For American pronghorn, play begins early in life. A young pronghorn will reach its peak play at about 4 weeks of age. Playtime includes a heavy dose of running. For pronghorns, running actually means sprinting. Running and playing as a fawn, however, come with risks. Play represents around 20% of total energy expenditure in fawns if you exclude growth and resting metabolic rate (Byers 1997). This type of energy expenditure could leave the fawns vulnerable to predation. So, why do they often sprint, leap, and twist during playtime if it could leave them exposed? The answer seems rather obvious. Fawns sprint because it is great practice for their adult lives. As adults, pronghorns are the fastest land mammals in North America, topping speeds of 55 mph or more. They have the ability to easily out run their predators. They are not sedentary animals. They cannot afford to not move. Moving is a good thing. Learning to run during playtime is probably just a form of “motor training” (Bekoff and Byers 1981). Pronghorn are made to run.
We, as humans, don’t have to worry about being chased by large predators, but some biologists have made the case that we, too, are made to run. Bernd Heinrich argues this very point in his book, Why We Run. Heinrich takes a natural history approach by comparing running and moving in multiple species across the biological spectrum. His central point is that we were once forced to be continually active to find food and survive, and because of this we never had the chance to be idle for prolonged periods of time. Now, we are often idle for long periods of time. We don’t explore the wilderness. We don’t go for walks. We don’t run. We are content just to sit inside and watch the television or play video games or stare at a Facebook feed.
Our bodies are designed in such a way that we store excess calories as fat in preparation for those times when we may have little food to eat. Since most Americans don’t really experience times of little food, this excess fat has consequences. Periods of idleness can result in obesity. Heinrich also makes the case that a prolonged sedentary lifestyle has negative consequences on our bones. If bones don’t receive the normal daily stress that comes from moving and running, they will become weak (osteoporosis). Think about astronauts who live in the zero-gravity environment of space for a period of time. Their bones become weak rapidly. Like pronghorn, we weren’t made to be sedentary. We were made to run.
Can you name the #1 outdoor game for kids between the ages of 3-10? I don’t have any confirmation, but I believe it is “tag”. Why do children (and lots of adults) love this game? We love this game because it’s easy, there is no equipment to purchase, you can play with as little as 2 people, it can be played just about any where and it’s fun. There are also definite benefits. It’s a great way to meet new friends, it improves critical thinking skills (strategy involved), it improves speed and agility, and it’s great exercise.
Yet, children are told not to run in the house (they might knock something over), not to run in the school hallway (it’s disorderly), not to run on the sidewalk (they might skin their knees). In some cases, it seems, kids aren’t even allowed to run outside during recess for fear of running into another kid or stepping in a hole. Some are even threatened with punishment if they are caught running.
We were made to run, but we often find ourselves in situations where we can’t.
Beckon, M. And J. A. Byers. 1981. A critical reanalysis of the ontogeny and phylogeny of mammalian social and locomotor play: An ethological hornet’s nest. In Behavioral development: The Bielefeld interdisciplinary project, ed. K. Immelmann, G. Barlow, M. Main, and L. Petrinovich, 296-337. Cambridge: Cambridge University Press.
Byers, J. A. 1997. American Pronghorn: Social Adaptations and the Ghosts of Predators Past. Chicago, IL: The University of Chicago Press.