Women's health and evolution: what the evidence says

Where does the book say to start on women's health?

Which popular claims about women's health hold up?

• Does cycle syncing your workouts work?

  Not supported. Train consistently and adjust on days you feel bad, whatever the reason.

  ●●○ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.

• Does hormone therapy cause breast cancer?

  Partly true and badly overstated. The risk is real, modest and depends on type and duration. It argues for a careful choice of treatment; it does not argue for refusing one.

  ●●●StrongEvidence grade: Strong. Multiple randomized controlled trials, or consistent large cohort studies with a well-understood mechanism.for the trial figures●●○ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.for the pooled observational ones

What does the body expect, and what does it get now?

The mismatch cards of the reference topics behind these chapters, as the library states them.

• Topic 32: The Reproductive Paradox

  ●●○ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.

  The reproductive axis, from the hypothalamic pulse generator to ovaries and testes, and the post-reproductive life course built around it.

  What it expects

  Steady energy availability, first births while fertility is at its peak, kin nearby to subsidize weaned children, and a lifetime of relatively few ovulatory cycles (Topic 22).

  What it gets

  Energy surplus or deficit rather than balance, a mean first birth at 27.5 in the United States, grandparents in other cities, and an industrial chemical environment nobody has fully characterized.

  What happens in the gap

  Ovulation stops in women who look healthy, obesity disturbs the same loops from the opposite side, sperm counts and testosterone drift downward across cohorts, and the biological window opens and closes on a schedule the social one ignores.

• Topic 22: Cancer in a New Environment

  ●●○ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.

  Cell division and the defenses that keep cells cooperating (tumor suppressors, DNA repair, cell suicide).

  What it expects

  A body of ancestral size and lifespan; menarche in the mid-teens, many pregnancies, years of breastfeeding; no tobacco and little alcohol.

  What it gets

  Longer lives; earlier menarche, fewer and later births and shorter breastfeeding (three to four times the Dogon's menstrual cycles); excess body fat; tobacco and alcohol.

  What happens in the gap

  More hormone-driven, obesity-related, tobacco and alcohol cancers; much of the remaining rise reflects age and closer looking.

• Topic 33: Born Too Soon

  ●●○ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.

  Human birth, and the first months of an infant who arrives unfinished.

  What it expects

  A labor attended continuously, several pairs of hands afterwards, a founding microbial community from the birth canal, milk carrying sugars for the infant's bacteria, and sleep within reach of an adult.

  What it gets

  More than one birth in five by cesarean, staff who rotate, formula without the same sugars, a mother recovering largely alone, and in many homes an infant asleep behind a closed door.

  What happens in the gap

  A different founding microbiome, missing feeding chemistry, more surgical births than medical need explains in some regions and too few in others, and caregiving loads that no ancestral mother carried by herself.

Terms

• Concealed ovulation
• Cooperative breeding
• Dogon
• Energy availability
• Functional hypothalamic amenorrhea
• Grandmother hypothesis
• Human milk oligosaccharides
• Obstetrical dilemma
• Peto's paradox