The problem of why sex exists, and in particular of why the vast inefficiency of maleness exists, seems to me biology's greatest, most exciting problem. I currently work on theories of sexuality and sexual selection and so do most members of my group. Proper understanding of all my earlier work on kin selection depends also upon its solution. My approach is mostly theoretical but several in my group are doing practical studies. This idea is that organisms need sex and recombination in order for their descendants better to combat rapidly evolving parasites.
Parasites are ubiquitous.
They are small and short-lived and therefore they continually and rapidly adapt to attack common genotypes of hosts. Part of my work on this theory is in showing that the unstable genetic coevolution brought about by parasites can, under plausible assumptions, both maintain polymorphism of alleles at many loci and maintain sex itself inspite of the short term inefficiency. The other part is concerned with side consequences of the theory for mate choice and sexual selection. The question to be answered here is whether sex is designed primarily against physical or biotic adversity. Mate choice near or far.