Brits are, in fact, taller than they used to be. More of them are able to digest milk, and more have blue eyes.
A new study published on BiorXive from researchers at Stanford University tracked the genomes of almost 3,200 Britons in order to look at short-term changes in human evolution. They found that in the past 2,000 years, more Brits had variations of genes specifying blond hair, blue eyes, and the ability to produce lactase, which helps break down milk. The same population also has more genes that make them taller.
Researchers looked at the frequency that the genes controlling for these traits occurred in modern genomes, originally collected as part of a project studying rare genetic diseases. When certain variations of different genes, like the ones controlling how the body makes lactase, appear more often, it means they were naturally selected for more frequently than in previous years.
Most other human evolutionary research compares modern genomes to those of our ancient ancestors from around 25,000 years ago; although scientists can see which traits we have now versus then, sometimes ancient genetic material is incomplete, and doesn’t show shifts over short periods of time, evolutionarily speaking.
Although a single gene variation controls whether or not we can digest milk, many genes play a role in determining how tall we are. Researchers also found that more of the genes related to being taller appeared in greater numbers in the genomes. When combined with findings that show more genes related to larger head size in infants and later menstruation in women, the results could begin to show how humans have subtly evolved in modern times.
The work has yet to be be peer-reviewed, and only looked at one population in a particular corner of the world. Jonathan Pritchard, a geneticist at Stanford University and lead author of the paper, told Nature that the results need to be replicated before larger conclusions can be drawn about the rate of short-term human evolution.