At the beginning of CBC radio’s science program Quirks and Quarks are brief audio snippets of scientists speaking. One of them is Francis Collins, of the Human Genome Project, saying “The human genome is a our shared inheritance.” On the eve of the new year, I thought I would reflect on what this means for us.
When the human genome was first published at the beginning of the century it was proclaimed that humans were 99.9% identical and that there was no genetic basis for race. Since that time, the estimate of our similarity has been revised downwards to about 99.5% and it could drop further. The reason is that the first estimate was based on patching together the genomes of about 100 different people so differences were underestimated. In the last few years, the genomes of individuals like Craig Venter and Jim Watson have been sequenced and the differences appear to be far larger. One of the more recent and unexpected findings is that Copy Number Variants, where pieces of the genome including entire genes are repeated are far more numerous than SNPs where differences in just a single nucleotide occur. Additionally, it now appears that members of different races can be distinguished genetically (see here for argument). It was once claimed that the variance within races swamped the differences between the means of the races. Now it appears that while this is true in most directions in genome space, there are directions where this is not true. It is still not known if the differences that are observable are meaningful.