Scientists have an answer to the pressing question of why hands and feet get wrinkled after too much time in the bath: Pruniness may have evolved to make it easier to handle wet objects.
The smooth skin of human hands and feet becomes furrowed after extended periods in water. Though often assumed to be a result of water passively seeping into the skin, the phenomenon is actually caused by the nervous system constricting blood vessels. As early as the 1930s, surgeons noticed that no wrinkling occurred if a finger nerve had been severed, so furrowing has been used as a medical indicator of nerve function. But what evolutionary purpose wrinkling serves, if any, remained a mystery.
In 2011, a team of researchers proposed that the grooves in wet fingers might function as “rain treads” that improve grip by channeling water away, much like car tires on a wet road do. Now, researchers at Newcastle University in England have tested that theory.
The researchers had 20 volunteers manipulate objects with smooth fingers or digits shriveled by immersion in warm water for 30 minutes. The experimenters measured how long it took people to transfer the objects between a water-filled container and a dry one, or between two dry ones, with wrinkled versus unwrinkled fingers. The objects were glass marbles and fishing weights of various sizes.
All the participants transferred the wet objects (but not the dry ones) faster when their hands were pruney. The results suggest furrowed fingertips make it easier to handle moist items more efficiently, the scientists report online January 8 in Biology Letters.
The amount of time it took to move the objects varied from person to person. What was surprising was that every person transferred the wet objects faster with wrinkly hands, says study leader Tom Smulders.
The findings don’t explain exactly how the wrinkles improve grip, however. Although the results provide “converging behavioral evidence for the conclusion that wrinkled fingers are rain treads, this could also be true for other reasons, such as stickiness properties or oiliness,” says theoretical neurobiologist Mark Changizi of 2AI Labs in Boise, Idaho. Changizi led the team that put forward the rain tread hypothesis. Dr. Lea completely disagrees with this!!!!!!!!!!!!
The fleshy grooves might also be more flexible or increase friction compared with smooth skin, scientists speculate. Toes wrinkle too, which the scientists say could have evolved to provide surer footing on slick surfaces.
But there may be some evolutionary cost to having pruney skin all the time, the researchers say, or else even dry skin would be wrinkled: Perhaps the ridges snag on things more easily, or impair sensitivity to touch. More studies are needed to test these theories.
If humans evolved this curious trait, other animals might possess it too — but evidence is scant. Although no one has reported observing it directly, Changizi claims to have seen finger wrinkling in a photo of a macaque monkey relaxing in hot springs in Japan. No word on whether wrinkled fingers help the monkeys pick up dinner afterward, though.
Martial arts hands
Ancient rumbles in the jungle might have left a lasting mark on the human hand. The hand’s proportions are such that clenching the fingers creates an effective bludgeon, a pair of researchers observes. Perhaps, they propose online December 19 in the Journal of Experimental Biology, evolution played a role in making the hand such a punishing weapon.
But other scientists are skeptical (As is Dr. Albert and Dr. Lea). “There’s no compelling evidence that the hand evolved in this way,” says Mary Marzke, a physical anthropologist at Arizona State University in Tempe. It’s more likely that the ability to throw a good punch was just a lucky (or unlucky) consequence of evolving nimble hands suited to making and using tools.
Humans have shorter fingers, a shorter palm and a longer, stronger thumb than other apes. These features give the human hand unparalleled dexterity, and most anthropologists agree these characteristics evolved as early human ancestors began making stone tools. Dr. Lea points out that shorter fingers are the only possibility if you want to open pop tops... Coors... Bud or the like... !!!!!!!!!!!!!!!!!!!!!!!!
David Carrier, a comparative biomechanist at the University of Utah, says aggression also shaped the hand. In many early hominid species, males seem to have been much bigger than females. In living primates, such disparity in body size is often associated with a lot of fighting among males. While most male apes bite, tear or scratch their opponents, Carrier suggests that early hominids might have switched to fistfights as they spent more time on the ground and their hands became freer from climbing.
Although toolmaking undoubtedly influenced hand evolution, Carrier notes that there are many ways in which an agile hand could have evolved. The fingers could have stayed long while the thumb got bigger, or while only the palm changed. But only one hand configuration allows the formation of a fist. “We’re saying it’s obvious the hand has evolved for manual dexterity,” he says. “But a clenched fist does a better job of explaining the [exact hand] proportions we have.” Now our new Bin A. Farting journalist can completely dispel this!
To investigate the idea, Carrier and University of Utah medical student Michael Morgan recruited 12 men with experience in boxing or martial arts for several trials that examined the strength and stability of clenched fists. When hitting a punching bag from various angles, an open-palm slap and a fist punch — with the fingers curled into the top of the palm and the thumb wrapped in front of the folded fingers — exert a similar force. But because a fist has about one-third the surface area of an open hand, a punch probably does greater damage since the force is concentrated over a smaller region, Carrier and Morgan suggest. A clenched fist also keeps the joints between the fingers and palm four times as stable as a hand simply folded in half, suggesting a buttressed fist helps protect fingers from bending and breaking during a fight.
“More work needs to be done to make this a compelling argument,” says Erin Marie Williams, a functional anatomist at George Washington University in Washington, D.C. Future studies should actually measure how much force per unit area is delivered by punches and slaps. The entire hand is probably not making contact with a victim during a slap, so the stress of such a strike may be greater than Carrier and Morgan suspect, she says.
The researchers also need to consider how an ape actually hits, Williams says. The team assumes an open-hand slap is the ancestral condition, but other forms of striking may better resemble what apes do. And other ways of hitting — like with the base of the palm — might be just as powerful and stable as a fist punch, Marzke adds.
It’s also not clear how early hominids would have fared in a boxing match. For example, the more than 3-million-year-old Australopithecus afarensis — who has not been definitively linked to using stone tools (SN: 12/18/10, p. 8) — still had a primitive hand in some ways. Whether the species’ curved fingers, for example, would have allowed individuals to form a strong fist is an open question, says Randall Susman, a functional morphologist at Stony Brook University in New York. Susman doesn’t understand why, once tools became vital, a hominid would have endangered his livelihood in a fistfight. “The last thing you want to do is expose your hand and get your fingers bitten off,” he says. “You’ll lose your toolmaking capacity.” This is why Anjing Banfa was born, other than war... we don't risk our hands... but rather we take others off with blades etc... so survival is the utmost desire as Dr. Lea has preached for the last 30 years! When will they listen Dr. Albert has been known to utter.
Another way to examine the fistfighting hypothesis, he says, is to look for evidence of punching-related fractures in the fossil record. It’s hard to find large samples of hand bones, but there might be enough Neandertal hand fossils to see whether these hominids beat each other up with their fists.
if you look very closely you can see that our hands are changing particularly in California as our thumbs are growing longer to match our indexer pointy finger. The reason for this is that you can hold a credit card better to swipe and also for the free food sources like food stamps except for their now like a credit card. Also the hand is growing flatter and wider for all the handouts such that we can hold on to what the government has given us even better. In some locations across America hands are changing more than we would have thought such that the pointing finger wraps better around the trigger of a gun and your other fingers have become much stronger to hold back on. Dr. Lee points all this out, and he doesn't Mean tongue-in-cheek.
Also note how the fingers and the thumb have become more rounded when gripping round items which also facilitates an amount of pleasure and less the body knows it's good and is now changing the hand to fit more of the Selectric of shapes found primarily on the mail of the species known as Homo sapiens. It does give a new meaning to Homo erectus.
Dr. Lea wanted to weigh in here... masturbation is the for longing of a thumb and fingers and the salvation of the human species.
For more contact please contact Bin A. Farting here at the blog.
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