Health & Science

Super-sizing the Last Supper

The modern struggle with portion control may not be so modern; a study of 52 artists’ depictions of the Last Supper indicates that “serving sizes have been marching heavenward for 1,000 years,” says the Los Angeles Times. Using computer technology, researchers analyzed and compared the meals served in 52 renderings of the Last Supper painted between the years 1000 and 2000, including works by El Greco, da Vinci, and Rubens. Relative to the size of the disciples’ heads, the portions steadily expanded: The loaves of bread grew by 23 percent over the millennium, the main meal grew by 69 percent, and the plates grew by 66 percent. Although the Bible says the meal consisted of bread and wine, in art it has come to include fish, fruit, and even the head of a lamb. Researchers say their findings reflect society’s growing expectations of what the average meal should look like. “The last thousand years have witnessed dramatic increases in the production, availability, safety, abundance, and affordability of food,” says Cornell University researcher Brian Wansink. “We think that as art imitates life, these changes have been reflected in paintings of history’s most famous dinner.”

The teen brain and learning

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Teenagers are a boiling stew of hormones, anxiety, and rebellion. If that weren’t handicap enough, says a new study, puberty may set off changes in the brain that make it the hardest time in life to learn new things. Scientists at SUNY Downstate Medical Center found that when mice hit puberty, unusual changes take place in the hippocampus, a region of the brain involved in memory and learning. There’s a sudden growth of receptors for a chemical that calms them down but also interferes with learning. As a result, adolescent mice perform worse on certain learning tests than both infant and adult mice. The researchers think a similar physiological change may unfold in the brains of human teens. Paradoxically, one thing that helped the “teen” mice was a dose of a stress steroid called THP, which may fight the lethargy teens often experience and focus their attention. “We are suggesting that mild stress is advantageous to learning in adolescence,” researcher Sheryl Smith tells Time. A similar therapy might compensate for learning deficits in humans, Smith says, though care would need to be taken not to aggravate the existing problems of teenhood. “We would have to be careful not to affect their mood.”

Generation me, myself, and I

It’s a frequent complaint among parents: Young people today are spoiled, self-centered, and have a huge sense of entitlement. A new study has found evidence that it may be true. Researchers examined the results of a standardized personality test given to college students nationwide between 1994 and 2009. Called the narcissistic personality inventory, the test measures the respondents’ degree of self-regard through a questionnaire that asks them to choose among such statements as, “I insist upon getting the respect that is due me,” or, “I usually get the respect I deserve.” (Narcissists favor the former.) The portion of students who registered as having high narcissism surged from 18 percent in 1994 to 34 percent in 2009. Psychologists have been debating the mixed results of various studies on whether self-centeredness is rising, but San Diego State University psychologist Jean Twenge tells Discovery News that she is “extremely confident” about her findings. “It’s clear narcissism is rising,” she says.

Why onions make us cry

It may be annoying when onions make you cry, but it’s a small price to pay for an ancient evolutionary trait that helped our ancestors avoid toxins and poisons. The reaction is triggered by a protein, called TRPA1, which is found throughout the body and prompts tears when it senses irritating chemicals, like those found in cigarette smoke, tear gas, and onions. Researchers at Brandeis University found the same protein in flies and animals, and have traced it through evolving species going back 500 million years, to a common ancestor of “every vertebrate and invertebrate alive today,” biologist Paul Garrity tells LiveScience.com. “Since that time, it appears that most animals, including humans, have maintained this same ancient system for detecting reactive compounds.” That the protein was so closely preserved among different species suggests that it offered an evolutionary advantage—by making creatures averse to foods or substances that could kill them.