Summary of the group selection debate on the evolution of sex:

• Group selection will tend to favor sexual over asexual reproduction because sexual populations will have a lower rate of extinction.

• The taxonomic distribution of asexuality suggests that asexual populations tend to go extinct relatively quickly in evolution.

• Biologists doubt whether group selection is the reason why sex exists, for two main reasons. One is a general disbelief in group selection; the other is Williams' balance argument.

• The objections are strong enough to have inspired biologists to look for a short-term, individual advantage to sex. We shall consider two of the most influential modern ideas.