Saturday, October 24, 2009

SOME COLOR SHADES OFFER BETTER PROTECTION AGAINST SUNS ULTRAVIOLET RAYS

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Economy-minded consumers who want protection from the sun's harmful ultraviolet (UV) rays — but rather not pay premium prices for sun-protective clothing — should think blue and red, rather than yellow. Scientists in Spain are reporting that the same cotton fabric dyed deep blue or red provide greater UV protection than shades of yellow.

Their study, which could lead to fabrics with better sun protection, is scheduled for the Nov. 4 issue of ACS' Industrial & Engineering Chemistry Research, a bi-weekly journal.

Ascensión Riva and colleagues explain that the color of a fabric is one of the most important factors in determining how well clothing protects against UV radiation. Gaps, however, exist in scientific knowledge about exactly how color interacts with other factors to influence a fabric's ability to block ultraviolet protection factor (UPF).

The scientists describe use of computer models that relate the level of UV protection achieved with three fabric dyes to their effects in changing the UPF of fabrics and other factors. In doing so, they dyed cotton fabrics in a wide range of red, blue, and yellow shades and measured the ability of each colored sample to absorb UV light. Fabrics with darker or more intense colors tended to have better UV absorption. Deep blue shades offered the highest absorption, while yellow shades offered the least. Clothing manufacturers could use information from this study to better design sun-protective clothing, the scientists indicate.

(Photo: Public-Domain-Photos.com, Jon Sullivan)

A 200,000-YEAR-OLD CUT OF MEAT

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Contestants on TV shows like Top Chef and Hell's Kitchen know that their meat-cutting skills will be scrutinized by a panel of unforgiving judges. Now, new archaeological evidence is getting the same scrutiny by scientists at Tel Aviv University and the University of Arizona.

Their research is providing new clues about how, where and when our communal habits of butchering meat developed, and they're changing the way anthropologists, zoologists and archaeologists think about our evolutionary development, economics and social behaviors through the millennia.

Presented in the Proceedings of the National Academy of Science, new finds unearthed at Qesem Cave in Israel suggest that during the late Lower Paleolithic period (between 400,000 and 200,000 years ago), people hunted and shared meat differently than they did in later times. Instead of a prey's carcass being prepared by just one or two persons resulting in clear and repeated cutting marks — the forefathers of the modern butcher — cut marks on ancient animal bones suggest something else.

"The cut marks we are finding are both more abundant and more randomly oriented than those observed in later times, such as the Middle and Upper Paleolithic periods," says Prof. Avi Gopher of TAU's Department of Archaeology. "What this could mean is that either one person from the clan butchered the group's meat in a few episodes over time, or multiple persons hacked away at it in tandem," he interprets. This finding provides clues as to social organization and structures in these early groups of hunters and gatherers, he adds.

Among human hunters in the past 200,000 years, from southern Africa to upstate New York or sub-arctic Canada, "there are distinctive patterns of how people hunt, who owns the products of the hunt, how carcasses are butchered and shared," Prof. Gopher says. "The rules of sharing are one of the basic organizing principles of hunter-gatherer cultures. From 200,000 years ago to the present day, the patterns of meat-sharing and butchering run in a long clear line. But in the Qesem Cave, something different was happening. There was a distinct shift about 200,000 years ago, and archaeologists and anthropologists may have to reinterpret hunting and meat-sharing rituals."

Meat-sharing practices, Prof. Gopher says, can tell present-day archaeologists about who was in a camp, how people dealt with danger and how societies were organized. "The basic logic of butchering large animals has not changed for a long time. Everyone knows how to deal with the cuts of meat, and we see cut marks on bones that are very distinctive and similar, matching even those of modern butchers. It's the more random slash marks on the bones in Qesem that suggests something new."

The Qesem Cave finds demonstrate that man was at the top of the food chain during this period, but that they shared the meat differently than their later cousins. The TAU excavators and Prof. Mary Stiner of the University of Arizona (Tucson) hypothesize that the Qesem Cave people hunted cooperatively. After the hunt, they carried the highest-quality body parts of their prey back to the cave, where the meat was cut using stone-blade tools and then cooked on the fire.

"We believe this reflects a different way of butchering and sharing. More than one person was doing the job, and it fits our expectations of a less formal structure of cooperation," says Prof. Gopher. "The major point here is that around 200,000 years ago or before, there was a change in behavior. What does it mean? Time and further excavations may tell."

Qesem, which means "magic" in Hebrew, was discovered seven miles east of Tel Aviv about nine years ago during highway construction. It is being excavated on behalf of TAU's Department of Archaeology by Prof. Avi Gopher and Dr. Ran Barkai in collaboration with an international group of experts. The cave contains the remains of animal bones dating back to 400,000 years ago. Most of the remains are from fallow deer, others from wild ancestors of horse, cattle, pig, and even some tortoise. The data that this dig provides has been invaluable: Until now there was considerable speculation as to whether or not people from the late Lower Paleolithic era were able to hunt at all, or whether they were reduced to scavenging, the researchers say.

(Photo: Dr. Mary Stiner)

Tel Aviv University

CHIMPANZEES HELP EACH OTHER ON REQUEST BUT NOT VOLUNTARILY

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The evolution of altruism has long puzzled researchers and has mainly been explained previously from ultimate perspectives—I will help you now because I expect there to be some long-term benefit to me. However, a new study by researchers at the Primate Research Institute (PRI) and the Wildlife Research Center (WRC) of Kyoto University shows that chimpanzees altruistically help conspecifics, even in the absence of direct personal gain or immediate reciprocation, although the chimpanzees were much more likely to help each other upon request than voluntarily.

The findings are published October 14 in the open-access, peer-reviewed journal PLoS ONE.

Shinya Yamamoto and colleagues studied six pairs of chimpanzees (three mother-offspring pairs and three non-kin adult pairs) in two different experiments, designed to test whether the chimpanzees would transfer a tool to a conspecific even if doing so would bring no immediate benefit to themselves. In each case, two chimpanzees would be situated in two adjacent, transparent booths, either in a straw-use situation where the chimpanzee would need access to a straw to be able to drink the juice box available to it, or in a stick-use situation where the chimpanzee would need access to a stick to drag a juice reward back into the booth.

In the first experiment, the two chimpanzees would have access to the opposite tool needed to obtain the reward in their booth—the chimpanzee that needed the straw would have access to the stick and vice-versa. In the second experiment, the mother-offspring pairs were tested in a situation where there was no opportunity for reciprocation because each individual was assigned a fixed role—giver or recipient—for 24 trials (one week's worth) before the roles were reversed.

The researchers found that the chimpanzees did spontaneously transfer tools in order to help their partner. This tool transfer occurred predominantly after the partner had actively solicited help (by poking its arm through a hole in the booth, for example, or by clapping), even when there was no hope of reciprocation from the partner (as in experiment 2) and even when the two animals were unrelated.

"Communicative interactions play an important role in altruism in chimpanzees," said Dr Yamamoto. "While humans may help others without being solicited, the chimpanzees rarely voluntarily offered an effective tool to a struggling partner. Indeed, simple observation of another's failed attempts did not elicit voluntary helping in chimpanzees."

Helping upon request may be a more economical and effective strategy. Altruistic behavior by definition produces no direct immediate benefit to the actor; making a request is a clear indicator to the actor that the recipient requires help, minimizing the risk to the actor of unnecessarily behaving altruistically. In this sense, "help upon request" is an ideal strategy since the helping is always helpful and not wasted. This type of altruism may have initially driven the prevalence and development of altruism during human evolution.

One important question for future research is whether high-frequency, voluntary altruism is a behaviour unique to humans. Some new world monkeys have demonstrated unsolicited prosociality suggesting that voluntary altruism evolved in phylogenetically diverse taxa but for now, there seems to be no consensus on what is the decisive factor in explaining species differences.

(Photo: Yamamoto S, Humle T, Tanaka M (2009) Chimpanzees Help Each Other upon Request. PLoS ONE)

PLoS ONE

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