“The immense capacity of the human brain to learn new tricks is under attack from an array of genetic mutations that have accumulated since people started since people started living in cities a few thousand years ago.”
Leading geneticist Dr. Gerald Crabtree, a professor at Stanford University, put the idea out that rather than becoming brighter, human intelligence has reached its peak several years ago and from then on has been a slow decline in our intellectual and emotional abilities. Crabtree explained that human intelligence and emotions depended on thousands of genes.
“I would wager that if an average citizen from Athens of 1000 B.C. were to appear suddenly amongst us, he or she would be among the brightest and most intellectually alive of our colleagues and companions, with good memory, a broad range of ideas, and clear-slighted view of important issues,” Crabtree said in a paper published in the journal Trends in Genetics.
Crabtree bases his argument on the fact that, for more than 99 percent of human evolutionary history, we have lived as hunter-gatherer communities, which has led to big-brained humans. Since the development of agriculture and cities, however, natural selection on our intellect has effectively stopped and mutations have accumulated in the critical intelligence genes.
Crabtree continued by saying, “Furthermore, I would guess that he or she would be among the most emotionally stable of our friends and colleagues. I would also make this wager for the ancient inhabitants of Africa, Asia, India or the Americas, or perhaps 2,000 to 6,000 years ago.”
Between the genomes of parents and children has revealed that on average there are 25 to 65 new mutations occurring in the DNA of each generation. Crabtree say that this analysis predicts about 5,000 new mutations in the past 120 generations, which covers the about 3,000 years.
“The basis for my wager comes from new developments in genetics, anthropology, and neurobiology that make a clear prediction that our intellectual and emotional abilities are genetically surprisingly fragile,” says Crabtree.
The life of hunter-gatherer was probably more intellectually demanding, Crabtree explains.
“A hunter-gatherer who did not correctly conceive a solution to providing food or shelter probably died, along the with his or her progeny, whereas a modern Wall Street executive that made a similar conceptual mistake would receive a substantial bonus and be a more attractive mate.”
Rhonda Bartlett is a fourth-year student majoring in professional studies and minoring in theatre and journalism. She can be reached at RB681837@wcupa.edu.