New Delhi, April 17 -- When we think about intelligent animals, farm species aren't usually the first to spring to mind. We may picture tool-using primates or puzzle-solving crows. But my recent research suggests that sheep, goats and alpacas - staples of the barnyard - deserve more credit.

In two separate studies, I tested how these animals learn, remember and make sense of the world around them. The findings reveal not only that we've underestimated their cognitive abilities, but also that there are important differences between species.

Of the three, goats came out on top - outperforming both sheep and alpacas in tasks testing memory and problem-solving.

Initial testing focused on spatial memory, which is the ability to remember the...