This sophisticated study reveals several aspects of the complexity of life and evolutionary processes. It shows how a mutation can simultaneously influence two of the most characteristic features of anatomically modern humans: their tall stature and high metabolic rate, compared to the closest primate species.

Again, this reminds us that we should not look for simple adaptive explanations to understand the evolution of phenotype (i.e., physical, physiological, and behavioral traits). In addition, the study shows that genetic modifications affecting stature and metabolic activity interact directly with environmental influences, in particular with increased meat consumption.

Thus, the same genetic mutation can simultaneously affect different phenotypic traits, all conditioned by environmental influences. Fantastic!

It is very interesting work, although basal metabolism—not to mention height—must depend on many more genetic variants. This one seems to have been selected in northern Europe over the last few thousand years.

The estimated age of this variant overlaps with the estimated time of divergence between modern humans and Neanderthals (where it is not present in the few genomes available from these extinct humans); given that Neanderthals clearly had a very high-calorie diet due to the extreme cold conditions of their environment, I think it is plausible that their adaptation to a high basal metabolism was due to other genetic variants that are still unknown. Beyond investigating possible cognitive differences with functional studies and organoids, it would certainly be interesting to also explore metabolic differences.