A Stanford geneticist says humans have so many genetic mutations that we’re less intelligent than our ancestors, and it’s getting worse. Eugenicists 100 years ago had similar hypotheses.
There’s this great recurring “Saturday Night Live” skit from several years back where Phil Hartman plays an unfrozen caveman who goes to law school. He pontificates on the American judicial system while marveling at modern technology like “the tiny people in the magic box” (a TV). It fits a common stereotype: Human ancestors were, well, cavemen, and not as smart as we are today. A provocative new hypothesis from a Stanford geneticist tries to turn this stereotype upside down.
Human intelligence may have actually peaked before our ancient predecessors ever left Africa, Gerald Crabtree writes in two new journal articles. Genetic mutations during the past several millennia are causing a decline in overall human intellectual and emotional fitness, he says. Evolutionary pressure no longer favors intellect, so the problem is getting exponentially worse. He is careful to say that this is taking quite a long time, so it’s not like your grandparents are paragons of brilliance while your children will be cavemen rivaling Hartman’s SNL character. But he does posit that an ancient Athenian, plucked from 1000 BC, would be “among the brightest and most intellectually alive of our colleagues and companions.”
His central thesis is that each generation produces deleterious mutations, so down the line of human history, our intelligence is ever more impaired compared to that of our predecessors.
Not surprisingly, the hypothesis, published in the prominent journal Trends in Genetics, has several geneticists scratching their heads.
“It takes thousands and thousands of genes to build a human brain, and mutations in any one of those can impair that process, that’s absolutely true. And it’s also true that with each new generation, new mutations arise ... but Crabtree ignores the other side of the equation, which is selection,” said Kevin Mitchell, associate professor at the Smurfit Institute of Genetics at Trinity College Dublin, who operates the blog Wiring the Brain. “Natural selection is incredibly powerful, and it definitely has the ability to weed out new mutations that significantly impair intellectual ability. There are various aspects in these papers that I think are really just thinking about things in a wrong way.”
Crabtree said he wanted to examine the cumulative effect of generation-to-generation mutation on intelligence, which is thought to be controlled by many genes. Using indices that measure X-chromosome-related mental retardation, he comes up with between 2,000 and 5,000 genes related to human intellectual ability. Using another index measuring average mutations that arise in each generation of children, he calculates that within 3,000 years, “we have all sustained two or more mutations harmful to our intellectual or emotional stability.”
“There is a general feeling that evolution constantly improves us, but it only does that if there is selection applied,” Crabtree said in an interview. “In this case, it is questionable about how much selection is occurring now compared to the process of optimizing those genes, which occurred in the jungles of Africa 500,000 years ago.”
There’s already evidence for this in other areas, he argues: Take our sense of smell. Humans have far fewer olfactory receptors than other animals, he said--we’re guided by our intellect now, not by smell. We can think about where a piece of food came from, how it was processed, which plant it’s from, who has been around it, and so on. A dog, on the other hand, simply sniffs something and either eats it or doesn’t.
“Once you place pressure on intellectual abilities, and take it off of olfactory abilities, the olfactory genes deteriorate,” Crabtree said.
Similarly, he believes evolution now selects for other traits--namely, the most healthy and the most immune, not the most intelligent. Human movement into communities and cities increased the spread of infectious diseases, and those with the strongest physical constitutions survived to pass on their genes, he argues. He said he wanted to publish this hypotheses because geneticists can test for this, in an expensive process that requires saving some genetic information that typically gets discarded.
Sweden plans to expel up to 80,000 asylum-seekers 2016-02-08 3:58
Sweden intends to expel up to 80,000 migrants who arrived in 2015 and whose application for asylum has been rejected, Interior Minister Anders Ygeman said Wednesday.
"We are talking about 60,000 people but the number could climb to 80,000," the minister was quoted as saying by Swedish media, adding that the government had asked the police and authorities in charge of ...
An Occupied Country 2016-02-06 5:42
When people refer to occupation governments or occupied countries, the first thought is often of military occupation—the garrisoning of foreign troops in one’s cities and civil administration by their military executives. The other vision is the trope of a cabal of Haredim sitting in a darkly-lit boardroom with a map of the world on the wall, a dated reading of ...
Immortal Symbols 1941 2016-02-06 2:07
Youtube description: Dutch film "Eeuwig Leevende Tekens" by Hamer - "Volksche Werkgemeenschap" (Folkish Study Group) - ancestral heritage, solar wheel, sun cross, tree of life, etc.
Subs by Otharus - http://fryskednis.blogspot.com
Ex-German media boss admits on live radio the national news agenda is govt controlled 2016-02-06 1:32
If you really want a lesson in how the Western popular press works, this is it.
Without question, Germany is the leading power in Europe. ZDF is its state broadcaster and most popular channel.
Together with sister network ARD; German's are obliged to pay €17.98 per month to fund it.
This week, during a radio event in Berlin, the retired head of ZDF ...