Question: How did Darwin and Lamarck differ in their thinking about change in species?

Robert Hampson answered on 19 Nov 2014:

Answer from the internet: “Darwin thought that organisms had to struggle to survive, while Lamarck thought that organisms could make adjustments when conditions became difficult.” It’s question number 4 here: http://www.biology-online.org/biology-forum/about38403.html

Darwin wrote in his “On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life”, that animals massively overproduce offspring and that these offspring naturally vary amongst themselves. The offspring then struggle with each other and the environment for survival and only those that are best adapted to survive to adulthood and reproduce.

Lamarck outlined his theories on evolution in three volumes: Recherches sur l’organisation des corps vivants, Philosophie Zoologique, and Histoire naturelle des animaux sans vertèbres. He proposed that the environment gives rise to changes in animals; he called this the influence of circumstances (in french: l’influence des circonstances). He also proposed that animals are subject to a movement to become more complex; he called this the power of life (in french: le pouvoir de la vie). He thought that both of these effects could then be inherited.

Eventually Lamarck’s ideas were discredited. However, recently the principle of ‘l’influence des circonstances’ has started to gain in acceptance again. The discipline of epigenetics has shown that some adaptions of animals to their environments can indeed be inherited through methylation signals and codes carried on DNA.

Research and science in the area continues…