Evolution of Male Baldness

While male baldness has become stylish in recent decades, it has long been a source of anxiety in men, especially when it develops at a young age.  Just look at the trouble our President goes to in order to hide his balding pate.

The evolutionary benefit (if any) of male pattern baldness has long been the subject of debate.  It is known that genetics play a major role; an X-linked gene (inherited from the mother) is clearly involved in many cases while inheritance from the father also occurs but is less well understood.  We also know that male baldness occurs in chimps, a species that shares more than 98% of our genes.

The question remains, however, why these genes have been retained throughout human history.  Some have suggested that male baldness is just the next stage in our evolution as the "naked ape" while others surmise that balding is sexually selected as a sign of maturity.  Since we evolved in the tropics, it is possible that hair loss from the scalp (which is highly vascular) may have been beneficial in the dissipation of heat during strenuous hunting activity.  In the end, baldness may just be genetically linked to other metabolic traits (e.g. higher testosterone levels) that somehow benefit survival.