Observations on Chimpanzee and Human Childbirth

Similarities in Childbirth Between Chimps and Humans

• Key Feature: Both chimps and humans have infants that emerge facing backwards relative to their mothers.

• Research Discovery: Observations were reported in Biology Letters indicating that chimpanzees share this childbirth characteristic with humans.

Observational Study Insights

• Study Conducted By: Satoshi Hirata and team at the Great Ape Research Institute.

• Methodology: Observations made of three captive chimpanzees during childbirth, revealing they give birth alone, contrary to prior assumptions that they would seek assistance.

• Key Insight: The backward-facing position of infants is not exclusive to humans, challenging previous theories about the role of fetal orientation in the evolution of midwifery.

Noteworthy Observations

• Pregnancy Behavior: Pregnant chimps prefer solitude during childbirth and may become nervous if others are present.

• Close Relations with Subjects: Researchers spent significant time with chimps (including overnight) to observe natural behaviors without disturbances.

Historical Context and Implications

• Previous Beliefs: Anthropologists suggested that the backward orientation of infants was significant in developing midwifery theories since the 1980s, based primarily on human observations.

• Hirata's Conclusion: Current evidence suggests that the assumption of the backward orientation being significant in evolution is unfounded for chimps, as they do not inherently require assistance during birth.

Expert Reactions

• Wenda Trevathan's Response: Acknowledgments that corroborative data on chimpanzee births advances scientific understanding of human childbirth.

• Trevathan's Position: While human childbirth is unique, the evidence does not necessarily contradict the idea that midwifery may still have evolutionary benefits due to the infants' orientation at birth.

Concluding Thoughts

• Human Uniqueness: The study challenges the notion that humans are unique in their birthing practices and behaviors, emphasizing a shared evolutionary trait with chimpanzees.

• Future Research Directions: The questions noted include why humans evolved midwifery while chimps did not, calling for further investigation into this comparative aspect of primate behavior.

• Reference Information:

  • Hirata, S. et al., Biol. Lett., doi:10.1098/rsbl.2011.0214 (2011).

  • Trevathan, W. R., Human Birth: An Evolutionary Perspective (Aldine, 1987).

This detailed account reinforces the need for comparative studies in understanding the evolutionary biology of childbirth across species, shedding light on commonalities and differences in practices.