Friday, August 12, 2011

Legumes: Neolithic or Not?

Some people have suggested that legumes are a relatively ‘new’ food in human diets, introduced only with agriculture, discordant with human biology, and causes of disease.   Some have raised concerns about a number of secondary plant compounds in legumes, especially isoflavones considered phytoestrogens.

I have decided to view human evolution in the larger context of primate evolution, because we share so many characteristics with other primates and have a genome 98 percent similar to that of our nearest relative, the chimpanzee.  Since modern humans eat legumes, and humans share a common ancestor with chimps, if modern chimps eat legumes, this would suggest that probably the last common ancestor of humans and chimps also ate legumes.

So I decided to find out, do modern wild chimps eat legumes? 

It only took a few internet searches to find that, indeed, non-human primates, including chimps, consume legume seeds, leaves, and flowers.

The most remarkable of the literature I have so far come across on this topic is a paper published in the American Journal of Primatology by Shoeninger, Moore, and Sept, entitled “Subsistence Strategies of Two “Savanna” Chimpanzee Populations: The Stable Isotope Evidence.” [1 pdf]  In this paper, the authors report on Ugalla chimps, living “in open, grassy woodland habitats similar to those in which the last common ancestor of apes and humans probably lived.”  These chimps consumed a diet very rich in fresh legumes, estimated at 50% of total food consumption, certainly a level requiring some level of physiological adaptation. 

This puts fresh legumes in a different class from grains.  So far as I know, we have no evidence of chimps consuming any significant amounts of immature grass seeds (grains).

Green Peas.  Source: Ecosalon
Based on this type of evidence, it seems probable that fresh legumes were part of hominoid diets for millions of years before the advent of agriculture.  This would give plenty of time for hominoid physiology to become adapted to regular intake of fresh legumes and their phytochemical constituents, and also provide an evolutionary pathway to the domestication of legumes.

I know many people feel worried about isoflavones with phytoestrogen properties affecting sexual development, function, and fertility.   They have the idea that plants produce these compounds to disrupt the fertility of animals consuming them.

It is easy to think of the herbivore as the enemy of the plants it consumes, and vice versa, but grazing herbivores provide water, nitrogen, and minerals to plants via saliva, urine, and feces deposited in the field while grazing.  Herbivore hooves also knead and soften the soil.   The plants receive many needed services from their ‘enemies,’  not the least of which is a supply of carbon dioxide, without which they can’t live.  The herbivores need the nutrients and oxygen the plants produce.  Food plants and animals using them form a yin-yang pair, complementary and opposite, but if antagonistic, both sides fail.

If a plant slightly limits the fertility of an animal grazing upon it, this actually serves the animal species.  Sure, some individuals may complain because they don't get the litters they want, but by keeping the animal numbers within limits, this reduces the chance that the animal population will overshoot its resource base and crash, while also increasing the amount of food/nutrients available for each individual animal, increasing the quality of life for the grazier.  The plant helps the animal maintain a sustainable population size, and by grazing, the animal helps the plant maintain a sustainable population size.   In the big picture, this is synergism, not antagonism.

The synergism and mutuality of plant-animal nutrition relationships is especially evident in human interactions with plants.  When humans like a plant, usually because the plant helps them thrive and reproduce,  the people take on the task of feeding, protecting, and promoting the reproduction of that plant.  Humans help plants that help humans thrive, so plants that help humans have become among the dominant plant species on the planet.

When thinking about evolutionary plant-animal interactions, I feel it is important to realize that organisms adapt not only to ‘beneficial’ but also to challenging aspects of their habitats, if given enough time. 

Let’s assume that at some point in the past, some herbivores were grazing on plants rich in phytoestrogens.  Let’s also assume that, initially, the herd grazing on these plants does have reduced fertility.  Nevertheless, within the herbivore herd a range of susceptibility to the phytoestrogens’ effects on fertility.  That is, some of the animals may be rendered completely infertile, some will have reduced fertility in varying degrees, some will have no reduction in fertility, and it is possible that in some animals the increase of phytoestrogens will actually increase fertility. 

If this process continues for several generations, gradually the animal population will move toward adaptation to the isoflavones.  The animals resistant to the anti-fertility effects of the isoflavones will have more offspring than those not resistant.   Eventually, the entire herd will have resistance to the effects of the typically encountered levels of isoflavones.  

Now, let’s suppose that the mechanism of action of the isoflavones is to reduce hormone levels in the animals.  In this situation, the animals resistant to the anti-fertility effects of these phytochemicals will be those who have an endogenous production of hormones high enough to counter the negative effects of the phytoestrogens.  Over several generations, the evolutionary result will be a species adapted to a phytochemical drain on its endogenous hormone production by virtue of a higher endogenous output of hormones to compensate for the losses induced by the phytochemical.

Now, if you take this species off of the diet to which it is adapted, removing or greatly reducing the ‘hormone disrupting’ phytochemicals, the animal’s usual hormonal output might be excessive.  As a consequence, the animal might develop disorders due to excessive levels of its own hormones.  Adding the phytochemicals back to its diet will reduce those hormone levels, producing a more balanced physiology, because the animal is genetically adapted to a diet containing chemicals that ‘disrupt’ its hormones.   It may actually need the ‘hormone disrupters’ to maintain hormone balance. 

Edamame.  Source:
I suggest that this may provide part of an evolutionary explanation for the growing body of research suggesting that consumption of legumes and other plant foods containing phytoestrogens may have positive effects on human health. 

I discussed here some research that supports the idea that plant-rich diets and specific whole plant foods can reduce the excessive sex hormone levels present in premature menarche, premenstrual symptoms, menstrual pain, polycystic ovary syndrome, hirsutism, menopausal syndrome, and reproductive system (breast, ovarian, etc.) cancers in women.

Tham et al of the Stanford Center for Research in Disease Prevention and the Department of Medicine discuss the growing evidence for potential health benefits of dietary isoflavones and lignans, two types of phytoestrogens  including prevention of cardiovascular disease, promoting bone health, and regulating hormone levels across the life cycle, in both men and women, to prevent sex hormone-linked reproductive system cancers. [2

World-wide patterns of human population growth seem to lend little support to the idea that phytoestrogens make people infertile.  Historically, growth rates have been luxuriant in nations consuming more plant-based diets (India, China, Asia in general) rich in phytoestrogens. 

Legume proteins may also have unique benefits.  For example, multiple studies have shown that substituting soy protein for animal protein might improve kidney function in type II diabetics with nephropathy [3, 4, 5, 6, 7, 8].  This may not be a property unique to soy, but an effect of legume protein versus animal protein, due to legume proteins having a different ratio of amino acids.  It certainly does not indicate lack of adaptation to legume proteins. 

I find it hard to fit this data into an picture of human evolution that considers legumes discordant with human biology, but it makes sense in a view that includes legumes among human ancestral foods. 
Lignans are another type of phytoestrogen.  As shown in this table, lignans occur in fruits and vegetables as well as seeds, nuts, legumes, and grains.  Although the seeds typically have the highest concentrations, sweet potatoes, carrots, asparagus, and garlic have levels comparable to pinto beans, peanuts, and several grains. 

Legumes like clover naturally occur in grasslands, and farmers grow clover as part of their pastures and fodder for ruminants.   Consequently, products from either pasture- or grain/legume-finished animals also can contain phytoestrogens, although in lesser amounts than in plants.  Hence, human ancestors probably would have gotten exposed to these compounds through eating wild game meat as well as plants.

Of course, as with every other item we ingest, dose and context affects outcome.  Nature never delivered isoflavones in concentrated pills or isolated legume proteins, absent counter-balancing compound present in the whole foods, nor did it give isoflavone-rich soy formula (based on soy protein isolate) to human infants.  Obviously, substituting soy infant formula for human breast milk is discordant with human biology.  

Now on to one of America's favorite beans.  
Coffee Bean.  Source: Whos3d3n

Did you know that coffee supplies the same isoflavones found in soybeans, albeit in smaller amounts? 

"This paper reports the isoflavone contents of roasted coffee beans and brews, as influenced by coffee species, roast degree, and brewing procedure. Total isoflavone level is 6-fold higher in robusta coffees than in arabica ones, mainly due to formononetin. During roasting, the content of isoflavones decreases, whereas their extractability increases (especially for formononetin). Total isoflavones in espresso coffee (30 mL) varied from 40 μg (100% arabica) to 285 μg (100% robusta), with long espressos (70 mL) attaining more than double isoflavones of short ones (20 mL). Espressos (30 mL) prepared from commercial blends contained average amounts of 6, 17, and 78 μg of genistein, daidzein, and formononetin, respectively. Comparison of different brewing methods revealed that espresso contained more isoflavones (170 μg/30 mL) than a cup of press-pot coffee (130 μg/60 mL), less than a mocha coffee (360 μg/60 mL), and amounts similar to those of a filtered coffee cup (180 μg/120 mL)."


Christian Wernstedt said...

The gut flora also impacts how isoflavones are biotransformed upon digestion. This factor is rarely accounted for in studies of harm/benefit.

Anonymous said...

Don. I have added beans back to my diet. Can you please provide your opinion on:

1) What are some of the best legumes to eat?
Many legumes are extremely high in omega 6. Compared to chickpeas Red Kidney beans seem to have a favorable omega 3 to 6 ratio.

The best seems to be mungo beans (black gram). According to nutrition data it seems to have a huge amount of omega 3.

2) What is the best way to prepare legumes? Soaking and dumping the water still gives me gas. Is it better to soak, then sprout, then grind, then ferment legumes into a batter such as dosas?

I hope you continue this thread into a more in depth look on the best ways to implement legumes into our diet.

Thank You

Chase Saunders said...

Nice post, Don.

Atticus said...

Is there any evidence that plants don't do everything possible to discourage herbivores?

Dr. John said...

When you talk about human adaptation, you must understand adaptation does not occur to a novel food in "a few" generations".
It takes thousands (as Darwin described) of generations. Adaptation also requires humans to literally die off and their genes removed from the pool. That means some of our children MUST die.
That does not happen today due to modern meds to ameliorate GI upset.
Also, when was the last time we found or observed any evidence of chimps cooking beans....?

Alan said...

>>> Soaking and dumping the water still gives me gas.

According to my understanding, and first hand experience during a long period of eating only meat, only fiber can generate gas.

I do eat vegetables anyway, for the hedonistic enjoyment; but I don't fool myself that fiber is necessary or beneficial.

I myself cannot not detect any "health" differences in myself between carnivory and omnivory.

Eating vegetables has made it rather easier for me to become overweight again. At this moment, I'm doing it anyway.

Ezer said...

Don, I posted about beans in my blog. I'm a brazilian, and rice and beans are our everyday lunch, along with meat and vegetables.

Hope you like it:

Gadfly said...

"I have decided to view human evolution in the larger context of primate evolution, because we share so many characteristics with other primates and have a genome 98 percent similar to that of our nearest relative, the chimpanzee. Since modern humans eat legumes, and humans share a common ancestor with chimps, if modern chimps eat legumes, this would suggest that probably the last common ancestor of humans and chimps also ate legumes."

Well, you do like to go big. Unfortunately, this would be a completely untenable conclusion by any reasonable measure. Moreover, comparing a hindgut fermenter (chimps) to those with a short colon (humans) is absurd, despite the sharing of genetic material. A simple inversion of your argument demostrates this: since humans ate plenty of meat during much of our evolution (and the overwhelming majority of researchers agree this is the case) it is therefore true that chimpanzees and apes ought to do it as well, because they share so much genetic material with us.

jesse said...

Hi Don,

I'm fairly new to your blog and enjoying the perspective. I still can't ignore the fact that we *are* different from chimps in some notable and drastic ways. So any dietary advice that stems from chimp and pre-chimp/human split would need to address those differences. That seems like a task much bigger than one man's blog and would require a lot of research, hypothesis, testing, retesting etc....

Often I read how some civilization at really high carb and low protein and such and how that proves that a good "paleo" diet is macronutrient agnostic. But then I realize thet they are an average height of 4'5" tall and weigh 80-110lbs. That doesn't meet my criteria of thriving. Chimpanzees are in that same category for me :)

So ultimately doesn't that leave us as individuals wanting answers *now* to simply do a Robb Wolf style elimination diet? Also, for the legumes my understanding (limited) was that the lectins are the real issue. Any comment on the lectins and digestion, inflammation, auto-immune?

I know that Paleo is young but some folks have been really successful with it. I have only been at it about 60 months. For the first 4-5 months I was going higher fat but that is not working for me anymore and I'm adding more fruits and veggies and tubers in.


STG said...


Thanks for posting about legumes-great info. I never have followed a strict paleo diet. I don't worry about legumes or nuts (omega 6's). Nourishing Traditions cookbook explains how to prepare legumes and nuts (soaking etc)to get the most nutrition form these whole foods.

Don said...


I think fresh legumes are better than dried. Smaller legumes are easier to digest than larger, especially the pea and lentil family. Soak, sprout, grind, and ferment will certainly be the ultimate prep.

Don said...

Dr. John,

I pointed to chimps and modern humans both consuming legumes, then surmised that the common ancestor of both must have also consumed legumes, which means there have been at least 6 million years available for adaptation.

Not all legumes need cooking. Cooking is one of the ways humans adapt foods to our gut...probably a driver of the shrinkage of human guts relative to chimps.

When was the last time someone died from eating a bowl of beans?

Don said...


Inverting the argument doesn't work because the shared genetic material comes from a common ancestor that passed that material to both humans and chimps. Any adaptations humans have to eating meat are in the 2% difference between chimps and humans; since chimps and other apes are not descendents of humans, we didn't and couldn't pass those adaptations on to them.

Instead of fermenting things in our hindguts, we cook them in fire. A significant minority of anthropologists and primatologists (example, Wrangham) believe that cooking, not meat-eating alone, drove the shrinkage of the human gut and shift from hindgut fermenting to current gut function.

And in actuality, we are still, to a small extent, a hindgut fermenter, deriving 5-15% of our energy from shrot chain fatty acids derived from fermentation of fiber and resistant starch.

McNeil MI, The contribution of the large intestine to energy supplies in man, AJCN 1984; 39:338-42.

Don said...


Humans already eat legumes. There is evidence that legumes provide health benefits. There is speculation that lectins cause diseases. Unfortunately, the autoimmune diseases some speculate are caused by legume lectins appear to occur more frequently in nations like the U.S., where legume consumption is rather low, than in Asian nations, where legume consumption is higher.

Apparently you think larger and heavier means healthier. There is evidence this may NOT be the case. Taller, heavier people are more likely to develop cancer:

Because the same mechanisms that make a person taller also promote cancer.

We also have evidence that taller, heavier people have shorter life expectancy:

So it depends on what you mean by thrive. If thrive means grow large and die younger, then growing large is thriving; if thriving means living a long life span, then growing large is not thriving.

Currently, the idea that legumes lectins cause inflammation and auto-immune diseases is speculative. Take a look at multiple sclerosis:

The high risk areas are Canada, U.S.A., and Europe, where people eat more dairy products and processed foods. Low risk areas are Asia, Africa, and South and Central America, where most people eat little or no dairy products and more plant-based diets including more legumes. This simple observation makes it unlikely that legumes are the primary driver of M.S.

I think the main driver of autoimmunity is feeding infants anything other than breast milk. In infancy, the gut lining is more permeable than after 4 years of age.

Don said...


Is there any evidence that prey animals don't do everything possible to discourage carnivores?

Is there any evidence that animals don't do everything possible to adapt to the plants they eat?

Adaptation is a two way street.

Check out my posts on Operation Hope.

That project very clearly demonstrated that grasses need herbivores to thrive, that taking herbivores off a grassland leads to the demise of the grasses.

Malena said...

"I think the main driver of autoimmunity is feeding infants anything other than breast milk. In infancy, the gut lining is more permeable than after 4 years of age."

I so wish you could read some material from Ursula Jonsson, however, its in Swedish and German.

Being an agronomist, she asked herself why pups and calfs MUST have mothers milk to become healthy with a robust immune system, whereas we just put anything into our babies bodies.

I've been in contact with so may people healing themselves from strictly excluding everything that was in their infant formulas (could be different depending what year you were born but anything from wheat, gluten, oats, rye, milk, lactose, milk protein, milk fats, wheat starch, soy, sometimes fish oils and citric acids, glutamate, yeast).

Symptoms and diseases can vary from all kinds of psychological issues (MBD, ADHD, depression, bipolar, anorexia), intestinal problems (IBS, Chrons, UC etc), rheumatism, joint problems, PMS the list goes on and on because the allergens are such masked intruders that have manipulated our immune system from start that no tests can be reliable. The only reliable method is an exclusion diet.

Malena said...


I think there should be an English translation of Ursula Jonsson's book "Nu räcker det" (Now it's enough) out soon which explains the theory of "Primary Allergy".

For anyone interested I think you could contact Dr Julie Ikomi-Kumm at

Anonymous said...

I LOVE MALENA's thought process...and you know, that makes sense. those who were formula fed have not only underdeveloped guts but lower mineral and nutrient reserves.

those breastfed(assuming the mom wasnt some cracked out drug addicted whore..) seem to be those who can eat what they want(beans, nuts, high carbs) and have no problem.

maybe whey protein isnt as bad for someone who was breast fed but one who was formula fed will react badly to whey, same with lactose and dairy. same with msg, carcinogens, lactic acid(and other acids) and even wheat. if you started your life with the ingredients in formula youve already f*cked yourself IMO and those will be the same ingredients you need to stay away from.

i think the difference is just sourcing. manufacturers assum LC PUFA from boobmilk is the same as LC PUFA sourced from plant fat, and at this stage in an infants life- obviously the ingredients in formula make NO SENSE whatsoever. wow, i never thought of it this way. i guess your sort of at a loss being formula fed forever then, it prolly also sets you up for neuroendocrine disruptions, arguably personality problems, ADHD, autoimmunity problems, an omega ratio that is beyond repair, low vitamin/mineral status. yikes, DOn please do a post!!

so wheat may not be bad for everyone, but for a formula fed offspring(such as myself) it prolly is.

i doubt there were beans in my formula so i guess(once i adapt to the gut/bloat reintroducing them) if i were to add them back i would be just fine. however, you have most bloggers extrapolating data so broadly to prove their point(ALL legumes, ALL dairy, ALL grains, ALL omega 6's...etc) that your lost in the good/bad and testable food.

i hope you continue to share insights about your ideas Don because i am interested in all boundaries. the more i stay away from the paleo community the more i am learning about myself and food how I REACT to certain diets.

oh and PS, your AHS stuff was awesome !

malena said...

Wow I'm impressed, not everybody gets it!

The thing is, diets are all a mystery today if you don't take primary allergy into account. There are lots and lots of people who have excellent health on yoghurt, granola and pasta and then others that feel they have to go on very strict diets without really understanding why (say paleo, raw food etc).

The trick is to exclude 100% of the primary allergens. My sister wrote a book on how she heald from ulcerative colitis where she, amongst other things, switched to a primary allergy diet. You can download it for free here: On page 7-16 you will find good advice on how to test yourself and how to avoid traps and a purchase guide that can be handy when you are out shopping or going to restaurants (actually I made that one :)).

What all this shows is that man is a fantastic omnivour that can thrive on almost anything, provided we had a good start. This thanks to our genes but also because of all the bacteria in our guts (amounting to more than the cells that we have in our bodies) that help us adjust to different environments.

Once the primary allergenes are sorted out, all of us can attaid excellent health provided we give the body enough time.