Messenger - Vol. 2, No. 3, Page 8
Summer 1993
On Research
Fossil humans probably needed midwives, too

     Ever wonder why human birth can be so painful for the mother? It's
because human babies have big brains and their mothers have small hips for
walking upright, says University of Delaware anthropologist Karen
     Between 2 million and 5 million years ago in eastern and southern
Africa, she says, early human ancestors, called australopithecines, walked
upright but had tiny brains-about one-third the size of a modern human
brain. Thus, australopithecine mothers like "Lucy," a famous Ethiopian
fossil estimated to be 3 million to 4 million years old, may have
experienced some difficulty during childbirth, she explains, but the
process was much easier than it is today. Lucy's babies didn't have to
wriggle or twist their bodies to squeeze through the birth canal.
     According to Rosenberg, giving birth was probably more difficult for
Lucy than it is for apes, which have a large birth canal compared to the
size of the baby. In all non-human primates, the birth canal is basically a
straight tube, making ape birth relatively simple.
     "Lucy probably would have experienced a labor similar to modern human
labor, with hard contractions, but the baby wasn't forced to change
positions in the birth canal, as it is today," explains Rosenberg, an
associate professor.
     By the time Neanderthals roamed the Near East and Europe, 40,000 to
120,000 years ago, birth had become a slow, torturous process because of
increased brain size, she says.
     Changes in the human birth process didn't take place overnight,
according to Rosenberg. Rather, she says, modern birth evolved from a
"mosaic" of biological changes that occurred at different times for
different reasons. When humans became bipedal, or two-footed, for example,
natural selection favored smaller hips, which are more efficient for
walking upright. A couple of million years later, the human brain expanded,
she says.
     As a result of these competing changes, modern human birth is unlike
birth in any other animal, the anthropologist says. The process is so
difficult, in fact, that newborn skulls are often temporarily molded into
the shape of the mother's birth canal, and babies must rotate during
passage, usually emerging face-down, she says. Since human mothers can't
easily reach their infants in this position, midwives and other attendants
provide critical assistance during delivery.
     Today, medical intervention is altering the way humans give birth, but
the birthing process is no longer evolving in the same way. After all,
Rosenberg says, we've been walking the same way for 3 million years, and
brain size hasn't changed for 100,000 years,
     Scientists like Rosenberg examine pelvic fossils to learn how human
ancestors gave birth.
     By studying the past, she says, we can better understand the roots of
such modern birthing customs as midwifery. While Rosenberg says she
believes doctors now perform too many caesarean sections, she also points
out that intervention and attendants have long been a part of the birthing
process. Even in Neanderthal times, attendants may have saved babies from
being strangled by their umbilical cords.
                                   -Ginger Pinholster