Originally published in the Bulletin of Primitive Technology on October 1, 2010.
Today we have a radically different lifestyle than that of Stone Age hunter-gatherers but genetically we are still very similar. According to the new field of evolutionary medicine, this mismatch between our modern way of life and our Stone Age genes is the cause of many health related problems. To find solutions, it is crucial to understand our ancestors’ lifestyle in detail, despite the fact that this knowledge is difficult to obtain.
Anatomically modern humans have been around for about 200,000 years and 95% of that time they were hunter-gatherers. Everything changed with the agricultural revolution about ten thousand years ago. Our lifestyle changed from foraging to farming, machines and supermarkets. Although this process took a few thousand years, it has been extremely fast in evolutionary terms and, as it turns out, too fast for our genes to keep up. Studies indicate that genetically we are still very similar to our hunter-gatherer forebears. We have become, as American physician and researcher S. Boyd Eaton put it, ‘Stone Agers in the fast lane’.
Eaton and his colleagues are at the forefront of a new perspective in medical science called evolutionary medicine. They argue that the current mismatch between our Stone age genes and the modern environment is causing an abundance of medical problems. For instance, our modern diet consisting of grains, domesticated livestock, dairy products and refined sugars combined with much less physical exertion than our Stone Age ancestors, is associated with overweight, diabetes and heart disease. Also, higher population densities, settled living and interactions with domesticated animals initially strongly increased infectious diseases. Furthermore, our modern reproduction pattern (earlier menarche, later first birth, lower parity, shorter nursing) is associated with an increased risk for breast, endometrium and ovary cancer. In fact, studies comparing contemporary hunter-gatherers to similar-aged Western populations have shown that the former, suffer significantly less from chronic degenerative diseases.
Our modern lifestyle could also be causing psychological harm. Chronic high workload, bureaucracy, economic inequality and overpopulation may all contribute to chronic stress. Chronic elevated stress hormones in turn are associated with heart disease, diabetes, reproductive defects, neural damage and depression. Some researchers also speculate that modern phenomena like current childrearing practices (e.g. reduced nursing and reduced physical contact between infants and adults), frequent contact with strangers, reduced support from kin and socially isolated elderly may contribute to syndromes such as attention deficit/hyperactivity, depression, anxiety disorders and substance abuse.
Considering these modern problems from an evolutionary perspective provides us with fundamental explanations but relies heavily on an accurate picture of the Stone Age hunter-gatherer lifestyle. Popular opinion on the ancestral way of life seems to come in two flavours. Some believe it must have been ‘brutish, nasty and short’, as 17th century philosopher Thomas Hobbes put it, imagining people with little food, constant threats from wild animals and the absence of virtually all comforts. Others like to romanticize the Stone Age lifestyle, like 18th century philosopher Jean-Jacques Rousseau, thinking of our ancestors as ‘noble savages’ living in peaceful harmony with nature and each other.
Getting evidence on the matter turns out quite difficult. The archaeological record is sparse when it comes to the Stone Age and many aspects of our ancestors’ life such as language, social system and cooperation strategies are extremely difficult to infer from the few artifacts that have been found. A more fruitful approach probably is the study of contemporary hunter-gatherer tribes. In the last century, a number of anthropologists did field work among the Kalahari San, the Arctic Inuit, Australian Aborigines and others. This type of research too is not without its challenges. By the time most studies were done, most tribes already possessed some knowledge of ‘modern civilization’ and weren’t true Stone Age equivalents anymore. Furthermore, researchers always run the risk of unintentionally influencing these groups while studying them, and complete ‘immersion’ was seldom realised because of to many differences in language, foraging skills, family ties, etc.
Besides the research challenges, you might wonder if a uniform hunter-gatherer lifestyle actually existed in the first place. Wouldn’t lifestyle greatly vary between people on different latitudes and in different time periods of the hunter-gatherer era? Studies of contemporary tribes suggest that indeed there must have been significant variation in how things were done (e.g. finding food in Africa is different from the Arctic). However, Eaton and his colleagues argue that the similarities between hunting and gathering peoples easily outweigh the differences when we compare this lifestyle to fundamental different ones like in agricultural and industrial societies.
Despite the obstacles in obtaining data, when combining all evidence to date, a high level picture of our Stone Age ancestors is emerging of which we can be fairly certain. They were most likely people that…
- lived in small nomadic bands of twenty to fifty people, mostly related by kinship
- gathered wild plants and hunted wild animals for food and materials
- moved around at least a couple of times a year depending on local resources
- were confined to themselves most of the time but did meet with other bands and exchanged information, gifts and women
- had a division of labor where men did most of the hunting and women, children, and the elderly did much of the gathering
- had bands that were egalitarian in nature although some differences in status did exist
- shared foods and in general had a common property regime
- had an intimate knowledge of animal behavior, plants, and the climate
Getting right the details of this lifestyle is extremely valuable. It is not only fascinating for primitive technology enthusiasts but it likely also holds the key to many problems that plague our bodies and minds today. Furthermore, experimental archaeology, Stone Age reenactment and similar activities could greatly contribute in obtaining new insights into this matter.
References
Eaton, S. B., Strassman, B. I., Nesse, R. M., Neel, J. V., Ewald, P. W., Williams, G. C., Weder, A. B., Eaton III, S. B., Lindeberg, S., Konner, M. J., Mysterud, I., & Cordain, L. (2002). Review. Evolutionary Health Promotion. Preventive Medicine, 34, 109-118.
Eaton, S. B., Cordain, L., & Lindeberg, S. (2002). Evolutionary Health Promotion: A Consideration of Common Counterarguments. Preventive Medicine, 34, 119-123.
Lee, R. B., & Daly, R (2000). Introduction: foragers and others. In: The Cambridge Encyclopaedia of Hunters and Gatherers (p. 1-18), edited by Lee, R. B., and Daly, R. Cambridge: Cambridge University Press.
Sapolsky, R. M. (1998). Why Zebras Don’t Get Ulcers. An Updated Guide to Stress, Stress-Related Diseases, and Coping. W.H. Freeman and Company, New York.
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Rousseau didn’t think that the noble savage lived in harmony with his peers – his “thought experiment” pictures savage man as generally isolated and individualistic, only interacting on rare occasions for purposes such as mating. Perhaps interesting given his own failures as a father! He regarded the small autonomous city state with a system of direct democracy as the most favourable and harmonious arrangement.
An interesting take on the hunter gatherer hypothesis comes from Wade Davis, who argues that he always found the New Guinea tribes he spent so much time with to be generally more quick-witted and healthy than contemporary city-dwellers. He speculates that this may be the result of the different selective pressures brought to bear: the New Guinea highlander is more likely to be murdered or killed in a hunting accident and must therefore be a quick-witted strategist, as well as possessing deep knowledge of his environment and lively curiosity. By contrast, humans in advanced societies are more likely to have survived due to resistance to diseases acquired from cattle and high – density settlement – something that has a more distant (if any) relation to one’s intelligence and strength. An interesting hypothesis, but, like all these speculations, it’s difficult to see how you could hope to get beyond the “just so” story.