The Paleo diet (primal/evolutionary) has become very popular in the last few years. Followers believe they are eating the way our stone age, or paleolithic, ancestors ate. Since our genes have not had time to evolve to match the drastic change in diet that occurred with the agricultural revolution, they argue, modern diets are making us sick and contributing to most of our chronic Western disease like atherosclerosis, diabetes and dementia.
True experts in evolutionary science have questioned most of the theoretical underpinnings of the Paleo movement. Marlene Zuk, an evolutionary biologist, has written an excellent critique in her recently published book “Paleofantasies: What Evolution Really Tells Us About Sex, Diet and How We Live.”
Dr. Zuk points out that there likely was no one single hunter-gatherer diet and that we have a very limited understanding of exactly what that diet consisted of. She also makes the point that this concept that at some point in the past, humans were perfectly adapted to their environment, is not true.
The Milk Paleofantasy
Although the Paleo movement is not monolithic on the topic, some of its leading figures are vehemently opposed to milk consumption.
For example, Loren Cordain (whose web site states that he is “widely acknowledged as one of the world’s leading experts on the natural human diet of our Stone Age ancestors”), has nothing but bad things to say about dairy and milk consumption. Cordain has a Ph.D in “health” and is quite a prolific author, having written “The Paleo Cure For Acne” (spoiler alert: the cure involves not drinking milk).
One major problem with the paleo concept of diet is the assumption that our genetic makeup has not changed or evolved over the last 10000 years.
It turns out that we are not stuck with the same genome of our caveman ancestors and that our ability to tolerate milk confirms this.
The Evolution of Lactose Tolerance
The main sugar in milk from all mammals is lactose. The ability to digest lactose depends on having the enzyme lactase present in the lining of the intestinal tract. All mammals at birth have lactase, but as they age, lactase production is reduced by around 90%. This loss of lactase leads to lactose intolerance.
Lactose that is not digested ends up being fermented by bacteria in the large intestines. This fermentation produces methane, hydrogen gases and other by-products, resulting in bloating, abdominal pain, and diarrhea.
Around 10-20,000 years ago, a mutation in the gene that controls production of lactase resulted in lactase persistence. Some of our paleolithic ancestors began noticing that they were lactose tolerant and could drink the milk of cattle that they had domesticated.
As Zuk writes:
Beginning about 7000 years ago, DNA studies of ancient bones reveal that there was a progressive increase in the frequency of lactase persistence. Increase in a genes frequency tends to correspond with a survival advantage suggesting that the ability to consume dairy prolonged lives.
Lactase persistence is present only in about 35% of the world’s population. It is common in Scandinavia and parts of Africa and the Middle East and about 90% of Americans have it.
The rapid increase in the dominant gene for lactase persistence in humans suggests that the Paleo concept of a genome stuck in the stone age is incorrect.
Stumbling onto a heart-healthy diet using Paleofantasies
Despite the lack of scientific support for the basic theories underpinning the movement, I do think the Paleo diet has some good points. For the most part, this is going to be a low-carb diet. Other areas I can agree with them on are:
-Avoid processed foods, added sugar, refined starches
-Eat lots of minimally processed vegetables
-Grass-fed beef is fine
-Wild game consumption is great (but wild game is hard to find)
But ultimately, the Paleos, as students of evolutionary biology, should be embracing the evolutionary changes humans underwent that allowed the consumption of dairy as adults.