Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

by Daniel E. Lieberman

(4) Antioxidants and immune function. Physical activity stimulates the body to spend energy on repair and maintenance systems to mop up the damage that exercise might cause in the first place.

Alzheimer’s Disease

At first she couldn’t remember where she had put things, whom she had just spoken to, and what she had eaten for lunch. Then, as her Alzheimer’s progressed, she started having trouble recognizing family members and friends and remembering basic words and key events in her life. Eventually, she lost her sense of both the present and the past. It was as if the disease had stolen her mind, leaving behind just her body.

Mounting novel evidence suggests Alzheimer’s is a kind of inflammatory autoimmune disease that initially affects cells in the brain known as astrocytes.

According to this theory, Alzheimer’s occurs when astrocytes produce these toxins in the absence of infections, thus attacking other cells in the brain.107

Alzheimer’s may thus be an example of an evolutionary phenomenon called the hygiene hypothesis. According to this idea, ApoE4, which can be expressed by cells in the brain, might have evolved long ago to help protect the brain when infectious diseases were ubiquitous. Those of us today who live in bizarrely sterile environments without many germs and worms, face an increased chance that these formerly protective immune mechanisms turn against us.

The most well supported is that physical activity—especially of longer duration but also more vigorous activities—causes the brain to produce a powerful molecule known as BDNF (brain-derived neurotrophic factor). BDNF first evolved to help mammals get energy during physical activity and at some point took on additional roles in the brain.114

Mental Health: Depression and Anxiety

Depression takes many forms including major depressive disorder, which is defined as more than two weeks of extreme sadness, loss of pleasure in formerly engaging activities, diminished energy, altered appetite and sleep, poor concentration, low self-esteem, and general purposelessness.

generalized anxiety disorders involve chronic obsessive worries about nonspecific threats that are potential rather than actual.

Our great-grandparents never confronted social media and 24/7 news cycles, not to mention as much obesity or physical inactivity.

To be sure, exercise is not a magic pill, but neither are drugs and psychotherapy, the most commonly used treatments. In fact, large-scale analyses of many trials find that exercise is at least as if not more effective than drugs and therapy.130

Exercise has additionally been shown to modestly but significantly improve memory, attention span, and various aspects of cognition including math and reading abilities.137

If you want to maximize levels of BDNF in your brain as a form of prevention, cardio appears to be more effective than weights, especially if you do high-intensity workouts.138

exercise is a fundamentally strange and unusual behavior from an evolutionary perspective.

All of us get only one chance to enjoy a good life, and we don’t want to die full of regret for having mislived it, and that includes having misused one’s body.

Make exercise necessary and fun. Do mostly cardio, but also some weights. Some is better than none. Keep it up as you age.

Green, T. A. (2001), Martial Arts of the World