Why do we use a different voice to talk to babies and dogs?

No one ever told me to change my voice when I talk to an infant or a dog, but I do it, and it seems to work. And I’m not the only one who does it.

The best way to describe the voice I use to talk to little kids or puppies is a cross between Marvin The Martian and Bart Simpson.

Why I do this, I do not know, ...