Men With Deep Voices Have More Children

Men with deeper voices have a reproductive advantage, according to an article published online for Biology Letters. Researchers chose to study the Hadza, a hunter-gatherer tribe in Tanzania, because members of the group pick their own spouses and use no birth control. This makes them a “natural fertility population,” where hypotheses about reproductive successes can be tested.

Researchers asked men questions about their reproductive histories and recorded their voices. They found that 42 percent of the variance in men’s reproductive success could be accounted for by the quality of their voices.

Women’s voices made no difference in the number of children they had.

Read the article from the NY Times.

Dolphin Calf Has Three Mommies

At the National Aquarium in Baltimore, a dolphin calf is being nursed by its mother and two other females.

Dolphins can spontaneously produce milk in the presence of a calf, but the phenomenon is not well-documented.

Aquarium officials are still trying to come up with a name for the baby dolphin.

Read the AP Story.

Robotic Roaches Fool Real Bugs

photo from sciam.com

Cockroaches like to hang out in dark places with other roaches. But they can go against their better instincts if they’re around roach-scented robots.

Researchers made battery-powered matchbox-shaped robots, which were good enough to fool the nearsighted cockroaches. They wrapped the robots in roach pheromones and sent them–along with real roaches–into a circular arena with two shelters. One shelter was dimly lit, the other bright.

Researchers placed 16 roaches in the arena, and the bugs headed for the darker shelter. But when four insects were replaced with robots programmed to head to the light, the real roaches followed suit 60% of the time.

Read the story from sciam.com or from the NY Times.

Congo to Protect Bonobos

picture from the New York Times

The bonobo is humans’ lesser-known cousin. Dubbed the “make love, not war” primate, the animal seems to have eschewed the bellicose ways of its chimpanzee cousin for more erotic conflict management. When chimps find a stash of food, they fight over it. When bonobos find food, they all have sex– and then share the snack.

The sexy ape is endangered, threatened by habitat loss and hunted for bush meat. The bonobo is found only in the Congo basin, south of the Congo River. The country of Congo just announced the creation of a rainforest preserve larger than the state of Massachusetts designed to protect the animal. The Sankuru Nature Reserve is being created through a partnership involving American and Congolese conservation groups and government agencies.

Read the story from the NY Times.

Stanford Hospital Separates Two-Year-Old Conjoined Twins

On Monday November 12th, surgeons separated Costa Rican conjoined twins Yurelia and Fiorella Rocha-Arias. I was at the press conference where they handed out these photos. You can read my article for The Stanford Daily here.

photos credit Lucille Packard Children’s Hospital

Scien-tastic articles from The Stanford Daily

Scientists investigating coat color in dogs get some surprises.

Athletes get tested for a heart condition that can make them drop dead.

Older women undergoing in vitro fertilization avoid multiple births with this technique.

Humans take over the world, extra spit genes responsible

Between two and four million years ago, an unremarkable primate grew a big brain and began the slow climb towards skyscrapers, jet planes, and science blogs. It’s not clear what made these proto-humans more successful than their neighbors, but scientists at UC-Santa Cruz may have found one piece of the puzzle.

It’s in the spit. Spit is full of enzymes that start digesting food before it even leaves the mouth. One of these enzymes is amylase, which breaks down starch into simple sugars. The UCSC researchers snatched spit from 50 undergrads and found that they had as many as 15 copies of the amylase gene. The same researchers rounded up some chimps and found that the animals had only two copies of the amylase gene. Fewer copies of the gene means less enzyme in saliva, which means chimps don’t digest starch as well as humans.

Chimps eat a lot of raw fruit, which doesn’t have much starch. But early humans, with their amylase-packed saliva, could have snacked on starchy grains, tubers, and roots. That extra nutritional boost could have made all the difference. Big brains take lots of energy, so scientists have long speculated that our cerebral ancestors must have found a better source of nutrition than other primates. Thanks to extra amylase genes, they may have found it in starch.

Read the press release.

Moray eels are toothy, creepy

photo credit: Rita Mehta

Scientists at UC Davis confirmed this week that moray eels are scary as hell. The eel uses its jaws to grab prey, and then–get this–a second set of jaws flies out of its throat and yanks the food into its esophagus. The top photo shows the ‘pharyngeal jaws’ in their normal position, resting in the eel’s throat. The bottom photo shows how the jaws move forward to seize food. The whole alien process takes just fractions of a second.

Read the press release.

“Blue tits are really ultraviolet tits”

It’s a classic stoner conundrum: “We all say the grass is green, right? But what if, like, what you see as green is what I see as blue?”

It’s weird to think that two people could perceive colors in totally different ways without realizing it. But forget people–when it comes to different color perception, we should be talking to birds.

I’m reading Sean B. Carroll’s The Making of the Fittest, and I’ve learned that birds see color differently than people. It all boils down to opsins: light-sensitive proteins in the photoreceptor cells of our eyes. Humans have three kinds of opsins, one each for short, medium, and long wavelengths. The short-wave sensitive opsin is what determines the upper limit of the our color vision. For humans, this opsin is tuned to 417 nm–that is, violet. Some birds have their short-wave sensitive opsin tuned higher–around 370 nm, which means they can see into the ultraviolet range.

This has important implications for bird behavior. Starling females choose mates based on UV-reflecting feathers on their throats. Researchers studying these birds filtered out UV light and the females’ preference was thrown off. Like starlings, male blue tits have UV-reflecting plumage–theirs is on the crest of their heads. This discovery prompted University of Bristol researchers to declare that “blue tits are really ultraviolet tits”.

Ultraviolet vision also plays a role when these birds raise a family. The mouths of chicks from eight different bird species have been shown to reflect UV. Hungry chicks flash these ultraviolet beacons to their worm-providing parents. The strongest chicks have the most reflective beaks.

Fruit flies like fizzy drinks

You may have about the five taste receptors in humans: sweet, sour, bitter, salty, and umami (savory). Like humans, flies have five taste receptors, but theirs are a bit different than ours. It turns out one of them is tuned to carbon dioxide.

It all started with a bottle of Sam Adams. Berkeley grad student Walter Fischler was frustrated in his efforts to stimulate an new type of fruit fly taste cell. To his surprise, the cells responded to a drop of Sam Adams beer.

There’s more than one compound in beer, however. Fischler tested flat beer and dry yeast, but those compounds didn’t make the cells light up. Then Fischler found a leftover bottle of Calistoga spring water.

Bingo! The CO2 in the spring water stimulated the flies’ taste cells. Researchers posit that the insects respond to CO2 because it helps them find their favorite snack of rotten fruit. Rotting fruit is host to lots of dividing yeast and bacteria, which bubble out CO2 gas.

It is not yet known if humans have a CO2 taste receptor.

Read the story.