Is the human race getting dumber? geneticist Gerald Crabtree thinks that human intelligence peaked several thousand years ago and from then on, has been on a slow decline.

His argument is based on the fact that for more than 99% of human evolutionary history, we lived as hunter-gatherer communities surviving on our wits, which led to the big brains we have today. Since the invention of agriculture and cities, however, natural selection on our intellect has stopped and mutations have accumulated in our critical "intelligence" genes. A comparison of the genomes of parents and children reveals that there are between 25 and 65 new mutations in the DNA of each new generation.

In the Independent, Steve Connor quotes Crabtree as saying, "I would wager that if an average citizen from Athens of 1,000 BC were to appear suddenly among us (the way MOTKE appeared to Whitley), 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." He obviously thinks these are attributes that few of us possess today.

Not everyone agrees with Crabtree. The Huffington Post quote geneticist Steve Jones as saying, "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?"

One of the dissenters is Nicholas D. Kristoff, who writes in the December 13th edition of the New York Times: "The average American in the year 1900 had an IQ that by today’s standards would measure about 67. Since the traditional definition of mental retardation was an IQ of less than 70, that leads to the remarkable conclusion that a majority of Americans a century ago would count today as intellectually disabled.

"The trend of rising intelligence is known as the ‘Flynn Effect,’ named for James R. Flynn, the New Zealand scholar who pioneered this area of research. Countless other scholars worldwide have replicated his findings.

"The average American IQ has been rising steadily by 3 points a decade. Spaniards gained 19 points over 28 years, and the Dutch 20 points over 30 years. Kenyan children gained nearly 1 point a year."

"It is now accepted science–although there is still disagreement about its causes and significance." Could one of the causes be chocolate? It works for snails, anyway, although scientists aren’t yet sure about humans.

Researchers Lee Fruson and Ken Lukowiak became curious about how diet might affect memory, so they concentrated on flavonoids, which are in so-called "superfoods" like chocolate and green tea.

Lukowiak was skeptical, saying, "I didn’t think any of this stuff would work," but he was surprised: When he fed dark chocolate to pond snails, he discovered that it improved the length and strength of their memories.

It turns out that chocolate doesn’t just help your weight and your love life–the cognitive effects of half a bar of dark chocolate could even help your grades. This good news for chocoholics worldwide.