Are Humans Naturally Folivores, Frugivores or Faunivores?

[Dean Pomerleau]

All,

 

Dr. Greger has an interesting video out today on "Paleo-Poop", discussing the evidence from fossilized human feces that our ancestors ate a very high fiber diet, > 100g of fiber per day vs. < 20g for most people today eating a standard American diet. This wasn't particularly new news to me, or to anyone reading this I suspect. 

 

But what I found most interesting about the video was at 2:30, where he discusses what was the likely source of all that fiber. In particular, whether ancestral humans were folivores (foliage / vegetable eaters), frugivores (fruit eaters) or faunivores (meat eaters). Its pretty clear from lots of evidence that we're not primarily meat eaters, and it has only been relatively recently in our evolutionary heritage that meat and other animal products became a large part of our diet. So we can knock faunivores out of the running - at least when considering deep evolutionary time.

 

What was most interesting was the distinction between the other two categories - folivores vs. frugivores. The evidence he shows in the video is from [1], and it is a plot of organism body size (x-axis) vs. density of gut mucosa (y-axis). Apparently the three categories (folivores, frugivores and faunivores) fall into distinct clusters. Here is the graph, with the range at which humans fall as the intersection of the horizontal and vertical lines with the label "Homo Sapiens":

 

 

As you can see, humans of today fall squarely in the cluster of frugivores, which the authors interpret to indicate that our distant ancestors were primarily fruit eaters. 

 

Obviously we're omnivorous now, and have been for quite a while, especially since we expanded out of Africa into environments where fruit isn't readily available in large quantities or year-round, and since we develop cooking and other processing techniques to make meat (as well as other parts of plants) more digestible, and more palatable! But being a fruit-lover myself, I thought it interesting to know that at least our distant ancestors appear to have been heavy fruit eaters like orangutan (who apparently also love durian!), rather than folivores like gorillas. 

 

--Dean

 

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[1] Claude Marcel Hladik, Patrick Pasquet. The human adaptations to meat eating: a reappraisal. Human Evolution, Springer Verlag, 2002, 17, pp.199-206. Free full text

 

Abstract

 

In this paper we discuss the hypothesis, proposed by some authors, that man is a habitual meat-eater. Gut measurements of primate species do not support the contention that human digestive tract is specialized for meat-eating, especially when taking into account allometric factors and their variations between folivores, frugivores and meat-eaters. The dietary status of the human species is that of an unspecialized frugivore, having a flexible diet that includes seeds and meat (omnivorous diet). Throughout the various time periods, our human ancestors could have mostly consumed either vegetable, or large amounts of animal matter (with fat and/or carbohydrate as a supplement), depending on the availability and nutrient content of food resources. Some formerly adaptive traits (e. g. the “thrifty genotype”) could have resulted from selective pressure during transitory variations of feeding behavior linked to environmental constraints existing in the past. Key Words: meat eating, hominids, gut allometry, thrifty genotype

 

[gracezw]

Dean, thank you for posting this! I watched the video!

[mccoy]

Our ancestral regimen has been a subject of my recent pondering.

 

According to present knowledge it appears that the hominidae (great apes) started to develop about 16 million year ago.

The bipedals specieses have allegedly started to develop around 8 Mya. Bipedalism suggests a diversification from the arborean apes, in that probably less foliage and fruit, more tubers and wild legumes started to be consumed, the savannah being explored at farthest lenghts.

 

The above musing are not about folivore or frugivore, but on plant-based or omnivorous. It appears that most if not all primitive societies  recently studied (hunter-gatherers) included to some extent not negligible amounts of animal food (meat & insects). Even though fibre-rich, the diet is usually not plant-based but omnivorous. Now, paleolithic spans by definition from 2.6 millions to about 10000 Y ago.

 

Are the observed examples of hunter-gatherers a degeneration and why? Are they examples to follow or to avoid and why? Does the alleged omnivorism of paleolithic (which has not been proven in all areas and times) supersede the much longer frugivorism and foliagisms of hominids? What governs, the most recent mutations or the most basic, older-than-Miocene metabolic pathways? Are the recent (paleolithic onward) mutations significant in the dietary framework, since basic anatomy hasn't evolved much? Do such mutations come with a burden (increased illness hazard)?

[mccoy]

Dr. Greger's interpretation is straightforward: the hunter-gatherers were/are a degeneration of the primal hominids. Their priority is not longevity, rather reproduction, so their dietary scheme is geared toward acquiring caloric-dense foods which prevent starvation. In his opinion, our bodies have not adapted to the prevalent paleolothic diet, rather longevity and healthspan is compromised. The arguments appear valid, especially the ones on the adaptation to maximum conservation of cholesterol. Which however raises the question as to why some people do not develop high blood cholesterol even when eating lots of saturated fats.

 

[Mechanism]

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[mccoy]

Hi mechanism, I'm reading Guyenet's 'The  hungry brain' and he really makes a good work of illustrating the neurological aspects of bodyweight homeostasis.

 

I can also recognize some of the guys you cited like Ben Greenfield, others I'm going to look up. Many, as you say, support an omnivorous regimen but tend to have an unbiased view , like Chris Kessner, Coppola and so on. I know them from their podcasts.

 

My problem here is that the undeniable, indisputable fact is that our very ancestral blueprint is plant-based and diet has deviated from that only in the latest 10% or so of our evolutionary history. There have not been significant physiological changes either. So I would expect an overwhelmingly larger mortality ratio for carnivores-omnivores (those who deviate from the rule), that is an overwhelmingly lower mortality hazard ratio for vegetarians and vegans, but we know that it is not so. Even though ratios for some diseases are favourable.

 

Maybe there are other issues more important and related to the evolutionary dependance on plants which govern, like hormesis and xenohormesis. In this POW, even eating some meat and fish would not be a big issue if enough hormetic chemicals are ingested from the vegetable kingdom.

 

The overall logical framework is confused though. 

 

The hypothesis I favour presently is that of the existance of some degree of intelligent design, where evolution has been pushed (for humans) along the optimum of plant-based regimen, allowing some slack to tackle critical situations. This slack comes not without a price though, since it may increase the hazard of some disease.

[Saul]

I tend to ignore all dietary gurus, and try to look at the evidence.

 

I also ignore those who believe that we should eat as did our paleo ancestors. E.g., we have the luxury of having

much more than adequate food available at all times, of varying quality; our ancestors didn't.

 

A good example: CR would be unthinkable for people constantly in danger of starvation. The evidence is high

that it is likely to increase our healthspan, and possibly even lifespan; so it's probably a good idea for our

practice -- but not for our paleo ancestors.

 

On the subject of vegan vs. plant-based, not-quite-vegan diets, I think that the evidence is that the latter is probably better.

 

(Although I wouldn't like to get into a polemic argument with the strong believers in veganism -- at least

they aren't jihadis!

 

:)

 

-- Saul

[Mechanism]

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[mccoy]

Fortunately there is a lot of convergence of data on the benefits of a Whole Foods diet. None of the blue zones had a tremendous amount of animal sources ( or added sugars, processed foods, refined seed oils, etc) and a primarily plant-based diet is clearly the winner. However this can mean vegan / vegetarian with judicious supplementation ( esp B12) but can also mean omnivorous / Zone / Mediarranean, etc. diet with modest portions of seafood, etc. with optimal longevity as well. Low, but not necessarily no animal products is consistent across the Blue Zones, with only a subset of the seventh day adventists being strictly vegan. Results have been mixed on the vegan vs vegetarian or plant based flexaterian/pescatarian/ mostly plant-based omnivore relative health status ( with all other variables held constant), and differences in the health outcome of one over the other have gemreraly been marginal in the best studies.

 

So any of these diets including vegan can produce great outcomes in the observational data. I deeply respect the

Vegan choice and way of life, I simply do not feel it has to represent based on current quality data the optimal diet per se. There are many other reasons to choose vegan including ethics, the environment, and taste. This is a choice we all face. For health, there are many roads to Dublin.

 

Mechanism, as you say there is evidence that an omnivorous, healthy diet containing little animal foods is correlated to the exceptional longevity which occurs in the blue zones. That's a fact.

 

What I'm less and less convinced about is the validity of the hunter-gatherer model as a reference of an healthy diet.

 

As Guyenet states in the 'hungry brain' book, survival of the species (reaching reproductive age and reproducing) is the priority of primitive society, non longevity. Health and longevity are not evolutionary imperatives of primitive societies, reproductive health is.The hunters-gatherers known by anthropologists inevitably eat animal foods. Moreover, they intuitively follow an algorithm based on the caloric density of foods and the caloric expense to obtain such foods.

In other words, the priority of hunter gatherers is quantity of energy obtained in relation to quantity of energy expended,  the priority is calories dense foods, animal or vegetal it doesn't matter, but usually animal is calorie-dense so they do tend to grab meat and fish whenever they can. This does not consitute a causal element of health, rather a survival imperative, whose long-term effects on health are irrelevant to that system because they do not mind about longevity.

 

The takeaway lesson to me is that the hunter gatherer is not a valid model to follow. Paleo guys may muse 24/7 about the dietary regimen of hunter gatherers, but that's mainly irrelevant to our situation where the feeding algorithm should rather be reversed, eschewing calorie-dense food (animal based prevalently) and acquiring calorie-sparse ones (plant based prevalently).

 

The cardiovascular and metabolic health of hunter gatherers may be caused not by diet, rather by many other factors, the brutal selection operated by the harsh environment being a fundamental one in my reasoning. No weak persons with flawed cardiovascular system are apt to survive in those difficult conditions. Those who survive are genetically and inherently healthy and robust. And they pretty much have to move around and physical exercise is a necessity, not a luxury.

 

Last but not least, a little cited aspect of hunter gatherers is that they are afflicted by intestinal parasites carried by the flesh they eat. Not an attractive idea to me.

[Mechanism]

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