly of S. birrea fruit. Gender differences in diet selection were observed. The diet of female greater kudu consisted mainly of C. apiculatum (44%) and C. mopane (20%), while the diet of male greater kudu mostly contained S. birrea (38%) and C. apiculatum (34%). Implications for the management and conservation of greater kudu in mopani veld are discussed.
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Savannahs are one of the largest biomes of the world, comprising about 20% of the land surface. Stated simply, they are tropical and subtropical grasslands, with scattered bushes and trees. Most savannah occurs in Africa, with a smaller amount in South America, India, and Australia. This book looks at: (1) the climate factors that determine the distribution of savannahs worldwide and briefly looks at savannahs in South America, Australia, India, and Africa; (2) the major plants (grasses, and trees such as Acacia) and large animals (mainly large mammals) that live in African savannahs; and (3) the biological and ecological factors that influence their population size, interactions (such as predation), and community composition. Conservation issues such as tourism, hunting, and the conflict between wildlife and farmers are discussed.
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THE YEASTS AND RELATED FLORA ASSOCIated with ripe fruits of the marula tree in Zimbabwe were isolated and identified as Aureobasidium pullulans, Geotrichum capitatum, Trichosporon brassicae, Rhodotorula mucilaginosa, Hansenula anomala, Hansenula jadinii and Hansenula species. The physiological characteristics of the organisms suggest that, generally, they are not important in traditional marula wine fermentation. The Hansenula spp. are fermentative, however, and may play a role in marula wine-making.
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Eighteen species of wild fruits were examined for fruit-decaying fungi in nature. Surface-sterilized and non-sterilized fruits were incubated for 1-4 weeks and the fruiting bodies were identified. A total of 540 samples and 495 microfungi from 102 taxa were identified. Colletotrichum and Phomopsis were the most frequently recorded fungal genera. Ilex cinerea had the most diverse fungal species, while Wikstroemia nutans had the lowest diversity. Fifty-eight percent of fungal genera found in this survey have not been recorded on cultivated fruits. The fungal community that developed on non-sterilized fruits after incubation was generally more diverse than on surface-sterilized fruits, but both were colonized mostly by non-specific fungi. Related fruit species did not, in general, have more similar fungal communities than unrelated species. The ability of detached fruits to resist fungal infection under incubation varied greatly, with 77% of fruits of Wikstroemia nutans still not infected after 4 weeks. Fungi were classified into three types: pathogens, latent opportunists and fast-colonizing opportunists. Fast-colonizing opportunists, such as Cladosporium, Fusarium and Penicillium, were the most important taxa on wild fruits.
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Bark is an important source of medicine in South African traditional healthcare but is poorly documented. From thorough surveys of the popular ethnobotanical literature, and other less widely available sources, 174 species (spanning 108 genera and 50 families) used for their bark in KwaZulu-Natal, were inventoried. Vernacular names, morphological and phytochemical properties, usage and conservation data were captured in a database that aimed to synthesise published information of such species. Data specificity was found to be the major limiting factor in the study and resulted in uneven distribution of information in the database. Overlapping vernacular names recorded in the literature indicated that it may be unreliable in local plant identifications. Most (43%) bark medicines were documented for the treatment of internal ailments. Sixteen percent of species were classed in threatened conservation categories, but conservation and management data were limited or absent from a further 62%. There is a need for research and specialist publications to address the gaps in existing knowledge of medicinal bark species and their management to conserve the South African flora.
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Humans and apes are placed together in the superfamily Hominoidea. The evolutionary trajectory of hominoids is intimately bound up with the exploitation of ripe, fleshy fruits. Fermentation of fruit sugars by yeasts produces a number of alcohols, particularly ethanol. Because of their pre-human frugivorous dietary heritage, it has been hypothesized that humans may show pre-existing sensory biases associating ethanol with nutritional rewards. This factor, in turn, could influence contemporary patterns of human ethanol use. At present, there seems little evidence to support a view of selection specifically for ethanol detection or its utilization over the course of hominoid evolution. Ethanol concentration in wild fruits consumed by monkeys and apes is predicted to be low. Wild monkeys and apes avoid consumption of over-ripe fruits, the class showing notable ethanol concentrations, and for this reason, ethanol plumes may act as deterrents rather than attractants. Any energetic benefits to wild primates from ingested ethanol appear negligible, at best. Mice and rats show patterns of ethanol self-administration similar to humans, indicating that a frugivorous dietary heritage is not necessary for such behaviors. In the natural environment, ethanol is predicted to be just one of many alcohols, esters and related compounds routinely encountered by frugivorous primates and of no particular significance. The strong attraction ethanol holds for some individuals could be due to a broad range of genetic and environmental factors. In some humans, the appetite for ethanol appears related to the appetite for sugar. The predisposition some individuals display toward excessive ethanol consumption could involve features of their genetics and biochemical similarities of ethanol and carbohydrate. Regular low ethanol intake is hypothesized to lower the incidence of cardiovascular disease in humans, perhaps through its effects on body fat distribution. Such a benefit, if confirmed, would appear to relate to features of the contemporary human rather than pre-human diet.
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Survival and reproductive success hinge on the perception of environmental stimuli. In this regard, foraging efficiency depends on discerning predictive signals in food. A widespread occurrence of ethanol in fruits indicates a sustained historical exposure of frugivores to this compound. Accordingly, Dudley (2000, Quart. Rev. Biol. 75:3-15) proposed that ethanol could represent a prominent sensory cue to primates because of direct and indirectly associated caloric and physiological rewards. However, little is known regarding the extent to which ethanol correlates with such parameters. This information is essential to estimating the importance of detecting and detoxifying ethanol in fruits. Here I present a preliminary analysis of fruits from Southeast Asia; low levels of ethanol were present in fruits of all developmental stages (range: 0.005-0.48%). Moreover, ethanol correlated positively with concentrations of soluble sugars, suggesting that it could be a valuable foraging cue. Recent findings on the sensitivity of primate olfaction and gustation to ethanol are consistent with this notion. However, when primates smell fruits deliberately, it often occurs together with digital and/or dental evaluation of texture. Here I show that softening texture also characterizes the fruit ripening process, and that color is of ambiguous importance to primates possessing trichromatic vision. I discuss the relevance of these findings to the origins of primates and the ecology of key sensory systems and deduce that detecting and selecting fruits on the basis of cues other than color is a persistent theme in primate evolution. Ethanol has likely played a significant and underestimated role in the regulation of primate foraging behavior.
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In this paper we discuss how yeast, fungi ubiquitously present in sugar-rich fruit, can influence the interaction between frugivores and fleshy-fruited plants via ethanol. We suggest that plants, the seeds of which are mostly dispersed by vertebrates, exploit the ethanol from alcoholic fermentation by yeast in their seed dispersal strategy. Moderate consumption of ethanol, i.e., at concentrations close to those in naturally ripening fruit, by frugivores may have beneficial short- and long-term effects for these potential dispersers, whereas consumption of larger quantities may have negative short- and long-term effects. Ethanol vapor emanating from palatable fruit may act as an odor cue, guiding bats and other frugivores to the fruit, and aiding them to assess its quality. In addition, we suggest that ingested ethanol may be an appetitive stimulant. We also evaluate the possibility that ethanol within fruit may be used as a source of energy by frugivorous vertebrates. Our preliminary data indicate that Egyptian fruit bats (Rousettus aegyptiacus) can use the odor of ethanol to assess food suitability, but also that it may not serve as an attractant over short distances (i.e., <1 m). Instead, ethanol is avoided at concentrations greater than 1%, a value which might typically characterize overripe and otherwise unpalatable fruit. Our initial results further indicate that Egyptian fruit bats significantly decrease their food consumption if it contains 1 or 2% ethanol. Overall, ethanol may play diverse roles in the nutritional ecology and behavior of fruit-eating bats, and in the interaction between frugivores and plants, in general.
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Understanding the evolutionary ecology of ethanol production may yield insights into why humans are prone to excessive consumption of ethanol. In particular, Dudley (2000) suggested that human ancestors developed a genetically based attraction to ethanol because they could use its odor plume to locate fruiting trees and because of health benefits from its consumption. If so, ethanol should be common in wild fruits and frugivores should prefer fruits with higher ethanol content. A literature review reveals that ethanol is indeed common in wild fruits but that it typically occurs in very low concentrations. Furthermore, frugivores strongly prefer ripe over rotting fruits, even though the latter may contain more ethanol. (Data on ethanol content of ripe and rotting wild fruit are lacking.) These results cast doubt on Dudley's hypothesis and raise the question of how humans became exposed to sufficiently high concentrations of ethanol to allow its excessive consumption. Because fermentation is an ancient and widespread practice, I suggest that humans “discovered” ethanol while using fermentation as a food preservation technique. They may have been predisposed to consume ethanol from previous and beneficial exposure to much lower doses or they may have become addicted to it at high concentrations because of fortuitous physiological responses.
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Ethanol is an important environmental variable for fruit-breeding Drosophila species, serving as a resource at low levels and a toxin at high levels. The first step of ethanol metabolism, the conversion of ethanol to acetaldehyde, is catalyzed primarily by the enzyme alcohol dehydrogenase (ADH). The second step, the oxidation of acetaldehyde to acetate, has been a source of controversy, with some authors arguing that it is carried out primarily by ADH itself, rather than a separate aldehyde dehydrogenase (ALDH) as in mammals. We review recent evidence that ALDH plays an important role in ethanol metabolism in Drosophila. In support of this view, we report that D. melanogaster populations maintained on ethanol-supplemented media evolved higher activity of ALDH, as well as of ADH. We have also tentatively identified the structural gene responsible for the majority of ALDH activity in D. melanogaster. We hypothesize that variation in ALDH activity may make an important contribution to the observed wide variation in ethanol tolerance within and among Drosophila species.
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Juice of the Sclerocarya birrea subsp. caffra (marula) fruit was fermented by indigenous microflora and different commercial Saccharomyces cerevisiae yeast strains at different temperatures, namely, 15 and 30 degrees C. Volatile acids, esters, and higher alcohols were quantified in the wine and distillates, and the results were interpreted using a multivariate analysis of variance and an average linkage cluster analysis. Significant differences between 15 and 30 degrees C and also among yeasts with respect to volatile compounds were observed. Yeast strains VIN7 and FC consistently produced wines and final distillates significantly different from the other strains. A panel of tasters and marula and brandy producers was asked to select wines and distillates that had an acceptable and typical marula "nose". They were also asked to detect the differences among wines and distillates fermented with the same yeast strain at different temperatures.
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To study the role of the indigenous yeast flora in traditional Irish cider fermentations. Wallerstein laboratory nutrient agar supplemented with biotin, ferric ammonium citrate, calcium carbonate and ethanol was employed together with PCR-restriction fragment length polymorphism analysis of the region spanning the internal transcribed spacers (ITS1 and ITS2) and the 5.8S rRNA gene in the identification of indigenous yeasts at the species level, from traditional Irish cider fermentations. By combining the molecular approach and the presumptive media it was possible to distinguish between a large number of yeast species, and to track them within cider fermentations. The Irish cider fermentation process can be divided into three sequential phases based on the predominant yeast type present. Kloeckera/Hanseniaspora uvarum type yeasts predominate in the initial 'fruit yeast phase'. Thereafter Saccharomyces cerevisiae type yeast dominate in the 'fermentation phase', where the alcoholic fermentation takes place. Finally the 'maturation phase' which follows, is dominated by Dekkera and Brettanomyces type yeasts. H. uvarum type yeast were found to have originated from the fruit. Brettanomyces type yeast could be traced back to the press house, and also to the fruit. The press house was identified as having high levels of S. cerevisiae type yeast. A strong link was noted between the temperature profile of the cider fermentations, which ranged from 22 to 35 degrees C and the yeast strain population dynamics. Many different indigenous yeast species were identified. The mycology of Irish cider fermentations appears to be very similar to that which has previously been reported in the wine industry. This study has allowed us to gain a better understanding of the role of indigenous yeast species in 'Natural' Irish cider fermentations.
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Examined whether harmful concentrations of alcohol from berries accumulate in waxwings Bombycilla garrulus and bullfinches Pyrrhula pyrrhula. In addition, the alcohol metabolism of waxwings, starlings Sturnus vulgaris and greenfinches Chloris chloris was examined.-from Authors
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The South African National Parks identified the need for autecological studies on specific rare indicator keystone plant species. The marula is one of the preferred tree species particularly selected for by elephant and whose current damaged condition and disappearance in a mature state in the Kruger National Park is causing serious concern. The density of marula trees and the current population structure of this tree species were examined in four major landscapes of the Kruger National Park. Results indicate that the marula population in the Colophospermum mopane shrubveld has become virtually extinct, while the Colophospermum mopane/Acacia nigrescens savanna has a markedly unstable population with a lack of immature trees. The marula populations in the southern landscapes (mixed Combretum/Terminalia sericea woodland and Sclerocarya birrea/Acacia nigrescens savanna) appear to be healthy. The population structures on the different substrata (granite and basalt) differed significantly. Results of this study further indicate that diversity of vegetation plays an important role in determining herbivory pressure, and consequently in influencing the marula population structure.
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Previous vegetation studies in the Kruger National Park have shown a dramatic decline in the density of large trees in four major vegetation units of the Park. An assessment of the damage status of Sclerocarya birrea (marula), identified as one of the most important tree species in the Kruger National Park, was conducted across three major landscapes of the Park. Previous studies indicated that marula were most utilized by elephants, resulting in weak regeneration and recruitment, with consequent changes to the population structure of the species. Furthermore, results indicated that the marula populations in two major landscapes of the Kruger National Park were threatened. The objective of this study was to generate a data set, which can be used in conjunction with future monitoring, to quantify the elephant damage to the marula population in the Kruger National Park. Results indicated that almost half the surveyed population suffered from damage due to elephant activity, predominantly in the form of bark stripping and felling. Felling resulted in a large proportion of marula trees being reduced to a height of less than five metres. Main stem breakage by elephant was the main cause of the 7% mortality observed in the marula population.
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This study, conducted in the Luangwa Valley, Zambia, examines the ecological influence of elephants on a population of Sclerocarya caffra and certain demographic features of this same population. Patterns of fruiting and seed germination are described, with an experimental design for the latter to test elephants' role as a seed dispersal agent. Size class distributions and spatial patterns of trees are also investigated. Results suggest that seed germination and seedling survivorship are enhanced from fruit ingestion by elephants. Frequency of size classes in the population indicate that younger trees are relatively scarce and that mortality of seedlings and saplings may be sufficiently high to prevent recruitment. The presence of seedlings in an area where the composition of mammalian browsers differs from the study area suggests a species other than elephant may be contributing to the low numbers of small trees. Dispersion pattern of trees was strongly aggregated and correlated with well-drained deep soils. Interpretations of these results focus on the ecological relationship of S. caffra with elephants and the management requirements of S. caffra in Luangwa Valley.
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Marula (Sclerocarya birrea subsp. caffra) is a medium-sized tree native to southern Africa producing edible plum-sized drupes utilized by rural people. Marula was examined by us with the aim of introducing new orchard crops to the Israeli Negev Desert. Young seedlings grown from seeds obtained from Botswana were planted in 1985-86 in four different locations in the Negev: Besor - moderate temperatures and good quality water (electrical conductivity, EC = 1 dS m-1): Ramat Negev Experimental Station - low winter temperatures (lowest, -7°C) and two water qualities, good and brackish (EC = 3.5-4 dS m-1); Qetura and Neot Hakikar - both warm sites, with summer temperatures that may rise to 46°C, and brackish water with similar EC (3.5-4 dS m-1), but with a higher concentration of Na+ and Cl- at Neot Hakikar. Growth was faster and yields were higher at Qetura and lagged behind at the other sites, especially at Ramat Negev, where frost events severely damaged the young trees. Results from a new plot established nearby at Kibbutz Revivim indicate that under certain growth conditions marula can also succeed in the Ramat Negev region. The trees differed in their flowering time, which ranged over 3-4 months (spring-early summer). Marula fruits abscise at the green stage, abscission time being related to the flowering time. Fruits collected immediately after abscission ripened after 14-17 days of storage at 20°C. During ripening the fruits turned yellow, firmness and acidity significantly decreased, and soluble sugars and soluble solids concentrations increased slightly. A surge of ethylene occurred toward the end of the ripening stage. Individual trees varied in fruit weight and the proportion of various fruit components. The main limitations to fresh consumption were the low content of flesh, presence of fibers in the flesh, and the thick peel. It was concluded that marula may be used as an industrial fruit crop in the arid regions of Israel where high summer temperatures and the brackish irrigation water restrict the cultivation of most common fruit trees.
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Wild plant foods in the Sahel region of West Africa play an important role in the diets of local residents. During periods of grain shortage, people in rural Niger increase their reliance on wild plant foods to supplement their diets. We report the partial nutrient content of the pit of the seed Sclerocarya birrea, a snack food eaten by children in rural Niger. The pit contained relatively large amounts of copper (24.8μg/g dry wt), magnesium (4210μg/g dry wt), and zinc (62.4μg/g dry wt). The protein content of the pit was high (36.4% of dry wt); however, the protein fraction contained relatively low proportions of leucine, phenylalanine, lysine, and threonine. Fatty acids accounted for 47mg/g dry wt of the pit, two-thirds of which was due to oleic acid. The essential fatty acid linoleic acid was present (24.5mg/g dry wt), but the other essential fatty acid, α-linolenic acid, was absent. Such data are useful for health and nutrition program planning by governmental and non-governmental organizations in Niger. The consumption of daniya pits by just children highlights the need to better understand the cultural context of how wild plant foods are used in a particular local context.
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All tested blood parameters are within the expected range for birds (Tab. 1). Starlings show a high rate of alcohol resorption. Experimentally ingested (per os) doses of 1, 2 and 3 g/kg ethanol (10 %-solution) were completely absorbed from the digestive tract within at least 30 min. Extraintestinal metabolic alcohol degradation is also very fast. Within 130 min even 3 g/kg ethanol were completely metabolised (blood alcohol values did not exceed 145 mg/1; Tab. 2, Fig. a). Alcoholdehydrogenase (ADH) activity is very high (ca. 14-fold of man) and shows a clear and fast adaptive plasticity in correlation to ingested alcohol concentration (Fig. b). There seems to be a clear pre-adaptation in ADH-activity in birds. We found low values in seed-eating birds and high values in fruiteaters. Under field conditions normal alcohol concentration as found in fermentated fruits and berries are so low, that - in connection with high ADH-activity - birds obviously have no problems to cope with alcohol.
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Nine different diurnal activities of elephant—grazing, browsing, debarking, drinking, wallowing, resting in the shade, resting in the open or sun, certain social activities and walking—were monitored during the day. Possible reasons for seasonal differences in time spent per hour engaged in each of these activities are given.
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This study determined the abundance, density and population structure of the marula tree, Sclerocarya birrea, in three game reserves in South Africa, and assessed patterns and amounts of new and cumulative impact of elephants. Elephant feeding was very patchy so several attributes of individual trees, sampled transects and communities that might influence elephant herbivory were investigated. The incidence and type of elephant impact (bark, branch or stem breakage) were significantly related to tree diameter, but not to fruiting nor proximity to roads. At the transect level, elephant impact was influenced by density of marula trees, but was not influenced by proximity to roads, nor proportion of marula trees bearing fruits in the vicinity. At the community level, elephant impact was higher on reserves with higher total marula densities. Fourfold differences in elephant densities (0.08-0.30 elephants km-2) did not explain marula consumption: the percentage of trees with branch damage was similar across reserves and bark damage was inversely proportional to elephant density. Variation across reserves may reflect local and landscape-level marula tree abundance, differences in alternative food plants and individual feeding habits. The recorded levels of impact appeared to be sustainable because mortality rates were low, affected trees often recovered, and small trees were not preferentially preyed upon.
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Caecal digestive functions were compared in 22 species of East African herbivores. Comparisons were made between ruminant pseudo-ruminant, and non-ruminant herbivores to assess the relative in vitro fermentation rate and composition of caecal contents from these species observed in their natural habitat. Measurements were made of caecal fermentation rate, organic acid composition, osmolality, pH and dry matter content. The data were compared by foregut structure, feed preference and body weight of the herbivores.
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Ethanol is an important larval resource and toxin for natural Drosophila melanogaster populations, and ethanol tolerance is genetically variable within and among populations. If ethanol-tolerant genotypes have relatively low fitness in the absence of ethanol, as suggested by the results of an earlier study, genetic variation for ethanol tolerance could be maintained by variation in ethanol levels among breeding sites. I selected for ethanol tolerance in large laboratory populations by maintaining flies on ethanol-supplemented media. After 90 generations, the populations were compared with control populations in egg-to-adult survival and development rate on ethanol-supplemented and unsupplemented food. When compared on ethanol-supplemented food, the ethanol-selected populations had higher survival and faster development than the control populations, but on unsupplemented food, the populations did not differ in either trait. These results give no evidence for a ‘trade-off’ between the ability to survive and develop rapidly in the presence of ethanol and the ability to do so in its absence. The effect of physiological induction of ethanol tolerance by exposing eggs to ethanol was also investigated; exposing eggs to ethanol strongly increased subsequent larval survival on ethanol-supplemented food, but did not affect survival on regular food, and slowed development on both ethanol-supplemented and regular food, partly by delaying egg hatch.
Article
Sclerocarya birrea (A.Rich.) Hochst. subsp. caffra (Sond.) Kokwaro. is a common species throughout the semiarid, deciduous savannas of much of sub-Saharan Africa. It is a favoured species and is frequently maintained in homestead plots and arable fields in an agroforestry situation. Although the abundance and popularity of this species has led to several initiatives to commercialise a number of marula products, the sustainability of the resource base with respect to fruit production has not been considered. This paper reports on a field experiment that monitored growth rates and fruit production of a sample of adult trees from several wild populations. Mean fruit production was 36.8 kg per tree in the first year, and negligible in the second. This was considerably less than previous estimates, which were based largely on small samples or anecdotal reports. The maximum recorded yield was 416.6 kg per tree. Fruit production was positively related to the size of the tree. Growth rates of adult trees were slow. There was a strong positive relationship between mean annual diameter increment and stem diameter. The slow growth rates and low fruit yields indicate that more attention is required regarding the sustainability of there source and its ability to provide sufficient fruit for the growing subsistence and commercial demand at both local and national scales.
Article
The population of elephant (Elephas maximus) in Block I of Ruhuna National Park, Sri Lanka was monitored through visual observations between 1960 and 1991. This represents perhaps the longest study of monitoring a single population of elephants in the world. Elephants were observed opportunistically for 23 years during the study period. In 166 days, a total of 579 observations were made during which 2246 sightings of elephants were recorded. There were 354 bull groupings and 225 family units or herds. The adults (males and females) make up 65% of the population. In general the proportions of the adult tuskers, makhnas (tuskless males), adult females, subadults and young have not changed much over the study period. But the proportion of tuskers among adult bulls shows wide fluctuation. Tuskers make up about 9.1% of the bulls in the park. The observed adult male:adult female ratio is 1:1.86. Almost all the solitary animals that were observed were males. Solitary bulls were encountered throughout each year, but their numbers reached a peak following the rains. The largest bull group consisted of seven animals. The most frequently encountered herd consisted of 3–10 animals. About 80% of the herds showed no association with adult males. The diurnal activity patterns of the bull groups and family units were largely similar but the bull groups were slightly more active in the mornings compared to the family units. The herds may be less tolerant of vehicles and people than the males and hence shift their activity towards the late evening hours. Although breeding may go on throughout the year, the calving intensity was found to vary. 85% of the young were seen during the rainy season. Despite its small size (140 km2), Block I of Ruhuna National Park is one of the best areas that support viable elephant populations. This shows that in poor countries, simple measures such as protection and monitoring of elephants are easier, cheaper, and more likely to be successful than high-tech methods such as translocations or reintroductions which are difficult, expensive and likely to fail. ©
Article
In classical Greek, the word “symposium” signifies a drinking party held for the purposes of intellectual discussion. This symposium introduces a new evolutionary perspective on an ancient question: why are many animals, including humans, attracted to ethanol? Recent research has shown that behavioral responses to ethanol and molecular pathways of inebriation are shared among many taxa (Wolf and Heberlein, 2003), and that the preferences of modern humans for alcohol consumption may derive from the diets of our fruit-eating ancestors (i.e., alcoholism as evolutionary hangover; Dudley, 2000, 2002). Placement of ethanol consumption within historical and comparative contexts may thus yield insight into contemporary patterns of human consumption and excessive use.
Article
1. A traditional approach to the nutritional ecology of herbivores is that larger animals can tolerate a diet of lesser quality due to a higher digestive efficiency bestowed on them by comparatively long ingesta retention times and lower relative energy requirements. 2. There are important physiological disadvantages that larger animals must compensate for, namely a lower gut surface : gut volume ratio, larger ingesta particle size and greater losses of faecal bacterial material due to more fermentation. Compensating adaptations could include an increased surface enlargement in larger animals, increased absorption rates per unit of gut surface, and increased gut motility to enhance mixing of ingesta. 3. A lower surface : volume ratio, particularly in sacciform forestomach structures, could be a reason for the fact that methane production is of significant scope mainly in large herbivores and not in small herbivores with comparably long retention times; in the latter, the substrate for methanogenesis – the volatile fatty acids – could be absorbed faster due to a more favourable gut surface : volume ratio. 4. Existing data suggest that in herbivores, an increase in fibre digestibility is not necessarily accompanied by an increase in overall apparent dry matter digestibility. This indicates a comparative decrease of the apparent digestibility of non-fibre material, either due to a lesser utilization of non-fibre substrate or an increased loss of endogenous/bacterial substance. Quantitative research on these mechanisms is warranted in order to evaluate whether an increase in body size represents a net increase of digestive efficiency or just a shift of digestive focus.
Article
Several wild cedar waxwings (Bombycilla cedrorum) fell from a rooftop following ingestion of overwintered hawthorn (Crataegus sp.) pommes. At necropsy, there was pericardial hemorrhage, although no microscopic abnormalities were found. Ethanol was present in crop contents (380 ppm) and in the livers (238 and 989 ppm). The cause of death was attributed to hemorrhage following a fall precipitated by ethanol intoxication. /// Varios alas de cera salvajes (Bombycilla cedrorum) cayeron del techo después de la ingestión de fruta de espino silvestre (Cratageus sp.). A la necropsia, se encontró hemorragia pericárdica pero no se observaron anormalidades microscópicas. En el contenido del buche se encontró etanol (380 ppm), lo mismo que en el hígado (238 y 989 ppm). La causa de la muerte fue atribuida a la hemorragia después de la caída, precipitada por la intoxicación con etanol.
Article
We have measured, by an intubation method, gastric evacuation and gastrointestinal absorption of alcohol ingested with a meal in seven healthy nonalcoholic subjects. A homogenized meal containing [14C]PEG and ethanol (1 g/kg body wt) was given intragastrically while saline containing [57CO]vitamin B12 was perfused into the duodenum. Of the ingested alcohol, 39.4 +/- 4.1% was absorbed through the stomach wall during the first postprandial hour and 73.2 +/- 4.2% during the total postcibal period, whereas only 24 +/- 3% was absorbed during the same time in the duodenum. Thus alcohol ingested with a meal is mainly and rapidly absorbed in the stomach; the contribution of the small intestine below the angle of Treitz to alcohol absorption is negligible.
Article
The Bushmen of southern Africa use the expressed contents of beetle larvae (Diamphidia, Lebistina and Polyclada species) as arrow poison. an aqueous extract of Diamphidia nigroornata larvae was fractionated by gel filtration on Sephadex G-50. Two fractions were obtained: one (I) of high molecular weight which contains a protein of 60 000 daltons, and a low molecular weight fraction (II) of non-protein nature. Both fractions proved to be lethal to mice: an LD50 of 0.5 - 0.95 (I) and 3.2 - 3.5 (II) mg/kg (intraperitoneal injection), respectively, was determined. The toxic principle of fraction I could be partly separated from the protein by ammonium sulfate precipitation followed by gel filtration. That of fraction II was further resolved into several subfractions by gel filtration of Sephadex G-10; however, the lethal activity was completely lost during purification. In thin-layer chromatography the low molecular weight toxin(s) did not react with reagents for steroids, alkaloids, sugars or terpenes, but showed a positive ninhydrin reaction. It is concluded that the toxic principle of the Bushman arrow poison is a highly labile, low molecular weight compound which is closely attached or bound to a protein protecting it from inactivation.
Article
To investigate whether the relative amounts of fat, carbohydrate (CHO), or protein in a meal influence the pharmacokinetics of a small dose of ethanol. Nine healthy men received ethanol (0.30 g kg-1 body weight) on five occasions in a randomized cross-over fashion. On three occasions the dose of ethanol was consumed within 15 min of eating a standardized breakfast of similar volume and calorific value but containing different amounts of fat, CHO, and protein. On two other occasions the same dose of ethanol was ingested on an empty stomach (overnight fast) or administered by intravenous (i.v.) infusion over 30 min. The blood-ethanol profiles showed large inter and intraindividual variations, especially when ethanol was ingested after eating food. The peak blood-alcohol concentrations (BAC) were 16.6 +/- 4.0, 17.7 +/- 7.1, and 13.3 +/- 4.0 mg dl-1 (mean +/- s.d.) after fat, CHO, and protein-rich meals and 30.8 +/- 4.3 and 54.3 +/- 6.4 mg dl-1 after fasting and i.v. infusion, respectively. The corresponding areas under the concentration-time profiles (AUC) were 1767 +/ -549, 1619 +/- 760 1270 +/- 406 mg dl-1 min after fat, CHO, and protein-rich meals compared with 3210 +/- 527 and 4786 +/- 446 mg dl-1 min after fasting and i.v. infusion, respectively. The time required to eliminate ethanol from the blood was shortened by 1-2 h in the fed-state. Drinking ethanol after eating a meal, regardless of the nutritional composition, decreases the systemic availability of ethanol. Because gastric emptying is slow and more prolonged with food in the stomach, the delivery of ethanol to the duodenum and the liver will be highly variable as will the hepatic clearance of ethanol. Provided that portal venous BAC remains fairly low and ethanol metabolizing enzymes are not fully saturated then part of the dose of ethanol can be cleared by hepatic first-pass metabolism (FPM), as one consequence of Michaelis-Menten elimination kinetics.
Article
Upon exposure to ethanol, Drosophila display behaviors that are similar to ethanol intoxication in rodents and humans. Using an inebriometer to measure ethanol-induced loss of postural control, we identified cheapdate, a mutant with enhanced sensitivity to ethanol. Genetic and molecular analyses revealed that cheapdate is an allele of the memory mutant amnesiac. amnesiac has been postulated to encode a neuropeptide that activates the cAMP pathway. Consistent with this, we find that enhanced ethanol sensitivity of cheapdate can be reversed by treatment with agents that increase cAMP levels or PKA activity. Conversely, genetic or pharmacological reduction in PKA activity results in increased sensitivity to ethanol. Taken together, our results provide functional evidence for the involvement of the cAMP signal transduction pathway in the behavioral response to intoxicating levels of ethanol.
Article
The alcohol dehydrogenases (ADH) and their genes (Adh) of Drosophila have been much studied by population and evolutionary biologists. I attempt to put some of these studies into a broad adaptionist perspective, suggesting the co-evolution of this enzyme with the fleshy fruits of angiosperms and fermenting yeasts. I suggest that these events occurred at about the K/T boundary (65 million years ago) and that the typical Drosophila (as exemplified by D. melanogaster) evolved from flies unable to use fermenting substrates as breeding sites. I also hint that the ADH enzymes of other flies (e.g., the tephritid fruit flies) may have evolved independently of those of Drosophila, but from a common ancestral gene.
Article
Evolutionary origins of alcohol consumption have rarely been considered in studies of ethanol addiction. However, the occurrence of ethanol in ripe and decaying fruit and the substantial heritability of alcoholism in humans suggest an important historical association between primate frugivory and alcohol consumption. Olfactory localization of ripe fruit via volatilized alcohols, the use of ethanol as an appetitive stimulant, and the consumption of fruits with substantial ethanol content potentially characterize all frugivorous primates, including hominoids and the lineage leading to modern humans. Patterns of alcohol use by humans in contemporary environments may thus reflect a maladaptive co-option of ancestral nutritional strategies. Although diverse factors contribute to the expression of alcoholism as a clinical syndrome, historical selection for the consumption of ethanol in the course of frugivory can be viewed as a subtle yet pervasive evolutionary influence on modern humans.
Article
Marula bark is widely used for bacteria-related diseases by indigenous cultures in Africa. This study was undertaken to investigate whether the ethnobotanical use can be validated by laboratory studies. Bark and leaves were extracted with acetone and MIC values were determined using a microplate serial dilution technique with Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecalis as test organisms. All extracts were active with MIC values from 0.15 to 3 mg/ml. Based on minimum inhibitory concentration values, inner bark extracts tended to be the most potent followed by outer bark and leaf extracts, but the differences were not statistically significant. There were two major bioactive components visible after bioautography of leaf extracts: one strongly polar and the other highly non-polar. The bioactive components could be separated from 92% of the non-active dry matter by solvent-solvent fractionation into the carbon tetrachloride, chloroform and n-butanol fractions; these fractions, however, still contained many different compounds. Using bark may be detrimental to the plant, but leaf material can also be used for antibacterial application.
Article
In the field of addiction research, the possibility of ancestral exposure to psychoactive compounds has generally been excluded. A paleobiological approach to the human diet, however, illustrates the potential utility of historical data in interpreting modern-day addictive behaviors. Low-level dietary exposure to ethanol via ingestion of fermenting fruit has probably characterized the predominantly frugivorous anthropoid lineage for about 40 million years. Potentially adaptive primate behaviors associated with the natural occurrence of ethanol include the olfactory use of ethanol plumes to localize fruit crops, the use of ethanol as an appetitive stimulant to facilitate rapid consumption of transient nutritional resources, and the physiological exploitation of the caloric benefits of ethanol. Such behavioral and energetic advantages probably pertain to all animal taxa that consume fermenting fruit, and may have been retained in modern humans in spite of considerable dietary diversification over the last several million years. In contemporary human environments, excessive consumption of ethanol would then represent maladaptive cooption of ancestrally advantageous behaviors given essentially ad libitum access to a compound otherwise found only within scarce nutritional substrates. Epidemiologically demonstrated health benefits of low-level alcohol consumption are consistent with an ancient and potentially adaptive exposure of primate frugivores to this most common of the psychoactive substances.
Article
Susceptibility to drug addiction depends on genetic and environmental factors and their complex interactions. Studies with mammalian models have identified molecular targets, neurochemical systems, and brain regions that mediate some of the addictive properties of abused drugs. Yet, our understanding of how the primary effects of drugs lead to addiction remains incomplete. Recently, researchers have turned to the invertebrate model systems Drosophila melanogaster and Caenorhabditis elegans to dissect the mechanisms by which abused drugs modulate behavior. Due to their sophisticated genetics, relatively simple anatomy, and their remarkable molecular similarity to mammals, these invertebrate models should provide useful insights into the mechanisms of drug action. Here we review recent behavioral and genetic studies in flies and worms on the effects of ethanol, cocaine, and nicotine, three of the most widely abused drugs in the world.
Article
Traditional remedies are part of the cultural and religious life of the African people. In this manuscript the nature and range of traditional remedies used for female complaints in relation to gynaecological conditions and disorders is reviewed. A total of 156 medicinal plant species are documented as being used for gynaecological complaints in South Africa. These are presented in a table with the local name, part of the plant used and specific gynaecological treatment. Medicinal plant species which are potentially toxic are noted as are the compounds responsible for the toxicity and the feature(s) of poisoning. Traditional remedies used in South Africa for the treatment of gynaecological problems are compared to those used elsewhere in the world. This manuscript indicates that a wide spectrum of herbal traditional remedies are used to regulate the menstrual cycle, enhance fertility and as either abortifacients or antiabortifacients.
Article
In order to appraise some of the ethnomedical uses of Sclerocarya birrea (A. Rich.) Hochst., subspecies caffra (Sond.) Kokwaro [family: Anacardiaceae], the present study was undertaken to investigate the analgesic, anti-inflammatory and anti-diabetic properties of the plant's stem-bark aqueous extract in experimental models of pain, inflammation and diabetes mellitus. The analgesic effect of Sclerocarya birrea stem-bark aqueous extract was evaluated in mice, while its anti-inflammatory and anti-diabetic effects were investigated in rats. Diclofenac (DIC, 100 mg/kg p. o.) and chlorpropamide (250 mg/kg p. o.) were used respectively as reference analgesic, anti-inflammatory and anti-diabetic agents for comparison. Like diclofenac (DIC, 100 mg/kg p. o.), Sclerocarya birrea stem-bark aqueous extract (SBE, 100-800 mg/kg p. o.) produced dose-dependent, significant protection (p < 0.05-0.001) against electrical heat-induced pain. The plant extract (SBE, 25-800 mg/kg p. o.) also produced dose- and time-related, sustained and significant reductions (p < 0.05-0.001) in the fresh egg albumin-induced acute inflammation of the rat hind paw oedema. However, the analgesic and anti-inflammatory effects of the plant's extract were found to be approximately 10-15 times less than that of diclofenac. In one set of experiments involving hypoglycaemic/antidiabetic evaluation of the plant's extract, graded doses of Sclerocarya birrea stem-bark aqueous extract (SBE, 25-800 mg/kg p. o.) were separately administered to groups of fasted normal and fasted diabetic rats. In another set of experiments, a single dose of the plant's aqueous extract (SBE, 800 mg/kg p. o.) was used. The hypoglycaemic effect of this single dose of Sclerocarya birrea stem-bark aqueous extract (SBE, 800 mg/kg p. o.) was compared with that of chlorpropamide (250 mg/kg p. o.) in both fasted normal and fasted streptozotocin (STZ)-treated diabetic rats. Following acute treatment, relatively moderate to high doses of Sclerocarya birrea stem-bark aqueous extract (SBE, 25-800 mg/kg p. o.) produced dose-dependent, significant reductions (p < 0.05-0.001) in the blood glucose concentrations of both fasted normal and fasted diabetic rats. Chlorpropamide (250 mg/kg p. o.) also produced significant reductions (p < 0.05-0.001) in the blood glucose concentrations of the fasted normal and fasted diabetic rats. Administration of the single dose of Sclerocarya birrea stem-bark aqueous extract (SBE, 800 mg/kg p. o.) significantly reduced (p < 0.01-0.001) the blood glucose levels of both fasted normal (normoglycaemic) and fasted STZ-treated, diabetic rats. The results of this experimental animal study indicate that Sclerocarya birrea stem-bark aqueous extract possesses analgesic, anti-inflammatory and hypoglycaemic properties. These experimental findings lend pharmacological support to the suggested folkloric uses of the plant's stem-bark in the management and/or control of pain, inflammatory conditions, and adult-onset, type-2 diabetes mellitus in some communities of South Africa.
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