An Evolutionary Neuroscience Perspective

We recently started a discussion on the utility of evolutionary neuroscience on current applications and understanding. In that discussion, I brought up some of what I see to be pitfalls in evolutionary neuroscience: falling for the guiles of reverse inference and letting your imagination run too far away. Today, I wanted to extend the discussion to a recent paper that shows how evolutionary neuroscience can lead to useful, testable hypothesis generation.

Most people know from experience that the body is adaptive, and so it is pretty intuitive that exercise is good for some organ systems. For example, if we exercise, our muscles use oxygen more quickly, so our heart needs to beat faster and harder to keep up with our muscles’ needs. Therefore, the heart gets stronger, and vessels grow to provide more blood to muscles. More surprisingly, there has been a wealth of recent research on the benefits of exercise on the brain, especially in the context of aging. Exercise, especially aerobic exercise, seems to preserve cognitive function in old age, and may provide a cognitive advantage across the lifespan.

So what's the news?

A new paper by David Raichlen and Gene Alexander, describes a new framework for taking on this perplexing question about why exercise seems to be so unexpectedly good for the brain. This paper takes an evolutionary neuroscience approach, looking at how a hunter-gatherer lifestyle may have affected the “adaptive capacity” of the human brain.

Their idea is basically that humans at some point became active hunter-gatherers, which led to tasks that were simultaneously physically demanding and cognitively demanding. Therefore, human physiology evolved to link exercise to cognition.

This idea makes good use of the what is known about evolutionary neuroscience to make testable hypotheses for future exercise research. This would be very useful to understanding the details of exercise effects on cognition. For example, the framework would predict that naturally sedentary animals would not have negative cognitive effects of a sedentary lifestyle (or put in opposite terms, would not see benefits of being more active).

The framework also makes some proposals about the ideal exercise for a human: that moderate aerobic exercise (the kind you get from gathering and hunting) in congruence with cognitively demanding strategic and spatial tasks would be the ideal way to enhance brain function.

I like the idea because it makes some counter-intuitive hypotheses. First, it seems more intuitive to think that if exercise improves cognition, exercising harder would improve the cognition more. Their hypothesis is that moderate exercise would be the most effective. Secondly, most researchers have focused on aerobic exercise interventions of walking, jogging, or riding a stationary bike without much concurrent cognitive stimulation. If researchers discovered that difficult mental tasks interacted with physical activity in a synergistic way, that may change a lot of people’s exercise regimens. Personally, I can’t for the life of me understand why anyone runs for a long time instead of playing more cognitively complex sports and games in the first place ;-)

Sources:

University of Arizona (2017, June 26). Brain Evolved to Need Exercise. NeuroscienceNew. Retrieved June 26, 2017 from http://neurosciencenews.com/evolution-brain-exercise-6982/

Image 1: By Gruban - File:Algerien 5 0049.jpg, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=23326304
Image 3: Photo Credit: Shane Sharp, Europe Regional Medical Command Public Affairs