Evolutionary Variation in Dim Light Abilities?

Started by AlanFrench, 07/27/2011 12:08PM
Posted 07/27/2011 12:08PM Opening Post
A fascinating article with some implications for amateur astronomers.

"Humans living at high latitude have bigger eyes and bigger brains to cope with poor light during long winters and cloudy days, UK scientists have said."

http://www.bbc.co.uk/news/science-environment-14279729

Clear skies, Alan
Posted 07/27/2011 01:49PM #1
Alan French said:

A fascinating article with some implications for amateur astronomers.

And the implication would be not to have an observing contest with someone who was born and lived all their life in Boulder, Colorado??
Posted 07/27/2011 06:03PM | Edited 07/27/2011 06:42PM #2
I tracked down the study write up, as I'm always skeptical about news claims since they often stretch truths. You can find it here: http://rsbl.royalsocietypublishing.org/content/early/2011/07/12/rsbl.2011.0570.full.pdf+html

I'm finding it a little hard to swallow as any firm conclusion. It is based on 55 skulls from their museum. A very small sample IMO. It also makes an assumption that the occipital lobe size meant the eyeball was actually bigger. They did address the possibility that it could have been insulative fat around the eye, but ruled that out based on mean temps from the individual's locations. This was a bit of a risky assumption IMO as they were not specific on what research they used to assess that particular temperatures could be ruled out. Bothersome to me was this and a few more assumptions they made relative to socket size. In other words, a more accurate approach would be to actually measure real eyeballs with live populations using an apporpriate imaging technique thereby eliminating all assumptions. There was not a lot about the 12 populations they used. This is pertinent because human eye sockets and eyeball size vary based on structural differences between humans of various races across the planet. Also no addressing of if same country/culture samples varied where there was a radical altitude change within the region. Most problematic was their lack of addressing socket and eyeball size differences between sexes in modern man, as well how significantly these are different depending if you have myopia or hyperopia -- for example, the most hyperopic individuals have an orbital volume 2.37 cm³ larger than the most myopic subjects (Chau, A., Fung, K., Pak, K., Yap, M (2004) Is eye size related to orbit size in human subjects? Ophthalmic and Physiological Optics, 24(1) 35-40).

All in all, a lot left wanting to draw any firm conclusions. Certainly "interesting" analysis and find, and enough so to warrent some further more detailed studies where not so many assumptions need to be made that could invalidate results. But stating based on this that there is an evolutionary variation in human eyeball size and brain processing correlated to altitude and dim light is a leap at best.

I'll tuck this story away in the interesting but not remotely strongly supported category. I think that probably one inch more in aperture in my telescope will do way more for bringing in faint fuzzies rather than asking what a Norwegian friend might see - LOL Thanks for finding and sharing this.