The recent burst of sunshine over here in the usually damp and grey British Isles has left me pondering the following two problems:
- Why do so many people suffer from hay fever? What possible advantage could there be to something which seems to be such a handicap, especially in the context in which most human evolution occurred? Even if we make the farfetched assumption that hay fever is some sort of warning mechanism against dangerous substances out there in the wild, shouldn't the genes which underlie it have been driven to fixity by now?
- Why don't we have some worthwhile means of estimating the number of genes underlying a quantitative trait which is usable with species which aren't amenable to controlled breeding*, e.g., our own? It's amazing that we still don't know how many genes there are underlying human variation in traits as easily ascertained as eye or skin** color, even though presumably only a handful are responsible in either case. If we can't get a handle on something as straightforward as getting even a rough estimate of how many genes control a trait, how are we ever going to pin down the actual genes responsible for it?
*Note that this excludes techniques like the Castle-Wright estimator or the one described in this paper.
**One problem with determining skin color is that it isn't exactly fixed: with the exception of albinos and (some) redheads, all human groups tan, even "black" people - I can testify to this at first hand. In fact, the darker the skin, the more quickly and intensely it tans.