First, it signifies that we should consider the role of evolutionary processes that might underlie any observed trends in phenotypes.
Second, it may produce eco-evolutionary feedbacks modifying the dynamics of modern populations (2, 8).
In agreement with this prediction, AFR declined from about 26–22 y over a 140-y period.
Crucially, we uncovered a substantial change in the breeding values for this trait, indicating that the change in AFR largely occurred at the genetic level.
To overcome these problems, recent studies of wild birds and mammals have tested for microevolution by directly measuring changes in breeding values (16–22; see ref. The breeding value (BV) of an individual is the additive effect of his/her genes on a trait value relative to the mean phenotype in the population, in other words the heritable variation that parents transmit to their offspring (11).
In quantitative genetic (QG) notation, the phenotypic measurement can thus be written as is a residual term that may include environmental and nonadditive genetic effects and measurement error.As reported for other such societies, natural selection favored an earlier age at first reproduction (AFR) among women.AFR was also highly heritable and genetically correlated to fitness, predicting a microevolutionary change toward earlier reproduction.This also implies that phenotypic changes, even those occurring in the predicted direction, may not provide robust evidence of evolution, as they may not be indicative of underlying genetic trends (15–17).These problems are likely exacerbated in long-lived species such as humans, where within-individual plastic responses to environmental variation, or viability selection, can drive phenotypic changes over the timescale of a study in the same direction as that predicted for genetic responses to selection (15).One could similarly argue that not much in evolution makes sense without recourse to ecological concepts: understanding diversity — from microbial adaptations to species assemblages — requires insights from both ecological and evolutionary disciplines.Nowadays, technological developments from other fields allow us to address unprecedented ecological and evolutionary questions of astonishing detail, impressive breadth and compelling inference.This likely applies to humans as well because () a number of these traits show heritable genetic variation (4–7), attesting the potential for a microevolutionary response to selection.This evolutionary potential of modern humans has major implications.This multidisciplinary open-access journal is at the forefront of disseminating and communicating scientific knowledge and impactful discoveries to researchers, academics and the public worldwide.Eminent biologist and theist Theodosius Dobzhansky’s astute observation that “Nothing in biology makes sense except in the light of evolution” has arguably even broader relevance now than when it was first penned in The American Biology Teacher in 1973.