The Evolution Of British People; Genome Analysis Shows Brits Weren’t Always As Tall And Blonde As They Are Today

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The British people have evolved to be blonder and have bluer eyes than their ancestors. Pixabay, Public Domain

While we may have come to associate the modern-day Brit with fair hair and blue eyes, a new study suggests their ancestors didn’t always look this way. Putting to use a new method they had found to analyze the human genome, Stanford University geneticists who studied the DNA of approximately 3,000 British volunteers were able to deduce exactly when certain common traits entered the British gene pool.

According to Wired UK, the new gene analysis technique is unique in that it is able to track down evolutionary changes within a much smaller timeframe. In doing this, it gives a more detailed background into how and when we evolved to become the species we are today. For example, other techniques can only track changes over the course of 25,000 years or rely on comparing “ancient human DNA” from bones against modern DNA to detect change. Unfortunately, these results are often unreliable. Instead the new technique uses a statistical analysis of whole-genome sequences to specifically pinpoint where certain traits, such as stature and hair color, first came about in this population.

The team tested their new technique on 3,195 members of the British population and found that over the past 2,000 years certain genes were favored over others and as a result the British people evolved to be blonder, taller, and more blue-eyed than their ancestors. Although scientists knew that the genetic mutation that leads to lactate tolerance later in life first entered the human genepool around 7,500 years ago, this new technique showed that the gene was actively selected in Britons for the past 2,000 years, Nature reported. Others changes observed in the British genome were the evolution of larger heads in infants, and larger hip size and later age of onset for menstruating women.

While the British are the first demographic for which the team’s new technique was used, it hopes to extend the research to other populations.  

“I’m just speculating, but I would think that there are many other as-of-yet unknown genetic variants that contribute to immune response or autoimmune disease,” Dr. Jonathon Pritchard, a researcher involved with the project, told Nature.

A study of the Dutch people from 2015 helped to explain how this population came to gain some of their most characteristic traits, particularly their height. The Dutch were not always as tall as they are today, and a review of national records from 1935 to 1967 revealed that their height has steadily increased.

The study determined that the increase in height was less based on the emergence of certain genes and more based on sexual selection. For reasons still unknown, the study revealed that in the Netherlands, the taller the individual the more children they were likely to have. Because height is an inheritable trait, this caused the tall gene to not only be passed on through generations but also enhanced. Today, the Dutch are considered the tallest people in the world with the average man measuring in at 6 feet tall and the average woman at 5-foot-7. According to the study, however, it’s likely this trend will not last forever; Dutch people will not grow to gargantuan heights. Instead, like most patterns of sexual reproduction, the trait will likely be favored for many generations, followed by a period of stabilization or a return to the opposite trait.

Source: Pritchard JK, Field Y, Boyle EA, et al. Detection of human adaptation during the past 2,000 years. BioRxiv. 2016

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