A few days back, as I was doing a couple of searches on PubMed in an attempt to find something interesting & worthwhile to read, I stumbled upon an article with the title Traditional diet and food preferences of Australian Aboriginal hunter-gatherers. It immediately caught my attention; not just because of its interesting title, but also because it’s written by Kerin O’Dea, the Australian professor who carried out the seminal study on the health impact of evolution-based lifestyle reversion in 1984. I suspect that I’ve come across the article, which has stayed largely out of the limelight, in the past; however, I didn’t get around to reading it until now.
Part of the reason why the paper hasn’t received much attention on the internet is undoubtedly that it was published all the way back in 1991; hence, it’s certainly not a fresh piece of writing. That doesn’t necessarily mean that it’s not good or relevant though. Actually, I would say it’s extremely relevant to what goes on in the world of health and medicine today, in the sense that it highlights the core reasons why a great number of people are now overweight or obese, and why we’re spending billions of dollars every year on health care.
In this post, I’m not going to write a lengthy piece about the health and customs of Australian Aborigines (If that’s something you’re interested in reading, then I suggest you check out Kerin O’Dea’s article); rather, I thought I’d briefly talk about how the health situation in Australia has changed recently, as well as highlight certain parts of the article that I feel are particularly important in the context of Darwinian medicine.
Australian Aborigines used to be lean and healthy
Australia is no different from other westernized nations in that it’s weighed down by the diseases of civilization, which include a variety of disorders, ranging from heart disease to colon cancer to acne vulgaris. Even many “disorders of the mind”, such as autism, ADHD, and depression, appear to largely be modern problems, as opposed to ones that humanity has struggled with for a long time.
In some respects, Australia is even more burdened than other nations. Obesity and diabetes rates have increased markedly over the most recent decades, and have now reached alarming heights. According to a recent report, almost one-third of adults in Australia are now overweight or obese (1). The problem starts early. On the basis of the BMI model, about 20% of children in the age group between 2 and 4 years carry excess adipose tissue (1). That’s a strikingly high number for kids of such a young age. Notably, indigenous Australians are even worse off than their non-indigenous neighbors (1).
Things haven’t always been like this. As we’ll see later, as we get to O’Dea’s paper, prior to the time when modern technology, bread, and fast food entered the Australian landscape, people were slim and unaffected by chronic ills such as type-2 diabetes. Following Homo sapiens’ exodus out of Africa, some migrators eventually reached the shores of Australia, effectively becoming the first Australian Aborigines. These people were already adapted to a hunter-gatherer way of life; however, they weren’t specifically designed for the Australian milieu; hence, natural selection would undoubtedly have had a bit of work to do, and would, over time, have slightly reordered the aboriginal physiology.
Australian Aboriginal hunter-gatherers certainly didn’t live in a utopia; however, their physical condition appears to have been pretty good. That’s not surprising in light of what we know about how evolution works. In nature, it’s generally better to be lean, physically robust, and healthy, in the context of Darwinian fitness, than fat, frail, and sick; hence, it’s not surprising that pictures and reports produced by explorers and researchers indicate that Australian Aboriginal foragers were vigorous and lean. This is consistent with the massive body of evidence linking the hunter-gatherer way of life with good physiological functioning.
The original state and way of life of Australian Aborigines
What makes O’Dea’s paper from 1991 unique is its detailed description of the diet and lifestyle of Australian Aboriginal hunter-gatherers. I already had a basic understanding of what things were like in Australia prior to when industrialization processes began; however, I found the paper both captivating and informative nonetheless. The following paragraphs and statements stood out to me as being particularly important with respects to the core themes of Darwinian medicine…
First off, here’s a quote and a table from an early section of the article in which O’Dea talks about the health status of Australian Aboriginal hunter-gatherers:
Although there is little reliable, quantitative data on diseases in Aborigines with little or no European contact, numerous early reports described them as heaving been lean and apparently physically fit (see Table 1). Undoubtedly, the nomadic lifestyle and its associated customs promoted survival of the fittest. In the most remote areas of Australia, small groups of Aborigines continued to live a nomadic lifestyle until 20-30 years ago, and data collected from such groups suggest they were very lean and had no evidence of chronic diseases that occur in epidemic proportions in westernized Aboriginal communities today. (2)
As a rule, there was one main mean in the day, in the late afternoon when people returned to camp after the day’s activities. However, people would eat snacks throughout the day while hunting and gathering: grubs, fruits, gum, honey ants and sugar-bag (honey from the wild bees). Hunters would sometimes cook and eat the liver of a kangaroo before carrying the carcass back to camp. Shellfish and fish were also often cooked and eaten on the spot or, in some circumstances, eaten raw. (2)
Towards the end of the article, O’Dea also brings up the results of the study I mentioned in the introduction to this post…
Although most Aborigines in Australia today live a sedentary, westernized lifestyle, many older individuals in remote communities retain the knowledge and ability to survive as hunter-gatherers. Collaboration with such people has allowed us to document the impact on health of a ‘reverse lifestyle-change’, a temporary reversion of westernized Aborigines (with all the associated contemporary health problems) to traditional hunter-gatherer lifestyle. The dramatic impact of lifestyle change on health is well illustrated by the observation that when overweight diabetic Aborigines made this temporary lifestyle transition for the brief period of seven weeks there was significant weight loss, and striking improvements in all of the abnormalities of diabetes together with a reduction in the major risk factors for coronary heart disease. (2)
Finally, before wrapping up, O’Dea makes the following noteworthy statements:
These observations have implications not only for the prevention of obesity, diabetes and cardiovascular disease for Aborigines, but can also be applied more broadly. It has been argued that the hunter-gatherer, or Paleolithic, diet and lifestyle is the one to which we, as modern humans, are genetically programmed, as the human genetic constitution has changed little in the past 40000 years since the appearance of modern man. Thus it is to this diet and lifestyle that we should turn when seeking explanations for (and solutions to) the characteristic pattern of chronic diseases that emerges in all populations when they become more ‘affluent ‘ economically and adopt a sedentary, westernized way of life. (2)
In the 21st century, we’re faced with a multitude of medical predicaments, many of which revolve around the terrorizing impact of the diseases of civilization. By applying Darwinian logic to the investigations into these issues, we can make some significant headway towards elucidating why and how we got into the trouble we’re in, as well as what’s required of us if we are to resolve the problems.
The Australian way of life has recently deviated substantially from that of the original Aborigines. The “Aboriginal biology” was originally selected for a natural environment that demanded a great deal of physical activity and in which energy-dense, fatty and sugary foods were hard to come by. This genotype is mismatched to the modern Australian milieu, which demands little to no physical activity and is filled with processed, calorie-dense foods. By emulating certain critical aspects of their original lifestyle, contemporary Aborigines can potentially regain their health and vitality.