SELECTION ON MENOPAUSE IN TWO PREMODERN HUMAN POPULATIONS: NO EVIDENCE FOR THE MOTHER HYPOTHESIS
Bibliographic record
Abstract
Evolutionary theory suggests that natural selection should synchronize senescence of reproductive and somatic systems. In some species, females show dramatic discordance in senescence rates in these systems, leading to a clear menopause coupled with prolonged postreproductive life span. The Mother Hypothesis proposes that menopause evolved to avoid higher reproductive-mediated mortality risk in late-life and ensure the survival of existing offspring. Despite substantial theoretical interest, the critical predictions of this hypothesis have never been fully tested in populations with natural fertility and mortality. Here, we provide an extensive test, investigating both short- and long-term consequences of mother loss for offspring, using multigenerational demographic datasets of premodern Finns and Canadians. We found no support for the Mother Hypothesis. First, although the risk of maternal death from childbirth increased from middle age, the risk only reached 1-2% at age 50 and was predicted to range between 2% and 8% by 70. Second, offspring were adversely affected by maternal loss only in their first two years (i.e., preweaning), having reduced survival probability in early childhood as well as ultimate life span and fitness. Dependent offspring were not affected by maternal death following weaning, either in the short- or long-term. We suggest that although mothers are required to ensure offspring survival preweaning in humans, maternal loss thereafter can be compensated by other family members. Our results indicate that maternal effects on dependent offspring are unlikely to explain the maintenance of menopause or prolonged postreproductive life span in women.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".