Lately I’ve been reading snippets of a new way of eating which seems to be the next big thing. The Paleo Diet states that we should eat the types of foods our hunter-gatherer ancestors survived on for millions of years. It also suggests that many modern illnesses (e.g. diabetes, cancers, cardiovascular disease, but even acne, depression and myopia!) are symptomatic of our bodies’ inability to cope with the modern diet of dairy, high carbs, alcohol and processed foods.
The Paleo Diet allows meats (including game and seafood), low carb vegetables, oils, nuts and fruit. It cuts out dairy, grains, fruit juices, starchy vegetables, legumes (includes soy products), alcohol and all processed foods (goodbye tomato sauce, chips and candy).
On the surface, the hype seems to make sense. The main argument hinges on the fact that agriculture is a reasonably late arrival to the evolutionary timeline; humans have only cultivated the land for the last 10,000 years. A blip in the human evolutionary timeline when you consider that the earliest hominids, Australopithecus roamed the earth nearly 4 million years ago.
I wanted to get some hard science to cut through all these hype. Paleofantasy by Marlene Zuk, a Professor of Ecology, Evolution and Behavior at the University of Minnesota, uses science to debunk the myth that our ideal modern lifestyle should mimic Pleistocene human adaptation. Prof Zuk also looks at the misunderstandings around social interactions, medical and daily activity, but I was predominantly interested in how our diet has evolved.
2,000 years, or even 10,000 years is too short for human to evolve to adapt to modern foods
Evolution is happening all the time, we are still evolving, all fauna and flora are still adapting to their environment. New phenotypes can occur in a mere 50 generations given the appropriate selection pressures.
We can recreate the diet of our ancestors
Fruits and vegetables in the Pleistocene era were totally different. Modern varieties have only been developed since the cultivation began in earnest and plant breeding became commonplace, at most 10,000 years ago. And what you see in the shops are likely even less than 50 years old. For example, Modern apples (Malus domestica) are bred from several different species, and would taste completely different, and have a different nutrient and phytochemical profile to its earliest wild ancestor (Malus sieversii). Plant breeders have bred larger and better tasting produce (higher sugar content, lower fibre) which have less phytochemicals (such as toxic compounds to deter grazing and beneficial but bitter phenolics).
Dairy consumption is unnatural, as human adults cannot produce lactase, the enzyme which breaks down lactose, or milk sugar.Reality:
Although lactase production ceases in many people after childhood, causing lactose to be broken down instead by colonic bacteria resulting in hydrogen and methane and causing a slew of unpleasant effects, many populations have evolved the genetic mutations (yes, different mutations) allowing lactase to be produced well into adulthood, and some populations (e.g. Somali) have evolved gut flora that break down lactose with no ill effects.
Grains are to be excluded from our diet as we have not evolved to break down high amounts of starch.
Recently, archaeologists found evidence of ‘bread’-making in 30,000 year old archaeology sites, and there are evidence of a reasonable level of starch the diets of even earlier hominids. High grain-eating populations have also evolved to have multiple copies of the gene which encodes amylase, the enzyme which breaks down starch,Whilst the premiss of the Paleo-diet have some great pillars of eating more fruits and vegetables, cutting out processed foods and alcohol, we have evolved to live quite successfully on our modern diet.
One of the issues that proponents of the Paleo-diet don’t seem to discuss is that our ancestors lived very short lives, most never lived past their 40’s.So, we really can’t go back but reading Paleofantasy has challenged how I think about evolution. I wonder what the pressures of modern diets and lifestyles will select for next….