Genetics and the myth of universal human nature

The belief in a universal human nature is widespread, and during the past decades it seems to have gained support from the fields related to genetics and the theory of evolution, most notably from the brave new sciences of sociobiology and evolutionary psychology. One of the claims - and in principle, a correct one - is that the human genome is one of the least diverse genomes known, being 99.9% identical between two human beings.

However, this is far from being the whole story, and I tend to believe that the underlying, often implicit belief in a universal human nature - something essential in us all that we inevitably share - has altered the rhetoric in which facts are presented in, in order to support and legitimize this belief. So here's a brief overview full story, and it's much different and more complex implications.

If you take two ordinary human beings and map their respective genomes, you will indeed discover that 99.9% of the two genomes are identical. The remaining 0.1% are the changes, the alterations, the mutations, technically called "single nucleotide polymorphisms", or SNPs - one of the bases for individual variation. But the point is that these mutations can occur anywhere in the genome. If you add a third person, his or her genome will also differ from the other two by 0.1%, but the SNPs are in different places from those of the others. Add more people, and each of them has these mutations in different locations along the genome. In fact, there is nothing in the genome that has to be shared by all humans, nothing that every individual has to have, nothing that makes him or her a human being, the changing of which will change him or her to something else. There is nothing essential in the human genome, nothing that makes us all "humans", nothing that makes us all the same.

Nevertheless, we never really hear it put this way. We hear that 99.9% of the human genome is essentially the same in all of us, justifying the belief that we are all the same, that we all share a universal human nature.

Even the very phrase "the human genome" is misleading. There is no such thing as "the" human genome. There are instead six billion human genomes, one inside every individual human being, all sharing 99.9% and nothing at all at the same time. To quote the biochemist David Cox, "all humans share nothing".

Luckily though, the exasperating reign of the modern synthesis seems to be slowly drawing to its end. More and more criticism is being levelled against its simplistic credo and its banal accomplices, the selfish genes, memes, and the the excesses of sociobiological thinking. I would like to point out a great new book, Evolution In Four Dimensions by Eva Jablonka and Marion J. Lamb. The Guardian review sums it up nicely.