6 really weird things we learned about humankind this year

2012's highlights include the reason only 10 percent of us are left-handed, and why our species might be getting dumber

President Obama
(Image credit: CC BY: The White House)

1. We used to eat grass

Fossil evidence from Central Africa suggests that, 3.5 million years ago, our early ancestors probably munched on grass in addition to berries, nuts, and whatever else grew on trees. In fact, grazing on grass (as well as the roots of other plants) probably allowed our bipedal ancestors to emerge from the forest to live on treeless plains and adopt a broader diet — including, eventually, protein-rich animal meat.

2. We might be getting dumber

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The comforts of modern living are limiting our intelligence, claims developmental scientist Gerald Crabtree at Stanford University. His argument: The human race has been getting dumber ever since we started living relatively cushy lives on farms and stopped consistently fighting for our lives. In the past, a hunter-gatherer who wasn't capable of devising a plan to fight off saber-toothed tigers probably died, whereas in modern times, a Wall Street executive who makes a comparable mistake may instead be rewarded with a substantial bonus and become more attractive to a potential mate. Plenty of skeptics disagreed with Crabtree's argument, citing physicist Stephen Hawking and other modern geniuses as obvious counter-examples.

3. Our cave-dwelling ancestors had dentists

Scientists found a 6,500-year-old cracked tooth repaired with beeswax, suggesting that our early ancestors knew a thing or two about dental work. One caveat: While evidence suggests that the cave-patient had his tooth repaired while he was still alive, experts couldn't rule out the possibility that the tooth was filled as a part of a funeral rite.

4. Cooking our food gave us an evolutionary edge

Gorillas spend 10 hours of their day eating in order to add fuel to their bodies, and yet their brains are still much smaller than ours. How are humans able to eat less while still powering the super-computer inside our skulls? The answer, it seems, is cooked food, which experts think gave us an evolutionary boost when hearths began showing up in humankind's archeological record 800,000 years ago. After all, says study author Suzana Herculano-Houzel, cooking is by far the easiest and most obvious answer to the question what can humans do that no other species does?

5. Bald men might just be evolutionarily superior

If losing your hair is as ill-fated as conventional wisdom suggests, why haven't men prone to baldness gone extinct? It turns out that baldness may be linked to a number of evolutionary advantages. A bald head connotes wisdom and maturity; absorbs more prostate cancer-fighting vitamin D from the sun than a thick head covered in hair; and may even signal power and dominance to rival dudes. (See: Michael Jordan, Rupert Murdoch, etc.)

6. Most of us are right-handed for a reason

A measly 10 percent of the population is left-handed, a ratio that's been constant for about 5,000 years. Why isn't there a 50-50 righty-lefty split? The answer: Evolution, in particular humankind's need to cooperate to survive. "The more social the animal… the more the general population will trend toward one side," says study co-author Daniel M. Abram. Feeble humans have long had an evolutionary need to cooperate in order to dominate stronger, more powerful beasts, namely when hunting in groups, carving new tools out of stone, or using scissors in a kindergarten classroom.

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