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 Karen Rosenberg is an evolutionary anthropologist whose work extends from womb to tomb.
Because of her expertise in anatomy and skeletal structure, the chairperson and associate professor of anthropology is sometimes called by the medical examiner’s office to determine the sex, age and height of an unknown person whose skeletal remains have been discovered.
However, her current research is concerned with human evolution, studying the evolution of the pelvis and childbirth from the times of the australopithecines, early ancestors of humans, who lived 4 million years ago. The best-known fossil of these forerunners of human beings is Lucy, who is over 3 million years old.
Rosenberg and Wenda Trevathan of New Mexico State University recently published an article, “The Evolution of Human Birth” in Scientific American. The article also was the subject of a story in the London Sunday Times. They previously contributed an article to Evolutionary Anthropology on this topic.
Rosenberg and Trevathan met at a conference on evolutionary anthropology and discovered their common interest in the evolution of childbirth. Rosenberg is interested in the evolution of anatomy, and Trevathan also is a biological anthropologist, as well as a midwife, who has assisted with the births of many babies.
The article is the result of the merging of their research, and they are currently collaborating on a book looking at childbirth from both a cross-cultural and evolutionary viewpoint.
“For some reason, there has not been much research done on the evolution of the pelvic bone, and I became interested in the topic of the pelvis in terms of women giving birth,” Rosenberg said. She has examined the human fossils from Europe, Israel, China and South Africa.
“The Evolution of Human Birth” begins with the birth of a baby by Sophia Pedro, who was trapped in treetops during a flood in Mozambique in 2000 and later rescued by helicopter.
As the authors point out. this is far from the norm for humans, although many other primates do give birth alone in treetops. “Human beings are the only primate species that regularly seeks assistance during labor and delivery,” the article points out, and Pedro did have help from her mother-in-law who was with her escaping the flood.
The reason for this need for help, according to the article, is that humans have big heads because of their large brains, but the birth canal through which the baby must pass, is limited by the constraints of humans’ upright stance. As a result, human mothers in labor need assistance.
For primates, the birth canal is a constant oval shape, and a baby primate faces forward so that the mother can guide it out of the birth canal. For humans, the long axis changes so that a human baby must go though a series of turns. The article points out that, “This journey through a passageway of changing cross-sectional shape makes human birth difficult and risky for the vast majority of mothers and babies.” In addition, the human baby faces the opposite direction, making it difficult for a human mother to guide the baby as it is born.
Seeking assistance may date back to the forerunners of human beings, or as long ago as five million years ago, when ancestors began walking upright, Rosenberg said.
Although the physical risk involved in childbirth was one reason mothers sought assistance, “pain, fear and anxiety more likely drove their desire for companionship and security,” according to the article. Those experiencing those emotions “seek the protection of companions, which would have given them a better chance of surviving,” an evolutionary advantage. Observation indicates these emotions are still common today during labor and delivery.
“The ways of assisting at birth may be different and vary from culture to culture,” Rosenberg said. “There are different positions laboring women assume from upright to lying down. There may be rules about who is present, or the disposal of the placenta, which is sometimes buried or, in Western society, is treated as medical waste. In some cultures, the umbilical cord is saved as an amulet.
“In the past decades, there have been changes in childbirth procedures in the Western world,” she said. “For example, family members now are allowed in the delivery room, and mothers have more choice in the circumstances surrounding the delivery of their babies.
“Whatever the culture, even those where women supposedly give birth by themselves, there is usually someone there to give support, and this physical and emotional need for support probably extends back to the earliest humans and beyond,” Rosenberg said.
Rosenberg has worked on another project locally with Jay Custer, professor of anthropology, on analyzing the skeletal remains of the Native Americans who have been reburied at the Island Field Site in Delaware.
A graduate of the University of Chicago, Rosenberg received her doctorate in biological anthropology from the University of Michigan and came to the University in 1987.
Story by Sue Moncure
Photo by Kathy Flickinger
May 6, 2002
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