No field of science has cast more light on both the past and the future of our species than evolutionary biology. Recently, the pace of new discoveries about how we have evolved has increased (Culotta and Pennisi, 2005).
It is now clear that we are less unique than we used to think. Genetic and palaeontological evidence is now accumulating that hominids with a high level of intelligence, tool-making ability, and probably communication skills have evolved independently more than once. They evolved in Africa (our own ancestors), in Europe (the ancestors ofthe Neanderthals) and in Southeast Asia (the remarkable 'hobbits', who may be miniaturized and highly acculturated Homo erectus).
It is also becoming clear that the genes that contribute to the characteristics of our species can be found and that the histories of these genes can be understood. Comparisons of entire genomes have shown that genes involved in brain function have evolved more quickly in hominids than in more distantly related primates.
The genetic differences among human groups can now be investigated. Characters that we tend to think of as extremely important markers enabling us to distinguish among different human groups now turn out to be understandable at the genetic level, and their genetic history can be traced. Recently a single allelic difference between Europeans and Africans has been found (Lamason et al., 2005). This functional allelic difference accounts for about a third of the differences in skin pigmentation in these groups. Skin colour differences, in spite of the great importance they have assumed in human societies, are the result of natural selection acting on a small number of genes that are likely to have no effects beyond their influence on skin colour itself.
How do these and other recent findings from fields ranging from palaeontology to molecular biology fit into present-day evolution theory, and what light do they cast on how our species is likely to evolve in the future?
I will introduce this question by examining briefly how evolutionary change takes place. I will then turn to the role of environmental changes that have resulted in evolutionary changes in the past and extrapolate from those past changes to the changes that we can expect in the short-term and long-term future. These changes will be placed in the context of what we currently know about the evolution of our species. I will group these changes into physical changes and changes that stem from alterations of our own intellectual abilities. I will show that the latter have played and will continue to play a large role in our evolution and in the evolution of other animal and plant species with which we interact. Finally, I will turn to a specific examination ofthe probable course of future evolution of our species and ofthe other species on which we depend.
Continue reading here: The causes of evolutionary change
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