Naturalist jean-baptiste lamarck promoted the theory of "inheritance of acquired characteristics". this theory stated that changes developed over the course of the life of an organism would be transmitted to the next generation. a famous example involves a blacksmith. working with heavy hammers, pounding iron all day, blacksmiths developed larger arms than average men. this trait, large and muscular arms, would then be passed down to the children of the blacksmith.

charles darwin developed a competing theory based on variation and a process he called "natural selection". his theory stressed how the differences among the individuals in a population would lead to different rates of survival and reproduction. through this process, in conjunction with what he called a "strong principle of inheritance", entire populations could adapt, and ultimately, evolve.

the fact that many blacksmith apprentices were not born to blacksmith fathers, and they still developed large arms, would have what impact on lamarck's theory?