WHY DO WE EXERCISE?
To survive we had to be fit
Animals need to move to survive and higher life forms, so-called vertebrates, have evolved muscles and bones for this purpose. Each animal’s musculoskeletal system has developed to suit its own survival needs – the cheetah has a system designed for speed to enable it to catch its prey and likewise the antelope has a system designed for speed to escape being eaten by the cheetah. For other species strength may be more important than speed. Think of the tiger, which can tear its prey limb from limb. For every animal there is an optimal mixture of speed and strength to enable it to survive and procreate efficiently.
Evolution has given humans a musculoskeletal system of great versatility. We are neither immensely strong nor immensely fast – but we do have the greatest intelligence in the animal kingdom and we use our brain power to make the most efficient use of this versatility. Man evolved to be a highly efficient hunter-gatherer – to hunt animals and to gather edible plants for our sustenance. For most of human history that has been the main function of our muscles. Primitive man took a lot of exercise because that is what he had to do to survive.
Primitive Man (pre-10,000 BC)
A number of studies of primitive societies have given us an insight into the ways in which early man exerted himself in his struggle for survival. Primitive, nomadic lifestyles required continual hunting and gathering of food. It was quite common for tribes to embark on one or two-day journeys to seek food and water. All these studies have a similar story to tell – that being a hunter-gatherer was tough. The most recent and well publicised was the study of anthropologist, Herman Pontzer, who spent several years with the Hadza people in northern Tanzania. He notes that this way of life is hard work – including walking about 8 or 9 miles a day. This is a pattern which is seen in many different parts of the world with time spent in obtaining enough to eat being in the region of twenty or more hours per week. A major activity was walking often interspersed with periods of more strenuous exercise. Days of long exertion were followed by easier days. The average energy expenditure may have been three to five times greater than that of an average westerner today.
Some of the work of hunter-gatherers included stalking and killing animals. It would have taken much effort to kill a deer, elk, moose, bison,and then butcher it and take it “home” or drag it there. Foraging for vegetables was no easier, involving inspecting, pulling and digging followed by putting the food in bags and packs and carrying the heavy haul around–in addition to carrying infants and small children—often for miles in a variety of weather. Success was not always assured, which meant ranging wide distances to search for provender. And, even if they were successful, the actual gathering and carrying the food all day was strenuous.. Anyone who gardens knows the feeling of fatigue and backache after just an hour of pulling weeds and bending over to inspect crops. It is estimated that the !Kung San women of South Africa walk up to 12 miles in a day of foraging, and this does not include their other daily activities
In brief, the characteristic activities of our ancestors included plenty of walking and carrying , occasional bursts of moderate to high intensity exercise, and a combination of a variety forms of muscular effort such as lifting, digging, carrying, climbing.
The results of stone-age life style
Numerous reports tell us about the physiques of historic “Natives” who ate unprocessed foods and who were consistently active. Many observers have commented on the beautiful physiques of hunter-gatherers – “they are undoubtedly the finest looking, best equipped, and most beautifully costumed of any ….. picturesque and handsome, almost beyond description” (Upper Missouri tribes), “straight bodied, strongly composed, smooth-skinned, merry countenanced….broad shouldered, brawny armed, long and slender handed, out breasted, small waisted, lank bellied, well thighed, flat kneed, handsome grown legs, and small feet”(Aberginians), “very well formed, with handsome bodies and good faces….All alike have very straight legs and no belly” (San Salvadorians), “tall, noble, well-made people; many of them about six feet high, with long black hair . . . their features good” (North American Indians).
When cardiorespiratory fitness has been measured it has been found to compare very favourably with that of people living in modernised societies. Primitive people do not become obese and have a very low level of non-communicable diseases (NCDs). NCDs include all those degenerative conditions which are so common in older members of Western societies – obesity, hypertension, heart disease, diabetes, osteoarthritis, osteoporosis, dementia to mention a few.
We do not know what prehistoric man did in the way of recreational exercise, though it is likely that during periods of relaxation he would have played around and perhaps danced. There is evidence that in the Paleolithic age (roughly 2.5 million–10,000 years BC) exercise played a part in social activities and inter-tribe visits. Following successful hunting and gathering excursions, tribes might travel many miles to celebrate with neighbouring tribes and then partake of dancing and cultural games. This Paleolithic pattern of subsistence pursuit and celebration demanded a high level of fitness.
Hunting wild animals allowed the need for food and clothing to blend with recreational sport. We see traces of this today in the activities of some primitive Amazonian tribes who incorporate conversation and singing into their hunting rituals. In the modern era the emphasis has been reversed. Fishing and shooting provide recreation first and food very much second, while in fox-hunting the need to eat the famously inedible spoils of the hunt has been dispensed with altogether.
What should we learn from our ancestors
It would seem logical that trying to replicate such a regime would give us the best physical health for which our evolution designed us. So the hunter-gatherer activity levels may be what we should strive for. More next week…..
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