Darwin's Fourth Postulate

By: Juan Flores


The fourth and final (main) postulate of Darwin's is extinction. What does this postulate want to say? basically that all traits which are not suitable for survival, so the traits die and wither, as well as the population in the species with that trait. This ties to the beetle situation I explained in the first bulletin. If a population of beetles which live in the desert ( a brown environment) has 60% brown beetles and 40% green beetles. The green beetle phenotype will die out all together with the beetles, since they're more prone to a predator consuming them. Their trait is not fit for survival in their environment, so eventually the trait and the green beetles will be wiped out into extinction. This is basically all that Darwin's fourth postulate is. In the images below, you can see visually some examples of the fourth postulate.


Darwin, C. (2009). The origin of species by means of natural selection: or, the preservation of favored races in the struggle for life.