Though failing to explain how evolution occurred, Darwinism held tremendous sway over generations of biologists; another example of the staying power of sophistic explanation by the well-respected, and a tendency to favor simplistic stories, thus crowding out more accurate but involved scenarios.
The term natural selection remains ubiquitous and is widely considered in much the same way that Darwin conceived: evolution via competition.
Lamarckism fell from favor in the 1880s, after German evolutionary biologist August Weismann facilely concluded that changes from use, such as lifting weights to increase muscle mass, and disuse, such as lazy lifestyle, were not heritable. Weismann also found Darwin’s theory “inadequate.”
In their stead, Weismann proposed the germ plasm theory: that the only carriers of inheritance are germ cells (eggs and sperm). The supposition lurking behind germ plasm theory is that heredity is entirely hard-wired, which snugly fits with DNA as the sole messenger of inheritance. What was unknown for decades is that DNA provides only a partial code, subject to interpretation and limited expression.