Re: Why don't female deer grow antlers?

Why don’t female deer grow antlers?

First, I must point out that some of them do. Female caribou and reindeer 
commonly grow antlers along with their male counterparts. In addition, 
some female white tail deer (and I suspect mule deer, although I don’t 
know for sure) will grow antlers. This phenomenon is well known to most 
deer hunters, who are not supposed to be shooting does but can get away 
with it if the doe has antlers. 

Now, to address this question (leaving out the exceptions noted above) we 
first need to ask – why should any deer grown antlers? Growing anything 
(an arm, a tail, or an antler) is associated with a metabolic cost – it 
takes food energy to grow that structure and gathering food exposes an 
animal to predation risk. Employing the adaptationist paradigm, we can 
assume that antlers serve a function that is important to males, but that 
function is not as important to females. In the case of deer, that 
function is the inter-male competition for mates. Deer really only use 
their antlers to fight with other deer. They are not usually used to fight 
off predators, which is one of the reasons that antlers are/can be shed 
annually. 

So, male deer need to antlers to fight with other male deer to gain access 
to females. Female deer do not employ the same competitive strategies 
among themselves, and so do not “need” antlers. What we see here is an 
example of sexual selection. Having large antlers actually works against 
the long term survival of the buck (these deer are the prime targets of 
hunters), but it does allow the buck to gain reproductive access to more 
females. And, from the biological perspective, reproduction is the entire 
purpose of existence.