Were climatic changes a driving force in hominid evolution?
J. Chaline, A. Durand, A. Dambricourt Malassé, B. David, F. Magniez-Jannin, D. Marchand, 2000. "Were climatic changes a driving force in hominid evolution?", Climates: Past and Present, Malcolm B. Hart
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A comparison of externalist and internalist approaches in hominid evolution shows that the externalist approach, with its claim that climate was responsible for the appearance of bipedalism and hominization, now seems to be ruled out by the biological, palaeogeographical, palaeontological and palaeoclimatic data on which it was based. Biological data support the embryonic origin of cranio-facial contraction, which determined the increase in cranial capacity and the shift in the position of the foramen magnum implying bipedalism. In the internalist approach, developmental biology appears as the driving force of hominid evolution, although climate exerts a significant influence and was involved in the following ways: (1) in the prior establishment of ecological niches that allowed the common ancestor to become differentiated into three subspecies; (2) by dividing up the area of distribution of species, resulting in the present-day subspecies of gorillas and chimpanzees; (3) by facilitating relative fluctuations of the geographical areas of distribution of the various species, particularly the spread of australopithecines across the African savanna from north (Chad, Ethiopia) to south (South Africa); (4) by determining adaptive geographical differentiations among Homo erectus and Homo sapiens (pigmentation, haemoglobin, etc.).
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The climate of the early Earth was probably very warm and has, in general, reduced since the Archean. However, it now seems that the world is about 0.6°C warmer than it was 100 years ago and estimates of the rate of global warming over the next century range from 0.16°C to 0.35°C per decade. Concurrently, global sea-level is predicted to rise from 2.4 to 10 cm per decade. These rates of change are much faster than those normally associated with the geological record, causing geologists and palaeontologists to reassess their data and their forecasts on rates of future change.
With the current interest in global climatic change and, more specifically, with global warming, it is clear that palaeontologists have valuable information to provide on the impacts of past climatic change. This volume contains papers from an international array of such geologists and palaeontologists, showing how studies of micro- and macrofossils, plant and vertebrate fossils from a range of geological ages have contributed to our understanding of how climate affects both local and more widespread areas. The contributions are arranged in geological order, ranging from the Permo-Carboniferous to the post-glacial recovery of the last 18,000 years, with an emphasis on climate change during the last two million years, particularly in NW Europe.
Climates: Past and Present will be of interest to palaeontologists, geologists and palaeoclimatologists who specialize in climatic reconstructions and any professionals enagaged in research into the geological aspects of climate change.