Posts Tagged ‘Simon Laughlin’

Why Don’t Our Brains Get Bigger?

December 12, 2018

This post is based on an article by David Robson titled “A Brief History of the Brain” in the New Scientist Collection titled “Becoming Human.”

The question raised in the title seems to be reasonable. Most developments are based on our brains aided by technology. Some even raise the fear that technology will outsmart us and take control.

Here is the answer provided in Robson’s article. Perhaps the most obvious answer is that we reached a point at which the advantages of bigger brains started to be outweighed by the dangers of giving birth to children with big heads. Another possibility is that it might have been a case of diminishing returns.

Our brains burn 20% of our food at a rate of about 15 watts, and any further improvements would be increasingly demanding. Simon Laughlin at the University of Cambridge compares the brain to a sports car, which burns ever more fuel the faster it goes.

For example, one way to speed up our brain would be to evolve neurons that can fire more times per second. However, to support a 10-fold increase in the “clock speed” of our neurons, our brain would need to burn energy at the same rate as Usain Bolt’s legs during a 100 meter sprint. The 10,000 calorie a day diet of Olympic swimmer Michael Phelps would pale in comparison.

The size of our brains ceased increasing around 200,000 years ago. In the past 10,000 to 15,000 years the average size of the human brain compared with our body has shrunk by 3 to 4 percent. However, size is not everything, and it’s possible that the brain has simply evolved to make better use of less grey and white matter. That seems to fit with some genetic studies, which suggest that our brain’s wiring is more efficient now than it was in the past.

It appears that further development depends on humans developing a neo-symbiotic relationship with technology. See the Healthymemory blogpost, “Neo-Symbiosis and Transactive Memory.”