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Human evolution, climate change and sampling bias

New research from Birkbeck questions the influence of climate change on human evolution.

The evolutionary history of our fossil ancestors, known as hominins, has long been thought to have been one of stasis, punctuated by rapid bursts of morphological experimentation or turnover – with these bursts often argued to be influenced by periods of climatic instability.

However, new research from Birkbeck, University of London questions this, suggesting that the influence of climate change on hominin evolution has been overstated as a result of uneven sampling on the fossil record. The influence of this uneven sampling on diversity patterns has not been analysed before now.

Using sampling-corrected methods to examine fluctuations in species diversity from 7-1 million years ago, Birkbeck scholars compared ‘taxic diversity’ - the numbers of species one can observe directly in the fossil record - with estimates of the amount of exposed rock available to sample and the collection effort by paleoanthropologists.

The research formed part of the PhD project for Simon Maxwell in the Department of Earth and Planetary Sciences. He said: “Our results show that peaks in observed early hominin diversity occur during periods of maximal rock availability and collection effort. We suggest that uneven fossil sampling, rather than climate dynamics, better explains the pattern of diversity in the fossil record and that scientists should work to improve the fossil record to better understand how and why patterns of diversification have occurred. The role of other processes, such as neutral drift and inter-species competition, also need to be considered.”

These results demonstrate that significant improvements in the quality of the fossil record are required before the role of climate in hominin evolution can be evaluated. The researchers believe future efforts by palaeoanthropologists should therefore focus on attempting to locate fossil hominins in under-exploited regions and geological formations.

The research is published in Proceedings of the National Academy of Sciences

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