author={Samuli Helle and Virpi Lummaa and Jukka Jokela},
  booktitle={Evolution; international journal of organic evolution},
Abstract Human twinning rates are considered to either reflect the direct fitness effects of twinning in variable environments, or to be a maladaptive by-product of selection for other maternal reproductive traits (e.g., polyovulation). We used historical data (1710–1890) of Sami populations from Northern Scandinavia to contrast these alternative hypotheses. We found that women who produced twins started their reproduction younger, ceased it later, had higher lifetime fecundity, raised more… 

Twinning in humans: maternal heterogeneity in reproduction and survival

From the largest historical sample of twinning mothers yet published, it is concluded that bearing twins is more likely for those with a robust phenotype and is a useful index of maternal heterogeneity.

Twinning as an Evolved Age-Dependent Physiological Mechanism: Evidence from Large Brazilian Samples

The hypothesis that twinning represents an evolved physiological mechanism, particularly in mothers of higher age, as an ‘all-or-nothing’ last chance strategy for reproduction just before menopause is explored.

Are reproductive and somatic senescence coupled in humans? Late, but not early, reproduction correlated with longevity in historical Sami women

The results suggest that reproductive and somatic senescence may have been coupled in these human populations, and that selection could have favoured late reproduction in historical post-reproductive Sami women.

Mothers with higher twinning propensity had lower fertility in pre-industrial Europe

Historically, mothers producing twins gave birth, on average, more often than non-twinners. This observation has been interpreted as twinners having higher intrinsic fertility – a tendency to

The rarity of twins: a result of an evolutionary battle between mothers and daughters—or do they agree?

Both selfish twins and their mothers might benefit by the death of a co-twin, indicating that there is no parent–offspring conflict responsible for the rareness of twins in these human populations.

Accelerated immunosenescence in preindustrial twin mothers.

Examination of reproductive effort in women born in preindustrial Finland between 1702 and 1859 found that mothers delivering twins had reduced postreproductive survival after age 65, and the mechanism mediating this cost might have been accelerated immunosenescence.

Natural Selection on Female Life-History Traits in Relation to Socio-Economic Class in Pre-Industrial Human Populations

The results show that the amount of wealth affected the selection pressure on female life-history in a pre-industrial human population, and the poorest women had the lowest age-specific survival throughout their lives and had lower fitness compared to the wealthier women.

Tykes, Toddlers, Teens, and Twins of Robust Mothers: Do the Offspring of Twinning Mothers Share in Their Mother’s Robust Phenotype?

The findings suggest that while bearing twins may reflect a robust maternal phenotype, the toll of Bearing twins may disadvantage subsequent offspring, especially during infancy.

Ecological volatility and human evolution: A novel perspective on life history and reproductive strategy

  • J. Wells
  • Biology
    Evolutionary anthropology
  • 2012
It is proposed that ecological volatility may have been a key stress, selecting in favor of the suite of traits in order to tolerate periods of energy scarcity, and increase reproductive output during periods of good conditions.

Comparing the survival outcomes for the siblings of twins

Examining mortality patterns of the singleton offspring of mothers of twins compared to the offspring of non-twinning mothers to determine whether the siblings of twins possess the enhanced phenotype of their mothers finds that male siblings who survive to age 18 experience an improvement in survival.