Midwifery is uniquely human — there is no other species where the female needs help giving birth

(written by lawrence krubner, however indented passages are often quotes). You can contact lawrence at: lawrence@krubner.com, or follow me on Twitter.

How much should the government play a role in enforcing license requirements regarding assistance during birth? In every such debate, in the background there is the issue of how much midwifery should professionalize, and also how much the government has any right to insist that this particular activity should be a credentialed one. It is worth remembering that being a midwife might, in fact, be the world’s oldest profession. The Proceedings of the National Academy of Sciences published the article “When did the modern human pattern of childbirth arise?

Human birthing is difficult owing to a tradeoff between large neonatal brain size and maternal pelvic dimensions, which are constrained by aspects of bipedal biomechanics (1, 2). The net effect is that human neonatal head size closely matches maternal pelvic dimensions, unlike in our closest living relatives, the great apes, whose pelvic dimensions are larger than neonatal head sizes. This size relationship, along with a twisted birth canal shape, makes human parturition mechanically difficult and results in a unique pattern of “rotational” birth (Fig. 1). As in humans, and unlike great apes, monkey neonatal head size closely matches the mother’s pelvic dimensions. Although birth rotation occurs in some monkeys, the rotation pattern is different from that in modern humans, with monkey neonates exiting the birth canal facing forward (1). Therefore, in both apes and monkeys, it is relatively easy for a mother to guide her infant out of the birth canal, keep the umbilical cord from wrapping around the neck, and extract mucous from the nose and mouth to facilitate breathing. All of these critical activities are much more difficult for a human mother, whose infant emerges facing backwards, and pulling on the infant from this position also risks serious neck injury. For these reasons, humans uniquely engage in assisted birth (obligate midwifery). Although unassisted birth, the norm for nonhuman primates, does occasionally occur in humans, assisted birth and its myriad social implications are the human norm cross-culturally (1).

…Until now, the consensus has been that rotational birth was not present in Early Pleistocene Homo (5), recently confirmed by the discovery of a largely complete 1.4–0.9 million-year-old female Homo erectus pelvis from Gona, Ethiopia (6), with the primitive nonrotational pattern persisting until the Middle Pleistocene (5). Resolving the appearance of rotational birth more precisely has been hindered by the paucity of fossil pelvic remains, especially from females, because of the fragility of pelvic bones. In a recent issue of PNAS, Weaver and Hublin (7) report on a virtual reconstruction of the pelvis of the Tabun C1 adult female Neandertal which indicates, surprisingly, that Neandertals retained the primitive birth pattern into the Late Pleistocene, and that the shift to a rotational birth pattern occurred later in human evolution than previously thought.

…What do the divergent Neandertal and extant modern human birthing patterns imply? Despite its male attribution, Sima 1 best represents pelvic shape in the last common ancestor of Neandertals and humans (9), and it has been used to infer neonatal midplane rotation (8). Weaver and Hublin raise caveats about that interpretation, but note that all agree on a transversely oval outlet in Sima 1. They argue that Middle Pleistocene encephalization trends (16) increased obstetric constraints in both the Neandertal and modern human lineages with divergent results. Neandertals continued to expand transverse pelvic outlet dimensions (the primitive condition), commensurate with large bi-iliac breadths and cold adaptation, with secondary consequences such as more or less equal pubic bone lengths in both Neandertal sexes (10). Modern humans, in contrast, underwent anteroposterior expansion of the birth outlet, since the African ancestors of modern humans were built on a transversely narrow pelvis bauplan related to warmer climate. The new wide-hipped female Homo erectus pelvis from Gona (6) complicates this climatic explanation, but does provide evidence for continuity in wide bi-iliac breadths from Australopithecus to Neandertals. New interpretations of the thorax in Neandertals mirrors this continuity by postulating that a wide body with high body mass represents the primitive hominin condition retained in Neandertals, which, if related to cold adaptation, represented an exaptation rather than cold adaptation per se (17). Finally, as Weaver and Hublin (7) acknowledge, the differences in the precise birthing pattern between Neandertals and modern humans should not let us lose sight of the fact that both lineages would have had difficult births, obligate midwifery, and all of the attendant social implications.

The last sentence is the most interesting. It implies that midwifery is at least as old as Neandertals, who first appeared 800,000 years ago. So midwifery is older than our species, homo sapiens. Midwifery has been around for most of the time that humans (the genus homo) have been on the planet. Midwifery is one of the few truly human activities. The various attempts to explain the difference between humans and animals have tended to focus on things which are only a matter of degree:

tool use (humans do a lot of it, but lots of species make primitive tools)

mourning for the dead (humans do a lot of it, but so do other animals. Elephant mothers who lose a child have been known to return to the spot where the child died, everyday for months, and turn the ground upside down.)

opposable thumbs (lots of animals have opposable thumbs)

Midwifery is uniquely human, it has no animal equivalent, there is no other species where the female needs help giving birth.

What are the appropriate modern boundaries that make sense for this activity? Money, is the obvious one. If a woman gives birth at home, and the woman’s mother is present during the birth, it seems unrealistic to insist that the mother should face some legal obligation to get a credential to be allowed to be present in the room. But if someone wants money to be in the room, then the modern regulatory state has some role to play in enforcing some standards. How rigid those standards really need to be is an interesting question, given how primal this form of helping is.

Post external references

  1. 1
    http://www.pnas.org/content/106/23/9125.full
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