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Homo sapiens: the first self-endangered species

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CHAPTER TWO
HOMO SAPIENS:
THE FIRST SELF-ENDANGERED SPECIES
TELMO PIEVANI AND ANDRA MENEGANZIN
ANTHROPOCENE DEFAUNATION: A VERY RISKY
TRANSITION
Edward O. Wilson, Niles Eldredge, Peter Ward and Norman Myers, all
distinguished evolutionists and biodiversity experts, claimed twenty years
ago that, in light of the dramatic rate of extinction of species induced by
human activities in recent centuries, the biosphere is going through a
‘mass extinction’, that is, a rapid loss of biodiversity on a global scale
(Eldredge, 1995, 1998; Myers & Knoll, 2001; Ward, 1994, 2000; Wilson,
2003). More precisely, they argued, we are confronting the Sixth Mass
Extinction, that is, nothing less than the last five catastrophes caused by
volcanic eruptions, ocean acidification, climatic fluctuations, changes in
the atmosphere’s composition, impacts of asteroids on Earth, or a
combination of these factors. The last of these was the best-known
massive event that 66-65 million years ago wiped out most of the
dinosaurs (except a small branching group that evolved into birds) and
almost two-thirds of all other organisms, and is known as the Cretaceous-
Tertiary extinction (K-T). As regards the speed of impact and the mortality
rate, Wilson and his colleagues argued (Eldredge, 1995, 1998; Ward 1994,
2000; Myers & Knoll, 2001; Wilson, 2003), the ongoing extinctions
caused by Homo sapiens today can be fairly comparable with the previous
five.
The official label “Sixth Mass Extinction” was first introduced by the
paleoanthropologist Richard Leakey and science writer Roger Lewin to
indicate the anthropic sequel of the Big Five in 1992, denouncing the
destruction of biodiversity (mainly large mammals) in Africa (Leakey &
Lewin, 1992). Two pioneering studies, separately proposed in 1995 by
Chapter Two
Robert May and Stuart Pimm’s authoritative teams (Lawton & May, 1995;
Pimm et al., 1995), gave the first confirmations. If we compare the rates
and amounts of extinction during the recorded mass extinctions with the
range of species losses over the past few centuries, we see very similar
trends. But what kind of evidence do we have that humans are now
allowing or even causing a new mass extinction?
At that time, the thesis was based on inevitably inaccurate statistics,
and described with the language of militant ecologist movements rather
than empirical science. Many received it as an exaggeration, a yielding to
‘catastrophism’. After all, it was estimated that the Earth could still be
inhabited by at least five million animal species. Several studies, however,
began to use the label “Sixth Mass Extinction”. In 2010, Hoffmann et al.
reported alarming percentages of extinction in amphibians, corals,
freshwater molluscs and sharks, in addition to mammals, reptiles and
birds.
In March 2011, an international team from Berkeley led by the
palaeontologist Anthony D. Barnosky verified the measures of “recent”
extinctions over the last few millennia by integrating palaeontological data
and current accounts in order to provide all the necessary statistical
precautions. They came to a rather worrying conclusion, which was
published in Nature (cf. Barnosky et al., 2011): the Sixth Mass Extinction
is not yet underway, but we are close, and doing nothing to stop it. The
title of Nature’s article was: “Has the Earth’s sixth mass extinction already
arrived?” The extinction rates of the past 500 years (22% in mammals, 47-
56% in gastropods and bivalves) far exceed those recorded in the fossil
record for the five major extinctions of the past 540 million years. Thus we
are on a mass extinction trajectory, with accelerating rates: “Our results
confirm that current extinction rates are higher than would be expected
from the fossil record. (…) The Earth could reach the extreme rates of the
Big Five mass extinctions within just a few centuries if current threats to
many species are not alleviated” (Barnosky et al., 2011, 51). Humans may
be more effective exterminators than asteroids and volcanic eruptions.
In July 2014, further confirmation was published in Science, and now
the statistics are becoming increasingly realistic. According to the refined
calculations produced by the ecologist Rodolfo Dirzo’s team at the
Department of Biology at Stanford, human impacts on animal biodiversity
are bringing about global environmental changes that are going to show
increasing effects on ecosystems’ functioning and on the health of our own
species (Keesing et al., 2010; Civitello et al., 2015; Ostfeld, 2017). Our
planet is no longer the same. The current analysis is not just based on
indirect extrapolations and calculations of the disappearances of whole
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Homo Sapiens: the first self-endangered species
species, but also on the demographic and biogeographic trends of local
populations in recent decades. The population level is crucial: for genetic
reasons, the size of a biological population is inversely related to the
vulnerability to extinction.
Every year we are losing a total amount of 11,000 to 58,000 species,
concentrated mainly in tropical regions (the level proposed by Edward O.
Wilson in 2003 was 30,000 species a year, perfectly in the midst of this
range). One species is being lost every twenty minutes. We are extinguishing
species that we have not yet even had time to describe. The frightening
technical term coined for this phenomenon by Rodolfo Dirzo in Science is
“Anthropocene defaunation” (Dirzo et al., 2014). Note that the hitherto
informal term “Anthropocene”, proposed by Paul Crutzen in 2002 in
Nature, is unofficially entering the scientific jargon (although there is no
consensus about its real utility and its starting point inside the Holocene)
(Lewis & Maslin, 2015; Monastersky, 2015). The current human impacts
are sufficiently large to be recorded in geological records. This represents
a singular evolutionary transition because, for the first time in the Earth’s
history, a single species, Homo sapiens, has become a major geological
force. Within a few centuries, our species has been successful in altering
the composition of the atmosphere and transforming the surface of the
planet at a level visible in the stratigraphic record (Crutzen, 2002). Hence
the justification for the name ‘Anthropocene’ for the new geological
epoch.
We do not pay money for ecosystem services, and therefore we are
often unaware of the true cost of maintaining them. But with the
disappearance of thousands of species every year, ecosystems are
becoming progressively less efficient in ensuring their services, such as
water purification, nutrient cycling and soil maintenance. The genetic
variability of populations and species is the fuel of evolution, free
insurance against adversities and attacks from pathogens. In the
Anthropocene, we are losing that vital genetic diversity (Novacek, 2001)
and late interventions will be much more expensive. As an example, 75%
of food crops in the world depend on pollinators. All of the above
concerns the effects of extinction, but what about the causes?1
THE FORTHCOMING MASS EXTINCTION
According to recent data, the Sixth Mass Extinction and the previous
Big Five share the same proximate geophysical causes for the loss of
1 For an extended discussion of this issue, see Pievani (2015).
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Chapter Two
biodiversity, making the comparison among them not a matter of
suggestive metaphors, but a valuable insight with regard to understanding
current environmental crises. Gerta Keller, Professor of Palaeontology and
Geology at Princeton University, proposed, along with her team (Keller,
2008), a model for the multiple convergent factors that caused the
extinction at the end of the Cretaceous. Keller argues that a theory for
mass extinctions cannot point at a single catastrophic cause to explain
macro-evolutionary patterns, since these result from a mix of different and
simultaneous conditions. For example, there is general agreement in
recognising that a single asteroid could not have been the only cause of the
mass extinction at the end of the Cretaceous, but rather a major
contributing factor. This means that the extinction’s magnitude would have
been lower in the absence of other stressors that had already triggered the
pump of extinction. This also applies for the past mass extinctions, and
may perhaps hold in the near future too.
According to such models (Arens & West, 2008; Brook et al., 2008), a
mass extinction will only occur when a synergy between unusual events
arises, like in a “perfect storm” when different critical parameters
converge. Namely, the three major processes, and the consequences of
their interactions, are as follows:
1 – accelerated climate change;
2 – alterations of atmospheric composition;
3 – ecological stresses with abnormal intensity.
4 – Along with positive feedback among the three.
The convergence of these processes has resulted in mass extinctions in
the past: “the loss of more than three-quarters of species in a geologically
short interval” (Barnosky et al., 2011, 51-52). The pump of extinction
starts its pruning with the branches of many different phylogenetic lines,
eventually reaching a peak, a culminating event like a collision or multiple
volcanic eruptions, that unleashes the final wave of global crisis (some
mass extinctions are composed of several waves of extinction). The
question now is if it is possible to apply the “Perfect Storm Model” to the
impact of human activities on biodiversity. According to Barnosky and his
colleagues (Barnosky et al., 2011), the current situation fits the description, as
follows:
1 – accelerated climate change? YES, in progress.
2 – alterations of atmospheric composition? YES, in progress.
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Homo Sapiens: the first self-endangered species
3 ecological stresses with abnormal intensity? YES, due to human
activities, since a long time ago.
4 – Positive feedback among the three? YES, in the early phase of this.
All the key conditions are met. In such a perfectly created storm, not
even catastrophic events like a large asteroid impact or a devastating
volcanic eruption are required to strike a fatal blow. According to Pereira
et al. (2010), in the absence of better and more efficient policies aimed at
mitigating the damage, global biodiversity will maintain its downward
trend over the 21st century
As can be seen, the key parameters of the ‘perfect storm’ are proximate
geophysical causes of mass extinctions, analysed from a paleontological
perspective. But what about the remote causes that placed Homo sapiens
in the condition of detonating a global geological and environmental crisis
of such proportions? It is an old story indeed. The last branch of genus
Homo flourished by out-competing at least three other human species. It is
well established that when Palaeolithic hunters colonised the Americas,
Australia, and Pacific Islands – even if some doubts remain about the role
played by concomitant climate oscillations – dozens of large mammals and
flightless birds who lived there died off within a few millennia of their
arrival. The archaeological record – today based on comprehensive
country-level data on the distribution of these large-bodied animals –
shows a series of regional mass extinctions of megafauna, as the animals
of these regions were unused to human contact and predation and had low
reproductive rates, making them particularly vulnerable. Thus the
destructive environmental impact of our species began in earnest towards
the end of the Pleistocene (Cavalli-Sforza & Pievani, 2012).
There is, however, an ongoing debate within the geologist community
on the problem of assessing the anthropogenic signatures in the geological
record and on the criteria that should be followed to formally mark the
beginning of a whole new geological epoch, the Anthropocene. The impact
of human activity should define a unique stratigraphic unit, observable in
geological and stratigraphic material (rocks, glacial ice, marine sediments)
for millions of years in the future (Lewis & Maslin, 2015).
Today, no formal agreement has yet been reached on where to set the
starting date of such a new geological epoch. Scholars are divided among
different options, based on the event or process they find most eligible to
mark the beginning of the Anthropocene. For example, the already
mentioned megafauna extinction between 50,000 and 100,000 years ago
that wiped out about half of the large-bodied animals around the world
was among the first proposed candidates. It is debated whether the uneven
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Chapter Two
losses across continents (18% in Africa, 36% in Eurasia) and the different
timings make the extinction lack the required precision for an
Anthropocene marker.
Another candidate is the origin of agriculture that first occurred around
11,000 years ago in South America, Southwest Asia and China, but that
still lacks global synchrony. More recently, the arrival of Europeans in the
Caribbean (1492), which has always been considered a major event in
world history, has been proposed as an Anthropocene marker too, due to
the rise of global trade and therefore the globalisation of human foodstuffs
and domesticated species, with well-preserved deposits of pollen marking
a stratigraphic change. Other options are the Industrial Revolution, due to
the accelerated fossil fuel use and societal changes at a global scale, and
1964, when the Great Acceleration reached a peak in anthropogenic
impact with the nuclear explosions.
It is important to note that setting an earlier date for the beginning of
Anthropocene should not mean ‘normalising’ the anthropogenically-
induced environmental change. Long-term processes must not be
politicised in terms of inevitable outcomes, thus lowering the sense of
responsibility of contemporary Homo sapiens and discouraging
environmental policies. From an evolutionary perspective, our interpretation
places the premise for today’s ecological dominance of our species in the
deep time of human history, at the end of the Pleistocene.
WE KNOW THE CAUSES
This story, therefore, does not present a single anthropic activity that is
causing the bad fate of biodiversity today. It has deep roots in human
history. Through a mix of different behaviours with variable impacts, we
have produced the conditions for a global and rapid extinction crisis. In
other words, the Anthropocene signals the fact that Homo sapiens has
become a dominant evolutionary force (Pievani, 2013). According to the
“HIPPO” causal model proposed by Edward O. Wilson (2010), updated
and revisited here (HIPPOC), the human impact on biodiversity is due to a
convergence of different and interacting factors:
H – Habitat fragmentation and alteration of species-areas relationships
(i.e. forest clearance, conversion into pasture, and intensive
cultivations, mining and quarrying activities);
I Invasive species and diffusion of new pathogens (the inter-
continental remixing of alien species due to travel and commerce
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Homo Sapiens: the first self-endangered species
has been able to cause mass extinctions on scales from local to
entire regions, as well as on islands and archipelagos);
P Population growth and urban macro-agglomerates (producing
barriers and limitations to the dispersal of animals and plants);
P Pollution (agricultural, industrial and chemical pollution of air,
water and soils);
O Overexploitation of biological resources by overfishing and
overhunting;
C Climate change: initially characterised only in crude estimates,
current models include climatic warming and growing evidence for
ecological mismatches in the seasonal cycles of species (mostly in
long-distance migratory birds), polar species becoming endangered,
the restructuring of ecological communities in tropical forests, and
alarming global effects triggered by ocean acidification (mostly in
coral reefs) (Pievani, 2015).
In addition, we should consider the non-linear interactions between the
six forces (for example, the fragmentation of territory and global warming
in tropical forests; devastating synergic effects of pollution,
overexploitation and climate change on coral reefs). This unprecedented
relationship between a globally invasive species and the biosphere
generates an evolutionary gap: the rates of biological evolution (i.e.
biogeographical displacements, adaptations to different temperatures, etc.)
are on average ten times slower than the rates of human-caused changes,
so the usual processes of ecological recovery after disturbance are being
overridden.
A distinction, however, needs to be drawn between two extinction
processes in biohistory. The background extinctions of species are normal,
steady (and necessary) processes in the economy of nature that occur at
relatively low rates and which result from the ongoing evolutionary
processes in environments characterised by high competition and limited
resources. In contrast to this, the major turnover-pulses of evolution had
far more dramatic rates and consequences. Those mass extinctions were
global catastrophes under which entire classes of terrestrial and sea
biodiversity collapsed (Bambach, 2006), like at the end of the Ordovician
(445 million years ago, related to a glaciation event); at the end of the
Devonian (360 million years ago); and at the end of the Triassic (200
million years ago, the mass extinction that paved the way for the
dinosaurs). It is interesting to note that the victims of one mass extinction
may well have been the lucky survivors of a previous one.
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The pattern of this periodic pruning of the tree of life is distinct from
background extinctions (which have an average rate of 2-4 taxonomic
families disappearing every million years), as if the ‘business as usual’ of
evolution were not simply accelerated but temporarily overwhelmed. Mass
extinctions unleash a disruptive power in a relatively short time on a
geological scale, and they strike across all classes and orders with low
selectivity.
THREATENING THE SURVIVAL OF OUR OWN CIVILISATION
The human-induced extinction wave we are witnessing today is likely
to bring self-harming consequences for our own species, since the ongoing
decimation of life-forms is also affecting the life-support conditions and
the ecosystem services on which our civilisation depends (Daily &
Matson, 2008; Cardinale et al., 2012; Ceballos et al., 2015). Humans’
dependence and impact on biodiversity have mostly been studied as
separate phenomena, but today’s urgency of rethinking the policies of
conservation demand an integrated perspective that must not be confined
to merely ethical and emotional appeals.
Plants, nonhuman animals and microbes define the ecological niche we
live in a delicate equilibrium of interdependent relationships, in which
we do not only represent the major active modifiers of the environmental
states and the selective pressures at work, but in which we are also
modified by the ecological and evolutionary feedback that the niche
returns to its constructors. “Niche Construction Theory” (NCT) (Odling-
Smee et al., 2003) provides a useful theoretical framework to appreciate
the current unsustainability of the human niche and the self-endangering
feedback at stake, providing an integrative scenario in which Homo
sapiens can no longer be treated as a mere exogenous phenomenon
(Albuquerque et al., 2014).
Unlike many other species that alter the environment through their
metabolic, physiological and behavioural activities, the major alterations
we impose are driven by our socially transmitted information and culture
(Laland & O’Brien, 2012). As we have seen, the major evolutionary event
that triggered a cascade of effects in the selective pressures was the
introduction of agriculture and the domestication of species. By the time
Homo sapiens reached the capacity for ecosystem engineering, the
biosphere had undergone dramatic changes, with the reshaping of global
species’ distribution and the introduction of new ones. These resulted from
intensive and complex niche construction activities that responded to the
17
Homo Sapiens: the first self-endangered species
needs of industrial economies, of an expanding population and of the
reinforcement of the transport network (Boivin et al., 2016).
The legacies of change in both biota and abiota, usually referred to as
“ecological inheritance” (Odling-Smee, 1988), do not require the existence
of environmental replicators but of the intergenerational persistence of the
causes of change (mainly through repeated acts of construction) (Laland &
O’Brien, 2012). This identifies a different form of inheritance than the
inheritance of genes: the transmission includes material resources that are
passed down to later generations without reproduction, but through an
external environment. Multiple organisms (not only genetic relatives) are
involved in a constant transmission process (i.e. not confined to single
reproductive events) to many other organisms throughout their whole
lifetime, within and between generations. When it comes to Homo sapiens,
as seen in previous paragraphs, the predominance of the human niche over
the biosphere has become increasingly alarming.
In environmental conservation and ecology, the impact of human
action has traditionally been investigated in two forms: acute disturbances
(drastic environmental changes) and chronic anthropogenic disturbances
(CAD; Singh, 1998). In the case of tropical forests, where the impact of
CAD is studied most, clear-cutting, logging, anthropogenic fires fall
within the first definition, whereas the chronic form is characterised by
more subtle activities that remove only a small fraction of biomass at a
time, but at a constant rate and for the long term. Such activities are, to use
the same example, the collection of firewood, fodder and secondary forest
products (seeds, leaves, tree oils, etc.). The main problem with chronic
activities is the fact that their persistence does not allow enough time for
the ecosystems to recover adequately, making CAD one of the most
widespread sources of habitat degradation in developing countries (Singh,
1998) and a cause of the decrease in taxonomic and phylogenetic
diversities (Ribeiro et al., 2015; Ribeiro et al., 2016). Human-driven
ecological disturbances, along with better-known drivers of biodiversity
loss like habitat fragmentation and defaunation, provide important
examples of human niche construction, whose effects persist for longer
than the lifetime of the constructors themselves and are passed on to the
following generations (ecological inheritance).
In NCT, organisms, including Homo sapiens, and environments are
engaged in reciprocally caused relationships that are at play both on the
ontogenetic and on the phylogenetic timescales. We have already explored
one form of this relationship in the previous sections by analysing the
history and magnitude of human impact on global biodiversity; it is crucial
now to explore the second form by focusing on the impact of biodiversity
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loss on human activities and health. There is a vast array of phenomena
that can be fruitfully analysed from a niche construction perspective,
ranging from the ecological and economic impact of pollinator declines to
the global consequences of overfishing and ocean acidification. Here we
will go through a couple of examples related to our health and the ecology
of infectious diseases.
There is a burgeoning body of literature that is beginning to show that
reduced biodiversity affects the transmission of pathogens to human
beings, livestock, wildlife and plants (Keesing et al., 2010; Civitello et al.,
2015; Ostfeld, 2017). The reasons behind the inhibitory effect on
pathogens displayed by environments with high biodiversity are linked to
biotic homogenisation and the so-called ‘dilution effect’, which arises
from the following observations. The majority of infectious human
diseases have a zoonotic origin, with pathogens that are for the most part
host generalist, meaning that they are capable of infecting multiple species
of the host (that vary in their susceptibility to infection). The reservoir-
hosts – the species that are more likely to acquire and transmit diseases
are those that are the most widespread, overrepresented and resilient to the
perturbations induced by humans. Consequently, higher interspecific
diversity (that includes species sensitive to anthropogenic perturbations)
can ‘dilute’ the effect of the reservoir species and the general risk of
infection.
A study conducted by researchers at the University of São Paulo, Brazil,
found that, in tropical forests, biodiversity can play a role in preventing
malaria outbreaks due to two different mechanisms: the dilution effect
provided by warm-blooded mammals acting as a biological ‘shield’ for
human people and the competition between vector and non-vector
mosquito species for blood feeding (Laporta et al., 2013). Malaria is
reported to have caused 429,000 deaths and 212 million new cases in 2015
(World Malaria Report, 2016), making it a concrete threat to nearly half of
the world’s population Sub-Saharan Africa still carries the greatest
portion of the global burden.
Another important case which is worth mentioning here is the Ebola
outbreak in West Africa, which is hypothesised to have been the result of a
combination of policy-driven changes in Guinea and Liberia, brought
about by neoliberal development (Wallace et al., 2014). According to such
hypotheses, the increase in oil palm plantations (Elaeis guineensis) in
Guinea’s forested regions seems to have strongly impacted the forest
epizoology. The first case of Ebola in West Africa was documented in the
Guéckédou area, with a landscape characterised by a mosaic of villages
enclosed by dense vegetation, with crop fields of oil palm that provide an
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Homo Sapiens: the first self-endangered species
ideal man-bat interface. Frugivore bats (Chiroptera, Pteropodidae) are a
key Ebola reservoir (healthy carriers), and they are attracted to oil palm
trees, where they migrate in search of food and shelter, thus shifting their
foraging behaviour as the forest gradually disappears. The lethal virus can
be transmitted through direct contact with the infected animal via
contaminated body fluids.
A more recent study (Olivero et al., 2017) got to the bottom of the
coupling between the loss of closed forests and the Ebola virus disease
outbreaks by confirming an increased probability of an Ebola outbreak in
sites that suffered recent deforestation events. A possible explanation is
that deforestation is likely to push infected wild animals into areas
inhabited by humans, increasing the probability of contact between them,
by disrupting animal movements and population densities. This provides a
straightforward case of undesired feedback induced by politically- and
economically-driven niche activities that impact the population
distribution of the endemic fauna and the ecosystem ecology in general,
reminding the representatives of Homo sapiens of their role and weight in
the interconnected nature of an ecosystem. As we know, pathogens are
among the strongest selective forces that have acted on human populations
throughout our entire evolutionary track. Since pathogens diminish the
host’s reproductive potential, due to poor health or death, selection is
therefore driven on the genetic variants that affect resistance, increasing
the frequency of favoured alleles, and decreasing that of detrimental ones
(Karlsson et al., 2014). This means that through changes in biodiversity
(and therefore in our niche), we are not only affecting the evolutionary
trajectories of other species (Palumbi, 2001), but also our own evolution,
posing new challenges that can reshape, in the long-term, the distribution
of human populations on the planet.
THE COST OF HUMAN NICHE CONSTRUCTION
The fact that one species interferes with the ecological equilibria and
the evolutionary trajectories of other species by altering the pace of
evolutionary change, modifying the population distribution or altering the
ideal environmental conditions for them to prosper is still part of natural
history. As regards extinction, about 99.9% of species that ever existed are
extinct. What is unprecedented today is the role of one species in
triggering a global mass extinction event, the fastest of all time, which
clearly presents harmful recoil effects for the dominant species itself.
Homo sapiens is actively altering the conditions that ensure its own stay
on the planet. To put it differently, the Anthropocene extinction is a threat
20
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not for biodiversity itself, but for the ecological conditions that currently
allow human survival. In a human niche construction perspective, the
beginning of Anthropocene should be established at the time when
anthropogenic-transformative niche activities became dominant over the
biosphere.
Even if the Sixth Mass Extinction cannot be considered a done deal,
the sad irony of the story is that our efforts to slow or stop the Sixth Mass
Extinction may not be enough. According to Butchart et al. (2010), one of
the outcomes of the United Nations Convention on Biological Diversity
local conservation initiatives – are multiplying and having success. It may
not be enough to reverse the general trends of habitat destruction, but
averting the dizzying decay of biodiversity loss and the ecosystem
services’ degradation is still possible, although the window for making
concrete changes is rapidly closing. This is the grand challenge for society
and researchers that must be solved within the next few decades. The
deadline can no longer be postponed. Pollution, long-lasting consequences
of climate change, disease outbreaks (as analysed in the previous section),
overpopulation and the overconsumption of resources must become a
priority in the global policy agenda.
In order to reach effective and rapid results, particular attention should
be paid to the economic impact of biodiversity loss and the risks for global
health i.e. the eco-evolutionary feedbacks that are already impacting
Homo sapiens. In the worst-case scenario, however, even if we are so
myopic as to endanger the conditions of our survival, scientific models tell
us that life will carry on anyway in other forms (Weisman, 2008), probably
to the advantage of the most opportunistic species, such as rats
(Zalasiewicz, 2008). Indeed, just after our departure, a cornucopia of new
experiments of life, like after every previous mass extinction, would
plausibly blossom on Earth. The end of our species would only represent
another new beginning. From a philosophical point of view, the Sixth
Mass Extinction can provide an anthropological warning about the
contingency of life and the fragility of our story as hominins.
Author contribution statements
Telmo Pievani contributed to this paper with sections 1, 2 and 3.
Andra Meneganzin contributed with sections 4 and 5.
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Homo Sapiens: the first self-endangered species
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Article
Wildlife protection and management are important priorities for landscape identity and biodiversity preservation. Feeding practices of fauna confined in facilities during temporary captivity are fundamental to support animal health and natural behaviour. Appropriate provision of feedstuffs appears to be necessary to support the best practices in respect of animal species-specific natural diet. This investigation explored the variation of the metabolic profile by means of selected metabolite and respective circulating levels in a group feral Giara horses undergoing the change of the diet, moving from natural free grazing in the wild to temporary captivity. Six Giara horses (4 mares and 2 stallions; estimated age: 2.5 to 3 ys; body weight: 163 - 170 kg) were captured to monitor the serological reaction to Equine Infectious Anaemia (EIA,screening at Coggins test). Animals were sheltered in a wildlife rescue center for a duration of four weeks and all received the same hay-based diet (ad libitum). On 0d and 28d of captivity, blood serum alpha-tocopherol (α-TOH) concentration was determined alongside selected metabolites (liver enzymes, total protein and fractions, cholesterol, triglycerides and macrominerals and trace elements). Comparative feces quality and composition were also assessed. Both serum samples (0d vs. 28d) displayed α-TOH levels below (<2 μg/ml) adequacy established for the domestic horse. Initial levels markedly (p=0.020) decreased after the four weeks of captivity (Δ= -32.5%). Vitamin E status and ALT levels varied significantly, but serum protein fractions did not point to significant variations before and after captivity. All horses tested negative to EIA. Monitoring of vitamin E status of wild and feral herbivores may be recommendable in the context of adequate feeding practices during captivity in order to prevent potential deficiency or excessive depletion.
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