Razib Kahn has a fascinating interview with Milford Wolpoff, one of the main scientists behind the research that argues that humans are not all part of a single family tree, descended from a single ancestor who moved out of Africa about 200,000 years ago.
This section focuses on the theory, and has a nice explanation of what mitochondrial DNA is (and why it’s important):
It gives an excellent perspective on how science works, and how scientists work (scientists are people too with all the problems that entails).
The entire thing is a bit dense, but it’s one of the better discussions I’ve seen describing the process of science in action, with little hints at all the challenges that arise from personality conflicts and competing theories.