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In Trends in Ecology & Evolution, University of Oxford Professor Fritz Vollrath puts forth his “hot testicle hypothesis”. Vollrath suggests that elephants may carry more copies of p53 encoding genes due to an evolutionary mechanism that functions to protect sperm against harsh temperatures, but serendipitously offers cancer protection.
Elephants a unique model for studying cancer biology
Vollrath, an evolutionary biologist in the department of biology at the University of Oxford, is the lead-author of the study. As a long-term trustee and chairman of the UK charity Save the Elephants, he has spent many years studying the ecology, evolution and behavior of the African elephant in its natural habitat.
Elephants offer a unique system for studying a scientific model known as Peto’s Paradox, named after its discoverer, British statistician Professor Richard Peto.
Peto identified a flaw in the longstanding theory that larger, multi-cellular organisms are at a greater risk of developing cancer. The proposed logic behind this theory was that cancer occurs as a product of mutations cropping up during cell division; therefore, the more cells an organism has, the greater its susceptibility to cancer. Peto’s paradox points out that, if anything, the opposite occurs – there is a lack of correlation between body size and cancer risk at the species level.
“Elephants (Elephantidae) have become a model organism to explore the implications of this paradox because elephants are not only very large but also, uniquely, carry more than one copy of the TP53 gene, which encodes for the p53 protein,” writes Vollrath.