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Sport is good for your health, of course. The idea of this article is not to encourage you to stand still – that would be absurd and counter-scientific. But even if this activity is important, an eminent Harvard professor declares that sport is not “natural” for humans. We explain.
Harvard professor: the human body was not made for sport, but…
Our modern liberal Western societies are increasingly elevating sport to cult status. It’s true that, with the development of the tertiary sector, we’re getting too dirty. It’s also true that a minimum amount of physical activity is very good for your health. The problem is that the cult of sport is so well-developed that people who don’t do sport are judged negatively and mocked by just about everyone. So it’s interesting to hear some serious scientific voices bringing some nuance to all this.
Daniel E. Lieberman, researcher in evolutionary biology and professor at the prestigious Harvard University, has analyzed and destroyed the myth that a healthy lifestyle is based on continuous physical exercise over time. In his book “Exercised”, Lieberman explains “Why an activity for which we have never evolved is healthy and rewarding” – this quote in quotation marks is actually the subtitle of the book itself. Please note that at no point does the researcher advocate a sedentary lifestyle – that would go against the current consensus. Nevertheless, his conclusions are very interesting to consider when talking about sport.
As you can see from the title of this article, Lieberman believes that human beings are not cut out for sport. There is no serious scientific evidence for this. From the point of view of evolutionary biology, we’re simply not coded to exercise. In other words, our bodies didn’t evolve for it. Again, the science here is descriptive, not prescriptive. Of course, the author believes that exercising has many benefits, not least for your health.
Lieberman insists, however, that sport can be harmful if not practised in moderation. More and more people around the world are pushing themselves to exercise as much as possible. It therefore calls for a general regulation of physical activity sessions. We need to make sure we do just the right amount, neither too much nor too little. Likewise, there’s no point in doing sport every day. It’s all a question of dosage.
Throughout the pages of “Exercise”, Lieberman supports his thesis that evolution did not make us athletes in general and runners in particular. Using grand scientific demonstrations, he asserts that mankind developed in environments in which it was not necessary to stand for long periods. For tens of thousands of years, homo sapiens took advantage of time spent sitting or lying down, telling stories or doing manual work, and it was this that enabled him to dominate the planet, not his physical abilities.
Let’s add a little more nuance: yes, when the time was right, our ancestors could walk more than 12 kilometers a day to obtain food, whether by hunting or gathering. We’re talking here about walking… not running. The author explains that walking is a more natural physical activity and less demanding on the body than running, and that exercise doesn’t have to be extreme to be beneficial. Just getting out of the metro a station early to walk a little more every day seems like a very good thing.
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Vital functions that drain our energy
In “Exercised”, the author points out that we have an innate “energy-saving” instinct. To quote Lieberman: “Compared to other mammals, humans have surely evolved to be particularly reluctant to exercise”. There’s a seemingly simple but complex reason for this: basal metabolism.
Basal metabolism corresponds to the minimum amount of energy required by the body to maintain vital functions at rest, i.e. in the event of total physical and mental inactivity. Blood circulation or body temperature regulation are part of basal metabolism. These minimal functions alon
e account for most of the body’s daily energy expenditure, i.e. some 60-75% of total energy use. The brain alone consumes between 20% and 25% of the energy required for basal metabolism. According to Lieberman’s data, an 82 kg person expends around 1,700 calories, even if he or she spends the whole day at rest.
Thus, Lieberman does not consider that sitting should be demonized, as it is a common activity in human life. Instead, he advocates adopting it in a healthy way by limiting uninterrupted sitting to 45 minutes and avoiding sitting all day. It’s like anything else, you need balance.
Although we can’t fully summarize the contents of “Exercised” here, it’s worth noting that the author recommends a few tried-and-tested practices for staying in shape, such as aiming to take around 7,000 steps a day (not 10,000, although that myth has a hard skin). Lieberman examines how sport influences our health and how it can help us prevent disease. For an in-depth understanding of his advice and analysis, we recommend reading the entire book.
