Why humans are more helpful than chimps.

Science, technology, and life.
March 3 2006 9:13 AM

Monkey See, Baby Do

Why humans are more helpful than chimps.

(For the latest Human Nature columns on abortion, Olympic doping, and remote-controlled killing, click here.)

Altruism is more sophisticated in toddlers than in chimps. When a researcher appeared to struggle with a task or accidentally drop an object, 18-month-old toddlers consistently offered to help, but only if the dropping of the object looked accidental rather than deliberate. In a similar experiment, three- and four-year-old chimps often helped, but less readily and only if helping was easy. Theories: 1) Very young humans have both "pro-social motivation" and comprehension of other people's goals. 2) Maybe chimps are less altruistic. 3) No, the chimps handled simpler altruistic tasks well, so the difference must be cognitive. 4) Both the comprehension and the cooperative inclination were probably crucial to our evolution.

William Saletan William Saletan

Will Saletan writes about politics, science, technology, and other stuff for Slate. He’s the author of Bearing Right.

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The human brain can't process curve balls. In a virtual-reality experiment, professional athletes failed to predict accurately whether soccer balls spinning at 600 revolutions per minute would go into a goal or miss it. Researcher's conclusion: "The human visual system just isn't equipped to track the curved course of a fast-spinning ball," because such spinning doesn't occur in nature, which shaped our evolution. Skeptical view: Then explain major-league hitters.

The military is funding research into remote control of animals. Using brain implants, scientists have trained rats to navigate rubble and detect explosives. Now they're manipulating monkeys, fish, and sharks. Method: From your laptop, you send a radio signal to an antenna implanted in the animal. Different signals stimulate different parts of the brain, directing the animal's movement. Meanwhile, you try to read from the animal's brain what it's seeing, smelling, or hearing. Goals: 1) Learn how animals operate. 2) Learn how to help disabled people control their movements. 3) Turn sharks into remote-controlled naval spies, since they're self-powering and quieter than underwater vehicles. (For Human Nature's take on remote controlled military vehicles, click here. For remote-controlled rats, click here.)

Social scientists are debating why women are quitting the work force. The percentage of women working outside the home peaked in 2000 and has since declined. Theories: 1) They decided they'd rather be home with the kids. 2) To make time for outside work, they married later, had fewer kids, slept less, and outsourced housework to machines, maids, and occasionally husbands. (Key stat: Employed mothers work 15 more office/home hours per week than non-employed mothers and get 3.6 hours less sleep.) Now these time savings have hit a "natural" limit. 3) The limit isn't natural; we could relax it if men and the government did more, e.g., by subsidizing child care. 4) The government might resort to that if women's departures from the work force impede economic growth. (For Human Nature's takes on the Larry Summers controversy over women and work, click here and here.)

The air taxi industry is ready for takeoff. Based on manufacturers' orders, the Federal Aviation Administration expects 100 or more "microjets" in operation this year, and more than 1,650 by 2010. The jets, which seat six people to eight people, are faster, lighter, and cheaper than today's small planes. They can fly above or below altitudes used by big passenger planes, and they can land on short runways at small airports the big planes can't use. The idea is that you'll fly into a big airport, then take an air taxi to a small airport within 20 minutes of your home or destination. (For a previous update on air taxis, click here.)

Oscar winners live nearly four years longer than losers. The study's architect decided to check out the data (on actors and actresses in lead or supporting roles) after noticing that winners looked "vivacious." His theory: Winners can bask in victory, while losers feel "only as good as their last picture." This dovetails with previous research showing that longevity correlates with higher pay and taller gravestones. (For this week's related news about the effect of optimism on cardiac health, click here.)

Chocolate cut the risk of death by 50 percent in a Dutch study of old men. This is the biggest, longest study so far to confirm the benefits of cocoa (not sugar). Eating "the equivalent of one-third of a chocolate bar every day" also lowered blood pressure, but researchers say the reduction in death risk came instead from cocoa's antioxidants and flavanols, which help the lining of blood vessels and disrupt cholesterol's role in causing heart attacks, cancer, and lung disease. Researchers' caveats: 1) The findings may apply only to old men. 2) Maybe chocolate was irrelevant, and the men who ate it shared other habits or traits that produced the good effects. 3) Too much chocolate will make you fat, which leads to hypertension and heart disease. (For Human Nature's previous updates on the benefits of chocolate, click here and here.)

Utah legislators killed a bill that would have labeled evolution unproven. The Republican House majority whip sabotaged it by amending it to say that curricular changes should be left to the state board of education. Legislators were persuaded that if they labeled evolution unproven, they'd have to do the same to other theories, and this was a job better handled by the education board. (But the education board opposes any change.) Sponsor's complaint: "I don't believe anybody in there really wants their kids taught that their great-grandfather was an ape, and yet you try and clarify that, and they confuse the issue, saying that it was going to challenge all of science." (For Human Nature's previous update on the Utah bill, click here. For Human Nature's take on intelligent design and Monty Python, click here.)

Scientists grew human prostate glands in mice. They combined mouse prostate cells with human embryonic stem cells, cultivated the combined tissue in the lab, and implanted it in mice, where it grew into functional human prostates. Advertised benefit: We can study the course, treatment, and prevention of cancer in these prostates without giving a damn about the hosts, since they're just mice. (For Human Nature's update on implanting human brain cells in mice, click here. For President Bush's warning against "creating human-animal hybrids," click here.)

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