Why do deer have antlers? And why is it “because they don’t have tusks anymore?” In the Cervidae — the “deer family” — antlers are a “morphological synapomorphy” (essentially a physical trait that defines members of the family). All cervids have antlers (except for one), all re-grow their antlers annually (which is a remarkable feat that deserves its own video), and in every species (except for one — caribou), only males grow antlers. While antlers may be occasionally used for self-defense, they