Trophy hunting isn't causing Alberta's bighorn sheep to evolve into something smaller and less impressive, a new study says.

Previous studies have suggested that hunters taking out the biggest males in a herd could be favouring the development of rams with smaller horns.

That's because the smaller animals would have more chances to reproduce and pass along their DNA.

But newly published research has found that a ram's size doesn't have that much to do with inheritance.

While large trophy rams are getting scarcer, the study found that's simply because hunters are picking them off.

The authors say that numbers of big sheep are likely to rebound if hunting pressure goes down.