Brain Trends: the Science isn't Settled

(Quora image)

Last September we posted about how the human brain has shrunk by the size of a lime since the end of the last ice age about 12,000 years ago. Scientists even hypothesized the reason:

Traniello said the inspiration for applying this idea to why human brains may have shrunk came from “ultrasocial” insects such as ants. Ants form highly cooperative societies in which division of labor has favored smaller-brained individuals due to an advanced level of social organization.

The researchers suggested that perhaps our need to maintain a large brain—to keep track of information about food, social relationships, predators and our environment—has also relaxed in the past few millennia because we could store information externally in other members of our social circles, towns and groups.

The increased offloading of storage and other tasks to the cloud means that our personal computers and cellphones don't need to have as much memory. The brain analogy: no longer do we have to memorize phone numbers, recipes, and addresses, nor do we have to know how to hunt, fish, and farm in order to survive. If we need it, the information is available on the internet. (Isaac Asimov envisioned a future where all knowledge is stored in an Encyclopedia Galactica.)

But what are we to make from this week's headline?

(Image from bigthink)

Our brains are getting bigger — and that could lower the risk of dementia

Human brains are gradually getting bigger, decade by decade, potentially lowering people’s risk of developing age-related dementia, according to a recent study published by Alzheimer’s researchers at UC Davis Health.

People born in the 1970s have more brain volume and more brain surface area than people born in the 1930s, according to the study, published March 25 in JAMA Neurology...

The reasons brains are getting larger are believed to be linked to improvements in the early childhood environment at the population level, including better prenatal care, nutrition, health care and education...

Researchers found that brain volume and surface area grew gradually but consistently in people who were born in each subsequent decade between the 1930s and 1970s. People born in the 1970s had 6.6% more average brain volume than those born in the 1930s — 1,321 milliliters compared with 1,234 milliliters, the analysis found. And people born in the 1970s had nearly 15% more average brain surface area — 2,104 square centimeters compared with 2,056 square centimeters.

There are scenarios where both studies could be true, for example, brains have been shrinking over millennia, but they have been growing over the past century. If I haven't lost so many brain cells, I might be able to think of more of them.