Evolutionary biologist and Marxist, Richard Lewontin, was credited for conceptually undermining the notion of human races, for a time:
https://en.wikipedia.org/wiki/Human_Genetic_Diversity:_Lewontin%27s_Fallacy
https://en.wikipedia.org/wiki/Richard_Lewontin
The argument, employed by this Marxist, was that the majority of genetic diversity is found between populations, not races, so no justification could be made for continual use of racial categories. As such the argument was incoherent in the face of it, since, it assumed the existence of races to begin the analysis. It found that 85.4 percent of genetic variation is between populations, while 8.3 percent of the variance is between races. All that shows is that there is more genetic variance between individuals that between races, which if true is nothing much to write home about, since individuals are extremely diverse. The argument was criticised by A. Edwards:
https://onlinelibrary.wiley.com/doi/abs/10.1002/bies.10315
