Answering the Paleo Debunkers, Part 1: Evolution and Hunter-Gatherers

Every diet always has its critics, but lately there’s been a wave of people trying to “debunk” Paleo, most notably Marlene Zuk’s recent book Paleofantasy and Christina Warriner’s TEDx talk. Some of these anti-Paleo arguments are serious and thought-provoking; others are completely ridiculous, or show that the person just doesn’t understand what Paleo actually is. But in any case, they’re getting a lot of press, and they’re only going to get more common as the ancestral health movement gains momentum.

It’s easy to brush off the “debunking” as silly if you’re already feeling the benefits of Paleo for yourself. A book theoretically arguing that we should be adapted to eat wheat just isn’t convincing if you’ve seen your own health turn around after getting rid of it. But just arguing from personal experience isn’t very good science, and it’s also not likely to convince other people when they bring it up in conversation. It’s much better to understand the actual reasons why these objections to Paleo don’t hold water.

With that in mind, this three-part guide presents Paleo rebuttals to some of the most common criticisms. Part 1 tackles the premise of the diet: evolutionary biology and evidence based on modern hunter-gatherers. Part 2 will handle purely nutritional objections, and Part 3 covers everything else.

Humans have kept evolving since the Agricultural Revolution; 10,000 years is plenty of time to adapt to eating grains.

This is a big part of the argument in Paleofantasy. But it’s based on nothing but a strawman: nobody is seriously arguing that evolution ended in the Paleolithic. Of course it’s true that humans have continued to evolve since the advent of agriculture, but that doesn’t mean we’re well-adapted to eating agricultural foods yet.

Paleo Rebuttals:

• Diets based on most types of cereal grains are actually much more recent than 10,000 years ago. Europeans have been eating wheat for closer to 7,000 years, and corn is even newer: it’s been a staple food for around 1,200 years. Some native peoples in the Americas have only eaten a significant number of calories from grains for 1-300 years. So several populations haven’t actually had 10,000 years to get used to grains.
• On a similar note, most of the grains people eat today are much, much newer than 10,000 years old. For example, modern dwarf wheat (which has significant genetic and nutritional differences compared to ancient wheat) was only introduced in the 1960s – that’s not even one generation ago. We’re changing our food faster than we’re evolving ourselves.
• One of the “proofs” that humans are now adapted to eating an agricultural diet is the evolution of more and more copies of a gene that helps us digest starch. But all this really shows is that humans are getting better and better adapted to carbohydrates, not to grains. That’s why Paleo is fine with safe starches, but still discourages grains: there’s much more to grains than starch. For example, there’s a chemical in grains and legumes called phytic acid. It binds to nutrients, especially iron and zinc, and makes them less bioavailable to the body. Rodents and birds produce the enzyme phytase, which breaks down the phytic acid so they can use the minerals, but humans produce it only in very limited amounts, insufficient to break down the phytic acid. So clearly there are some aspects of eating grains that we still haven’t adapted to.
• At the very beginning of the agricultural revolution, people with extremely severe sensitivities to grains may have died out before they could reproduce. So in that sense, we’re adapted to carry on the species on a grain-based diet. But our goal should be to eat the foods that make us optimally healthy, not the ones that merely allow us to survive until reproductive age.

What about lactase persistence? The gene for that has spread rapidly since the advent of agriculture; doesn’t that disprove the Paleo theory that we haven’t adapted to Neolithic foods?

This argument is closely related to the one above. Again, there’s a kernel of truth in the premise. With dairy, a lactase persistence adaptation that arose in one person around 7,500 years ago has since spread to 80 percent of Europeans and 35% of people worldwide.

Paleo Rebuttals:

• The development of one gene to digest one component of one specific Neolithic food doesn’t prove that we’re adapted to digest all of these foods in general. Lactose isn’t the only reason why some people react to milk (casein sensitivity is another one, for example), so lactase persistence doesn’t mean we’re entirely adapted to eating dairy. It’s a sign that we’re evolving to meet the challenges of our new food environment, but not proof that we’re already there.
• Lactase persistence is somewhat of a special case, because it’s an ability that all humans have at birth, and then evolved to keep after infancy. Retaining something we had from birth into later life is not the same thing as developing the ability to digest an entirely new food group from scratch.
• The case of dairy is a perfect example of how Paleo uses evolutionary history as a guide, not as dogma. We can see that the ability to digest lactose in adulthood is evolutionarily new, and that humans as a whole aren’t perfectly adapted to it yet. On the other hand, we can also see that some people have developed an adaptation and tolerate dairy very well. The result is classifying dairy as a “gray area” food that’s up to each individual person to experiment with. It’s not about a fixation on “what cavemen ate;” it’s about using the history of the species as a starting point for further investigation.

Humans evolved from gorillas, so we must be adapted to a vegetarian diet.

This is an argument you’ll get all the time from vegetarians and vegans, especially raw vegans. The theory is that even the Paleolithic is too recent; we need to go even further back into humans’ evolutionary past to find out what we’re really adapted to eat. It’s an interesting idea, but doesn’t hold much water, mostly because it relies on a false dichotomy between herbivores and carnivores, without accounting for the fact that humans are neither: we’re omnivores. We share some similarities with primates because we’re built to digest plants, but we also share some similarities with carnivores because we’re built to digest animals, too.

Paleo Rebuttals:

• Gorillas a rough stomach lining and an enormous colon to digest and ferment all the fiber they eat into fat. Humans don’t. Instead, we have a smooth stomach lining and a large small intestine, a pattern much more typical of carnivores.
• Compared to other primates, humans have a much smaller digestive system in proportion to our body size, indicating that we’re built to eat smaller quantities of more calorie-dense foods, not massive amounts of low-calorie plant matter like gorillas.
• It’s misleading to claim that humans clearly aren’t adapted to eat meat because we don’t have the dental structure or claws of predator animals. We never evolved to need those things, because we’ve always used tools instead.
• Some useful statistics (data from here): For humans, the colon is 17% of total gut volume; for primates, it’s much larger (53% for gorillas, 54% for orangutans, and 52% for chimpanzees). This makes sense, because other primates eat a diet extremely high in fiber, and need to ferment all that fiber into fat in their colons. If humans were designed to eat only raw plant food, we’d have the same anatomical adaptation to it.
• On the other hand, humans have a much larger small intestine (67% of total gut volume) compared to gorillas (14%), orangutans (28%), or chimpanzees (23%). The larger small intestine is an adaptation typical of carnivores.
• For further reading, this article provides an incredibly thorough, detailed, and well-researched look at the claim that humans are “naturally” vegetarians or fruitarians.

Paleo is just evolutionary make-believe – there’s too much we don’t know. Trying to re-enact some mythical “caveman lifestyle” is ridiculous.

This objection is usually raised by people who picture the “Paleo diet” as a cult of unhygienic modern cavemen running around in loincloths and eating raw meat. It’s a good way to make the diet sound unreasonable and weird, but it’s a lazy and dishonest argument, and it’s attacking a strawman. Nobody is trying to re-enact life in the Paleolithic.

Paleo Rebuttals:

• Paleo isn’t about trying to imitate cavemen. That’s silly. It’s about trying to understand biology in light of evolution, and use evolution as a kind of framework and background for making sense of all the facts we know about nutrition and health. Evolutionary biology is a basis for making hypotheses, not some kind of unquestionable truth.
• We’re happy to use modern technology when it contributes positively to our health – refrigeration, for example. We didn’t evolve eating refrigerated food, but there’s no evidence that it’s dangerous and plenty of proof that it actually helps protect us from disease.

Modern meat (or any other modern food) wasn’t available in the Paleolithic, so trying to eat a “Paleo diet” is useless.

Paleo Rebuttals:

• No, modern plants and animals didn’t exist in the Paleolithic – that’s why Paleo is a starting point and not a step-by-step guide. We aren’t trying to literally eat what cavemen ate, we just use evolutionary biology as a starting point for evaluating the foods we do have.
• Even though eating beef and eating Paleolithic animals aren’t the same, nutritionally, there are still significant differences between meat as a food group and grains as a food group. So the fact that we evolved to eat the mammoth gives us a clue that when we consider the food options we have today, the beef is a better choice than the bread.
• Even if we assume that the foods in the Paleolithic would have been better for us than the foods available today (not necessarily true), it doesn’t mean that we should give up and go back to junk food just because we can’t get meat from a free-roaming wooly mammoth. There’s a lot to be said for doing the best we can.

Paleo is based on the naturalistic fallacy/fallacy of antiquity

The naturalistic fallacy is the idea that “anything natural is good because it's natural,” and the fallacy of antiquity is the idea that “anything old is good because it's old.” Obviously, both of these ideas are silly: hemlock is natural and infanticide is an attested ancient practice.  People who think that Paleo is just about imitating cavemen often accuse it of falling into one or both of these traps.

Paleo Rebuttals:

• Taking into account what’s natural or traditional is not the same thing as blindly embracing it. Thinking about what’s evolutionarily “natural” and looking at primitive societies help us form hypotheses to test with scientific research, but every claim about something being “not natural” and therefore not Paleo has to be backed up by actual science for anyone to take it seriously. Peanut oil isn’t unhealthy because it’s “not natural,” it’s unhealthy because it has a high concentration of omega-6 fats, which are usually oxidized by the time the oil gets to your plate, and therefore it’s inflammatory.
• Sometimes, we actually endorse an “unnatural” choice, if it’s better or more effective at supporting health in real life. An example would be supplements. It’s more “natural” to get your Vitamin D from the sun, but that’s not always possible during the winter or for people who live in northern areas. Since Vitamin D is so essential, a supplement is sometimes the healthiest choice even though it’s a modern invention.
• There are also plenty of ancient practices that Paleo dieters don’t follow. Infection by parasites was “natural” before modern medicine, and there’s even evidence that the lack of parasitical infections in the modern world makes us more likely to have allergies, but we still don’t run around ingesting tapeworms for the sake of imitating our ancestors.
• Further reading: How Not to Sound like a Crazy Hippy: Avoiding the Naturalistic Fallacy.

Cavemen all died when they were 25 – why would you want to eat like that?

This is one of the simplest arguments to refute, because it’s usually based on nothing but misunderstanding or hearsay evidence. In fact, there’s a long article on the site about this, completely deconstructing the idea that “all cavemen died young.”

Paleo Rebuttals:

• That statistic includes the infant mortality rate (babies who died very young). This was much more common back then, because of the lack of medical care. If you take out infant mortality, people eating a traditional diet often live into their 70s.
• Cavemen were also extremely susceptible to any kind of parasite, infected wound, or infectious disease, because they had no antibiotics. Now we have the antibiotics to treat those diseases, so we live longer, but that doesn’t say anything about our diet compared to theirs.
• Think about it logically. Most hunter-gatherer women have their first baby at around age 19. If cavewomen all died at age 25, all their babies would die without them, and the species would go extinct pretty fast.
• One study found that, for hunter-gatherers who lived past 15, the most common age of death was 72.

Didn’t they find grains in Ötzi’s stomach?

Ötzi is a skeleton found frozen in the Alps in 1991; he’s often described as a “caveman” or an “iceman,” so people assume he’s somehow “Paleo.”  Researchers who analyzed the contents of his stomach found that his last meals had included both Einkorn wheat and meat.

Paleo Rebuttals:

• Ötzi died approximately 5,000 years ago, well after the advent of agriculture, so it doesn’t prove anything about Paleolithic diets.
• Interestingly, as well as the wound that killed him, Ötzi also had a long list of other health problems, including terrible teeth, gallstones, Lyme Disease and arteriosclerosis (plaque in the arteries). Of course, one example doesn’t prove anything, but it’s interesting evidence that agricultural diets might not be the healthiest way of eating.
• Further reading: Stephan Guyenet has a fantastic series all about Ötzi; parts one, two, and three.

Real Paleolithic and/or modern hunter-gatherer diets had/have a lot of variety. It’s silly to eat steak and bacon every day and call it the same thing.

This is an easy objection to answer, because you’re really agreeing with the person – it’s more about broadening their idea of Paleo than refuting some kind of flawed logic or incorrect information.

Paleo Rebuttals:

• Actually, Paleo recognizes and embraces this variety. One of the lessons of human evolution is that humans are resourceful omnivores who can thrive on many different diets. There is no one way to do Paleo, just like there was no one “diet” in the Paleolithic or at any other time period. Some people eat more starch; others eat less. Some people eat almost exclusively fish and vegetables; others focus on red meat. This is actually a benefit to the community as a whole; it helps us learn from each other and discover new things.
• Traditional diets weren’t entirely based on meat, but n defense of the insistence on at least some animal food, one study found that 73% of hunter-gatherers got more than half of their subsistence from animal foods, while only 13.5% got more than half from plant foods. Overall, no groups were strict vegans, but 20% were entirely or almost entirely dependent on animal foods. So, there’s a lot of variety in the amount and type of animal products eaten, but eating at least some animal food seems to be part of the human tradition.
• The emphasis on eating a lot of steak and bacon at every meal is just a stereotype. It gets repeated in the media because that’s what most people are familiar with as “meat.” Actual Paleo recipes put a lot of emphasis on organ meats, seafood, fermented foods, and vegetables; we eat every part of the animal, just like people used to do before the modern food industry, because the organs and non-luxury cuts have unique nutritional benefits. It’s definitely not all bacon, all the time.

Didn’t they find evidence of atherosclerosis in Paleo people/hunter-gatherers/Ötzi?

This is usually a question about the Horus study, which showed evidence of atherosclerosis in mummies from around the world, including one hunter-gatherer group. It might also refer to the Maasai, traditional pastoralists in Africa who live on cow’s milk, meat, and blood. A recent autopsy of several Maasai men revealed that many of them had atherosclerosis. Alternately, people might cite the iceman Ötzi (a skeleton discovered in the Alps, and dated to approximately 5,000 years ago). Ötzi had serious arteriosclerosis.

Paleo Rebuttals

• None of these people are technically “Paleo,” since all of them lived after the advent of agriculture. Ötzi’s diet was probably very grain-heavy, and many of the mummies in the Horus Study (especially the Egyptians) also ate grain-based diets. So the only groups that even approximate a Paleo diet were the Maasai and one of the groups in the Horus Study.
• The Horus Study used such a small sample size from the hunter-gatherer group (5 people) that it’s hard to base a coherent argument on it.
• There is evidence of atherosclerosis in people of all ages from every civilization around the world, eating all kinds of diets, and as far back in time as we have technology to measure it. This suggests that atherosclerotic plaque may be an inescapable part of human aging. So in other words, the presence of atherosclerosis isn’t necessarily a sign that someone is eating an unhealthy diet.
• What’s really interesting here is that although atherosclerosis seems to be universal, heart attacks (the presumed consequence of atherosclerosis and the main reason why plaque is considered dangerous) are not. The most famous example of this is the island of Kitava. So what we really need to find out is, if everyone has plaque, why do some populations suffer from heart attacks and others don’t?  The research is still ongoing, but it seems that the real culprit may be infection and inflammation, which causes the plaque to rupture and cause cardiac events, not the plaque itself.

Diet is not the only difference between hunter-gatherers/people in the Paleolithic and us.

This is also true – again, the “rebuttal” here is more about changing people’s misconceptions about Paleo than about refuting their actual point.

Paleo Rebuttals:

• That’s why the Paleo community is also big on things like getting enough sleep, managing your stress, and gaining strength through exercise. These things are also part of our evolutionary health environment – Paleo is an integrated lifestyle approach to regaining health, not just a diet.
• So why does the diet part get all the attention? The food recommendations get a lot of press because they’re different and it’s easy to make them sound extreme, so they get a lot of attention. “New lifestyle approach recommends 8 hours of sleep and moderate exercise” isn’t a great headline.

Conclusion

Hopefully, this guide can help put to rest some of the common myths about Paleo and evolution, and how we use evidence from modern hunter-gatherer societies. There are some good points on the anti-Paleo side, but they're mostly based on a misunderstanding of what Paleo actually is - if you look at the truth and not the stereotypes, these arguments often end up supporting Paleo!

Still to come in this series are Part 2 (nutritional arguments) and Part 3 (all the other miscellaneous ways that people try to "debunk" Paleo) - if you have any particular objections that you'd like to see addressed, let us know on Google+!