(PhysOrg.com) -- University of Texas at Austin anthropologist Liza Shapiro and two fellow researchers on Thursday won an Ig Nobel Prize -- dedicated to "achievements that first make people laugh, and then make them think" -- for a 2007 study on the evolutionary reasons pregnant women don't tip over.
"I guess if I'm never going to win a real Nobel, this is the next best thing," Shapiro joked after learning of the prize, which is handed out annually at Harvard University by Annals of Improbable Research magazine.
Shapiro's fellow researchers—University of Texas graduate Kathleen Whitcome and Daniel Lieberman, who are both at Harvard—accepted the award Thursday at a ceremony attended by 10 Nobel Prize laureates. Their findings were first published in the journal Nature.
Scientists (as well as far more casual observers of the human condition) have long noticed that pregnant women lean back to avoid toppling over. But that can put extra pressure on their spines, leading anthropologists to theorize that women's lower vertebrae evolved to reduce such pressure during pregnancy.
Shapiro and her fellow researchers found out just how. By studying 19 pregnant women, they discovered that a woman's lumbar, or lower back, curve extends across three vertebrae. In men, it extends across two. The joints between the vertebrae also are larger in females and angled differently from those of males to better support the extra weight.
Researchers attribute the difference to an adaptation that first appeared at least two million years ago in an early human ancestor. Because the difference doesn't appear in chimpanzees, they believe walking upright led to the adaptation.
"This is something that certainly half the population has thought about," says Marc Abrahams, editor of Annals of Improbable Research. "Every woman who is, has been or has ever contemplated the possibility of being pregnant has thought about this but never had an answer until now."
Shapiro, a professor in the Department of Anthropology, says the research is 100-percent serious but understands why it might qualify for an Ig Nobel, given headlines that boasted of an answer to the age-old question of "Why Pregnant Women Don't Tip Over."
More information: More information about the award can be found at www.improbable.com
Provided by University of Texas at Austin (news : web)