Illustration of a woman Australopithecus sediba carrying a baby
JOHN BAVARO LIBRARY OF ART/SCIENCE PHOTOGRAPHS
Childbirth was difficult and dangerous for our bee ancestors, just as it is for women today. A new study of the basins of Australopithecus suggests that childbirth exerted powerful forces on their pelvic floor – ie Australopithecus mothers were at risk of rupture of the dam.
“We show that Australopithecines are quite similar to modern humans,” he says Pierre Frémondièremidwife at Aix-Marseille University in France. “If they had a lot of births, they would probably have a higher risk of pelvic floor disorders.”
For a modern person, vaginal delivery requires a lot of strength, as a baby with a large head is forced to pass through a relatively narrow pelvis. One area that is prone to damage is the pelvic floor, the layer of muscle that connects the left and right halves of the pelvis. Many women tear their pelvic floor during labor and it is estimated that this is the case 1 in 4 women you suffer from pelvic floor disorders such as incontinence or organ prolapse.
Frémondière and his colleagues wanted to find out if our extinct ancestors had similar problems. They focused on Australopithecuswhich lived in Africa about 2 million to 4 million years ago. These early hominins walked upright, but were also still adapted to spend time in trees and may have made and used stone tools. They could have been ancestors Homothe genus we belong to.
Based on a handful Australopithecus pans that were found, the team knew that Australopithecus birth canals were oval: they were wide from left to right, but narrow from front to back. Non-human primates such as chimpanzees have the opposite arrangement, while the modern human birth canal is more circular.
Explore what would happen in Australopithecus work, the team simulated the pelvises of three individuals from different species: Australopithecus afarensis, Australopithecus africanus and Australopithecus sediba. To model the pelvic floor muscles, the researchers took an MRI scan of a pregnant woman, extracted a three-dimensional image of the pelvic floor and reshaped it to match Australopithecus pan. They then simulated the baby pushing through the pelvis and estimated how much force would be exerted on the pelvic floor.
They found that Australopithecus the pelvic floor experienced forces of 4.9 to 10.7 megapascals, similar to the 5.3 to 10.5 MPa exerted on the human pelvic floor during childbirth.
The team did well to use more Australopithecus pelvis and make comparisons with live human birth data, he says Lia Betti at University College London. “It’s a really good way to check that your model is robust.”
Still, Betti is cautious about the results. He says we don’t know if the pelvic floor muscles Australopithecus were different from ours, which may have made them more or less resistant to tearing. To check, the team also modeled two modern human births, and in one case the baby did not rotate in the birth canal as in real life. This suggests that key factors are missing from the simulations, he says.
“The problem is that we don’t have a lot of evidence,” says Betti. Three Australopithecus pans – all from different species – is a small data set. There are no known pelvises from earlier hominin species.
“I think we’re just at the beginning of this kind of study,” says Frémondière.
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