Wednesday, 28 May 2014

Human Evolution: Genes, Genealogies, and Phylogenies

Cell biologist and cancer researcher Graeme Finlay writes in today's BioLogos blog post how his research into oncogenes and retroviruses provided him with unarguable evidence for common descent from shared retroviral elements:
I became involved in cancer research, and in the early 1980s, read avidly to inform myself of dramatic developments in the genetics of cancers. It was then that I came across oncogenic retroviruses. These are a subtype of virus that had a cunning mode of propagating themselves, and they were revolutionizing our understanding of how cancers developed. They brought to light a class of genes known as oncogenes. I struggled to assimilate the deluge of data, totally focused on cancer biology, my professional interest. But to my enormous surprise, I was following a continuous track which led to the point where I found myself reading in the area of evolutionary biology. 
Retroviruses provided a way of demonstrating that many cancers are produced from a single abnormal cell. Counter-intuitive though it may seem, the billions of cells that may populate a tumour are the descendants of a single ancestral cell, so cancers are said to be monoclonal. And, almost unbelievably, retroviruses provided a way of showing that multiple species may be derived from a single progenitor species (indeed, ultimately from a single cell). Such related taxa of organisms are said to be monophyletic. 
As I read, I found that a large variety of genetic markers established both the monoclonal nature of tumours on the one hand, and the monophyletic nature of groups of species on the other. Humans, chimps, gorillas and orang-utans, for example, share millions of genetic markers that show – unambiguously – that the four species share a common history. The genetic principles applicable to cancer (or immunology or microbiology or whatever) and evolutionary phylogenetics were the same, thoroughly established and non-controversial.
Finlay is also a Christian who is active in showing that Christianity and evolutionary biology are not mutually exclusive. His BioLogos post is definitely worth reading, as well as a 2012 post co-authored with David Layzell on the same subject, which goes into more detail. Finally, Finlay's 2013 book Human Evolution: Genes, Genealogies and Phylogenies is arguably the final word in showing how the genomic evidence confirms the reality of human-ape common ancestry. I cannot recommend it highly enough. Anyone with an open mind who reads it will come away accepting that we share common ancestry with the apes.