I will be happy when people stop referring to intelligence as a binary state. My dog is intelligent, mice are intelligent, nematodes are intelligent. The ability to interact with and adapt to the environment is present in all of these creatures. The degree to which something is intelligent is something we need a much richer vocabulary for. I am sad to say it but this is most clearly put in comic form (http://www.smbc-comics.com/index.php?id=2867#comic)
> The ability to interact with and adapt to the environment is present in all of these creatures.
Not a very useful definition as it is a basic property of all living creatures, and some non-living ones.
I think it's clear that when we talk about intelligence we mean intelligence of the kind that involves neurons and very-short-feedback-loop problem solving (seconds, not years, like DNA). Of course every animal has that.
Some feel that only the ability to do abstract problem solving qualifies as intelligence. Still, humans are not unique in that. Second, I'm pretty sure every cluster of neurons can do that, most just don't have any use for it (humans, and other species, use it for social bonding).
