From natural selection to social selection

Since the rise of culture, evolution has taken a particular direction. It cannot be said anymore that natural selection is shaping evolution in its biological definition.

What is natural selection?

Natural selection is the principle by which selection of genes which encode certain traits that will favour survival will spread.

This is linked with an organism’s fitness to survive in an environment.

For example, insects evolve resistance to plant toxins to be able to reuse the plant as a food source, and increase their survival and then the plants will acquire new toxins to repel the insects once again. This is evolution by natural selection.

Big population favours the spread of mutations

Human populations in the last 10 000 years have gone through rapid changes in frequencies of genes (1,2). Changes in the environment, such as the invention of agriculture, the incorporation of new foods, our news ways of living, including larger populations in a same area, have favoured disease transmission and the possibility for mutated alleles to spread in the population.  As population increases so does the chance of the mutation to being selected within the population. When we look at the successful adaptation of humans in new ecologies we can speculate that this has been possible because of high population numbers, which allow rapid selection for advantageous genes.

Social selection

Agriculture has selected a few plant species and intensified their cultivation, many foods we are consuming today were only recently incorporated to our diet.  For example, 10 000 years ago population in Northern Europe could not digest milk, since then the frequency of the gene lactase which permits the digestion of lactose is present in more than 75% of populations in Northern Europe  (3). It is estimated that 90 % of Northern Europe’s population is lactose tolerant (4). However, other parts of the world such as in Asia where milk has not been consumed for as much time are mostly intolerant to milk, as time will pass, it can be supposed that cultural pressure will positively select for lactose tolerance, as it has happened  in Europe. This is evolution by social selection.

Human actions are guiding evolution through what society decides to market.

In the Darwinian world, survival is directed by natural selection, however in our society survival is guided by social selection.

We continue to change today, but we are no longer changing through natural selection. Remember how our actions are driving markets, and how this, in turn, may even reshape our own genetics on your next purchase!

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References

1. Cochran, G(2009). The 10 000 year explosion BasicBooks
2. Hawls, J(2008).Conversation: Evolution Overdrive Archaeology61.
3. Hollox, E (2005). Evolutionary Genetics: Genetics of lactase persistence-fresh lessons in the history of milk drinking European Journal of Human Genetics 13, 267-269.
4. Wiley( 2002). Lactose Intolerance [Online] Available:http://www.wiley.com/college/boyer/0470003790/cutting_edge/lactose_intolerance/lactose_intolerance.htm [Accessed 26/03 2014].