Homo Erectus Women Had Big-Brained Babies, New Fossil Suggests

By Eliza Strickland | November 14, 2008 9:45 am

Homo erectus pelvisThe fossilized pelvis of a Homo erectus woman who lived 1.2 million years ago on the banks of an Ethiopian river has been discovered, and while researchers say it casts new light on human evolution, some of their conclusions are challenging previous theories about these early human ancestors. The pelvis reveals a short, squat woman who wasn’t built for long-distance running, but also a woman with a wide birth canal to accommodate big-brained infants.

Study coauthor Scott Simpson says the pelvis’s wide birth canal indicates that hominds’ increasing brain size was a driving factor in human evolution. Getting through the birth canal is “the most gymnastic thing we ever do,” he says. To accommodate big-brained babies, humans must have developed larger and wider birth canals over time, but with few pelvic fossils, researchers had little idea when these changes began. The Busidima pelvis shows that a wide birth canal was already in place 1.2 million years ago [New Scientist].

The findings, published in Science [subscription required], seems to contradict an earlier theory on the appearance of these hominids: H. erectus females were assumed to have had narrow hips and relatively small birth canals that could allow the passage of only small-brained infants. But such theories were largely based on measurements of the pelvis of “Turkana Boy,” a 1.5-million-year-old juvenile male H. erectus fossil discovered in Kenya in 1984 [National Geographic News]. Simpson says it was difficult to make broad assumptions based on the Turkana Boy; the fossil was very fragmented, he says, and men and women can have very different anatomical features.

Researchers say the newly discovered pelvis belonged to a woman in her 20s who stood about 4 feet 5 inches tall. This also challenges previous theories, as the Turkana Boy was thought to be over 6 feet tall, with a long and lean frame well suited for distance running. Anthropologist Daniel Lieberman says that earlier find led to the theory that long-distance running enabled H. erectus to hunt effectively without spearheads and to obtain enough meat to support the evolution of increasingly large brains. “This pelvis is a nice addition to the fossil record, but it raises more questions than it answers” [Science News], says Lieberman. With such divergent views on the table, Lieberman and some other experts say Simpson needs more evidence to support his theories.

Related Content:
80beats: Neanderthal Mothers Had It Tougher Than Modern Moms
DISCOVER: The Third Man explains how Homo erectus fossils have confused theories of human evolution

Image: Scott Simpson

CATEGORIZED UNDER: Human Origins
  • James Michael Howard

    It is my hypothesis that human evolution occurred because of increases in testosterone (“Androgens in Human Evolution,” Rivista di Biologia / Biology Forum 2001; 94: 345-362 ). In Homo erectus, or a similar species, the female increased in size compared to the male. I suggest this is due to an increase in testosterone in the females.

    The consequences of the foregoing is that female pelvis size should decline and the exposure of the fetus to increased maternal testosterone would increase subsequent brain size in the offspring, which would occur after birth. (Please read my article, if interested.) I suggest this pelvis may have existed in H. erectus before H. erectus females increased in testosterone or a subsequent species produced females that increased in testosterone.

  • Dov Henis

    Wide Hips Led To Big-Brained Babies

    Innovative Telltale Sign Announced By Indiana University
    And Reported By Royal Society’s Science Coverage

    A. In “Science Coverage” at
    http://royalsociety.org/news.asp?id=8122

    “Intelligent humans developed because our female Homo erectus ancestors had wide hips which allowed them to give birth to babies with big brains, according to Indiana University research in Science.
    The Daily Telegraph, p18, 1 col
    The Independent, p23, 1/2p”

    B. Dictionary

    Intelligent = revealing or reflecting good judgment or sound thought.

    C. Wonderment

    To what extent this telltale sign held in regards to the mothers of the above Indiana University researchers and Royal Society’s science coverers…

    Dov Henis

    (A DH Comment From The 22nd Century)
    http://blog.360.yahoo.com/blog-P81pQcU1dLBbHgtjQjxG_Q–?cq=1

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