A trans-species polymorphism. Some genetic polymorphisms are found in distantly related species, having persisted across multiple speciation events. (source) It is widely known that considerable genetic overlap exists between human populations, even those that are geographically distant from each other and quite different physically. You probably learned in BIO101 that genetic variation is much greater... Read More

The ‘hot’ hair color this year (source). While there seems to be a general trend to prefer average physical characteristics, this doesn’t seem to apply to hair color. People seek colors that are uncommon or even unnatural. Europeans have departed from the species norm of black hair and brown eyes by evolving a wide range... Read More

Although blue eyes are more recessive than brown eyes, eye color does not follow a simple recessive/dominant mode of inheritance. There is a wide range of intermediate hues. As discussed in my last post, one puzzle of human evolution is the diverse palette of European hair and eye colors. Although these two polymorphisms have largely... Read More

I’ve been fascinated by a puzzle of modern human evolution: the diverse palette of hair and eye colors that has developed in some populations (Frost, 2006; Frost 2008). Hair may be black, brown, flaxen, golden, or red, and eyes may be brown, blue, gray, hazel, or green. Both polymorphisms are largely confined to Europeans, especially... Read More

Are there other theories on the origins of male homosexuality? Yes, quite a few. These theories generally fall into two categories: those that explain the relatively small variance due to genetic factors (30-45%) and those that explain the larger variance due to some environmental factor. Conceivably, we could be looking at an interaction between the... Read More

Male homosexuality has always puzzled evolutionary biologists. It has 30-45% heritability, so there must be some genetic predisposition (Bailey et al., 2000). But how could such a predisposition get passed down from generation to generation? It ought to die out, by its very nature. Well, not all predispositions are fully expressed. This observation led the... Read More