[monkeywire] Monkeys Illuminate Language Advance
axh69 at po.cwru.edu
Wed Jan 28 22:13:07 EST 2004
Wednesday, January 28, 2004
Adapted by Kathleen M. Wong, California Academy of Sciences
The talent that gave humans alone mastery over language may have been identified. In a new study, psychologists Marc Hauser of Harvard University and W. Tecumseh Fitch of the University of St. Andrews, Scotland, compared the ability of monkeys and humans to recognize grammar rules.
The concept of word ordering - the idea that certain kinds of words must follow other types of words, as in the article-pair "a tree" - is a basic component of language. The scientists played recordings of one-syllable words spoken alternately by a man and a woman to both cotton-top tamarin monkeys and college students. The monkeys looked at the loudspeaker whenever the pattern varied, indicating they had noticed the change; the human subjects also picked up the pattern alterations. The scientists then played recordings of a man speaking one to three words, followed by a woman speaking the same number of words. The rule corresponds to the "if ... then ..." phrase structure of language.
All the human subjects correctly identified pattern changes, even though they were often unable to articulate the structure of the pattern itself. The monkeys, however, recognized none of the variations. The cognitive ability to spot recursive language patterns may have been what allowed humans to develop their linguistic genius, the researchers report in the journal Science.
Mountain Lions Lurk Nearby
Many hikers set out in search of quiet and solitude, but if you're hiking in San Diego County, chances are you're not alone. A new study suggests mountain lions linger unsettlingly close to human recreational trails.
Walter Boyce of the University of California, Davis Wildlife Health Center and colleagues tracked the movements of 20 radio-collared mountain lions living in and around Cuyamaca Rancho State Park east of San Diego. They found the big cats often hid in brush a mere 100 to 300 meters from trails and might move even closer in the late afternoon. The animals spent most of the night hunting and occasionally ranged into nearby communities to kill livestock or pets. Usually, however, they stuck to wild game such as deer and bighorn sheep.
The study ended December 31, just days before a mountain lion killed one mountain biker and injured another in Orange County, south of Los Angeles. Expanding human communities and a hunting ban has made human encounters with the big cats more frequent in recent years. Yet puma attacks in California are very rare. Only a dozen attacks have been recorded since 1890; of those, five ended in deaths.
Humans Gained Color Vision, Lost Smell
Our ability to appreciate the colors of the rainbow came at the expense of our sense of smell. The advantages of full-color vision, scientists say, rendered a sensitive nose unimportant. Evolutionary biologists Yoav Gilad and Svante Paabo of the Max Planck Institute for Evolutionary Biology in Leipzig, Germany, analyzed olfactory genes in humans and 18 other primates.
Of this group, humans have the weakest olfactory abilities. About 60 percent of the human genes studied carry a mutation that renders them inactive. Old World monkeys and apes have lost 30 percent of these genes. By comparison, less than 20 percent of the New World monkey genes are inactive - a figure similar to that in dogs - with one exception. Howler monkeys, like their Old World cousins, had lost 30 percent of these genes. And like humans, howlers have full-color vision.
These smell loss levels are no coincidence, the researchers report in the Public Library of Science. The ability to see rotting or diseased food may have made the need to smell signs of poisons or decay evolutionarily less important, allowing animals with Technicolor sight to jettison their smelling genes with few consequences to survival.
Disgust Helps Humans Dodge Disease
Disgust may have evolved to help humans avoid disease and illness. People find objects that might be contaminated with bodily excretions or fluids far more disgusting than other images, report scientists in the journal Royal Society Biology Letters.
Valerie Curtis of the London School of Hygiene and Tropical Medicine and colleagues showed 40,000 test subjects a series of images and asked them to rate how disgusting each picture appeared. The images included photos of a white cloth stained with either a blue or brownish-yellow liquid, and a viscous liquid that was either blue or yellow with red flecks. The subjects consistently rated the images that appeared to be associated with disease, feces, or blood as far more disgusting than the more neutral blue images.
Women and children had the strongest sense of revulsion, while adult men were less discriminating. Older people also seemed to be less squeamish. Women's sense of disgust increased during their childbearing years and declined with age. The scientists conclude that disgust may be stronger in women because they are the primary caregivers for children.
Mole with Magnetism
Ground dwellers such as gophers and moles face a tricky conundrum: how to find their way around in complete darkness. Now scientists have discovered how one subterranean resident, the naked mole rat of Africa, can get around without GPS; it uses an internal compass. Naked mole rats live in large colonies and seldom venture above ground. They use their sense of balance and smell to navigate during short trips. Yet these blind rodents embark on relatively long foraging trips.
To determine how mole rats get around, Tali Kimchi of Tel Aviv University and colleagues placed mole rats into laboratory mazes and let them learn how to find their way back to their nests. But when the researchers began varying the magnetic fields surrounding the maze, the mole rats got hopelessly lost.
The rodents stop periodically to take magnetic readings and readjust their course, the scientists report in the Proceedings of the National Academy of Sciences. Mole rats and wood rats are the only land mammals known to have magnetic sensing ability.
Monkeys Illuminate Language Advance: Scientific American / New Scientist / MSNBC (Science)
Mountain Lions Lurk Nearby: San Francisco Chronicle (Associated Press)
Humans Gained Color Vision, Lost Smell: New York Times
Disgust Helps Humans Dodge Disease: Discovery.com / BBC
Mole with Magnetism: Scientific American / New Scientist
Source: California Academy of Sciences
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