A new study has looked at evolution of West Eurasians over the past 10 000 years and has revealed that nearly 500 genes have changed. It was a large-scale study including the analysis of 16 000 genomes. For evaluation questions we always look at the sample size as we want to know it’s large enough to be representative of the whole population.

Evolutionary changes happen due to mutation (random changes in the DNA base sequence), natural selection (features that are advantageous increase reproductive success), gene flow (due to migration) and genetic drift (random changes in allele frequency due to random events).

Bioinformatics has allowed data to be stored in large data bases and then computational biology has allowed the fast analysis of the data using software that can carry out statistical tests and algorithms. Natural selection was evident in 479 gene variants. There was a strong positive selection for resistance to HIV and leprosy infections but also for blood type B. In addition, traits such as fair skin tone and red hair has a greater selection. Another change showed a lower chance of having male-pattern baldness and also a lower risk of rheumatoid arthritis.

What is more difficult is to work out why these traits have been selected for. Fair skin tone could be linked to an increase in the synthesis of vitamin D leading to more calcium and phosphate absorption that hardens the bone matrix. A lack of vitamin D is linked to the development of a deformed pelvis in females and a decrease in having a successful childbirth.

But why the red hair? It is possible that the phenotype of red hair alone was not the selective advantage but instead the genes may be linked to a different characteristic that was important in selection or that some of the multiple genes involved in getting red hair, affected a different characteristic that was advantageous. I am curious to find out – in the meanwhile I will celebrate my red hair!

Download the article from the Lifescience.com page here

Download the article form the Guardian page here