Using Geographic Distance as a Potential Proxy for Help in the Assessment of the Grandmother Hypothesis

Engelhardt, Sacha C.; Bergeron, Patrick; Gagnon, Alain; Dillon, Lisa; Pelletier, Fanie

doi:10.1016/j.cub.2019.01.027

Cited by 42 publications

(42 citation statements)

References 31 publications

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“…One hypothesis is that CMI, by reducing the probability of birth, increases the period between two successive pregnancies when the woman is young, thus conserving resources for existing children. [85,86] Thus, CMI may be actively selected because of intrinsic evolutionary benefits, likely related to the prolonged period of postnatal child dependency in humans. This might be advantageous because i) the woman may be too old to fully raise the child, [83] ii) a decreased investment in reproduction, especially in older women, will decrease the risk of diseases and increase longevity; [84] and/or iii) cessation of child bearing will make older women available to help with the raising of children of younger women, the so-called "grandmother effect."…”

Section: Why Does CMI Exist?mentioning

confidence: 99%

Crossover Interference, Crossover Maturation, and Human Aneuploidy

et al. 2019

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A striking feature of human female sexual reproduction is the high level of gametes that exhibit an aberrant number of chromosomes (aneuploidy). A high baseline observed in women of prime reproductive age is followed by a dramatic increase in older women. Proper chromosome segregation requires one or more DNA crossovers (COs) between homologous maternal and paternal chromosomes, in combination with cohesion between sister chromatid arms. In human females, CO designations occur normally, according to the dictates of CO interference, giving early CO-fated intermediates. However, ≈25% of these intermediates fail to mature to final CO products. This effect explains the high baseline of aneuploidy and is predicted to synergize with age-dependent cohesion loss to explain the maternal age effect. Here, modern advances in the understanding of crossing over and CO interference are reviewed, the implications of human female CO maturation inefficiency are further discussed, and areas of interest for future studies are suggested.

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Section: Why Does CMI Exist?mentioning

confidence: 99%

Crossover Interference, Crossover Maturation, and Human Aneuploidy

et al. 2019

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“…However, the possibility that disruption of DI...I.D is associated with some fitness advantages is highly intriguing and worth further investigations. For example, the disruption of DI...I.D may increase fitness (i) directly if the carriers are healthier at reproductive age and thus have higher fertility, or (ii) indirectly if increased longevity of parents and grandparents is advantageous to offspring due to the grandmother effect ( (Chapman et al 2019;Engelhardt et al 2019) . Currently the potential beneficial loss of DI...I.D combinations is supported by the (i) deficit of observed DI...I.D combinations in the human mtDNA as compared to the expected (chapter 8) and (ii) by the negative correlations between the abundance of repeats and mammalian longevity (Samuels 2004;Khaidakov, Siegel, and Shmookler Reis 2006;Yang, Seluanov, and Gorbunova 2013) .…”

Section: Discussionmentioning

confidence: 99%

“…However, the disruption of the common repeat may also increase fitness (i) directly -if carriers are healthier during reproductive age and/or have higher fertility, or (ii) indirectly if increased longevity of parents and grandparents is advantageous to offspring (grandmother effect). Potential importance of the grandmother effect in human population has been discussed in several recent interesting papers (Chapman et al 2019;Engelhardt et al 2019) . Here, we only focus on direct effects, which may provide evolutionary benefits to the carriers of the disrupted common repeat.…”

Section: No Evidence That Disruption Of the Common Repeat Is Evolutiomentioning

confidence: 99%

Risk of mitochondrial deletions is affected by the global secondary structure of the human mitochondrial genome

Mikhailova

Shamanskiy

Ushakova

et al. 2019

Preprint

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Aging is associated with accumulation of somatic mutations . This process is especially pronounced in mitochondrial genomes (mtDNA) of postmitotic cells, where accumulation of large-scale somatic mitochondrial deletions is associated with age-related mitochondrial encephalomyopathies. Here we revise risks of somatic mtDNA deletions and uncover that additionally to direct repeats, known to affect deletions, there is a strong impact of the secondary structure of single-stranded mtDNA during replication. The secondary structure is shaped by inverted repeats which can form stems and shorten effective distance between two direct repeats increasing chances of deletions. Our results support recent discovery that the replication slippage can be the main mechanism of origin of mtDNA deletions. Taking into account strong interaction between direct and inverted repeats it is possible to predict the deletion burden of different haplogroups and associate it with age-related phenotypes. For example, the increased longevity of D4a and D5a haplogroups is in line with their expected low deletion burden.

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“…10–12). In particular, the grandmother effect predicts that postreproductive grandmothers increase their inclusive fitness by supporting grandoffspring that are dependent on provisioned food for some time following weaning (13–15). There is substantial support for the grandmother effect across a range of human societies, including modern hunter-gatherer societies and preindustrial populations, which show that postreproductive grandmothers increase the survival of their grandoffspring, thus increasing their own inclusive fitness (10, 11, 14, 16–19).…”

mentioning

confidence: 99%

Postreproductive killer whale grandmothers improve the survival of their grandoffspring

Nattrass

Croft

Ellis

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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Understanding why females of some mammalian species cease ovulation prior to the end of life is a long-standing interdisciplinary and evolutionary challenge. In humans and some species of toothed whales, females can live for decades after stopping reproduction. This unusual life history trait is thought to have evolved, in part, due to the inclusive fitness benefits that postreproductive females gain by helping kin. In humans, grandmothers gain inclusive fitness benefits by increasing their number of surviving grandoffspring, referred to as the grandmother effect. Among toothed whales, the grandmother effect has not been rigorously tested. Here, we test for the grandmother effect in killer whales, by quantifying grandoffspring survival with living or recently deceased reproductive and postreproductive grandmothers, and show that postreproductive grandmothers provide significant survival benefits to their grandoffspring above that provided by reproductive grandmothers. This provides evidence of the grandmother effect in a nonhuman menopausal species. By stopping reproduction, grandmothers avoid reproductive conflict with their daughters, and offer increased benefits to their grandoffspring. The benefits postreproductive grandmothers provide to their grandoffspring are shown to be most important in difficult times where the salmon abundance is low to moderate. The postreproductive grandmother effect we report, together with the known costs of late-life reproduction in killer whales, can help explain the long postreproductive life spans of resident killer whales.

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Using Geographic Distance as a Potential Proxy for Help in the Assessment of the Grandmother Hypothesis

Cited by 42 publications

References 31 publications

Crossover Interference, Crossover Maturation, and Human Aneuploidy

Crossover Interference, Crossover Maturation, and Human Aneuploidy

Risk of mitochondrial deletions is affected by the global secondary structure of the human mitochondrial genome

Postreproductive killer whale grandmothers improve the survival of their grandoffspring

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