Two things have been known for some time now: Human brains get bigger as you go north, and the volume of the primate eye and the primate brain are correlated.
This COULD mean, and this may not be true, that as you go north in human populations you’ll get larger brains (for thermoregulatory reasons) and you’ll therefore get larger eyes (because eyeball and brain size is somehow correlated). But a new paper suggests a different model: Large eyes evolve at high latitudes because there is more dark, and the larger eye demands a larger brain.
Maybe, but I doubt it. the largeness of high latitude brains is way higher in magnitude than could be explained by even a two digit increase in the volume of optical processing of data. But maybe. On the other and, the relationship between orbit size and brain size demonstrated some years ago by John Kappleman (but at first ignored for reasons that I’ve never understood) is cross species an may not apply within species (many such relationships don’t). So, it is all rather mysterious for the present.
In any event, the new research could be of interest.
Continue reading Eyes, Brains and Latitude
