What's the Point of Sex, Anyway?
A review of Lixing Sun's book "On the Origin of Sex" explores the evolutionary puzzle of why sexual reproduction exists, given its inefficiencies compared to asexual reproduction. Sun argues that sex serves as a mechanism to filter out harmful mutations and adapt to changing environments. The review examines the scientific debate and evidence surrounding this fundamental biological question.
Background
- Lixing Sun is a biologist at Central Washington University; his book "On the Origin of Sex" proposes a new hypothesis for why sexual reproduction evolved instead of simple cloning, a long-standing puzzle in evolutionary biology.
- Sex is costly and inefficient (only half your genes get passed on, you need a mate), yet it dominates complex life. The leading theory — the "Red Queen" hypothesis — holds that sex helps hosts stay ahead of fast-evolving parasites by shuffling genes.
- Sun argues the Red Queen alone is insufficient. He contends that sex originally evolved not for genetic mixing but as a quality-control mechanism: a way for primitive cells to repair DNA damage by using a partner's genome as a template, with recombination (gene shuffling) emerging later as a side effect.
- The review also discusses the "dead-end hypothesis" for why males exist — Sun suggests males are evolutionary "test runs" that allow harmful mutations to be culled in a disposable sex, protecting the female line.