Transmissible cancer and the evolution of sex
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Sex may have originated to prevent cancer being transmitted between individuals.
Asexual-reproducing organisms essentially clone themselves. In contrast, sexual reproduction typically involves enormous energy expenditure in finding potential mates and only females can bear offspring. Yet, nearly all multicellular organisms reproduce sexually. This is one of the greatest enigmas in evolutionary biology.
Now, a team that included Deakin University researchers has proposed a new explanation for this.
The rise of multicellular organisms made possible the arrival of cancers. Asexual reproduction produces genetically identical offspring between which cancers can spread because the offspring’s immune system cannot detect any difference in the cancer genome. Sexual reproduction, however, rearranges the genome, making cancers easily distinguishable between individuals.
This hypothesis could explain the scarcity of transmissible cancers in sexual reproducers, and their almost exclusive occurrence in homogeneous populations.
- PLOS Biology 17, e3000275. doi: 10.1371/journal.pbio.3000275