Thriving or surviving? The isotopic record of the Wrangel Island woolly mammoth population
Arppe et al.
Quaternary Science Reviews, 2019
Scenarios related to water quality problems stemming from increased weathering, and a possibility of a catastrophic starvation event as a cause of, or contributing factor in their demise are discussed.
Disappearance of Icelandic walruses coincided with Norse settlement
Keighley et al.
Molecular biology and evolution, 2019
The high value of walrus products such as ivory on international markets likely led to intense hunting pressure, which – potentially exacerbated by a warming climate and volcanism – resulted in the extinction of walrus on Iceland. We show that commercial hunting, economic incentives and trade networks as early as the Viking Age were of sufficient scale and intensity to result in significant, irreversible ecological impacts on the marine environment. This is to one of the earliest examples of local extinction of a marine species following human arrival, during the very beginning of commercial marine exploitation.
Il y a toujours eu des poussées d’extinctions d’espèces, notamment lors d’événéments climatiques violents. Mais les extinctions des 125 000 dernières années sont différentes : elles touchent plus spécifiquement la mégafaune au paléolithique, ce qui conduit les auteurs à conclure que ce sont bien les humains qui sont responsables des extinctions particulièrement importantes du paléolithique supérieur.
Body size downgrading of mammals over the late Quaternary
Smith et al.
Here, we quantify mammalian extinction selectivity, continental body size distributions, and taxonomic diversity over five time periods spanning the past 125,000 years and stretching approximately 200 years into the future. We demonstrate that size-selective extinction was already under way in the oldest interval and occurred on all continents, within all trophic modes, and across all time intervals. Moreover, the degree of selectivity was unprecedented in 65 million years of mammalian evolution. The distinctive selectivity signature implicates hominin activity as a primary driver of taxonomic losses and ecosystem homogenization. Because megafauna have a disproportionate influence on ecosystem structure and function, past and present body size downgrading is reshaping Earth’s biosphere.
Big data little help in megafauna mysteries
Price et al.
But in our view, the ‘big-data’ approach cannot, at this point, get us closer to an answer. There simply aren’t enough good-quality data. An understanding of what drove the extinctions requires detailed analysis on a species-by-species basis. This means investing effort into finding more fossil specimens and verifying the ages of those that have already been discovered using improved dating methods. It also means relating the timing of species’ existence and disappearance to detailed local environmental, climatic and archaeological records.
Population reconstructions for humans and megafauna suggest mixed causes for North American Pleistocene extinctions
Broughton & Weitzel
Nature communications, 2018
The results suggest that the causes for extinctions varied across taxa and by region. In three cases, extinctions appear linked to hunting, while in five others they are consistent with the ecological effects of climate change and in a final case, both hunting and climate change appear responsible.
The Evidence for Human Agency in the Late Pleistocene Megafaunal Extinctions
Encyclopedia of the anthropocene, 2018
But the extinctions at the end of the Pleistocene are uniquely different because they unfolded almost instantly on an evolutionary timescale and had a disproportionate bias for megafauna, a term once applied to any animal larger than a rabbit and now meaning animals with average adult body mass44 or 45 kg (100 lbs). Alroy (2001, p. 1893) deemed the Late Pleistocene extinctions “unparalleled in the deeper fossil record” of North America, which they also seem to be on the other continents. This set of extinctions is not just another example of natural processes eliminating many animal genera; it is a first sign of irreversible human effects on the biosphere.
Plio-Pleistocene decline of African megaherbivores: No evidence for ancient hominin impacts
Faith et al.
The record of sloth coprolithes in north and south America : implications for terminal pleistocene extinctions.
Hunt & Lucas
New Mexico Museum of Natural History and Science Bulletin, 2018
There is an acme of sloth coprolite preservation in the latest Pleistocene (also the only latrinites of Mammuthus and Bison) whichsuggests greater usage of caves by large herbivores at this time. The pattern of preservation of sloth coprolites suggests that climate rather than overkill was most significant in the extinction of ground sloths.
The large mean body size of mammalian herbivores explains the productivity paradox during the Last Glacial Maximum
Dan Zhu et al.
Nature ecology and evolution, 2018
The present-day results of potential grazer biomass, combined with an empirical land-use map, infer a reduction in wild grazer biomass by 79–93% owing to anthro-pogenic land replacement of natural grasslands. For the LGM, we find that the larger mean body size of mammalian herbivores than today is the crucial clue to explain the productivity paradox, due to a more efficient exploitation of grass production by grazers with a large body size
Chronological and Isotopic data support a revision for the timing of cave bear extinction in Mediterranean Europe
Terlato et al.
Historical biology, 2018
The carbon (δ13C) and nitrogen (δ15N) isotopic values of bone collagen exhibit values similar to those of older cave bears from Swabian Jura and France, suggesting that the feedings preferences of cave bears remained unchanged until the disappearance of this species in Europe. Several bear remains preserved traces of human modification such as cut marks, which enables a reconstruction of the main steps of fur recovery and the butchering process.
Humans rather than climate the primary cause of Pleistocene megafaunal extinction in Australia
Van der Kaars et al.
Nature communications, 2017
We record high levels of the dung fungus Sporormiella, a proxy for herbivore biomass, from 150,000 to 45,000 years ago, then a marked decline indicating megafaunal population collapse, from 45,000 to 43,100 years ago, placing the extinctions within 4,000 years of human dispersal across Australia. These findings rule out climate change, and implicate humans, as the primary extinction cause.
Au moins localement, les populations animales ont pu résister plus longtemps à la colonisation humaine.
At least 17,000 years of coexistence: Modern humans and megafauna at the Willandra Lakes, South-Eastern Australia
Westaway et al.
Quaternary Science Review, 2017
We show that there is at least 17,000 years of overlap between people and megafauna at one of Australia’s richest archaeological landscape.
The research undermines the rapid kill hypothesis and suggests that megafauna extinction was likely the results of a combination of factors.
It is clear that much more research is required if we are to understand how the Australian megafauna became extinct.
Climate change, human overkill, and the extinction of megafauna: a macroecological approach based on pattern-oriented modelling
Matheus S. Lima-Ribeiro & José Alexandre F. Diniz-Filho
Evolutionnary ecology research, 2017
such overkill scenarios unrealistically predicted earlier extinction times than that observed for Megatherium. Moreover, the high human population growth required to simulate overkill scenarios was attained only recently after the industrial revolution, specifically in the mid-1900s, and it is therefore not applicable for Pleistocene hunter-gatherers. Conversely, although less frequent across simulations, models that correctly predicted the observed extinction time (16%) revealed plausible and empirically acceptable demographic parameters, encompassing low growth rates (rh<0.70%) and mortality for the human population(mo<0.60%), combined with moderate values of individual meat consumption (CI>70 g) andgeographical range collapse in Megatherium, which is produced by climate change. Conclusions: These findings, based on POM reasoning, highlight that unique mechanisms such as the overkill explanation for LQE, although feasible from model simulations, only occur with implausible parameter combinations and predict unrealistic extinction dynamics.
On the roles of hunting and habitat size on the extinction of megafauna
Abramson et al.
Quaternary international, 2017
We show that the presence of hunters drives the superior herbivore to extinction even in habitats that would allow coexistence, and even when the pressure of hunting is lower than on the inferior one. The role of system size and fluctuating populations is addressed, showing an ecological meltdown in small systems in the presence of humans. The time to extinction as a function of the system size, as calculated with the model, shows a good agreement with paleontological data. Other findings show the intricate play of the anthropic and environmental factors thatmay have caused the extinction of megafauna.
Climate warming and humans played different roles in triggering Late Quaternary extinctions in east and west Eurasia
Xinru Wan & Zhibing Zhang
The royal society publishings, 2017
Here, our analyses showed that temperature change had significant effects on mammoth (genus Mammuthus), rhinoceros (Rhinocerotidae), horse (Equidae) and deer (Cervidae). Rapid global warming was the predominant factor driving the total extinction of mammoths and rhinos in frigid zones from the Late Pleistocene and Early Holocene. Humans showed significant, negative effects on extirpations of the four mammalian taxa, and were the predominant factor causing the extinction or major extirpations of rhinos and horses. Deer survived both rapid climate warming and extensive human impacts.
What caused extinction of the Pleistocene megafauna of Sahul?
Johnson et al.
Proceedings of the royal society B, 2016
During the Pleistocene, Australia and New Guinea supported a rich assemblage of large vertebrates. Why these animals disappeared has been debated for more than a century and remains controversial. Previous synthetic reviews of this problem have typically focused heavily on particular types of evidence, such as the dating of extinction and human arrival, and have frequently ignored uncertainties and biases that can lead to misinterpretation of this evidence. Here, we review diverse evidence bearing on this issue and conclude that, although many knowledge gaps remain, multiple independent lines of evidence point to direct human impact as the most likely cause of extinction.
Climate change not to blame for late Quaternary megafauna extinctions in Australia
Saltré et al.
Nature communications, 2016
When coupled with analysis of several high-resolution climate records, we show that megafaunal extinctions were broadly synchronous among genera and independent of climate aridity and variability in Australia over the last 120,000 years. Our results reject climate change as the primary driver of megafauna extinctions in the world’s most controversial context, and instead estimate that the megafauna disappeared Australia-wide ∼13,500 years after human arrival, with shorter periods of coexistence in some regions. This is the first comprehensive approach to incorporate uncertainty in fossil ages, extinction timing and climatology, to quantify mechanisms of prehistorical extinctions.
Synergistic roles of climate warming and human occupation in Patagonian megafaunal extinctions during the Last Deglaciation
Metcalf et al.
Science Advances, 2016
We identify a narrow megafaunal extinction phase 12,280 ± 110 years ago, some 1 to 3 thousand years after initial human presence in the area. Although humans arrived immediately prior to a cold phase, the Antarctic Cold Reversal stadial, megafaunal extinctions did not occur until the stadial finished and the subsequent warming phase commenced some 1 to 3 thousand years later. The increased resolution provided by the Patagonian material reveals that the sequence of climate and extinction events in North and South America were temporally inverted, but in both cases, megafaunal extinctions did not occur until human presence and climate warming coincided. Overall, metapopulation processes involving subpopulation connectivity on a continental scale appear to have been critical for megafaunal species survival of both climate change and human impacts.
The controversy space on Quaternary megafaunal extinctions
Monjeau et al.
Quaternary international, 2015
We postulate that nowadays this controversyspace is suffering a period of conceptual blockage. This may be because authors are assembled aroundtwo major paradigms: environmental versus anthropic causes. Each of these two theoretical positionslooks at a portion of reality that may be partially true, but incomplete in terms of a global theory ofextinction. We propose that this conceptual blockage could be solved by developing a mathematicalmodel in which each hypothesis plays a role in a mechanistic way. The relative importance of eachhypothesis may vary depending on its respective context. It follows from this that it should not matterwhich cause is favored: the emphasis should be given to all causes acting together in a predictablemanner.
Robustness despite uncertainty: regional climate data reveal the dominant role of humans in explaining global extinctions of Late Quaternary megafauna
Bartlett et al.
Our results show that human colonisation was the dominant driver of megafaunal extinction across the world but that climatic factors were also important. We identify the geographic regions where future research is likely to have the most impact, with our models reliably predicting extinctions across most of the world, with the notable exception of mainland Asia where we fail to explain the apparently low rate of extinction found in in the fossil record. Our results are highly robust to uncertainties in the palaeological record, and our main conclusions are unlikely to change qualitatively following minor improvements or changes in the dates of extinctions and human colonisation.
Pleistocene megafaunal interaction networks became more vulnerable after human arrival
Pires et al.
Proceedings of the royal society, 2015
We show Pleistocene and modern assemblages share similar network topology, but differences in richness and body size distributions made Pleistocene communities significantly more vulnerable to the effects of human arrival. The structural changes promoted by humans in Pleistocene networks woul dhave increased the likelihood of unstable dynamics, which may favour extinction cascades in communities facing extrinsic perturbations.
Pleistocene Overkill and NorthAmerican Mammalian Extinctions
David J. Meltzer
Annual review of anthropology, 2015
Overkill proponents argue that there is more archaeological evidence than we oughtto expect, that humans had the wherewithal to decimate what may have been millions of animals, and that the appearance of humans and the disappearance of the fauna is too striking to be a mere coincidence. Yet, there is less to these claims than meets the eye. Moreover, extinctions took place amid sweepingclimatic and environmental changes as the Pleistocene came to an end. It has long been difficult to link those changes to mammalian extinctions, but the advent of ancient DNA, coupled with high-resolution paleoecological, radiocarbon, and archeological records, should help disentangle the relative role of changing climates and people in mammalian extinctions.
Abrupt warming events drove Late Pleistocene Holarctic megafaunal turnover
Cooper et al.
The causes of the Pleistocene extinctions of large numbers of megafaunal species in the Northern Hemisphere remain unclear. A range of evidence points to human hunting, climate change, or a combination of both. Using ancient DNA and detailed paleoclimate data, Cooper et al. report a close relationship between Pleistocene megafaunal extinction events and rapid warming events at the start of interstadial periods. Their analysis strengthens the case for climate change as the key driver of megafaunal extinctions, with human impacts playing a secondary role.
Late Quaternary megafaunal extinctions on the continents: a short review
Anthony John Stuart
Geological journal, 2014
This paper provides an overview of the contentious issue of global megafaunal extinctions in the Late Quaternary. The main proposed causes are ‘overkill’, environmental change or a combination of both. There are major objections to the other suggested causes. Extinctions were highly variable in their severity between different zoogeographical regions, with the greatest impact in North America, South America and Australia, but also substantial in northern Eurasia. Sub‐Saharan Africa and Southern Asia were much less affected. For northern Eurasia, detailed chronologies show a staggered extinction pattern, in which each megafaunal species exhibits unique and complex distributional shifts, culminating in extinction for some species and survival in others. Environmental drivers were clearly very important, although the possible role of humans is not yet clear. Alaska/Yukon also has a good radiocarbon record which also suggests a staggered extinction pattern. However, the available data for the rest of North America are largely unsatisfactory. South America also boasted spectacular extinct megafauna, but again the currently available dates are insufficient to reliably discern patterns or possible causes. Australia and New Guinea also suffered major losses, but extinctions probably occurred much earlier than elsewhere, so that establishing a chronology is especially difficult. Africa and Southern Asia have the least available data. In order to make meaningful progress, it is vital to establish a large database of reliable radiocarbon dates for each region made directly on securely identified megafaunal remains. The need is for much more high quality data, not more debate based on imperfect evidence.
Global late Quaternary megafauna extinctions linked to humans, not climate change
Sandom et al.
Proceedings of the royal society B, 2014
We present, to our knowledge, the first global analysis of this extinction based on comprehensive country-level data on the geographical distribution of all large mammal species (more than or equal to 10 kg) that have gone globally or continentally extinct between the beginning of the Last Interglacial at 132 000 years BP and the late Holocene 1000 years BP, testing the relativeroles played by glacial–interglacial climate change and humans. We show that the severity of extinction is strongly tied to hominin palaeo biogeography, with at most a weak, Eurasia-specific link to climate change. This first species-level macroscale analysis at relatively high geographical resolution provides strong support for modern humans as the primary driver of the worldwide megafauna losses during the late Quaternary.
Extinct New Zealand megafauna were not in decline before human colonization
Allentoft et al.
. Contra-dicting previous claims of a decline in moa before Polynesian settle-ment in New Zealand, our findings indicate that the populationswere large and stable before suddenly disappearing. This interpre-tation is supported by approximate Bayesian computation analyses.Our analyses consolidate the disappearance of moa as the mostrapid, human-facilitated megafauna extinction documentedto date.
Climate change frames debate over the extinction of megafauna in Sahul (Pleistocene Australia-New Guinea)
Wroe et al.
Human involvement in the disappearance of some species remains possible but unproven. Mounting evidence points to the loss of most species before the peopling of Sahul (circa 50–45 ka) and a significant role for climate change in the disappearance of the continent’s megafauna.
Holocene survival of Late Pleistocene megafauna in China: a critical review of the evidence
Turvey et al.
Quaternary Science Reviews, 2013
Evidence for Holocene survival of any Chinese Late Pleistocene megafaunal species is weak or untenable.
New perspectives on middle Pleistocene change in the large mammal faunas of East Africa: Damaliscus hypsodon sp. nov. (Mammalia, Artiodactyla) from Lainyamok, Kenya
Faith et al.
Paleogeography, Paleoclimatology, paleoecology, 2012
Although Lainyamok is no longer represented entirely by extant species, the absence of species common earlier in the middle Pleistocene of East Africa suggests substantial faunal turnover between 500 and 400 ka. Damaliscus hypsodon persisted in East Africa until the end of the Pleistocene and its extinction can be attributed to a loss of arid grassland environments at the onset of the Holocene. The fossil evidence from southern Kenya suggests that the development of the taxonomically modern large mammal community was a long-term process characterized by the extinction of grazing specialists, with marked turnover occurring between ~ 500 and 400 ka and near the end of the Pleistocene.
Pleistocene Megafaunal Collapse, Novel Plant Communities, and Enhanced Fire Regimes in North America
Gill et al.
we established that the megafaunal decline closely precededenhanced fire regimes and the development of plant communities that have no modern analogs. The lossof keystone megaherbivores may thus have altered ecosystem structure and function by the release ofpalatable hardwoods from herbivory pressure and by fuel accumulation. Megafaunal populationscollapsed from 14,800 to 13,700 years ago, well before the final extinctions and during the Bølling-Allerød warm period. Human impacts remain plausible, but the decline predates Younger Dryas coolingand the extraterrestrial impact event proposed to have occurred 12,900 years ago
Rise and Fall of the Beringian Steppe Bison
Shapiro et al.
The widespread extinctions of large mammals at the end of the Pleistocene
epoch have often been attributed to the depredations of humans; here we
present genetic evidence that questions this assumption. We used ancient DNA
and Bayesian techniques to reconstruct a detailed genetic history of bison
throughout the late Pleistocene and Holocene epochs. Our analyses depict a
large diverse population living throughout Beringia until around 37,000 years
before the present, when the population’s genetic diversity began to decline
dramatically. The timing of this decline correlates with environmental changes
associated with the onset of the last glacial cycle, whereas archaeological
evidence does not support the presence of large populations of humans in
Eastern Beringia until more than 15,000 years later.
Determinants of loss of mammal species during the Late Quaternary ‘megafauna’ extinctions: life history and ecology, but not body size
Proceedings of the Royak Society B, 2002
First, large size was not directly related to risk of extinction;rather, species with slow reproductive rates were at high risk regardless of their body size. This findingrejects the ‘blitzkrieg’ model of overkill, in which extinctions were completed during brief intervals ofselective hunting of large-bodied prey. Second, species that survived despite having low reproductive ratestypically occurred in closed habitats and many were arboreal or nocturnal. Such traits would have reducedtheir exposure to direct interaction with people. Therefore, although this analysis rejects blitzkrieg as ageneral scenario for the mammal megafauna extinctions, it is consistent with extinctions being due tointeraction with human populations.
Pleistocene extinctions: the pivotal role of megaherbivores
Cambridge university press, 1987
The elimination of megaherbivores elsewhere in the world by human hunters at the end of the Pleistocene would have promoted reverse changes in vegetation. The conversion of the open parklike woodlands and mosaic grasslands typical of much of North America during the Pleistocene to the more uniform forests and prairie grasslands we find today could be a consequence. Such habitat changes would have been detrimental to the distribution and abundance of smaller herbivores dependent upon the nutrient-rich and spatially diverse vegetation created by megaherbivore impact. At the same time these species would have become more
vulnerable to human predation.