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Human adaptations to meat eating
Abstract
It is argued that Homo sapiens is a habitual rather than a facultative meat eater. Quantitative similarity of human gut morphology
to guts of carnivorous mammals, preferential absorption of haem rather than iron of plant origin, and the exclusive use of
humans as the definitive host by Taenia saginata and the almost complete human specificity of T. solium are used to support
the argument.
... La dentición de los homininos no proporciona una indicación clara sobre la ingesta de carne 53 . Los chimpancés al igual que los Homo, no muestran signos de adaptación dental para masticar carne, y en relación con el peso corporal, sus mandíbulas y dientes masticadores son ≈ del mismo tamaño; por lo tanto, cabe esperar que los chimpancés mastiquen carne a tasas ≈ similares a las de los humanos. ...
... Se argumenta que el H. sapiens es un comedor de carne habitual en lugar de facultativo. La similitud cuantitativa de la morfología del intestino humano con los intestinos de mamíferos carnívoros se utiliza para apoyar ese argumento 53 . La relación entre la longitud del cuerpo y la longitud del intestino es en: gatos 1:4; humanos 1:5; perros 1:6; babuinos 1:8; caballos 1:12; cerdos 1:14; ganado 1:20; ovejas y cabras 1:27 53,66 . ...
... La similitud cuantitativa de la morfología del intestino humano con los intestinos de mamíferos carnívoros se utiliza para apoyar ese argumento 53 . La relación entre la longitud del cuerpo y la longitud del intestino es en: gatos 1:4; humanos 1:5; perros 1:6; babuinos 1:8; caballos 1:12; cerdos 1:14; ganado 1:20; ovejas y cabras 1:27 53,66 . La relación entre la longitud corporal y la longitud intestinal muestra que el patrón humano se ajusta entre los carnívoros (perro y gato) 53 . ...
La alimentación humana está condicionada por factores ideológicos, climáticos, geográficos, tecnológicos y religiosos, entre otros. Esos factores crean patrones de dieta que los humanos eligen por variedad de razones, como preocupaciones éticas, deseo de una mejor salud, creencias religiosas y consideraciones ambientales, entre otras.
El condicionamiento en la alimentación es creado en un ambiente sociocultural, que dista en tiempo, de la alimentación originaria en un ambiente natural; la cual por modificaciones conductuales, en la especie humana, evolutivamente, han causado cambios en adaptaciones anatómicas y fisiológicas en humanos. El estudio de esas adaptaciones genera hipótesis enmarcadas dentro de un contexto con validez bajo distintos puntos de vista, lo que dificulta establecer, en parte, la verdad sobre la alimentación humana.
Para la elaboración de este libro se consultó literatura puramente científica. Los temas tratados abarcan la adaptación evolutiva de primates humanos, no humanos y algunas otras especies, existentes y extintas, con énfasis en la anatomía comparada; la experiencia multisensorial en la comunicación entre plantas y animales; la evolución de la dieta humana y aspectos nutricionales y de salud asociados al procesamiento de alimentos, al consumo de macronutrientes de origen animal y vegetal, y de compuestos fito y zooquímicos; además, relaciones entre la microbiota intestinal y las dietas. Temática que ofrece al lector diversidad de argumentos que llevan a suponer sobre lo que los humanos modernos, deberían o no, comer.
... e relationship between body mass and Basal Metabolic Rate (BMR): the Kleiber line characterizing relationship between BMR and body size is identical for all mammals, including humans. Since maintenance of gut and brain tissues are equally expensive, Aiello and Wheeler proposed that gut reduction allowed the emergence of the large brain in hominids. Henneberg et al. (1998) developed further arguments concerning the role of meat eating in human evolution. For these authors, the quantitative similarity of human gut morphology to that of carnivorous mammals is a strong argument for the proposition that the human status is that of a " well evolved meat eater " . These authors also provided additional argument ...
... Together with their aguments on parasitology and digestive physiology, Henneberg et al. (1998) presented some data on energy intake. These suggest that human absorption efficiency is intermediate between that of herbivores and carnivores, but closer to that of carnivores. ...
... In other populations (i.e. in Europe) the disappearance of selective pressure for the insulin response with the advent of plant and animal domestication between 8,000 and 5,000 BP explains the relatively low prevalence of diabetes mellitus and obesity at the present time (Miller and Colagiuri, 1994). In the same vein, the persistence for more than 100,000 years, of taenioid parasites that had coevolved with humans as they hunted with dogs during periods of large game consumption -a hypothesis proposed by Henneberg et al. (1998) as evidence for habitual meat consumption -can be viewed as an inheritance from these ancient times. It is generally recognized that specialized forms (such as parasites) cannot return to their initial, unspecialized forms. ...
In this paper we discuss the hypothesis, proposed by some authors, that man is a habitual meat-eater. Gut measurements of primate species do not support the contention that human digestive tract is specialized for meat-eating, especially when taking into account allometric factors and their variations between folivores, frugivores and meat-eaters. The dietary status of the human species is that of an unspecialized frugivore, having a flexible diet that includes seeds and meat (omnivorous diet). Throughout the various time periods, our human ancestors could have mostly consumed either vegetable, or large amounts of animal matter (with fat and/or carbohydrate as a supplement), depending on the availability and nutrient content of food resources. Some formerly adaptive traits (e. g. the “thrifty genotype”) could have resulted from selective pressure during transitory variations of feeding behavior linked to environmental constraints existing in the past.
... As such, we show a number of anatomical and physiological adaptations to a more carnivorous diet than that of the great apes, our closest living relatives, and these adaptations probably arose in Africa at the origin of the genus Homo ~2.6 Myrs ago. For example, the gastrointestinal tract of H. sapiens is 40% shorter than the one expected for a primate of our size (Chivers and Hladik, 1980;Henneberg et al., 1998). As a result, the ratio of intestinal length to body length of humans (5:1) is lower than the one of baboons (8:1), not to speak on those of truly herbivorous mammals like the horse (12:1) and cattle (20:1), but is included within the range of values depicted by the extant carnivores (6-4:1). ...
... Dietary quality relates inversely in primates with body mass and with metabolic rate per unit mass, which allows the great apes to subsist with a diet in which vegetal matter represents between 87% and 99% (Milton, 2003). However, the human diet is more digestible and more energy-rich (in kJ per day and kg of body mass) than the one expected from our metabolic rate, which is the typical for a primate of our body mass (Leonard and Robertson, 1996;Henneberg et al., 1998). This relates to the high maintenance costs of the nervous tissue, which sums up to 20-25% of the basal metabolic rate in humans compared with 8-10% in chimpanzees (Leonard and Robertson, 1994). ...
... As such, we show a number of anatomical and physiological adaptations to a more carnivorous diet than that of the great apes, our closest living relatives, and these adaptations probably arose in Africa at the origin of the genus Homo ~2.6 Myrs ago. For example, the gastrointestinal tract of H. sapiens is 40% shorter than the one expected for a primate of our size (Chivers and Hladik, 1980;Henneberg et al., 1998). As a result, the ratio of intestinal length to body length of humans (5:1) is lower than the one of baboons (8:1), not to speak on those of truly herbivorous mammals like the horse (12:1) and cattle (20:1), but is included within the range of values depicted by the extant carnivores (6-4:1). ...
... Dietary quality relates inversely in primates with body mass and with metabolic rate per unit mass, which allows the great apes to subsist with a diet in which vegetal matter represents between 87% and 99% (Milton, 2003). However, the human diet is more digestible and more energy-rich (in kJ per day and kg of body mass) than the one expected from our metabolic rate, which is the typical for a primate of our body mass (Leonard and Robertson, 1996;Henneberg et al., 1998). This relates to the high maintenance costs of the nervous tissue, which sums up to 20-25% of the basal metabolic rate in humans compared with 8-10% in chimpanzees (Leonard and Robertson, 1994). ...
... Esta "metamorfose", de recolector e caçador oportunista a caçador metódico, representou um salto determinante na sua própria evolução (Larsen, 2003). As evidências de uma herança adquirida ao longo de milhões de anos, suportada num intenso consumo de carne, revelam-se principalmente: 1) nas alterações craniofaciais sofridas (Speth, 1989); 2) na morfologia gastrointestinal adaptada à digestão da carne (Henneberg, Sarafis & Mathers, 1998); 3) na consequente encefalização (Foley & Lee, 1991;Aiello & Wheeler, 1995), resultante de um maior aporte energético (Martin, 1981;Mann, 1998) e no fornecimento de ácidos gordos poliinsaturados ao cérebro (Crawford, 1992;Chamberlain, 1996). Paralelamente, surgiram outros modelos de investigação, que testemunham a presença de carne na dieta dos nossos ancestrais hominídeos, nomeadamente: 1) de rácios de isótopos (Sr/Ca e C13/C12) encontrados nos remanescentes fósseis ósseos (Sillen, 1992;Lee-Thorp et al., 1994;Sillen & Lee-Thorp, 1994;Sponheimer & Lee-Thorp, 1999); 2) de análise custo/benefício descrita como "Theory of Optimal Foraging" (Pyke, Pulliam & Charnow, 1977); 3) de padrões alimentares das sociedades primitivas ainda existentes (Mann, 2007); 4) de modelos de co-evolução entre a Taenia saginata, a Taenia solium e o Homem (Henneberg, Sarafis & Mathers, 1998). ...
... As evidências de uma herança adquirida ao longo de milhões de anos, suportada num intenso consumo de carne, revelam-se principalmente: 1) nas alterações craniofaciais sofridas (Speth, 1989); 2) na morfologia gastrointestinal adaptada à digestão da carne (Henneberg, Sarafis & Mathers, 1998); 3) na consequente encefalização (Foley & Lee, 1991;Aiello & Wheeler, 1995), resultante de um maior aporte energético (Martin, 1981;Mann, 1998) e no fornecimento de ácidos gordos poliinsaturados ao cérebro (Crawford, 1992;Chamberlain, 1996). Paralelamente, surgiram outros modelos de investigação, que testemunham a presença de carne na dieta dos nossos ancestrais hominídeos, nomeadamente: 1) de rácios de isótopos (Sr/Ca e C13/C12) encontrados nos remanescentes fósseis ósseos (Sillen, 1992;Lee-Thorp et al., 1994;Sillen & Lee-Thorp, 1994;Sponheimer & Lee-Thorp, 1999); 2) de análise custo/benefício descrita como "Theory of Optimal Foraging" (Pyke, Pulliam & Charnow, 1977); 3) de padrões alimentares das sociedades primitivas ainda existentes (Mann, 2007); 4) de modelos de co-evolução entre a Taenia saginata, a Taenia solium e o Homem (Henneberg, Sarafis & Mathers, 1998). ...
... Any surplus of pyruvates may be stored as fats (de novo lipogenesis) while Acetyl CoA may also be metabolized into cholesterol. In terms of the total energy of food consumed and the size of the gastrointestinal system relative to body size humans are closer to carnivores than to other primates (Henneberg et al. 1998,Table 1). Human gastrointestinal tract is only about 60% of the size of that of a chimpanzee of the same total body weight (Aiello and Wheeler 1995). ...
... Comparison of human gut length and energetic value of food ingested with some other mammals. Data from various sources described in Henneberg et al. 1998 AnimalsTable 2 (Shepard et al. 1969, Schafer 1977). This table shows that the Toronto citizens are much fatter than their Eskimo counterparts, particularly amongst the men. ...
Obesity is considered a major epidemic of the 21st century. In developed countries, about 1/3 of adults are obese and another 1/3 overweight according to the oversimplified measure - the Body Mass Index. More precise indicators of adiposity: waist circumference, skinfolds, underwater weighing and absorptiometry indicate similar levels of fatness. Obesity per se does not necessarily lead to pathological states, nor to premature mortality. Recent results of large sample studies indicate that more than 1/3 of people classified as obese by fatness indices are physiologically normal. Others, however, suffer from a number of pathological conditions, common among them being the metabolic syndrome and cardiovascular disease. The classical explanation for increasing obesity is the positive energy balance - too much food intake and too little exercise. It seems, however, that this explanation is too simplistic. In societies, and in families, exposed to overeating and lazy lifestyles, about 1/3 of individuals have normal body mass and low levels of fatness, while others become obese. There is, therefore, individual variation in propensity for obesity. We have identified two specific variables differentiating fatness. People who have large lean trunk frames - large volumes of abdominal cavities and thus large gastrointestinal tracts - put on more subcutaneous fat than those with smaller trunk frames (Henneberg and Ulijaszek 2010). This may be a result of larger volumes of food required for antral extension to release ghrelin, or larger surface area of small intestines for food absorption. The second variable is concentrations of Alanine Transaminase, an enzyme responsible for conversion of an amino acid to a carbon skeleton that can be used in fat synthesis. Our study of 46000 young Swiss males (Henneberg, Rühli, Gruber and Woitek 2011) found consistent correlation between levels of Alanine Transaminase and body weight in groups of normal body mass individuals, overweight individuals and moderately obese individuals. Coupling this finding with the fact that among vegetarians, even those living in North America with overabundance of food and low levels of exercise, obesity and overweight are much less common than among non-vegetarians, we have now hypothesized that the increased obesity of modern affluent societies is a result of consumption of animal protein when energy needs are already covered by carbohydrates and fat consumed concurrently. Until the advent of agriculture, humans relied on consumption of a variety of terrestrial and aquatic animals supplemented by relatively small amounts of plant foods. In this situation our bodies became adapted to use proteins as a source of energy, and became efficient at storing occasional surpluses of amino acids by their deamination and conversion to fats. In the modern diets carbohydrates are abundant and provide, together with fats, energy required by human bodies, proteins after deamination are efficiently converted to fats. When new types of crops are introduced to mass production of cheap foods our bodies may not be able to react correctly to all their contents and some of the ingredients may cause additional fatness. An example of widespread recent introduction of industrially processed soybean products that correlates with prevalence of obesity across countries of the world is discussed.
... The ratio for frugivores (such as baboons, 8 : 1) is midway between that for folivores and carnivores, whereas that of humans (5 : 1) is more similar to that of carnivores. Similarly, the ratio of the surface area of the gastrointestinal tract to that of the whole body in humans (0.6 : 1) is closer to that of carnivores (0.4 : 1) than that of frugivores (1.1 : 1) or folivores (up to 3 : 1) (Henneberg et al. 1998). ...
... Numerous other lines of evidence (Mann 2007) support the contention that our hominin ancestors consumed ASF as an integral part of their diet. These include a decreased ability to synthesise taurine from precursor amino acids (Chesney et al. 1998), hence, a reliance on ASFs as a source of taurine; the presence of carnivore parasites (cestodes) of the family Taeniidae that use humans exclusively as their host (Henneberg et al. 1998) and reliance on ASFs as a source of preformed long-chain omega-3 PUFA such as eicosapentaenoic acid (EPA, 20:5n-3) and DHA because of a poor ability to synthesise these fatty acids from shorter forms found in plants (Emken et al. 1992). ...
Despite negative press reports on the effect of meat and other animal-source foods (ASFs) on human health and a vocal minority who contend that humans evolved as vegetarians, scientific evidence contradicts these views. For several million years before the development of agriculture, our ancestors were heavily reliant on ASFs as a source of energy and critical substrates such as protein and long-chain omega-3 fatty acids. Numerous lines of evidence in the anthropological literature have confirmed this scenario. Studies on ASF composition and clinical trials on ASF consumption have provided clear evidence of a requirement for meat in the diet to provide nutrients essential to health, such as Vitamin B12, long-chain omega-3 fatty acids and bioavailable forms of iron and zinc. Other studies have demonstrated that lean ASFs have a role in cholesterol-lowering diets and are important for mental function. Finally, it is possible and desirable to produce meat of a lean nature that mimics the many healthy attributes of wild-game meats and, by emphasising pasture feeding over grain feeding, this can be achieved to a large extent in Australia.
... Considering their body size, primates in general and humans in particular, have metabolically expensive large brains which are due to the so called encephalisation process (Aiello, 1992). However, according to Henneberg (Henneberg, Sarafis, & Mathers, 1998), the unusual human brain encephalisation is not clearly related with increases in the human brain but a relative decrease in human body size. This could be explained by taking into account the macro-evolutive enlargement suffered by the human brain in parallel with other mammals, their co-evolution with body size, the micro-evolutive decrease in human body size during considerable intellectual and cultural changes, and the virtual absence of an intra-specific correlation between brain size and human intelligence assessment methods. ...
... Humans are intermediate hosts for parasites that affect carnivores, such as tapeworms from Taeniidae family from Taenia saginata and Taenia solium that can be present in raw meat (Henneberg et al., 1998). ...
Meat has exerted a crucial role in human evolution and is an important component of a healthy and well balanced diet due to its nutritional richness. The present review attempts to sum up meats role and importance in human nutrition as well as examine some pejorative beliefs about meat consumption. Meat is a valuable source of high biological value protein, iron, vitamin B12 as well as other B complex vitamins, zinc, selenium and phosphorus. Fat content and fatty acid profile, a constant matter of concern when referring to meat consumption, is highly dependent on species, feeding system as well as the cut used. Pork meat can have the highest fat content but poultry skin is not far behind. It is also crucial to distinguish meat cuts from other meat products especially regarding its association with disease risk. As in other dietary components, moderation is advisable but meat has been shown to be an important component of a balanced diet.
... The EGM would have undergone continual evolutionary changes along with hominin adaptations to their environments and diets. For example, probably during the Pliocene/Pleistocene transition (∼3.2-2.6 Ma), the GIT of hominins underwent size reduction due to the introduction of meat and, later on, cooked food (Aiello and Wheeler, 1995;Henneberg et al., 1998;Mann, 2007). These two elements would have also contributed to alterations in the microbiome, which selected bacteria that favoured omnivorous diets (Shahab and Shahab, 2022 Although, the human EGM is less diverse than that of the great apes, (Moeller et al., 2014;Davenport et al., 2017), intestinal biodiversity has further been altered by several biocultural changes from the Neolithic revolution (circa 10,000 ka) onwards. ...
Although evolutionary medicine has produced several novel insights for explaining prevalent health issues, it has yet to sufficiently address possible adverse mental health effects of humans during long-term space missions While evolutionary applications to medicine have increased over the past 20 years, there is scope for the integration of evolutionary applications in the new branch of space medicine called bioastronautics, which analyses the effects on human bodies when in outer space. Evolutionary principles may explain what kinds of space environments increase mental health risks to astronauts, both in the short and long term; secondly, evolutionary principles may provide a more informed understanding of the evolutionary mismatch between terrestrial and space environments in which astronauts exist. This information may assist in developing frameworks for improving mental health of astronauts and future space colonists. Consequently, this paper will focus on some of the major evolutionary mismatches currently confronting astronauts’ mental health, with an aim to improve medical knowledge. It will also provide possible therapeutic countermeasures based on evolutionary principles for reducing adverse mental effects on astronauts.
... The first significant shift unfolded approximately two million years ago with the appearance of Homo erectus, marked by notable growth in height, body mass, and brain size, which were partly due to higher levels of ASFs in their diet [16][17][18][19][20]. Other physiological changes from other primates point to TASF nutrition (intake, absorption, and metabolism), including the lost capacity to absorb vitamin B12 derived from gut bacteria [21]; preferential absorption of heme iron versus non-heme iron [22,23]; greater dependency on dietary choline [21,24]; reduced capacity to produce taurine from amino acid precursors [25,26]; and lowered levels of alpha-linolenic acid conversion into eicosapentaenoic acid (EPA)/docosahexaenoic (DHA) [27]. ...
Background. Animal source foods are under scrutiny for their role in human health, yet some nutritionally vulnerable populations are largely absent from consideration. Methods. Applying a Population Intervention/Exposure Comparator Outcome (PICO/PECO) framework and prioritizing systematic review and meta-analyses, we reviewed the literature on terrestrial animal source foods (TASFs) and human health, by life course phase. Results. There were consistent findings for milk and dairy products on positive health outcomes during pregnancy and lactation, childhood, and among older adults. Eggs were found to promote early childhood growth, depending on context. Unprocessed meat consumption was associated with a reduced risk for anemia during pregnancy, improved cognition among school-age children, and muscle health in older adults. Milk and eggs represent a risk for food sensitivities/allergies, though prevalence is low, and individuals tend to outgrow the allergies. TASFs affect the human microbiome and associated metabolites with both positive and negative health repercussions, varying by type and quantity. Conclusions. There were substantial gaps in the evidence base for studies limiting our review, specifically for studies in populations outside high-income countries and for several TASF types (pig, poultry, less common livestock species, wild animals, and insects). Nonetheless, sufficient evidence supports an important role for TASFs in health during certain periods of the life course.
... There are numerous highly published fields of investigation used by anthropologists to deduce the evolutionary diet of our evolving hominin ancestors, and they include the following: (1) changes in cranio-dental features; (2) fossil isotopic chemical tracer methods; (3) comparative gut morphology of modern humans and other mammals; (4) the energetic requirements of developing a large ratio of brain to body size; (5) optimal foraging theory; (6) dietary patterns of surviving hunter-gatherer societies; (7) specific diet-related adaptations; (8) fossil evidence of animal butchery (Mann 2000(Mann , 2018 and; (9) coevolution of mammalian hosts and their various parasites. Cestodes of the family Taeniidae, for example, are parasites of carnivores, spread by eating meat (Henneberg et al. 1998). ...
It is clear that the societal role of meat is being challenged with ideological and simplified logic without substantiation from robust data-driven science. With this background, the international summit titled ‘The societal role of meat – what the science says’ was held in Dublin, Ireland, during October 2022, to provide evidence-based evaluations and the Dublin Declaration was signed by over 1000 scientists. In this paper, we provide a synopsis of the summit and then give context for evaluating the societal role of meat in Australia. The key themes of the summit were the essential roles of meat in (1) diet and health, (2) a sustainable environment and (3) society, economics and culture. Evidence clearly showed the role of meat as a nutrient-dense source of high-quality protein and micronutrients that can be safely consumed by humans. Further, the complementary role of livestock in agricultural systems was highlighted with both plant- and animal-based agriculture reliant on each other to maximise the efficient production of food. Thus, from both an Australian and world perspective, very little food considered to be human-edible is fed to livestock. The role of livestock in rural societies across the world was emphasised to underpin regional and national economies, with particular importance in those countries with developing economies to facilitate growing wealth to ‘step out’ of poverty and provide gender equality. Meat production, particularly from ruminants, is a critical part of Australian primary production and it is concluded that the Dublin Declaration is highly relevant to Australia. Finally, concern regarding future funding and organisation of research and extension is discussed. There is a need to continue funding highly collaborative programs that bring a broad range of disciplines together, in conjunction with undergraduate and postgraduate teaching to underpin the social license to operate for meat and livestock production.
... The intestinal length to body length ratio of humans (5:1) is like dogs (6:1) and markedly different to grazing mammals (cattle, 12:1). Another measure of digestive system structure is the gastrointestinal surface area to body surface area ratio, with humans (0.8:1) once again being more similar to carnivores (dogs, 0.6:1) than grazing mammals (cattle, 3:1) (Henneberg et al., 1998). Even compared with their closest evolutionary relatives, the chimpanzees and gorillas, humans have a distinct digestive tract that shows differences favoring reliance on higher-quality foods. ...
... 60,61 Benefits of meat eating include better physical growth and development, 62 optimal breastfeeding of neonates, and offspring growth. 63 Human adaptation to meat eating and mechanism to digest and metabolise meat 6,59,62,[64][65][66][67] have been supported by studies in human dietary evolution. This may also be reflected in the importance of meat eating for human's whole life span. ...
Background
The association between a plant-based diet (vegetarianism) and extended life span is increasingly criticised since it may be based on the lack of representative data and insufficient removal of confounders such as lifestyles.
Aim
We examined the association between meat intake and life expectancy at a population level based on ecological data published by the United Nations agencies.
Methods
Population-specific data were obtained from 175 countries/territories. Scatter plots, bivariate, partial correlation and linear regression models were used with SPSS 25 to explore and compare the correlations between newborn life expectancy (e(0)), life expectancy at 5 years of life (e(5)) and intakes of meat, and carbohydrate crops, respectively. The established risk factors to life expectancy – caloric intake, urbanization, obesity and education levels – were included as the potential confounders.
Results
Worldwide, bivariate correlation analyses revealed that meat intake is positively correlated with life expectancies. This relationship remained significant when influences of caloric intake, urbanization, obesity, education and carbohydrate crops were statistically controlled. Stepwise linear regression selected meat intake, not carbohydrate crops, as one of the significant predictors of life expectancy. In contrast, carbohydrate crops showed weak and negative correlation with life expectancy.
Conclusion
If meat intake is not incorporated into nutrition science for predicting human life expectancy, results could prove inaccurate.
... Little systematic evolution-guided reconstruction of HTL has been published to date. Henneberg et al. (1998) cited the similarity of the human gut to that of carnivores, the preferential absorption of haem rather than iron of plant origins, and the exclusive use of humans as a carnivore host by the Taenia saginata, a member of the Taeniidea family of carnivores' parasites, as supporting Homo sapiens' adaptation to meat-eating. Mann (2000) Pointed to gut structure and acidity, insulin resistance, and high diet quality as evidence of physiological adaptation to consuming lean meat during the Paleolithic. ...
The human trophic level (HTL) during the Pleistocene and its degree of variability serve, explicitly or tacitly, as the basis of many explanations for human evolution, behavior, and culture. Previous attempts to reconstruct the HTL have relied heavily on an analogy with recent hunter‐gatherer groups' diets. In addition to technological differences, recent findings of substantial ecological differences between the Pleistocene and the Anthropocene cast doubt regarding that analogy's validity. Surprisingly little systematic evolution‐guided evidence served to reconstruct HTL. Here, we reconstruct the HTL during the Pleistocene by reviewing evidence for the impact of the HTL on the biological, ecological, and behavioral systems derived from various existing studies. We adapt a paleobiological and paleoecological approach, including evidence from human physiology and genetics, archaeology, paleontology, and zoology, and identified 25 sources of evidence in total. The evidence shows that the trophic level of the Homo lineage that most probably led to modern humans evolved from a low base to a high, carnivorous position during the Pleistocene, beginning with Homo habilis and peaking in Homo erectus. A reversal of that trend appears in the Upper Paleolithic, strengthening in the Mesolithic/Epipaleolithic and Neolithic, and culminating with the advent of agriculture. We conclude that it is possible to reach a credible reconstruction of the HTL without relying on a simple analogy with recent hunter‐gatherers' diets. The memory of an adaptation to a trophic level that is embedded in modern humans' biology in the form of genetics, metabolism, and morphology is a fruitful line of investigation of past HTLs, whose potential we have only started to explore.
... Given the correlation between this transition and a reduction in overall gastrointestinal tract length (84), it is plausible that interactions between the peripheral and central eCB systems were re-configured during the evolution of humans within the hominin lineage. This scenario could potentially explain the higher energy intake and increased diet quality (i.e., animal flesh and fat sources) that coincided with brain expansion over time in the hominin lineage's members (85). ...
When primitive vertebrates evolved from ancestral members of the animal kingdom and acquired complex locomotive and neurological toolsets, a constant supply of energy became necessary for their continued survival. To help fulfill this need, the endocannabinoid (eCB) system transformed drastically with the addition of the cannabinoid-1 receptor (CB1R) to its gene repertoire. This established an eCB/CB1R signaling mechanism responsible for governing the whole organism's energy balance, with its activation triggering a shift toward energy intake and storage in the brain and the peripheral organs (i.e., liver and adipose). Although this function was of primal importance for humans during their pre-historic existence as hunter-gatherers, it became expendable following the successive lifestyle shifts of the Agricultural and Industrial Revolutions. Modernization of the world has further increased food availability and decreased energy expenditure, thus shifting the eCB/CB1R system into a state of hyperactive deregulated signaling that contributes to the 21st century metabolic disease pandemic. Studies from the literature supporting this perspective come from a variety of disciplines, including biochemistry, human medicine, evolutionary/comparative biology, anthropology, and developmental biology. Consideration of both biological and cultural evolution justifies the design of improved pharmacological treatments for obesity and Type 2 diabetes (T2D) that focus on peripheral CB1R antagonism. Blockade of peripheral CB1Rs, which universally promote energy conservation across the vertebrate lineage, represents an evolutionary medicine strategy for clinical management of present-day metabolic disorders.
... Ungar (2004) suggests likewise that, according to dental topography, early Homo relied on tough and elastic food, probably meat. A long history of meat eating is also embedded in modern gut morphology, and in the development of exclusive parasites such as Taenia saginata, while isotope ratios in early hominins suggest significant meat intake (Henneberg et al., 1998), in good accordance with the evidence of butchering activity at Bouri, the 2.5 Ma site in East Africa (De Heinzelin et al., 1999). Regular hunting of large game is actually part of the European scenario during the Middle Pleistocene, after the evidence discussed by , and most notably after the extraordinary finds of Schöningen . ...
... Ungar (2004) suggests likewise that, according to dental topography, early Homo relied on tough and elastic food, probably meat. A long history of meat eating is also embedded in modern gut morphology, and in the development of exclusive parasites such as Taenia saginata, while isotope ratios in early hominins suggest significant meat intake (Henneberg et al., 1998), in good accordance with the evidence of butchering activity at Bouri, the 2.5 Ma site in East Africa (De Heinzelin et al., 1999). Regular hunting of large game is actually part of the European scenario during the Middle Pleistocene, after the evidence discussed by Roebroeks (2001), and most notably after the extraordinary finds of Schöningen (Thieme, 1997). ...
... based on the relationship between body mass and Basal Metabolic Rate (BMR): the Kleiber line characterizing the relationship between BMR and body size is identical for all mammals, including humans. Since maintenance of gut tissue is as expensive as that of brain tissue, Aiello and Wheeler proposed that gut reduction compensated for brain increase. Henneberg et al. (1998), following this point of view, developed further arguments on the role of meat eating in human evolution. For these authors, the " quantitative similarity of human gut morphology to guts of carnivorous mammals " is a strong argument for a human status of " well evolved meat eater " . In fact, one should ask if there is actual evidence o ...
Theories of hominid evolution have postulated that switching to meat eating permitted an increase in brain size and hence the emergence of modern man. However, comparative studies of primate intestinal tracts do not support this hypothesis and it is likely that, while meat assumed a more important role in hominid diet, it was not responsible for any major evolutionary shift.
... Our ancestors adapted to increased reliance on meat as our gastrointestinal system attests [41][42][43]. Animals with carnivorous tendencies often derive their energy requirements from animal fats and proteins through efficient metabolic systems. Ingested fats, followed by simple sugars are the simplest to break down and utilise for energy production for somatic use [44]. ...
Recently, a positive correlation between alanine transaminase activity and body mass was established among healthy young individuals of normal weight. Here we explore further this relationship and propose a physiological rationale for this link.
Cross-sectional statistical analysis of adiposity across large samples of adults differing by age, diet and lifestyle.Subjects: 46,684 19-20 years old Swiss male conscripts and published data on 1000 Eskimos, 518 Toronto residents and 97,000 North American Adventists.Measurements: Serum concentrations of the alanine transaminase, post-prandial glucose levels, cholesterol, body height and weight, blood pressure and routine blood analysis (thrombocytes and leukocytes) for Swiss conscripts. Adiposity measures and dietary information for other groups were also obtained.
Stepwise multiple regression after correction for random errors of physiological tests showed that 28% of the total variance in body mass is associated with ALT concentrations. This relationship remained significant when only metabolically healthy (as defined by the American Heart Association) Swiss conscripts were selected. The data indicated that high protein only or high carbohydrate only diets are associated with lower levels of obesity than a diet combining proteins and carbohydrates.
Elevated levels of alanine transaminase, and likely other transaminases, may result in overactivity of the alanine cycle that produces pyruvate from protein. When a mixed meal of protein, carbohydrate and fat is consumed, carbohydrates and fats are digested faster and metabolised to satisfy body's energetic needs while slower digested protein is ultimately converted to malonyl CoA and stored as fat. Chronicity of this sequence is proposed to cause accumulation of somatic fat stores and thus obesity.
... Ungar (2004) suggests likewise that, according to dental topography, early Homo relied on tough and elastic food, probably meat. A long history of meat eating is also embedded in modern gut morphology, and in the development of exclusive parasites such as Taenia saginata, while isotope ratios in early hominins suggest significant meat intake (Henneberg et al., 1998), in good accordance with the evidence of butchering activity at Bouri, the 2.5 Ma site in East Africa (De Heinzelin et al., 1999). Regular hunting of large game is actually part of the European scenario during the Middle Pleistocene, after the evidence discussed by , and most notably after the extraordinary finds of Schöningen . ...
... Assuming that hominids were both adapted to meat consumption and in need of eating it (e.g. Henneberg et al., 1998, Mussi, 1999, but see Hladik and Pasquet, 2002;Arcadi, 2006), in depicting the scenario that allowed the hominin's first dispersal to be successful, special attention has to be given to the structure of the carnivore guild, to which the genus Homo belongs, and to the competition for suitable prey (e.g. Turner, 1992;Brantingham, 1998;Dominguez-Rodigo, 2001;Palombo and Mussi, 2006). ...
Throughout the Early to Middle Pleistocene several origination and extinction bioevents led to a progressive rebuilding of the structure of the Mediterranean mammalian communities. Understanding whether faunal dispersal and turnovers developed on a backdrop of climatic changes or intrinsic biotic factors exerted a more important control, it is an outstanding interest in elucidating the ecological scenario, enabling humans to disperse towards and across the Mediterranean region. Although a link between human dispersal and climate change possibly exists, many archaeologists continue to reject environmental determinism. The first dispersal of some human groups towards the Mediterranean was undoubtedly part of the Early Pleistocene faunal renewal triggered by climate changes, but the increase of suitable prey and limited competition with other predators would have been beneficial to human peopling.
... Third, taeniid tapeworms are host-specific parasites for whom carnivores are definitive hosts and herbivores are intermediate hosts. Three species, Taenia saginata, T. asiatica, and T. solium, use humans exclusively as their primary host, indicating the occurrence of human meat consumption more than ~1 mya (Henneberg et al. 1998;Hoberg et al. 2001). Fourth, humans lack the ability to efficiently synthesize from plant-based raw materials the long-chain polyunsaturated fatty acids (PUFA) required for cell membrane growth, structure and function, and fetal and postnatal brain development (Clandinin 1999;Broadhurst et al. 2002). ...
For our body size, humans exhibit higher energy use yet reduced structures for mastication and digestion of food compared to chimpanzees, our closest living relatives. This suite of features suggests that humans are adapted to a high-quality diet. Although increased consumption of meat during human evolution certainly contributed to dietary quality, meat-eating alone appears to be insufficient to support the evolution of these traits, because modern humans fare poorly on raw diets that include meat. Here, we suggest that cooking confers physical and chemical benefits to food that are consistent with observed human dietary adaptations. We review evidence showing that cooking facilitates mastication, increases digestibility, and otherwise improves the net energy value of plant and animal foods regularly consumed by humans. We also address the likelihood that cooking was adopted more than 250,000 years ago (kya), a period that we believe is sufficient in length for the proposed adaptations to have occurred. Additional experimental work is needed to help discriminate the relative contributions of cooking, meat eating, and other innovations such as nonthermal food processing in supporting the human transition toward dietary quality.
Humans are considered to have a unique reliance on meat compared to other primates, as much of humans unique evolutionary trajectory, such as human brain expansion, is linked to the increased consumption of meat for calories and nutrients. However, other primates such as chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) are also known to consume meat. While humans meat consumption is considered to be unique in humans' increased incorporation of tools to process the prey carcass and consumption of a broader range of prey, these distinctions are less obvious when contextualized within the broader behavioral repertoire of Pan species carnivory. This research seeks to identify if the taste perception of meat is different between humans and other ape clades through gene selection analyses. Specifically, this work examines the umami taste receptor genes, TAS1R1 and TAS1R3, which enable the savory flavor perceived when eating meat. Using PAML, we test for positive selection in these genes across several ape clades. We infer positive selection in TAS1R1 for the homininae clade and positive selection in TAS1R3 for the Homo/Pan clade. No selection was detected in only the human lineage, which complicates claims that human carnivory is unique compared to other primates while simultaneously suggesting the role of meat may be unappreciated in chimpanzees and bonobos as well as the role of insectivory in gorillas.
To this day, our diet is determined by fire. However, the settling down of humans after the Stone Age brought new foods into the diet, such as cereals, milk, and dairy products, as well as new techniques, like controlled fermentation. In order for milk to become digestible for humans, a point mutation in the DNA was necessary. Lactose tolerance was able to prevail in some niches.
The Middle Pleistocene is associated with a new level of technology, Mode 2, commonly called the Acheulean Culture. This appears in Africa and Western Asia, but only later in Europe and not at all in Asia. It appears to be an indicator of communication, if not actual migration, among these areas. Climate swings, particularly in Europe, suggest that some forms of shelter and clothing had been invented, but more direct evidence is scarce. Controlled fire appears about a million years ago, but what traces are found suggest it was not widely used. Hunting of larger animals is well documented in the Middle Pleistocene employing weaponry such as lances and throwing spears. Meat consumption appears to have increased in importance, especially in temperate Europe. Strangely, Asian populations did not follow the same behavioral trends.
Bis heute wird unsere (Ess-)Kultur durch das Feuer bestimmt. So ist es nicht verwunderlich, dass wir, wie es immer wieder von vermeintlichen Hightech-Köchen belächelt wird, heute noch so essen wie vor Tausenden von Jahren.
Many historic generations of meat eaters would be dumbfounded if they could learn of the condemnations now being brought against the eating of red meat. They would be astounded to hear that the food they considered to be premier is now being condemned. They might even consider these condemnations slander. These criticisms of red meat as a food have largely arisen in the West after World War II. It is true that no food is without fault in terms of the provision of health to the eater. Therefore, it is important to address the healthfulness of red meat from an objective point of view. The truth of the matter is important to everyone who considers eating red meat. Therefore, this chapter reviews the scientific literature of the healthfulness of red meats presenting research results that are both favorable and unfavorable in an attempt to obtain a clear vision of the healthfulness of eating red meat.
Anthropological investigations have confirmed many times over, through multiple fields of research the critical role of consumption of animal source foods (ASF) including meat in the evolution of our species. As early as four million years ago, our early bipedal hominin ancestors were scavenging ASFs as evidenced by cut marks on animal bone remains, stable isotope composition of these hominin remains and numerous other lines of evidence from physiological and paleo-anthropological domains. This ASF intake marked a transition from a largely forest dwelling frugivorous lifestyle to a more open rangeland existence and resulted in numerous adaptations, including a rapidly increasing brain size and altered gut structure. Details of the various fields of anthropological evidence are discussed, followed by a summary of the health implications of meat consumption in the modern world, including issues around saturated fat and omega-3 fatty acid intake and discussion of the critical nutrients ASFs supply, with particular emphasis on brain function.
We have analysed the structure of the faunal complexes of the Italian final Pliocene, as well as the changes during the Early and Middle Pleistocene, in order to better understand which resources were available at the time of the earliest peopling of Italy. We assume that to successfully adapt to middle latitudes and to seasonally available resources, meat had to be consumed on a regular basis by humans. Confrontation with other carnivores had to be expected, and was enhanced or reduced following changes in herbivore richness and diversity. In the latest Pliocene, the carnivore guild is dominated by large carnivores, which are active hunters and both flesh eaters and carcass destroyers. Pack-hunting canids join the guild at the Plio-Pleistocene boundary. The structure of the faunal assemblages of the Early Pleistocene (late Villafranchian) is characterised by more richness and diversity among carnivores than among herbivores. Accordingly, the Italian environment was not favourable to human expansion. At the end of the Early Pleistocene (early Galerian), there is a renewal of the carnivore guild: some species disappear, such as the hyper carnivore Lycaon falconeri, and the superpredator felid Megantereon, possibly allowing a sporadic colonisation by humans. The hypothesis of an early peopling would be in accordance with evidence from other parts of southern Europe. A faunal turnover, however, occurs later, in the latest early and in the Middle Pleistocene (early and middle Galerian): carnivores diminish, and then herbivores increase. This new scenario allows, for the first time, a human settlement, which is fully documented at a number of archaeological sites. From then onwards, human groups successfully compete with modern carnivore species. During the Late Pleistocene, neither Neanderthals nor anatomically modern humans seem to be challenged by carnivores, which are again more diversified and numerous.
The role of nanomedicine in developing therapies to combat disease and body morbidity has received a plethora of theoretical analysis. While nanomedicine has well defined therapeutic value, its role in body enhancement needs greater theoretical consideration. This article focuses on the potential marriage between nanomedicine and future body enhancement. It argues that nanomedical enhancements have the possibility of overriding physical limitations of the human body. The paper discusses both current approaches to body enhancement and future applications of nanomedicine such as cosmetic neurology.
Human ancestral diets changed substantially approximately four to five million years ago with major climatic changes creating open grassland environments. We developed a larger brain balanced by a smaller, simpler gastrointestinal tract requiring higher-quality foods based around meat protein and fat. Anthropological evidence from cranio-dental features and fossil stable isotope analysis indicates a growing reliance on meat consumption during human evolution. Study of hunter-gatherer societies in recent times shows an extreme reliance on hunted and fished animal foods for survival. Optimal foraging theory shows that wild plant foods in general give an inadequate energy return for survival, whereas the top-ranking food items for energy return are large hunted animals. Numerous evolutionary adaptations in humans indicate high reliance on meat consumption, including poor taurine production, lack of ability to chain elongate plant fatty acids and the co-evolution of parasites related to dietary meat.
Scientific evidence is accumulating that meat itself is not a risk factor for Western lifestyle diseases such as cardiovascular disease, but rather the risk stems from the excessive fat and particularly saturated fat associated with the meat of modern domesticated animals. In our own studies, we have shown evidence that diets high in lean red meat can actually lower plasma cholesterol, contribute significantly to tissue omega-3 fatty acid and provide a good source of iron, zinc and vitamin B12. A study of human and pre-human diet history shows that for a period of at least 2 million years the human ancestral line had been consuming increasing quantities of meat. During that time, evolutionary selection was in action, adapting our genetic make up and hence our physiological features to a diet high in lean meat. This meat was wild game meat, low in total and saturated fat and relatively rich in polyunsaturated fatty acids (PUFA). The evidence presented in this review looks at various lines of study which indicate the reliance on meat intake as a major energy source by pre-agricultural humans. The distinct fields briefly reviewed include: fossil isotope studies, human gut morphology, human encephalisation and energy requirements, optimal foraging theory, insulin resistance and studies on hunter-gatherer societies. In conclusion, lean meat is a healthy and beneficial component of any well-balanced diet as long as it is fat trimmed and consumed as part of a varied diet.
The chimpanzee (Pan troglodytes, Pongidae) among all other living species, is our closest relation, with whom we last shared a common ancestor less than five million years ago. These African apes make and use a rich and varied kit of tools. Of the primates, and even of the other Great Apes, they are the only consistent and habitual tool-users. Chimpanzees meet the criteria of working definitions of culture as originally devised for human beings in socio-cultural anthropology. They show sex differences in using tools to obtain and to process a variety of plant and animal foods. The technological gap between chimpanzees and human societies living by foraging (hunter-gatherers) is surprisingly narrow, at least for food-getting. Different communities of chimpanzees have different tool-kits, and not all of this regional and local variation can be explained by the varied physical and biotic environments in which they live. Some differences are likely customs based on non-functionally derived and symbolically encoded traditions. Chimpanzees serve as heuristic, referential models for the reconstruction of cultural evolution in apes and humans from an ancestral hominoid. However, chimpanzees are not humans, and key differences exist between them, though many of these apparent contrasts remain to be explored empirically and theoretically.
Mitochondrial DNA control region sequences were analyzed from 162 wolves at 27 localities worldwide and from 140 domestic
dogs representing 67 breeds. Sequences from both dogs and wolves showed considerable diversity and supported the hypothesis
that wolves were the ancestors of dogs. Most dog sequences belonged to a divergent monophyletic clade sharing no sequences
with wolves. The sequence divergence within this clade suggested that dogs originated more than 100,000 years before the present.
Associations of dog haplotypes with other wolf lineages indicated episodes of admixture between wolves and dogs. Repeated
genetic exchange between dog and wolf populations may have been an important source of variation for artificial selection.
Under conditions of normal calcium metabolism, Sr/Ca ratios have been shown to reflect the trophic level of contemporary and recent terrestrial fauna. A procedure is investigated for the analysis of biogenic and diagenetic apatite in vertebrate fossils, on the basis of solubility differences among carbonate, hydroxy-, and fluorapatites. When applied to the 2Ma BP fauna of the Omo Basin (Ethiopia), distinct characterization of the herbivore, omnivore, and carnivore fauna in conformity with trophism was descerned, in spite of anomalous Sr/Ca of one highly specialized carnivore, Homotherium. Possible metabolic and/or taphonomic explanations of this anomaly are discussed, and future basic research into the solubility profile procedure is outlined.-from Author
Diagnostic procedures in the field of medical parasitology require a great deal of judgment and interpretation and are generally classified by the Clinical Laboratory Improvement Amendments of 1988 (CLlA '88) as high complexity procedures. The majority of diagnostic parasitology procedures can be performed either within the hospital setting or in an offsite location. There are very few procedures within this discipline that must be performed and reported on a short turnaround time (STAT) basis. Two procedures fall into the STAT category: request for examination of blood films for the diagnosis of malaria and examination of cerebrospinal fluid for the presence of free-living amebae, primarily Naegleria fowleri. The specimen commonly submitted to the diagnostic parasitology laboratory is the stool specimen, and the most commonly performed procedure in parasitology is the ova and parasite (O&P) examination, which comprises three separate protocols: the direct wet mount, the concentration, and the permanent stained smear.
Brain tissue is metabolically expensive, but there is no significant correlation between relative basal metabolic rate and relative brain size in humans and other encephalized mammals. The expensive-tissue suggests that the metabolic requirements of relatively large brains are offset by a corresponding reduction of the gut. The splanchnic organs (liver and gastro-intestinal tract) are as metabolically expensive organs in the human body that is markedly small in relation to body size. Gut size is highly correlated with diet, and relatively small guts are compatible only with high-quality, easy-to-digest food. The often -cited relationship between diet and relative brain size is more properly viewed as a relationship between relative brain size and relative gut size, the latter being determined by dietary quality. No matter what is selecting for relatively large brains in humans and other primates, they cannot be achieved without a shift to a high-quality diet unless there is a rise in the metabolic rate. Therefore the incorporation of increasingly greater amounts of animal products into the diet was essential in the evolution of the large human brain.
Nucleotide sequence variations in a region of the mitochondrial cytochromec oxidase subunit I (COI) gene (391 bp) were examined within seven species of the genusTaenia and two species of the genusEchinococcus, including ten isolates ofT. taeniaeformis and six isolates ofE. multilocularis. More than a 12% rate of nucleotide differences between taeniid species was found, allowing the species to be distinguished. InE. multilocularis, no sequence variation was observed among isolates, regardless of the host (gray red-backed vole, tundra vole, pig, Norway rat) or area (Japan, Alaska) from which each metacestode had been isolated. In contrast, six distinct sequences were detected among the tenT. taeniaeformis isolates examined. The level of nucleotide variation in the COI gene withinT. taeniaeformis isolates except for one isolate from the gray red-backed vole (TtACR), which has been proposed as a distinct strain or a different species, was about 0.3%–4.1%, whereas the COI gene sequence for TtACR differed from those of the other isolates, with levels being 9.0%–9.5%. Phylogenetic trees were then inferred from these sequence data using two different algorithms.
Strontium-calcium ratios (Sr/Ca) are normally reduced at higher trophic levels in foodwebs, due to discrimination against strontium in favour of calcium by animals. This phenomenon has not generally been applied to the study of fossil foodwebs and the diets of early hominids because of diagenetic changes which obscure or obliterate biological Sr/Ca. The examination of compartments of fossil apatite having differing solubility, however, is a promising method for independently measuring biological and diagenetic Sr/Ca. In this study, Sr/Ca in Member I fossils from the site of Swartkrans were examined using a solubility profile procedure. Sr/Ca relationships observed among Swartkrans fauna match those seen in modern African foodwebs, suggesting that biological Sr/Ca accounts for the observed variation.When specimens of the fossil hominid Australopithecus robustus were examined, Sr/Ca values were inconsistent with that of a root, rhizome or seed-eating herbivore, suggesting that the diet of this species was more diverse than previously believed, and almost certainly included the consumption of animal foods.
A model of mastication, derived from studies on modern Homo sapiens, is proposed to analyse postcanine tooth size in hominids. It is suggested that a tendency towards larger tooth size will follow an adaptation to eating small amounts of small abrasive food objects which are broken to gain chemical access to the foodstuff. A trend towards reducing tooth size is suggested for concentrations on large amounts of large food items of low abrasiveness and which may form into boli before swallowing. This analysis is applied to Plio-0leistocene hominids where it is suggested that Australopithecus robustus was indeed a specialized grass seed, legume and root eater whereas early Homo had a much more diverse fruit, root and meat diet.
Studies of an optimal body size for individuals of different species based upon their foraging efficiency are reviewed and a detailed analysis of data specifically collected for this purpose is presented for Microtus pennsylvanicus. The natural selection of body sizes for some species is shown to be consistent with their foraging efficiency. However, a general model of optimal body size based on foraging efficiency (Reiss, 1986), unlike the species by species approach presented here, is shown to be incorrect.
There has been a considerable upsurge of interest recently in the concept of interspecific allometry (Gould, 1966), which relates to the scaling of individual characteristics to match body size in different species. Two particularly important developments have been taking place in theoretical aspects of allometry (e.g., see other contributions to this volume) and in the extension of allometric analysis to new fields of enquiry. One example of the application of allometric principles to an entirely new area of research is provided by the work conducted by Chivers and Hladik (1980) on the morphology of the gastrointestinal tract in primates and other mammals. Further development of this particular approach forms the subject of this chapter.
We address the interpretation of Plio/Pleistocene hominid 'home-base' sites in East Africa by integrating data from archaeology, primatology, and carnivore biology. Revisionist views of Plio/Pleistocene sites have emphasized the limited capacities of early hominids and the danger posed by large carnivores. We argue that flight and avoidance were not the most likely strategies for meat-eating hominids facing competition and increased risk of predation. Instead, we suggest, these pressures promoted increased sociality, cooperative protection from predators, and cooperative defense of resources. We present a resource-defense model of hominid land use in which, because meat represents a movable high-quality resource, hunted and scavenged carcasses were transported to focal sites that offered spatially fixed and defensible resources such as water, trees, and plant foods. Repeated use of such focal sites for a variety of diurnal and nocturnal activities would have resulted in a home-base or central-place pattern similar to that proposed by Glynn Isaac. However, we suggest that the use of home bases does not necessarily imply monogamy and a well defined sexual division of labor.
Rates of chimpanzee predation on mammals are calculated using data on 75 kills recorded during focal observation in Gombe National Park, Tanzania, from January 1972 to April 1975. The chimpanzees were members of two study communities (Kanyawara, or Northern, and Kahama, or Southern, community), and were observed as focal individuals for 14,583 hr by more than 30 researchers and field assistants working in pairs. The rate of predation by females was too low to allow reasonable estimates. For males, the mean rate of killing during the study period was 0.31 kills per male per 100 hr ( N =17 males), or 4.65 kills per 100 hr in the two communities. In contrast to results from Mahale Mountains, there was no difference in predation rate between wet and dry seasons. However, predation rates varied over time, increasing by four times between the first three and last four seasons of the sample period. In an average year the 15 adult and subadult male chimpanzees are calculated to have killed 204 prey per year in an area of 16 km 2 , varying between 99 and 420 prey per year in periods of low and high predation rate. Red colobus were the most frequent prey, followed by bushpig and bushbuck. Predation rates varied greatly on different prey species, and were not related to either the proportion of time spent within 200 m of male chimpanzees, or to their population densities. In relation to encounter rates and population density, baboons, blue monkeys, and redtail monkeys were killed at a fraction of the rate of red colobus monkeys, which suffered severe mortality from chimpanzee predation. Predation on bushpig and bushbuck also appears to have been high in relation to population density. The amount of food provided by predation is estimated to have averaged 600 kg per year for chimpanzees in the two communities (totalling 14–17 adult or subadult males, 18–20 adult of subadult females, and about 19 infants or juveniles). This suggests that adult males consumed around 25 kg of meat per year, although any average figure undoubtedly masks considerable individual variation. Present data suggest that chimpanzees in Gombe and Tai National Park, Ivory Coast, prey on mammals at rates higher than other populations. Peer Reviewed http://deepblue.lib.umich.edu/bitstream/2027.42/41607/1/10329_2006_Article_BF02380938.pdf
A generalized herbivore gut is modelled as (i) a well-stirred anterior chamber in which microbial fermentation occurs; (ii) a tubular reactor in which digestion but no fermentation occurs; and (iii) a posterior fermentation chamber. The rate at which the herbivore gains metabolizable energy is calculated for diets that can be eaten at different rates and contain different energy densities of easily digested cell contents, and of cell wall materials that can be fermented but not digested. The optimum gut structure for each diet is determined. Chewing probably speeds digestion and fermentation but reduces eating time. Optimal chewing times are determined for particular diets and guts. Herbivores often have a choice between poorer food that can be eaten fast and richer food that can only be eaten more slowly. Energy costs may be incurred in travelling between patches of the richer food. Optimal diet choices are predicted for herbivores with particular gut structures.
Taenia solium and Taenia saginata are of such close taxonomic relationship that each can be regarded as a model for the other. In these particular species the only available hosts are either humans or large domesticated animals. This has imposed severe safety and/or economic restrictions on the extent of the experimental work which could be attempted. Furthermore, there is a limit to the relevance of work with less closely related species such as Taenia ovis, Taenia taeniaeformis and Taenia pisiformis with their differing host species, larval forms and locations within the intermediate host tissue. However, the application of both monoclonal antibody based and modern molecular biological techniques to the T. solium and T. saginata systems does much to overcome or circumvent some of the problems. Thus advances made in the analysis, diagnosis or immuno-prophylaxis of one of these species are at least potentially both of direct and immediate or indirect benefit to the work on the other species.
The close correspondence often observed between the taxonomy of parasites and their hosts has led to Fahrenholz's rule, which postulates that parasites and their hosts speciate in synchrony. This leads to the prediction that phylogenetic trees of parasites and their hosts should be topologically identical. We report here a test of this prediction which involves the construction of phylogenetic trees for rodents and their ectoparasites using protein electrophoretic data. We find a high degree of concordance in the branching patterns of the trees which suggests that there is a history of cospeciation in this host-parasite assemblage. In several cases where the branching patterns were identical in the host and parasite phylogenies, the branch lengths were also very similar which, given the assumptions of molecular clock theory, strongly suggests that the speciation of these hosts and ectoparasites was roughly contemporaneous and causally related.
A total of 450 portions of grilled beef (suya) measuring 0.5--4 cms thick were prepared from a bovine carcass heavily infested with Taenia saginata cysticerci. After the "suya' were considered "cooked' and ready for human consumption, the cysticerci were dissected out of the meat and placed in petri dishes containing normal saline solution to which 30% ox-bile had been added and incubated at 37 degrees C for 1 to 2 hours. Of the 265 cysticerci recovered and treated 7(2%) showed clear signs of viability by evagination and motility.
Three categories of dietary adaptation are recognized—faunivory, frugivory, and folivory—according to the distinctive structural and biochemical features of animal matter, fruit, and leaves respectively, and the predominance of only one in the diets of most species.
Mammals subsisting mainly on animal matter have a simple stomach and colon and a long small intestine, whereas folivorous species have a complex stomach and/or an enlarged caecum and colon; mammals eating mostly fruit have an intermediate morphology, according to the nature of the fruit and their tendency to supplement this diet with either animal matter or leaves. The frugivorous group are mostly primates: 50 of the 78 mammalian species, and 117 of the 180 individuals included in this analysis are primates.
Coefficients of gut differentiation, the ratio of stomach and large intestine to small intestine (by area, weight, and volume), are low in faunivores and high in folivores; the continuous spread of coefficients reflects the different degrees of adaptation to these two dietary extremes.
Interspecific comparisons are developed by allowing for allometric factors. In faunivores, in which fermentation is minimal, the volume of stomach and large intestine is related to actual body size, whereas these chambers are more voluminous in larger frugivores and mid-gut fermenting folivores; fore-gut fermenters show a marked decrease in capacity with increasing body size. Surface areas for absorption are related to metabolic body size, directly so in frugivores; area for absorption is relatively less in larger faunivores and more in larger folivores, especially those with large stomachs.
Indices of gut specialization are derived from these regressions by nonlinear transformation, with references to the main functional features of capacity for fermentation and surface area for absorption.
These are directly comparable with the dietary index, derived from quantitative feeding data displayed on a three-dimensional graph, with all species within a crescentic path from 100% faunivory through 557ndash;80% frugivory to 100% folivory, perhaps illustrating, at least for primates, the evolutionary path from primitive insectivorous forms through three major ecological grades.
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An Introduction to Human Evolutionary Anatomy
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