Negative Selection

The study of genetics has given us essential information about the human body, how it's wired, and how it has evolved over the years. Genomics, a branch of genetics that deals with the sequencing and analysis of the genome of an organism, has been particularly useful, especially in furthering our understanding of diseases. It turns out, it can also be useful in determining just how smart we could be, according to a groundbreaking study published in the online edition of the Proceedings of the National Academy of Sciences (PNAS).

In the study, scientists at deCODE Genetics explored how human genetic propensity for education has evolved over the years. Using several decades of genomic and genealogical data from a huge population selection in Iceland, the researchers discovered that individuals that carry a specific genetic variation linked to higher levels of education have fewer children compared to most people. This has resulted in a significant decline in these genetic variations over the years. Essentially, the human genome sequence variations correlated with more education are becoming rarer in the population today.

The scientists were able to arrive at this conclusion by having access to deCODE's unique and extensive genetics resources. This allowed them to review and analyze the change of the genetic propensity for education in 129,808 Icelanders. They covered data from 1910 to 1990 and came up with a polygenic score for propensity to educational attainment (POLYedu), which is a weighted average of about 620,000 variations in the genome's sequence.

Average educational attainment polygenic score and year of birth (yob). Results for 10-year bins are presented. Error bars indicate plus/minus 1 SE. The blue line is a quadratic fit for the full yob range indicated. The red line is a linear fit applied to individuals with yob ≥1940.

Genes and Society

In the evolutionary sense, this genetic propensity for education is under negative selection. “These findings are an example of how we can use genomics to shed light on the evolutionary causes and consequences of observed social trends in modern human society,” according to one of the authors of the study, Kari Stefansson, who is also the CEO of deCODE. “As a species, we are defined by the power of our brains. Education is the training and refining of our mental capacities. Thus, it is fascinating to find that genetic factors linked to more time spent in education are becoming rarer in the gene pool.”

What's even more interesting is the fact that this genetic variation decline happened during a time when educational levels were supposedly increasing. According to Stefansson:

In spite of the negative selection against these sequence variations, education levels have been increasing for decades. Indeed, we control the environment in which these genetic factors play out: the education system. If we continue to improve the availability and quality of educational opportunities, we will presumably continue to improve the educational level of society as a whole. Time will tell whether the decline of the genetic propensity for education will have a notable impact on human society.

Indeed, despite the fact that our genes are well embedded inside of us, what happens on the outside can affect how they change over time. That's what, essentially, evolution is. It's how we adapt to our environment. Hopefully, a better education system can reverse this downward genetic trend. Perhaps a curriculum based on genetics and an individual's DNA can be the key? Only research and time will tell.

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