The same sort of thinking gets in the way of people's understanding of animals. "Why don't they act like humans?" is the repeated question. But why should they? They're not humans--but that doesn't mean they don't have equivalently rich lives.
One of the main aspects of the search for humanness in animals is language. Why don't animals speak like humans do?
Back in December, in the New York Times, there was an article describing how a Scottish group of scientists had managed to decipher words and syntax in the spoken language of Campbell's monkeys (that's one in the picture), thus giving them credit for at least a little human equivalency.
But a month later, the same writer in the NYT reports on some other, more pessimistic scientists, who contend that even these monkeys cannot have a rich language because they cannot conceive of the idea that another animal has a mind similar to their own; therefore they have no need to communicate.
I don't know why it is that so many scientists take a completely stupid course when it comes to their inability to understand animals. These pessimists will contend that an animal can't do this, or can't think that, or can't relate to another. They forget one fact that makes their arguments invalid:
Careful observation always proves these pessimists wrong. Why would a cat, for example, have a way to say, "I'm sorry" --which they do-- if there was no inkling that another cat or person had a mind of its own? So why should anyone assume that a social animal like a monkey would not be able to realize that?
The gist of the latest NYT article is that animals can't communicate in anything resembling a human language, and this must mean they don't think or understand.