What did 19th century imperialism have to do with this 20th century genocide ?

what do they have in common is a narrowly racist or (perhaps in a more scientific language) social Darwinian perspective that was supposed to justify 19th-century colonization. It means that both 19th-century colonialism and 20th-century genocide were justified as a Darwinian "law of history" according to which the strongest dominate or eliminate those who are weaker.

Explanation: Racism is a surprisingly modern term (from the 19th century) that was imported from natural sciences (in natural sciences appeared in 18th century). This import took place especially thanks to social Darwinism which spread across Europe during the 2nd half of the 19th century. Genocide was practiced always (not always with this name)unfortunately it seems that it is only Homo sapiens sapiens whos is able to commit such a massive killing.

genetics is the study of how dna works, the methodologies defining the new recent technologies allow scientist to have a panoramic view of the entire dna landscape, especially how genomes interact with their environment, including off course, factors outside their organisms.

thus is very possible the existence of both scenarios, where populations of isolated individuals have different genetic traits, and share traits related to genetic mutation, due rats can easily travel overseas using human transport channels. so scientists could get a vast number of data, including human interaction, evolution of rodents, health development, spread of infections, development of new organisms, how genomes evolve in different environments and so on.