Did humans wipe out the Pleistocene megafauna? This is a question that can be asked separately for each area of the world colonized by Homo sapiens. It is also a question that engenders sometimes heated debate. A new paper coming out in the Journal of Human Evolution concludes that many Pleistocene megafauna managed to go extinct by themselves, but that humans were not entirely uninvolved.
The paper by Pushkina and Raia (“Human influence on distribution and extinctions of the late Pleistocene Eurasian megafauna”) examines sources in the literature and a number of databases for Eurasian localities. The researchers attempt to measure “species commonness” as the proportion of sites of a given time period for which a particular species is present, for about 30 species. “Commonness is a proxy of abundance of the species remains in a fossil locality or assemblage, because it is likely that within a given region a species abundant in some sites will be present in most of them…” These data were further analyzed for uneven sampling across time and other biases in the fossil record.
An important part of this analysis is the temporal framework for human presence in the region, which the authors summarize as follows:
Long before 100,000 years ago, humans coexisted with the megafauna without causing any extinction. In western Europe, there is archaeological evidence of human occupation as early as about 800,000 years ago … The Acheulean cultures are known from the Caucasus from about 583,000 years ago … Humans were present in northern Eurasia (Eurasian Plains) at about 45,000-40,000 years ago .. Anatomically modern humans inhabited western Europe at about 34,000-36, 000 years ago … The earliest modern human occupation or early Late Paleolithic occupation for southern Siberia is recorded at 43-39,000 yrs ago and they appear to have occupied all of northern Asia by 13,000 yr ago …
An overarching pattern seen in this study is that many of the megafaunal species did not overlap totally with human habitation. Hominids, being essentially tropical, kept to warmer areas while many of the famous Pleistocene megafauna were found in cooler habitats. In the mean time, humans tended to hunt the most abundant prey. As this relationship evolved, the researchers believe that many of the megafauna suffered from habitat loss due to climate change, and became rare (or went extinct) primarily because of this transition.
The relative commonnes of the large mammals of Eurasia were influenced by human activity to some extent. People became increasingly able to hunt abundant prey species, many of which, however, are still living. Humans became able to exclude large carnivores from their sites or defend their homes. By the latest Late Paleolithic populations of large mammals of the “mammoth-steppe” were already suffering from the deterioration and contraction to the north of their preferred habitat, while humans appeared to show little interest in the now-extinct species, even when a conservative archaeological approach was used that should have favored finding human influence on extinct fauna. Only the extinct steppe bison appears to have been negatively influenced by humans. Our findings are mainly consistent with the climatic explanation of the late Pleistocene extinctions in Eurasia.
PUSHKINA, D. (2008). Human influence on distribution and extinctions of the late Pleistocene Eurasian megafauna. Journal of Human Evolution DOI: 10.1016/j.jhevol.2007.09.024