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.
The debate over the heritability of IQ has been stoked recently by Malcolm Gladwell’s recent book “Outliers”, which takes the politically correct view that success is mostly due to effort and environment and not innate ability. However, I’m not going to enter this debate here except to point to an interesting blog post on the topic here. What I’m going to ask instead is this: Suppose that most of the attributes such as intelligence, musical ability, athletic ability, and other traits useful for success in the the twenty first century are genetic, what then?
I’m going to argue that the more innate our abilities may be the less we “own” or should benefit from them because the human genome is our shared inheritance and thus belongs to everyone. Every great scientific discovery, Olympic gold medal, or virtuoso music performance is possible because of the genetic diversity that arose throughout human history. A gene for a beneficial attribute may have only arisen because of some completely unrelated gene for some previous attribute that is no longer so beneficial. For example, genes for intelligence may have been allowed to become fixed in a population only because a previous mutation for resistance to an ancient virus first arose. A given set of genes may be beneficial for our current times but they may not have been in the past or may not be in the future. Every human is a reservoir for genetic variability that may be useful at some point in time for all of humanity.
This is a scientific reason for why eugenics is such a bad idea. To increase our chances for survival we need to increase genetic diversity not decrease it. The environment can always change and we can never tell what may be beneficial in the future. People often think that humans are no longer evolving because modern medical care is saving people that would have otherwise died and allowing couples to have children that otherwise could not have. However, although there may be less pressure on us now due to natural selection (although that’s debatable, e.g. here), we are actually bank rolling more genetic variability. Hence, our potential for evolving is actually increasing because of modern interventions. Every ill person we keep alive and every baby born through some intervention is preserving and perhaps increasing genetic diversity that may save us all some day. So, we should all embrace diversity; the person most different from you may be the reason your great great great great grandchildren survive.