The evolution of recombination is part of the discussion. It's not necessarily the same as the evolution of sex but many of the explanations for the evolutionary origin of sex invoke homologous recombination.
When I asked my students to explain the evolution of sex they mostly came up with arguments about why it is advantageous to generate genetic diversity in a population. Some of this diversity requires recombination to create new combinations of alleles on the same chromosome. The problem with this argument is that for every new combination produced, an old one will be restored. As John Maynard-Smith pointed out in 1968, when genes/alleles are in linkage disequilibrium then recombination does not result in a change in allele frequencies (i.e. evolution).
This led Joe Felsenstein to write the following in 1988.
It is worth noting that Maynard Smith's argument invalidates the earliest genetic argument for the evolution of recombination, that advanced by East (1918). That argument is also the one commonly found in textbooks, which tend to be a bit out of date (in this case, by over 50 years). East argued that recombination creates new genotypes. So it does. An AB/ab parent will have among its gametes not only the two types that formed it, AB and ab, but also Ab and aB if there is recombination between the two loci. But if the population is in linkage equilibrium, then somewhere else an Ab/aB parent will be undergoing recombination, which will remove Ab and aB gametes and replace them by AB and ab. These two processes will exactly cancel each other if the two types of double heterozygote, coupling (AB/ab) and repulsion (Ab/aB) are equally frequent. This will happen precisely when the population is in linkage equilibrium. In that case no new genotypes arise by recombination.Is it true that what students are being taught is wrong? What did Joe Felsenstein really mean?
We have that anomalous situation that a detailed population genetic analysis analysis reveals not only that the standard explanation for the evolution of recombination will not work, but also that there is a good evolutionary reason for believing that modifiers will be selected to eliminate recombination.
Felsenstein, J. (1988) "Sex and the evolution of recombination." in The Evolution of Sex: An Examination of Current Ideas. R.E. Michod and B.R. Levin eds. 74-86. [PDF]