Thursday, May 27, 2010

Smaller fingers provide women a better feel

A guy who absentmindedly scratches his chin late in the day feels the stubble that has grown in since his morning shave. But if his girlfriend were to pass her hand along that same chin, there's a good chance that she would be better able to feel the individual hairs.

For pianists and guitarists, small fingers are a curse. But a study published in the Journal of
Neuroscience on December 16, 2009, suggests that diminutive digits do have an advantage: they are more sensitive.
To study differences between the sexes' sense of touch, Daniel Goldreich of McMaster University in Hamilton, Ontario recruited 100 college students to play a game of tactile whack-a-mole. Undergraduates placed their fingertips over a small hole where a cylinder with grooves carved into the top popped out and pressed against the skin. The student's job was to identify whether the grooves ran horizontally across or vertically up and down as they felt new cylinders with increasingly smaller grooves.

"If you use your fingers to explore a pimple or a scab or to rub the 'sleep' from the corner of your eyes after waking up, you are performing a tactile task that involves spatial dimensions similar to those of the grooves we used," said Goldreich.
The paper reports that sensory receptors called Merkel cells, which discern the texture and structure of materials pressed against the fingertip, are more closely packed on small fingers as compared with large ones. Because women tend to have smaller fingers than men, they are, in general, better able to distinguish the shapes of the things they feel.Females and males with similarly-sized fingers and hands showed similar abilities of detection.

A few months ago, Ellen Lumpkin of Baylor College of Medicine in Houston provided strong evidence that we require Merkel cells in order to interpret Braille, compare rougher and finer grains of sand paper or manipulate strands of dental floss. She created mice with altered genes that grew and developed normally but lacked Merkel cells in certain parts of their bodies. The modified rodents could still feel vibrations, temperature changes and pain, but their nerve cells stopped responding to light touches.

Merkel cells are difficult to spot in a human finger. So instead of looking for them directly, Goldreich looked closely at the sweat glands on his subjects' fingertips, which are usually found above Merkel cells. He noticed that in larger fingers the sweat glands -- and presumably the Merkel cells beneath -- were spaced farther apart.

No comments:

Post a Comment