How Much Brain Do We Need?

There's a fascinating article at Wired by Grace Browne who tells us of a woman in her fifties who for privacy reasons goes by her initials EG and who, amazingly enough, is missing the left temporal lobe of her brain. What's amazing about this is that the left temporal lobe is thought to be involved in language processing, and yet...

missing a large chunk of her brain has had surprisingly little effect on her life. She has a graduate degree, has enjoyed an impressive career, and speaks Russian—a second language–so well that she has dreamed in it.

She first learned her brain was atypical in the autumn of 1987, at George Washington University Hospital, when she had it scanned for an unrelated reason. The cause was likely a stroke that happened when she was a baby; today, there is only cerebro-spinal fluid in that brain area.

For the first decade after she found out, EG didn't tell anyone other than her parents and her two closest friends. “It creeped me out,” she says. Since then, she has told more people, but it's still a very small circle that is aware of her unique brain anatomy.

Over the years, she says, doctors have repeatedly told EG that her brain doesn’t make sense. One doctor told her she should have seizures, or that she shouldn’t have a good vocabulary—and “he was annoyed that I did,” she says. (As part of the study at MIT, EG tested in the 98th percentile for vocabulary.)

EG was eventually put in touch with Evelina Fedorenko, a cognitive neuroscientist at MIT who studies language, and the two hit it off. Browne writes:

Just how remarkably little effect the uniqueness of EG’s brain has on her day-to-day life shows how sheerly expendable big chunks of our brains can be. Fedorenko points to a surgical practice called hemispherectomy used for children with epilepsy whose condition does not respond to medication.

The practice entails removing the half of the brain where the seizures are taking place, and these children have been shown to retain typical cognition. “If you can remove half of a brain and you work fine, that suggests there's a lot of bits in our typical brains that are redundant,” says Fedorenko.

“There's apparently a lot of stuff in our brain that is fully redundant, which is—engineering-wise—a pretty good way to build the system.”

The reality is that if the brain is damaged, it will often find a way to rewire itself.

Remarkably, EG’s sister is missing her right temporal lobe and is largely unaffected by it, suggesting there's likely some genetic component to the early childhood strokes that can explain the missing brain regions, Fedorenko says.

This raises a few questions. One is how much of the brain can one lose and at what stage of life can one lose it without it having any serious effect on one's ability to function? Evidently, much, or even most, of what is going on in our cognitive experience is not totally dependent on the brain.

The orthodoxy among materialists is that our cognitive functions are due solely to the material brain in our heads. In their ontology there's no room for an immaterial mind. Yet, if they're correct why would we evolve more brain matter than what we need to survive and function?

Another question is how did this ability to rewire itself and develop redundancy ever evolve by random mutations and natural selection? As Fedorenko says, “There's apparently a lot of stuff in our brain that is fully redundant, which is—engineering-wise—a pretty good way to build the system.”

Indeed, but blind, mindless processes like Darwinian evolution don't engineer systems. Intelligent engineers do.

It's remarkable that when talking about living things scientists find it very difficult to avoid using the language of intelligent design. Perhaps that's because the intuition that living things are intentionally designed for a purpose is so overwhelmingly powerful.