From left to right: Siberian musk deer (which isn't a true deer), Reeves's muntjac, and a Western roe deer.
The notion of tusked deer is a bit foreign to North Americans, but people living in the UK will know that two small deer that were introduced from Asia, the Reeves’s muntjac and the Chinese water deer, actually possess sharp canine teeth.
It is thought that the ancestral deer was very similar to the so-called musk deer of Asia. Musk deer have several features that true deer lack, and one of the most notable is their lack of antlers. Musk deer have very well-developed canine teeth, and they look almost like saber-tooth cat crossed with a deer.
Musk deer are solitary animals, and if they meet, they use these long canine teeth on each other.
Just as it is the male true deer that typically have the antlers, it is the male musk deer who have the really impressive canine teeth.
The reason why it is thought that modern deer were much like musk deer is that many smaller species of deer in which the males possess impressive canine teeth.
The water deer of Asia has the long canine teeth, and neither sex has antlers. Water deer can form small groups, but they are less social than other true deer.
Reeves’s muntjac, which is native to temperate parts of Asia, has smaller canine teeth than a musk deer, and the bucks have antlers. These antlers are quite small compared to other species of deer, and they use them primarily as a way of knocking their opponents off balance. After they knock their opponents off balance, they use their canine teeth on them.
Most modern deer have lost their canine teeth entirely. The antler has become the primary weapon.
But before deer had antlers, they had fangs.
And some still have them today.
The species we call reindeer or caribou (depending upon location and whether one is wild or domestic) probably could have had some use out of fangs. Both sexes of caribou/reindeer possess antlers, which they use against each other. It is thought that this species of arctic deer developed this trait– which is normally a trait of sexual dimorphism in other species– in order to give the females better tools to fight off other deer when the foraging gets tough in the winter. Antlers take a lot of energy and nutrients to grow every year, so as weapons, they are pretty costly to the animal. Fangs really aren’t that costly, and they have them all the time.
Deer likely evolved super ornate antlers as a result of sexual selection. The females are just more attracted to males with more ornate head weapons.
Caribou evolved from deer that had gone down this evolutionary road, so the trait of both sexes possessing antlers had to be built out of that lineage.
So female caribou have to devote energy and nutrients into growing antlers and into feeding their offspring. No other female deer has this problem.
That’s a major tax on any animal.
Ah, yes, we have another example of why intelligent design is crap.
And intelligent designer would have given caribou fangs.
But I don’t think Rudolph would be all that cute if he had the dentition of a saber-toothed cat!
