Health & Science

Autism: Developed in the womb?

Environmental factors may be responsible for more than half of all autism cases, a surprising new study reveals. Researchers who studied about 200 pairs of twins concluded that 58 percent of autism cases arose from conditions encountered in the womb, while 38 percent appeared to be genetic. Scientists had previously thought that about 90 percent of cases were genetic in origin. The finding is “a massive claim” that “flies in the face of the previous data,” Angelica Ronald, a geneticist at the University of London, tells the Los Angeles Times. But other researchers note that autism, which affects 1 in 110 U.S. children, is six times more common now than it was two decades ago—an increase far too rapid for genetic mutation alone to explain. Indeed, a second study published alongside the first shows that women who take antidepressants during their first trimester of pregnancy are three times more likely to have an autistic child than are women who don’t. Other environmental risk factors may include low birth weight, infections contracted in utero, stress, and medications. Researcher Clara Lajonchere says the findings underscore that “prenatal care is critical” to reducing the chances of a child developing autism.

The universe’s brightest spot

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At the edge of the observable universe, European astronomers have detected the brightest object ever seen. It’s a quasar, which is a galaxy that emits astonishing amounts of energy as it is eaten by a black hole, and it lies about 13 billion light-years away. Formed in the universe’s infancy, the quasar emits as much light as 63 trillion suns. Scientists believe the quasar is so bright because the black hole swallowing it is super-massive—the size of 2 billion suns. But they can’t explain how the early universe could have supported a black hole that large, since they’re believed to develop over hundreds of millions of years. “It is like finding a 6-foot-tall child in kindergarten,” University of Michigan astrophysicist Marta Volonteri tells Science News. The finding suggests that black holes may grow much faster—and require much less matter to form—than previously thought. Since this quasar is 170 million years older than any found before, it may hold crucial clues about how the early universe evolved. “The existence of this quasar,” says Chris Willott, a researcher at the Canadian Astronomy Data Center, “will be giving some theorists sleepless nights.”

A private part made public

A glance at a man’s right hand may be enough to reveal the size of his penis. Korean researchers have found that the longer a man’s right ring finger is as compared with his index finger, the longer his member is likely to be. That’s probably because the amount of testosterone a man is exposed to in the womb “is responsible for both” penis and digit formation, Denise McQuade, a biologist at Skidmore College, tells Reuters​.com. That means doctors could look at men’s hands as a “noninvasive and easy to measure” way of checking their prenatal history. A number of recent studies have linked the amount of testosterone encountered in utero to a host of qualities. For instance, the more of the hormone a male fetus receives, the more aggressive, athletic, risk-taking, and attractive he’s likely to be as an adult. But higher testosterone levels in the womb also put men at greater risk of developing arthritis, Lou Gehrig’s disease, and prostate cancer—diseases that their fingers could help predict.

Bad news for bananas

Americans’ favorite breakfast fruit is chronically inbred and therefore at heightened risk of extinction, Discovery News reports. A new study by Australian National University researchers shows that for the past 7,000 years, almost all of the world’s popular banana species have failed to crossbreed in the wild. For millennia, humans have instead artificially bred hybrids of natural varieties, but those hybrids—including the common Cavendish found in supermarkets—are themselves infertile. To increase production, farmers have to clone their banana trees, making each plant and its fruit genetically identical, and thus vulnerable, since a single opportunistic pest or pathogen could wipe out world production. It’s about more than breakfast: A major die-off would “have immediate consequences,” says study author Mark Donohue, “possibly leading to famines.” About 85 percent of bananas grown around the world are staples of the local diets where they’re harvested. Donohue says researchers should urgently search for a fertile, genetically diverse banana species to refresh the gene pool of our current, disease-prone crop before disaster strikes. Such a resilient banana probably exists on a remote farm or in the wild, he says, “if we could only find it.”