The ability to stand upright and stride on two feet was a critical milestone in setting the human species apart from our ape ancestors. Paleoanthropologists say it's what eventually allowed humans to develop bigger brains, and it likely took a while to evolve. Based on the fossil evidence, researchers have long suspected Australopithecus afarensis, the species whose most famous member is 3.2-million-year-old Lucy, was among the first to spend the majority of its day on two feet. Problem is, Lucy's skeleton is missing key foot bones, which left researchers to debate how much time Lucy spent upright--most of the time, like us, or only periodically, like the apes?
Now scientists report they have found a crucial clue: a fourth metatarsal, one of the long bones connecting the toes to the ankle, from one of Lucy's contemporaries. That fossil speaks volumes about how we evolved. The bone shows signs of an arch, both from front to back and from side to side, which suggests that A. afarensis's foot could absorb shock and bear the weight of an animal that stood upright for long periods. It is strong and stiffer than those found in most apes' flexible, handlike feet, which not only splay flat on the ground but can also curl around branches--the better to sustain a tree-based existence. Being fully upright likely gave Lucy and her ilk an advantage over other hominids some 3 million years ago, particularly as the cooling planet caused the dense, lush forests of eastern Africa to give way to grasslands, where walking--and running--would have been more useful than climbing.
Sources: Science; Cochrane Library; American Academy of Orthopaedic Surgeons presentation; Archives of Internal Medicine
New Study Shows Zinc Helps Sniffles
Is it hope or hype? Consumers spend billions of dollars a year on remedies like zinc to fend off impending colds--with no solid scientific evidence that they work. But now an updated review of studies on the effects of zinc finds that the mineral may prevent some sneezes and sniffles, as long as you take it within 24 hours of the first signs of a cold. The review of 15 trials, involving more than 1,360 people who were randomly assigned to take zinc lozenges, syrups or placebos, suggests that zinc cut the duration of colds by about a day and reduced the severity of symptoms by 40%. What's more, children who took zinc protectively for five months or longer caught fewer colds and had fewer sick days than kids who didn't take zinc. They were also less likely to use antibiotics to try to battle the cold-causing rhinovirus--something that could help in controlling antibiotic resistance. More trials are needed to detail proper dosing, but in the meantime, it seems that zinc may no longer be just for slathering on noses in the summer.
To Stretch Or Not to Stretch?
For many runners, the prerun stretch is a sacred routine that's supposed to lengthen muscles and reduce the risk of injury during the pounding to come. But in the first study of runners randomly told either to stretch for three to five minutes before running or to skip the routine altogether, researchers found little difference in injury rates over three months. The good news for those who still like a good stretch before working out: it doesn't appear to increase injuries either.