Peter Kropotkin was surely on the left. He was one of the founders of what is now called 'sociobiology' or 'evolutionary psychology' with his book Mutual Aid, arguing that human nature had evolved in ways conducive to the communitarian anarchism that he espoused.
Noam ChomskyI don't think that the United States cares. They just assume that North Korea will soon have nuclear weapons.
Noam ChomskyWhat is the nature of the genetic endowment? How does acquisition proceed? Etc. Scientists do routinely ask similar questions about the visual system, system of motor organisation, and others - including, in fact, the digestive system.
Noam Chomsky