O'Leary's new post at ARN:The unfeeling reptilian brain: Don't mess with its babies

Recently, while doing research for a book on human neuroscience issues, I ran into a really neat explanation of the brain, as follows:

Neurologist Paul MacLean first proposed in 1970 that the human brain has three parts, each one of which grew on top of the other, over evolutionary
time:

- the reptilian brain (includes the brain stem and cerebellum)

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This "three brains" hypothesis sounds neat — three nested brains — but it does leave the reptile without the ability to feel emotions other than aggression or perhaps fear.

Indeed, Maclean himself liked to say that "it is very difficult to imagine a lonelier and more emotionally empty being than a crocodile." For example, two behaviors that he did not think crocodilians could manage were care for offspring and playfulness.

[ ... ]

One really good thing about the "three brains" hypothesis is that it can be tested. That's a key sign of a good hypothesis in science. Does the evidence reasonably show that crocodilians do not show emotions other than fear or aggression?

If you like this blog, check out my book on the intelligent design controversy, By Design or by Chance?. You can read excerpts as well.