How do I best study the evolution of consciousness?

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Start looking back at the reptile - mammal brain split.

Most people think human consciousness is special. It’s not really. The only thing that makes it different than other mammals is language, and only two small parts of the brain are implicated in that.

The much bigger change happened all the way back in the Permian, some 250 million years ago. If you look at the basal ganglia, what we call the reptile brain, in humans it’s a small nugget at the very base of the brain. Surrounding it is the so-called old mammal brain, the limbic system, regulating what we call emotion. Surrounding that is the ‘new mammal’ brain, the seat of thought.

Two areas of the brain are implicated in language, the formation of brain activity into transmissible units of thought, one is towards the front of the brain, the other is located towards the rear, both fairly centrally located. If the front area, Broca’s area isn’t working right, then you can’t form thoughts into words in order to speak them.

If the rear area, Wernicke’s area isn’t working right, then you can form thoughts into words, but the words will lack meaning, they won’t be coherent. This is because this part of the brain is involved in selecting the words, when it’s damaged, it just won’t select the right ones. The patient will seem to feel like he’s speaking coherently, but won’t be.

Brains kept developing in both reptiles and birds and, particularly birds, have their own limbic systems that are quite different in structure to ours. You can look at their brains and sometimes be able to tell what sort of overall personality the bird will have. Owls are dumb as bricks, their entire brain is focused on hunting and not social behaviors. But parrots are sensitive and communicative.