Dogs' stronger responses to our emotional gestures could have arisen simply because they have had longer to adapt to life with humans.
But for now it is too early to draw conclusions. While there has been plenty of research into dogs' minds, there have been remarkably few studies of how cats respond to human gestures.
They may be our most popular pet but we still have a lot to learn about them: we do not even know why they purr. But this study might go some way to repairing cats' reputation for being uncaring. It may be that they simply do not show their affection for us as much as dogs do.