The Elephant and the Spandrel.

Comparative oncology has made great strides in identifying patterns of cancer prevalence and risk across the tree of life. Such studies have often centered on elucidating the evolution of mechanisms that prevent the development and progression of cancer, especially in large animals such as elephants. Conclusions from this approach, however, may have been exaggerated, given that the deep evolutionary origins of multicellularity suggest that the preeminent functions of the identified mechanisms may be unrelated to cancer. Instead, cancer suppression may have emerged as an evolutionary byproduct, or "spandrel". We propose a novel evolutionary perspective that highlights the importance of somatic maintenance as the underlying axis of natural selection. We argue that by shifting the focus of study from cancer suppression to somatic maintenance, we can gain a deeper understanding of the evolutionary pressures that shaped the mechanisms responsible for the observed variation in cancer prevalence across species.