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Human Intelligence Peaked Thousands of Years Ago: Study

Stupidity trend will continue, says new research, but collective education can save us

Common Dreams staff

Humankind's intelligence peaked thousands of years ago and advanced civilization has made life so easy for so many that our trend towards stupidity will continue as the ingenuity and intellect once needed for basic survival erode even further.

This, anyway, is the argument of a new study out in the journal Trends in Genetics, authored by  Stanford University professor Gerald Crabtree.

Crabtree's study claims that harmful genetic mutations—occurring generation after generation as society advanced—have reduced our "higher thinking" abilities and the accumulated result has led to a gradual dwindling of our intelligence as a species.

The Guardian explains that Crabtree's thinking is a speculative idea—one he'd be happy to have prove wrong—but also a simple one:

In the past, when our ancestors (and those who failed to become our ancestors) faced the harsh realities of a hunter-gatherer lifestyle, the punishment for stupidity was more often than not death. And so, Crabtree argues, enormous evolutionary pressure bore down on early humans, selecting out the dimwits, and raising the intellect of the survivors' descendants. But not so today.

“I would wager that if an average citizen from Athens of 1000BC were to appear suddenly among us, he or she would be among the brightest and most intellectually alive of our colleagues and companions, with a good memory, a broad range of ideas and a clear-sighted view of important issues,” Professor Crabtree says in the paper.

“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, of perhaps 2,000 to 6,000 years ago,” he continues. “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.”

Speaking with the Telegraph, Prof Robin Dunbar, an anthropologist at Oxford University, pushes back against Crabtree's hypothesis, saying:

[Prof Crabtree] takes the line that our intelligence is designed to allow us to build houses and throw spears straighter at pigs in the bush, but that is not the real driver of brain size.

In reality what has driven human and primate brain evolution is the complexity of our social world [and] that complex world is not going to go away. Doing things like deciding who to have as a mate or how best to rear your children will be with us forever.


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Personally I am not sure that in the foreseeable future there is any reason to be panicking at all, the rate of evolution with things like this takes tens of thousands of doubt the ingenuity of science will find solutions to these things if we do not blow ourselves up first.

Other scientists were also skeptical. “At first sight this is a classic case of Arts Faculty science. Never mind the hypothesis, give me the data, and there aren’t any,” said Professor Steve Jones, a geneticist at University College London.

"I could just as well argue that mutations have reduced our aggression, our depression and our penis length but no journal would publish that. Why do they publish this?” Professor Jones said.

“I am an advocate of Gradgrind science – facts, facts and more facts; but we need ideas too, and this is an ideas paper although I have no idea how the idea could be tested,” he said.

"You don't get Stephen Hawking 200,000 years ago, he just doesn't exist," University of Warwick psychologist Thomas Hills told website LiveScience.

"But now we have people of his intellectual capacity doing things and making insights that we would never have achieved in our environment of evolutionary adaptation."

Despite his own research, Crabtree does not predict a future of diminishing returns for civilization and says that the species' ability to thrive is inherent in advanced civilization, and specifically in our ability to share information with one another. "Remarkably it seems that although our genomes are fragile," Crabtree says, "our society is robust almost entirely by virtue of education, which allow strengths to be rapidly distributed to all members."

The Independent offers this quick survey of man's descent into stupidity:

Hunter-gatherer man
The human brain and its immense capacity for knowledge evolved during this long period of prehistory when we battled against the elements

Athenian man
The invention of agriculture less than 10,000 years ago and the subsequent rise of cities such as Athens relaxed the intensive natural selection of our “intelligence genes”.

Couch-potato man
As genetic mutations increase over future generations, are we doomed to watching soap-opera repeats without knowing how to use the TV remote control?

iPad man
The fruits of science and technology enabled humans to rise above the constraints of nature and cushioned our fragile intellect from genetic mutations.

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