If you take a functionalist view of the mind, just a pattern within a system of like elements, then you have to consider that intelligence could arise anywhere.

Like a flock of bird all flying perfectly together, each bird represents a neuron, and their interacting give rise to a sort of group consciousness.
Sort of. A key tenet of Functionalism is precisely Multiple Realizability (the ability for multiple physically distinct systems to realize a mental state).The most common comparison in philosophy of mind literature is (bizzarely) octopi and humans.

Octopi are different enough from humans that it is safe to believe their brains work significantly differently. Now, if we were to have a device to pinch an octopus' tentacle, and we see it recoil the tentacle in shock, we would usually say that it is feeling the mental state of 'pain.' We obviously don't have access to the octopus' intensional (with an s) state, so we cannot be sure, but from observing the octopus' behaviour we can infer it pretty readily.

How do we do so? We observe that the physical stimulus of the pinch (call it P*) leads to sudden evasive action (E) and perhaps cautious behaviour when approaching the pinching-device in the future/unwillingness to approach the device. The thing about functionalism is that it doesn't necessarily depend on any behaviours, but on inter-related mental states. So, pain is defined as something like:

Octopi are in pain just in case: physical stimuli P* leads to mental state E (evasive action) and results in C (future cautious behaviour). Whenever these states (or others - 'crying' or 'rush of adrenalin' for example) are instantiated, whatever that mental state is, we call it 'pain'.

Obviously there are many more complex states involved in feeling pain, such as perhaps 'seeking medical help' etc, but this is a general example. The mental states depend upon the function they perform via linking to other mental states, and the behaviours/actions these cause.

There are a few problems with functionalism, the primary one being a problem constructed by Jaegwon Kim against non-reductive physicalism (which is what functionalism is), which concerns mental causation. I'm happy to outline it if anyone is interested.