“This type of thought is not present in animals.”
Rather, we don’t believe this type of thought is present in animals. It is impossible for us to actually know what is present in the thoughts of animals, because we can’t experience that, observe it, or measure it in any reliable way. The best we can do is try to come up with tests that might detect it if it was present, by the external reactions and behavior of the animals.
“So when did it emerge in humans?”
The question is based on an unsupported assumption. We have no idea that it ever “emerged” at all. For all we know the first human to exist already had the capability.
Maybe. Dhowever, do we have any evidence whatever that any animal counts to 100 or can conceptualize what 1,000 is? See e.g. Butterworth, Can Fish Count?: What Animals Reveal About Our Uniquely Mathematical Minds. I think we can agree that this kind of thought is unique to humans.