The value of broad taxonomic comparisons in evolutionary medicine: Disease is not a trait but a state of a trait!

In this short paper, we argue that there is a fundamental connection between the medical sciences and evolutionary biology as both are sciences of biological variation. Medicine studies pathological variation among humans (and domestic animals in veterinary medicine) and evolutionary biology studies variation within and among species in general. A key principle of evolutionary biology is that genetic differences among species have arisen first from mutations originating within populations. This implies a mechanistic continuity between variation among individuals within a species and variation between species. This fact motivates research that seeks to leverage comparisons among species to unravel the genetic basis of human disease vulnerabilities. This view also implies that genetically caused diseases can be understood as extreme states of an underlying trait, that is, an axis of variation, rather than distinct traits, as often assumed in GWAS studies. We illustrate these points with a number of examples as diverse as anatomical birth defects, cranio-facial variation, preeclampsia and vulnerability to metastatic cancer.

Automated summary

This paper argues that there is a fundamental connection between medical sciences and evolutionary biology, as both study biological variation. Evolutionary biology states that genetic differences among species come from mutations within populations, which implies a mechanistic continuity between variation within a species and between species. Research that leverages comparisons among species can help uncover the genetic basis of human disease vulnerabilities. Genetically caused diseases can be understood as extreme states of an underlying trait, rather than distinct traits as assumed in GWAS studies.