Menopause facilitates grandmas146; important role in evolution

Menopause facilitates grandmas8217; important role in evolution
Today many women feel marginalised once they reach menopause. But research suggests that far from being a burden to societies, grandmothers have played an important role in the evolution of human longevity. Studies of modern hunter-gatherers in Tanzania, Venezuela and Eastern Paraguay8212;societies that offer insights into how humans evolved8212;consistently show that Grandma is doing much of the work. Researchers have even measured the muscle strength of men and women in these communities and weighed the baskets and bundles carted around by them. Often, the scientists find, women in their 60s are as strong as women in their 20s. 8220;It8217;s the women over 40 who are carrying the heavy loads,8221; said Dr Kristen Hawkes, an anthropologist at the University of Utah. The research is the basis for the grandmother hypothesis that may help explain why menopause occurs. The basic idea is that an end to a woman8217;s reproductive years allows her to channel her energy and resources into caring for her children and grandchildren, thereby providing her descendants with a survival advantage.

Report sees solar plants in space as a viable option
Beam it down, Scotty. A new study released in the US on Wednesday concluded that continued increases in oil prices finally might make the generation of solar power in orbit economically competitive. The orbiting power plants would reduce dependence on oil and help reduce the production of carbon dioxide that is contributing to global warming, according to the report led by the National Security Space Office, part of the Department of Defense. 8220;This is a solution for all mankind,8221; said former astronaut Buzz Aldrin, now chairman of the spaceflight advocacy group ShareSpace Foundation. Aldrin joined with a group of other space advocacy organisations to unveil the report in Washington. Since the advent of the space age 50 years ago, scientists have dreamed of launching acres of photovoltaic cells into orbit and beaming the electricity electromagnetically to Earth8217;s surface but have stumbled over the cost of the project and the technical difficulties. The report estimated that in a single year, satellites in a continuously sunlit orbit could generate an amount of energy nearly equivalent to the energy available in all of the world8217;s oil reserves.

A bird8217;s-thigh view of tool-making sheds light on crows
Christian Rutz, a biologist at the University of Oxford in England, and his colleagues developed a half-ounce video camera, location-tracking transmitter and battery that can be attached to a crow8217;s tail feathers. The lens points between the crow8217;s legs and transmits about an hour of video to researchers nearby. Rutz and his colleagues captured more than seven hours of video that sheds new light on the behaviour of New Caledonian crows, one of only a few species that use tools. The researchers report in Science that two crows fashioned tools from dried grass stems, a previously unknown tool, and used them to probe the ground. 8220;In the past everybody thought they mainly used stick tools to fish for large beetle larvae in rotting wood,8221; Rutz said. One crow showed a preference for a particular stick8212;using it, putting it down, using it again, and then flying with it about 100 yards to a new location. Rutz said this behaviour suggested 8220;the cost of transportation is outweighed by the benefits of this being a particularly good tool8221;.