Editing James Mark Baldwin (section)

===Baldwin effect===
{{Main|Baldwin effect}}
Baldwin's most important theoretical legacy is the concept of the [[Baldwin effect]] or "Baldwinian evolution". Baldwin proposed, against the [[Lamarckism|neo-Lamarckian]]s of his day (most notably [[Edward Drinker Cope]]), that there is a mechanism whereby [[epigenetic]] factors come to shape the congenital endowment as much as&nbsp;– or more than&nbsp;– [[natural selection]] pressures. In particular, human behavioral decisions made and sustained across generations as a set of [[culture|cultural]] practices ought to be considered among the factors shaping the human genome.

For example, the [[incest taboo]], if powerfully enforced, removes the natural [[natural selection|selection pressure]] against the possession of incest-favoring instincts. After a few generations without this natural selection pressure, unless such genetic material were profoundly fixed, it would tend to diversify and lose its function. Humans would no longer be innately averse to incest, but would rely on their capacity to internalize such rules from cultural practices.

The opposite case can also be true: cultural practice might [[Artificial selection|selectively breed]] humans to meet the fitness conditions of new environments, cultural and physical, which earlier hominids could not have survived. Baldwinian evolution might strengthen or weaken a genetic trait.