Eating like our great ape relatives

Lately, I’ve had some interesting conversations with my friend Cathy, who is an artist and designer, about a whole raft of topics in medicine and science. She proclaims she has no scientific background, but she’s intensely curious about science and about what I write, so what else could a blogger want? Recently, we were discussing what constituted a good diet. I was trying to cut through what was myth and what was science, but sometimes it can be difficult to do so. My thoughts have always been that the human physiology is amazingly resilient, and as long as you have no chronic diseases, there is nothing one can do that will make the situation much better or much worse. Yes, maintaining levels of certain nutrients, such as vitamins C and D, iron, and others, are critical, but in the modern world, it’s almost impossible to miss out on those micronutrients.

And as I’ve mentioned, you’re not going to prevent or cure cancer with supplements (or presumably foods that have those nutrients). Nor will antioxidants. Nor will other foods make you lose weight. 

A lot has been written about the diets of our ancestors, some of which are used to support whatever diet myth is trending at the time. Some vegans will claim that humans evolved to be vegetarians, but according to modern scientific research

…since the evolutionary split between hominins and pongids approximately 7 million years ago, the available evidence shows that all species of hominins ate an omnivorous diet composed of minimally processed, wild-plant, and animal foods.

Some vegans will make a claim that humans “evolved” to be more vegetarian over the past few thousand years as we moved to an agrarian based culture, but that ignores the fact that evolution does not work that quickly on a species that has such a long lifespan and such a low population. There just is no scientific evidence that we evolved to be an exclusively vegetarian species.

On the other hand, there is a current fad for the paleolithic diet, which is based on the presumed ancient human diet of wild plants and animals that various hominid species habitually consumed during the Paleolithic era. It consists mainly of fish, grass-fed pasture raised meats, vegetables, fruit, fungi, roots, and nuts, and excludes grains, legumesdairy products, salt, refined sugar, and processed oils. It really attempts to be scientific (much more so than vegans), but it seems to border on the edge of pseudoscience, and can be considered a fad. The diet itself probably has no more validity than any other diet (lots of anecdotal evidence of success, and no actual scientific clinical studies). The problem is that there is little evidence that paleolithic humans actually followed this diet (pdf), and their diet probably was in response to a huge  seasonal, annual and longer duration environmental variability in food sources. But more than anything, is there any evidence that paleolithic humans lived longer or healthier than modern humans? Well, actually the Paleolithic lifespan was around 33 years, whereas modern man is around 67 years (varying from country to country). In other words, despite what many consider to be a terrible modern diet, we’re living longer (which is a result of a lot of things including hygiene, sanitation, medicines, vaccinations, and probably, better nutrition). 

Coincidentally, Rob Dunn recently wrote an article in Scientific American about how chimpanzees eat in the wild. As a bit of background, chimps and bonobos (subtribe Panina), diverged from the line that lead to humans about 5-6 million years ago, and also shares about 97% of genetic material with humans. So they can be used as a proxy to human dietary preferences in the wild, though with a few million years of intervening evolution. But they can be a “crude measure” of our ancient diets, and can tell us an interesting story about what our modern diet should be.

study by David Watts of the chimpanzee diet in the Kibale National Park in Uganda provided some detailed analysis of their diet in the wild:

  1. Diversity—The Kibale chimpanzees  consumed around 102 species (and possibly many more) of plants either in the form of fruit or leaves. I don’t mean to be picky, but how many species of plants are in your local Whole Foods? And 20 different varieties of apples is still one species of apple. Human ancestors, in a planet with limited food resources, probably were just as fungible with their choices in plant foods as chimps. Modern humans just aren’t.
  2. Figs—Nearly half of all of the food consumed by chimps appears to be one or another kind of fig, fruit of the Ficus trees. Fig trees produce large amounts of fruit that are favored by a number of animals including most primates (including gorillas and many human cultures) and fruit bats. They are highly nutritious and contain a lot of energy, and have a wide number of ecological niches so that it would be distributed throughout the chimpanzee habitat. Early humans would have also found figs throughout their habitats in Africa, and figs were domesticated about 10,000 years ago, and have been a significant part of human agriculture in certain societies. It’s clear that along with increasing the number of plant varieties in our diet, we need to seriously increase the quantities of figs.
  3. Clumps—Chimps eat a wide variety of fruit throughout the year, but only eat one or two species of fruit at one time. So they might eat apples one day then oranges the next. So, they may eat what is “in season” or what is available. Many plants fruit seasonally, or even just for a few days, so the chimps eat what is available. There are a few continually fruiting plants, but they are rare, even in the tropics, so the chimps choose what is available.
  4. Meat–Although we focused on fruits and plant foods, chimps do eat meat, and are considered omnivores, just like their closely related cousins, humans. Chimps favor eating seven kinds of primates, including their favorite, red colobus monkeys along with three other mammal species. However, only 3% of the average chimp diet comes from meat. Given the availability of high energy plant foods, the energy expenditure required to acquire mammalian food probably is too high unless it’s easily obtained.
  5. Variety—One of the myths of our ancestral diets is that our ancestors ate some imagined ideal diet for their bodies. The observation of the chimp diet is that there isn’t an ideal diet, and they eat what they find. Even though figs are a significant portion of their diet, when they find no figs, they don’t eat figs, and change to something else. Some chimps eat more mammal meat than others, if that meat is available, not because of some evolutionary advantage to do so. The authors determined that although some species must eat a specific mix of foods to survive; chimps (and man) are not one of those species.
  6. Termites and ants (and their chitin)—Some chimps are good at eating termites, honey bees and driver ants. It’s unclear if chimps have any special ability to digest the chitin (exoskeleton of insects), but insects do have a lot of energy content. Again, chimps seem to have a broad choice in foods, and eat almost anything that is available. 
  7. Other–Chimps at Kibale ate dirt. Gorillas eat wood and the occasional stone. What we might assume is not food seems to be food for the apes of the Kibale National Park. So, if you want to have an ancestral diet, apparently you have to open your mind to food sources that aren’t just plants and animals.

Before we head to the conclusions from this article, one thing is important. Figs. Really, we almost have to wonder if primates would not have evolved without figs. That fruit is a critically important part of the chimpanzee diet, and, given the ubiquity of the plant, we must presume that it was critical to early Hominims that evolved into modern humans. Maybe we shouldn’t be growing corn and wheat across the world, but fig trees. In fact, many human societies domesticated ficus for a fruit crop. Maybe I have to revise what I told Cathy, and tell her, “go to Whole Foods, and buy as many figs as you can eat, and eat them until you’re full.” I like figs. Maybe I’ll have to write the “Whole Fig Diet”.

But seriously, back to ancestral diets. Here’s what Dunn says about that:

And that eating some ancestral diet on its own will not make us healthy. Our ancestors did not eat diets perfectly in tune with their body. Rather, they took the best advantage of the foods around them they could in light of their bodies which, like ours, were whittled by evolution out of more ancient forms and so flawed, complicated, and filled with tradeoffs. 

So, that’s the answer. Our bodies are what they are, thanks to millions of years of evolution. There is little you can do to your body with food (except for those damn figs, I suppose), so you take advantage of what food is available to you. You’re not going to live longer if you eat something or another. You’re not going to prevent or cure cancer. Don’t eat more than you burn is about the best advice you’re going to get. And eat more figs. So Cathy, there you go. Figs. 

Key citations

The Original Skeptical Raptor
Chief Executive Officer at SkepticalRaptor
Lifetime lover of science, especially biomedical research. Spent years in academics, business development, research, and traveling the world shilling for Big Pharma. I love sports, mostly college basketball and football, hockey, and baseball. I enjoy great food and intelligent conversation. And a delicious morning coffee!

10 Replies to “Eating like our great ape relatives”

  1. I disagree to your approach to Cathy's question, because you tackle the complex issue of an optimal human diet based on the habits of our ancestors, and there is very little direct and reliable evidence, and much disagreement on this topic. For example, regarding paleolithic lifespan, very few human remains over 10,000 years have been found (and perhaps the conditions that preserved such bones are the same ones that shortened the lifespan of their bearers). Genetically, chimps and bonobos are about equally close to humans, but they are very dissimilar from each other in terms of social and dietary habits. One would thus obtain 2 different profiles of social behavior in early humans when extrapolating from one or the other.

    Perhaps the answers to our optimal health (and maybe even to how our ancestors behaved) lie in the behavioral patterns and physiological constitution of the modern human.

    Physiologically, humans are omnivores, requiring vitamin B12 that is not found in plants. Its sources are the traditional meat, dairy and eggs; however they can also be found in the soil (some suggest our ancestors obtained them from unwashed fruits and berries) and in insects (for which humans have specific digestive enzymes…).

    The body and build of the natural human, without tools, is not equipped to hunt or eat animals, except for very small creatures.

    Ingestion of meat in humans is proportionately associated to colon and breast cancer.

    Human vegans tend to have an overall longer lifespan, be slimmer and suffer from less chronic illnesses (cardiovascular disease, diabetes, cancer, and some even suggest a lower incidence and impact of autoimmune disorders) than non-vegan humans. Long-term studies carried out on people switching to low-fat plant-based diets have shown astonishing results.

    There are also other factors, such as biomagnification (i.e., the longer the food chain, the higher the concentration of toxins, such as pesticides) or the low resistance of humans to common meat-borne infections (Staph. aureus, cisticercosis, the newer fllu viruses, which is why, unlike carnivores, we are uncapable of eating "unfresh" meat without paying for it), that point to a plant-based diet being the optimal diet for humans.

    1. Just about everything you wrote is either contrary to accepted scientific evidence or is lacking in scientific evidence.

      Let's start with your errors. First, few remains have been found from the last 10,000 years? Based on what evidence is that? We have vast amounts of remains, but much of doesn't exist because it's in tropical environments which are less favorable to preservation of remains.

      Bonobos? I didn't discuss bonobos at all, except to state that they diverged from humans at the same time as chimps. Don't create strawman arguments when none were proffered, since it's annoying.

      Modern humans have not evolved whatsoever from earlier humans, except in tiny insignificant ways. You might want to understand a bit more about evolution.

      What digestive enzymes do humans have for insects? Please provide real scientific evidence for that, because I do not believe that humans can digest polysaccharides.

      Ingestion of meat is associated with colon cancer and breast cancer? Please provide a peer reviewed high impact journal study. In fact, please provide that for all of your claims. And if you pick and choose articles, I'm just going to delete it, you need to provide meta-reviews, not primary data that is one-off study that just shows confirmation bias.

      Nothing you've stated is scientific, just your lame attempt to support your belief in veganism, a religion from all I can tell. You really ought to read the article again. I do not promote eating meat. I do not talk about bonobos. I do use peer-reviewed studies.

    2. I apologize for the many misunderstandings in my response. I was under the impression you had a medical background.

      I suppose if veganism is a religion then there's something to be said about faith keeping people healthy. Assuming you have an inquisitive mind, I would urge you visit PCRM's website for more information about plant-based diets, so that perhaps you may provide your readers with more informed recommendations.

    3. I have a medical background. I expect that people bring evidence to a discussion not opinion, all that you bring is opinion. PCRM is not a scientific based medicine organization. Give me a break.

    4. Well, if you do have a medical background (if that doesn't mean that you're standing in front of a hospital billboard) then you need to go back to your basic sciences, because human polysaccharide digestion (which you stated that you "don't believe in") is covered in high school-level biology.
      Most of what you demand evidence for is in the text books. It's common sense for some for someone with a degree in medical sciences.

      PCRM (Physicians' Committee for Responsible Medicine) is a solid organization that conducts research and bases its recommendations on evidence-based (not "science-based") medicine.

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