How We Do It

The Evolution and Future of Human Reproduction by Robert Martin

Many parents have questions about how to raise children “naturally.” When is the natural time to wean a baby? Is early toilet training natural? What about suggestions to eat the placenta?

Martin, a primatologist, looks to evolutionary history for clues to how humans have parented through time. He leads a dizzying tour through evolutionary aspects of human reproduction, starting with sperm and egg, winding through pregnancy and parental care, to reach the decidedly unnatural topics of contraception and in vitro fertilization.

The book is a gold mine of cocktail party trivia. Humans, for instance, have the fattest babies of all primates, and our disdain for dirty diapers is something of an evolutionary anomaly. Most mammals, including our closest relatives, deal with their infant’s waste by swallowing it.

Martin often touches on practical issues. He devotes an entire chapter to breast-feeding and marshals evidence that humans evolved with a normal weaning time greater than three years. But he never makes clear whether he thinks modern mothers would benefit from breast-feeding as the ancients did.

He also discusses more controversial questions, such as whether environmental toxins are harming male fertility or whether the rhythm method leads to more miscarriages. Although Martin clearly suspects the answer to both questions is yes, he acknowledges that only more research can settle such matters. That should be a warning to anyone seeking a practical, rather than intellectual, guide. People who are fascinated by  humans’ past should read this book. Those looking for advice would be better off talking to their doctors.

Basic Books, 2013, 304 p., $27.99

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