“Find someone nice”: Mothers might actually know best
Often organisms will be described as successful; Successful at colonizing a new habitat; at adjusting to change; but in the end it all comes down to being reproductively successful. As nothing lives forever, the only way organisms can persist through time is by passing on as much of the information defining them, their genes, to the next generation so that it, in turn can do the same and so on and so forth. Typically reproductive success is measured as the number of children and grandchildren, but few studies have considered grandchild count. Considering that fewer children can produce more grandchildren if they are of “superior quality”, that’s a big literature gap.
A new paper published in November’s issue of Evolution and Human Behavior by Berg et al., explores exactly that and suggests that there are no quality-quantity trade-offs in personality/reproductive success associations while additionally providing the first robust evidence that personality may affect reproductive success over several generations in humans, and potentially other species.
The study was conducted on 10.688 American seniors between 60 and 70 years of age and investigated family history associations to personality traits of the widely accepted Five Factor Model (FMM), which categorizes personality traits in five major categories: extroversion, neuroticism, agreeableness, conscientiousness and openness to experience.
It was found that larger number of children and grandchildren are associated with higher extroversion, lower conscientiousness and lower openness to experience. Interestingly, education weakened the associations between extroversion and openness to experience, making the later irrelevant. Additionally, personality effects were similar in nature and magnitude on children and grandchildren, i.e personality traits affected the entire lineage similarly.
Explanations include genetic influences, such as genes coupling personality traits with reproductive success (e.g. extrovorsion is linked to testosterone production). On the other hand the effect might be environmental and a result of the grandparents’ involvement with grandchildren’s lives, such as agreeableness resulting in grandparent being more likely to offer support. Considering the effect of education, a purely environmental and social stimulus, on the association of extroversion and openness to experience with reproductive success, this final suggestion might be a distinct possibility.
Whether it’s nature, nurture or both, more work is needed and considering the average span of a human generation… that might take a while. So don’t hold your breath!
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