Researchers explain how and why physical activity was incorporated into the biology of humans. The study reveals biomedical and evolutionary evidence explaining that humans, evolving to live many years after their reproductive years, also evolved to be reasonably active in their old age.1✅ JOURNAL REFERENCE
DOI: 10.1073/pnas.2107621118
Physical activity in our later years moves energy away from health compromising functions and in the direction of health prolonging body mechanisms. The researchers hypothesize that we evolved to stay physically active as we grow older, and in doing so to set energy aside for physiological processes which slow the gradual deterioration of the body over time. This protects against chronic conditions like type 2 diabetes, cardiovascular disease, as well as some cancers.
It’s commonly thought in Western society that it’s normal to slow down and do less as we age. It however becomes much more crucial to stay physically active as we age.
The study makes use of our ape cousins as a starting point. In the wild, apes usually live about 35 to 40 years, hardly ever surviving past menopause, and are significantly less active compared to the majority of humans, indicating that there was human evolution selection not only to live longer but to be more physically active as well.
This stands out when compared to modern-day hunter-gatherers, who engage in an average of approximately 135 minutes of daily moderate to vigorous physical activity. That amount of activity, approximately 6 to 10 times more than the average American, may be one of the factors to why hunter-gatherers surviving childhood have a tendency to live about 7 decades, about 20 years longer than the age at which humans usually stop bearing children. Fossil evidence shows that these extended life spans were common by 40,000 years ago, despite the belief until recently that the human life span was short. The researchers emphasized that the primary health benefit of physical activity is for extending the human health span, which is determined as the life years lived in good health.
The researchers looked at 2 pathways by which lifetime physical activity reallocates energy for improving health. The 1st involves diverting excess energy away from mechanisms that are potentially harmful, such as excess fat storage. They also determined the way physical activity allocates energy for maintenance and repair processes. The study shows that apart from calorie burning, physical activity is physiologically stressful, which causes damage to the body at the cellular, molecular, and tissue levels. The response of the body to this damage is however essentially to build back stronger, which includes healing microfractures, repairing cartilage damage, and repairing tears in muscle fibers.
The response also leads to the release of exercise-related anti-inflammatories and antioxidants, as well as improving blood flow. Without physical activity, these responses are not as activated as much. The DNA and cellular repair processes have been found to help reduce the risk of obesity, diabetes, cancer, osteoporosis, depression, and Alzheimer’s.
The main takeaway point is that the body requires physical activity to age well because humans evolved to be active throughout life. Previously, daily physical activity was necessary to be able to survive, but nowadays we have to choose to be physically active in the interest of health and fitness.
Levels of physical activity have been declining worldwide as technology and machines replace human labor, and people are participating in less physical activity compared to what they did 200 years ago. The good news is you don’t have to be as physically active as a hunter-gatherer. Just 10 or 20 minutes of physical activity daily can substantially reduce the risk of mortality.
