University of Iowa News Release
Feb. 9, 2004
UI's Russell Ciochon Writes The Book On Early Man
Picture two bighorn sheep butting heads, fighting for the right to mate with the herd's females. Now substitute prehistoric men beating one another over the head with clubs in a quest for dominance, and you have a good idea of how scientists believe Homo erectus, precursor to Homo sapiens, our own species, developed its extremely thick skull.
The story of the discovery and study of early human or "hominid" remains, originally made famous as the bones of "Peking Man," is recounted in a book published Feb. 9, "Dragon Bone Hill: An Ice-Age Saga of Homo erectus," (Oxford University Press) co-authored by Russell L. Ciochon, professor of anthropology in the University of Iowa College of Liberal Arts and Sciences. Together with co-author Noel T. Boaz, professor of anatomy at Ross School of Medicine, Ciochon argues Homo erectus survived for some 1.5 million years - much longer than modern man has been around - partly because of its thick, bicycle-helmet-shaped head.
"Homo erectus had a very thick cranium," he says. "Skulls from hominids before and after Homo erectus don't look this way. Why?"
"Our answer is that the thick skull was protection against interpersonal violence," he says. "In an aggressive society, those individuals with the thickest skulls likely would have survived to pass along these traits to their offspring. The authors note that a thin-skulled Homo erectus would have succumbed to the same type of injury that can threaten modern man: "When a person is injured in the head today, whether or not the skull is fractured often makes the difference between life and death. What might seem like a relatively minor break in the skull can tear blood vessels that adhere tightly to its inside surface. The buildup of blood under the skull, known as a hematoma, pushes on the brain. Coma and, eventually, death can result." Why didn't we inherit thick cranial bones from Homo erectus? The book suggests that evolution may have favored lighter skulls to balance off against an evolving heavier and larger brain, or a thinner skull to help cool the brain."
The book goes on to frame the history of the search for modern man's origins and to illuminate how multidisciplinary research is capable of testing human evolutionary hypotheses. Homo erectus was the first species to use fire and now new computer-generated maps of the excavations at Dragon Bone Hill show for the first time how burned bones and the hominid fossils are spatially associated. Ciochon and Boaz set out their argument that most of this important site was accumulated by the giant cave hyena, and not by "man the hunter." Many stone tools show that Homo erectus was there, but as a scavenger from the kills of the big carnivores. To explain the evolutionary origins and eventual extinction of Homo erectus, Ciochon and Boaz propose a new hypothesis, "clinal replacement," that accounts for both the mounting molecular data on our origins and the ever-better dated and more complete fossil record.
A website for the book "Dragon Bone Hill" will be available Monday afternoon at: http://www2.uiowa.edu/dragon/. This site also contains links to related research by the authors on their work at Dragon Bone Hill.
The authors met three decades ago while paleoanthropology graduate students at the University of California at Berkeley. Ciochon went on to do fieldwork in Burma, India, China, Vietnam and Indonesia while Boaz worked in Libya, the Congo and Uganda. They joined forces during the 1990s in an exploration of the famous fossil site, Dragon Bone Hill, located about 30 miles southwest of Beijing, China.
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