The opening night of the University of Melbourne Festival of Ideas featured Matt Ridley- a science writer with an interest in genetics. He spoke about “Genes, Technology and the Evolution of Culture” or more precisely the idea of nature via nurture. That is, our cultures and behaviors lead to changes in our DNA and biology.
He first spoke about LCT- a gene coding for the enzyme that digests lactose (the sugar in milk). Clearly this gene is necessary for babies and infants as milk is their primary food source. However, it appears that overtime, this gene has become expressed in European adults, but not Asian adults. Given that dairy producing animals such as cows and goats are found in Europe, it would make sense that as individual begin to drink milk for a greater duration of their lifespan, those with mutations leading to longer expression of LCT become healthier, and as a result are more likely to pass on this advantageous mutation in LCT. This shows a change in culture (farming) leading to a change in biology.
However, isn't it just as possible that everyone had the LCT gene expressing throughout their lifespan, and through a random mutation the Asian population lost expression in adulthood?Due to the lack of dairy in the Asian diet this mutation would have had no selection acting against it and hence through genetic drift and random events this mutation became fixed. (I did have some problems streaming the start of the discussion so when it's up again I'll have a listen and see if this is addressed).
He had some other examples- As populations moved north, there was less vitamin D and the people would suffer from rickets and other sickness. A mutation leading to blue eyes, paler skin and lighter hair also increased the absorption of vitamin D. Hence, these blue eyed individuals were healthier, and passed on the mutation to healthier offspring.
He then spoke briefly about the Darwinian way that culture evolves. Culture has “descent with modification”- over time a clubbing rock has turned into an axe, and shows “succession and extinction”- shown in the preeminence and decline of technology such as audio tapes giving way to CDs and so on. Culture also has “variation”, “replication”, “competition” and “recombination”. The idea of cultural recombination was unique and fascinating- that everything that occurs is from cumulative processes of many people’s ideas.
Ridley believes that our (homo sapiens) main change or evolution over the past million years is that of “exchange”. He was quick to point out this was not reciprocity- you do something for me, and I’ll return the favor, but rather the exchange of different things at the same time. Homo sapiens were different from Neanderthals in that they had sexual division of labor, and hence exchange would occur between the women gathers and the male hunters. In modern society, the idea of exchange is vital- so many other things are done by others in exchange for primarily money but occasionally other goods or services.
What do you think? Do you like the idea of nature via nurture? Do you think that as a species we have a greater control over our biology that we realize? I’m certainly not an expert in evolution so feel free to correct or expand on any of my points.
Also, check back in a few days, or follow me on twitter and I’ll let you know when a video link of this discussion is up.
