www.cnn.com/2004/TECH/science/02/12/coolsc.thickskulls/index.html
ET Scientists: Hard heads a key to survival Clubbing heads may have been part of mating rituals By Marsha Walton CNN This re-creation of homo erectus shows the thickness of the brow ridge and the slope of the skull. This re-creation of homo erectus shows the thickness of the brow ridge and the slope of the skull. Story Tools RELATED 30 Ancient skull more ape than human? Scientists say the bulky craniums of the human ancestor, homo erectus, may have helped the species survive some aggressive mating rituals. After studying fossils in a region called Dragon Bone Hill in China, anthropologist Russell Ciochon of the University of Iowa concluded males of the species were clubbing one another over the head, probably to win females. Those with thicker skulls who survived these bloody confrontations would pass that trait to offspring, Ciochon said. For more than 100 years, researchers have pondered the odd shape of homo erectus' skull, which looks something like a bicycle helmet. Designed to protect the brain, eyes and ears from impact, homo erectus' head was bulkier than those of hominids before it, and after it. It would have been a tremendous advantage for survival, less likely to break on impact and geared toward winning fights. Over the years other explanations for the thick skulls didn't completely add up. For example, the skull could not save them from a major predator of the day, the giant hyena. Hyenas would likely have aimed for softer, more vulnerable parts of the homo erectus body, researchers say. And the animal's fierce teeth could pierce even the thickest pre-human head. The researchers used modern tools to reach their conclusions, studying fossil casts, fossil bones, ethnographic records and comparative anatomy. They experimented with human cadavers to establish how much force it would take to break bones. They gathered evidence from dozens of fossils with healed skull fractures: presumably from the hard-heads who got the girls. Researchers compared the mating rituals of the hominids to those of bighorn sheep, who charge at each other at speeds up to 20 mph and butt heads for the right to mate with females. Ciochon said evolution eventually favored a lighter skull to accommodate a heavier and larger brain. An excerpt of the book is in the February issue of Natural History magazine. Story Tools 35 Click Here to try 4 Free Trial Issues of Time!
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