The Secret Diet That Works for Every Living Organism
Though our cognitive abilities and potential for abstract thought set us apart from other animals, we shouldn’t be tricked into thinking that we are different in respect to how our genetics express themselves in with our environment. We are still animals, designed to thrive in our natural environment.
A species-specific diet
Evolution was first proposed by Charles Darwin with the theory of natural selection and is one of the most powerful scientific concepts we know today. Evolution is to biology what the theory of relativity is to physics. The hypothesis that subtle and persistent pressure of survival selects for the adaptations that allow an organism to thrive within its specific environmental niche, applies to all life from bacteria to plants to insects to mammals including human beings [1].
We know from animals in captivity that if we change a species’ environment and diet from what would be found in nature, the animal will fail to thrive, develop disease, and is more likely to suffer a premature death. To give an extreme example, an obligate carnivore like a tiger is not going to survive on a diet of lettuce in the same way a herbivorous gorilla won’t last being fed meat. Though this seems obvious, all non-evolutionary appropriate diets for any organism lies somewhere between these two extremes [2].
How is this relevant to humans?
Though our cognitive abilities and potential for abstract thought set us apart from other animals, we shouldn’t be tricked into thinking that we are different in respect to how our genetics express themselves in with our environment. We are still animals, designed to thrive in our natural environment.
Weston A. Price was a Canadian dentist practicing early in the 1900s. He traveled the world spending time with people living pre and post modernised lifestyles. He found, not only did pre-modern individuals have extremely low levels of cavities compared to modernised individuals, but they also had much lower rates of chronic disease [3].
Because our pre-industrial ancestors had no access to modern dental treatment and losing teeth at a young age would have been a death sentence, Price theorised there must be something about our modern lifestyles that contributed to tooth decay, which was not experienced by our ancestors.
Since the observations of Weston A. Price numerous studies have been done on the shrinking number of pre-industrial populations to monitor disease, prevalence of finding similar outcomes is also shrinking [4,5,6].
Don’t pre-industrial people die young though?
This is a common misconception. It’s commonly quoted that our ancestors, hunter-gatherers or other peoples without the benefit of modern health care have an average life expectancy of 30-45.
There is some truth to this as 30-45 is the average life expectancy we see in hunter-gatherers today. However, this has to be taken into the context of huge child mortality, with up to almost 50%of children not seeing their 15th birthday with most of these not seeing their 5th. Those that survived to 15 were very likely to live past 70 and die free of chronic disease [7].
Evolutionary evidence of longevity is menopause.
Nothing evolves by accident and as we are only one of two species of the planet where the female goes through menopause (the other species are Killer Whales), there should bean evolutionary explanation as to why this would happen later in life.
The grandmother hypothesis poses that older women who are more likely to have birth complications, add value to their family through wisdom that they have acquired during life, child care and support their already created genetic line whilst being protected from the risks of later life pregnancy [8].
So what do pre-industrial people eat?
Definitely not biscuits, pizza and donuts.
Aside from this obvious point, the answer is a lot of different things depending upon the environment but also with some commonalities.
People living closer to the equator have more access to year-round edible plants in the form of fruits or vegetables. A well-studied example is the Kitavans of Papua New Guinea. The Kitavans eat a very high carbohydrate diet comprised primarily of root vegetables supplemented with coconuts and fish, and they suffer low rates of chronic disease common in western countries [9].
People living further away from the equator don’t have access to year-round plants tend to have diets based largely on animals. The Sami of Finland (some of whom still live ancestral lives) herd reindeer and live primarily on their meat and organs, supplemented occasionally with plants that are seasonally available.The Sami who continue to live the traditional lifestyle suffer low rates of chronic disease but this is now a growing problem as more Sami start to consume a more industrialised diet [10].
There are no examples of traditional cultures eating no animal products and no plants. In fact, the trend tends to be where one food type is abundant; the opposite tends to be more prised. There are also several anatomical adaptations confirming human beings as omnivores which covered in a separate blog.
Whether more plant or more animal, all pre-industrial diets are comprised of whole foods. Refined foods like flour, sugar and seed oils that are abundant in western diets today didn’t exist without the industry to create them.
So should we live like pre-industrial people?
In short – no.
No one alive today would be supportive of a 50% child mortality rate, or a 10% homicide rate, an infected wound would likely result in death, a broken limb and you’re probably toast, a famine and your families finished, or a snake bite with no antidote [11,12,13].
However, we live in a wonderful time where we can have all the benefits of modern healthcare and industry and still choose to observe what environment we were likely to have evolved in and mimic our ancestor’s nutrition to achieve our optimal health.
What about evidenced-based nutrition?
Nutrition science has come a long way since the days of Weston A. Price and we now have some good scientific data to support or detract from the observed hypothesis.
This is great. However, though the scientific process is perfect, the human beings who carry it out and are still prone to bias, fallibilities, and prejudice.
This statement is not meant to take away from the evidence we have, but to acknowledge the fact that all evidence is limited – this particularly applies to nutrition. Not using evolution to contextualise the nutritional data would be like rocket science without the theory of relativity.