Question: Evolution, Genetics & Diet

This query is directed to those people with some background in evolutionary theory, evolutionary psychology, or genetics.

My question is, what is the effect of genetics on diet?

For example. My ancestors are from the Azores (islands in the middle of the Atlantic) and Madeira (a group of islands off the coast of Morocco). The Azorean are renowned for being rapacious fish eaters. And the Madeirans as well eat a great deal of Fish. This would imply that my physiology is largely influenced by the nutritional benefits of sea food.

My direct ancestors ate it everyday. It was a basic element of their diet. Omega 3, EPA and DHA. These are the fats that my genetic structure is suited to having. But having been born in Suburban Toronto, Canada, and from a young age, taken a particular dislike to the taste of sea food, I have more or less lived without it. More than any of my siblings - all of whom eat fish 2 or 3 times a month, and will have tuna or mackerel a few times a week - I deal with chronic anxiety.

Interestingly, my aunt as well, I've been told, took a disliking to fish when she was growing up. She was also the more disobedient, discontent and unruly of my mother's siblings. This appears to suggest a connection between diet and genetic predisposition.

Am I genetically encoded to eat more fish? Have any studies been done on this? My ancestors lived on an Island. Their diet largely consisted of fish and crustaceans. I eat neither of these things. I hate the taste. Would this avoidance of sea food - and the fats, proteins, etc, that these particular foods provide - incline me towards anxiety, insomuch as my body is being deprived of a diet that has supported the genetic physiology of my ancestors for countless generations?

I guess the only way to verify this hypothesis is by deciding on eating more fish, more frequently, and noting the effects it has on my psychological health. Omega 3, after all, has been implicated as important for stronger brain function, giving fish the reputation of being "brain food".

reply to post by Astrocyte


The longer generations have stayed in one specific habitat, the more their genetics evolve based on conservation and efficiency.

Any fairly healthy human plucked out of it's habitat and forced to rely on a different environment would go through a withdraw type scenario. Noticeable or unnoticeable, for better or worse, it will.

Adaptation will get you to the end...

Adapt to survive.

Also, for better or worse.

The better question is perhaps what are the effects of diet on genetics. The role of evolution is to make sure a species adapts to best survive in a particular environment. Darwin's finches are prime examples of how diet impacts evolution, as different birds on different islands had different diets, leading to different kinds of beaks; some apt for eating fruit where the primary food was fruit, others apt for eating bugs where the primary food was bugs. The same effect occurs in humans, though to a less extreme extent. Many Asians and Polynesians, for example, have evolved scooped teeth for better consumption of fruit as it has been a staple in their diet.

Similarly, our diet as a species has shifted towards softer foods ever since we began cooking our meat. This has lead to more and more people today being born without ever developing wisdom teeth, and will eventually cause our teeth to become smaller and more apt for the consumption of softer foods.

Our ancestors tended to have very large teeth because their diet consisted of nuts, bark, dirt, etc.

While I am of Hungarian descent, my ancestors were viking raiders. It is possible my bloodline began with either a settlement, or through a more violent beginning (raids have always included such things as murder and rape).

In any event, I am a fish and shellfish lover. I eat shrimp or scallops 3-4 times a week. I eat regular fish at least 1 time a week, unless I have a sushi binge. Then I may it eat every day. I like to order fish to be caught and shipped to me (we recently had an amazing blue marlin shipped in from Hawaii. Sushi grade, and heavenly).

My wife hates fish. She will eat the more mild white fishes, but the red fishes she avoids. Rarely she can do shrimp, but likes scallops. Crab and lobster are never an issue.

Originally posted by Astrocyte
My question is, what is the effect of genetics on diet?

Its a matter of time.
In the long term, and I'm talking millions of years here, yes the effect can be huge.
But in the short term, you have to remember that evolution is slow.

So if your ancestors were island people for only a few thousand years, I'd suspect you couldnt find much genetic change at all.
For a few tens of thousands of years... possibly a bit.

OP, check out the blood type diet. It is a paleolithic diet based on your blood type. According to Dr. D'Adamo type O has been around about 500,000 years, Type A, 30,000 years, Type B, 10,000 years and AB 5,000.

Your preferences may be more related to this rather than your ancestry, as in, how long were your ancestors there and did they originate from elsewhere?

I mention this because I went on the diet (not as in weight loss) and had so many problems eliminated that I will never eat by any 'catch all' standard again.

An interesting fact that I have read from mainstream docs, Type A is most prone to colon cancer. According to the bloodtype diet, type A is the most able to be vegetarian, and as you probably know, they recommend no meat and more veggies for patient with colon cancer.

reply to post by alfa1


The isolation of island inhabitants in more ancient times could lead to a more rapid genetic drift. Bottlenecks are known to create significant changes in short order.

reply to post by Astrocyte


You answered your own question Only you can do the testing to see if it makes a difference. The fish your ancestors ate was saltwater fish. I would guess that your Junk DNA has adapted to need this in the diet, it will take more than a few generations to change that. Instead of thinking of it as fish is good for us, think of it as we need fish in our diet because our ancestors ate fish. If your ancestors didn't eat fish for many generations, it may have negative benefits to you.

I seem to feel much better if I eat fish at least three times a month. Those boxed breaded portions rarely have any positive effects for me, they are highly processed. I don't mind canned salmon, it seems to satisfy the craving but not as well as fresh caught fish. I don't like the fresh fish from the store, it seems that it is treated with something like sulfites to extend it's shelf life. I can't see paying such a big price for an inferior product.

Let me know if your trial has possitive effects

reply to post by alfa1

So if your ancestors were island people for only a few thousand years, I'd suspect you couldnt find much genetic change at all. For a few tens of thousands of years... possibly a bit.

You're confusing macro and micro-evolution.

Everything we do shapes our genes/brains. In terms of diet, if you have 20 + generations eating the same omega 3 rich foods, you would expect some negative affects in the 22nd generation eater who avoids those omega 3 rich foods.

reply to post by liveandlearn

OP, check out the blood type diet. It is a paleolithic diet based on your blood type. According to Dr. D'Adamo type O has been around about 500,000 years, Type A, 30,000 years, Type B, 10,000 years and AB 5,000.

Interesting. I'm curious as to which areas of the brain these diets are most relevant. Also, I think its more complex than reducing it to just one factor. While blood type might incline me to one sort of diet, heritable genetic coding would incline me to another.

I can't imagine that what your ancestors ate for 20 or so generations doesn't exert some subtle influence on your present physiology.

Your preferences may be more related to this rather than your ancestry, as in, how long were your ancestors there and did they originate from elsewhere?

The Azores were colonized in the late 1500 hundreds by the Portuguese, so I can't imagine that my ancestors go further than 400 years. However, 400 years is more than enough time to shape a diet in a particular way. An island diet is not as mixed as a continental diet. I'm not sure what the ratio is between seafood, land animals and vegetation, but I would wager the Azorean diet was at least 60% seafood, judging mainly by what my grandmother and her family eat, and my two weeks in the Azores a few years back, where I got to analyze the food culture of the island.

Also, as someone else also mentioned, living on an island tends to speed up adaptation to new conditions. Having less options to eat, a result of being heavily isolated from the mainland (Azores is smack dab in the middle of the Atlantic ocean, probably one of the most isolated Island chains on planet earth) may have shaped my physiology in such a way as to "work" in tandem with sea food. While I can still function and live without it - a throwback to older diets coded within my more primitive genes - there's very likely a withdrawal effect of being deprived of the nutrients that were a mainstay in my immediate ancestors diet.

I will try this diet out. Although, I must admit, the thought of eating sardines makes me want to puke. But somewhere in me, somewhere in this Portuguese body of mine, must be a person who enjoys the taste of fish.

Appreciate the help so far.

Originally posted by DestroyDestroyDestroy
The better question is perhaps what are the effects of diet on genetics. The role of evolution is to make sure a species adapts to best survive in a particular environment.

I think this is the way to look at it.

Also note that for natural selection to occur (evolution), this means that more successful adaptations breed more and less successful adaptations breed less, which usually involves mortality (the not so well adapted population dies at a higher rate and therefore doesn't reproduce as much).

This isn't about diet, but it illustrates a studied feature of human adaptation and note the mortality factor which is key in this adaptation:

homepages.ed.ac.uk...

It has been shown that Tibetan women with a high likelihood
of possessing high oxygen saturation genotypes have
more surviving children. The mean offspring mortality for
the high oxygen saturation genotype was significantly
lower, at 0.48 deaths compared with 2.53 for the low oxygen
saturation homozygote, suggesting that the selective
pressure by high-altitude hypoxia is even stronger than the
classic case of an environment with endemic falciparum
malaria (Beall et al. 2004). It has been proposed that genetic
changes in genes regulating oxygen delivery under hypoxic
conditions contribute to the functional outcome
of successful high-altitude adaptation (Beall 2007).

So in order for this adaptation to show up in evolutionary terms, meant that individuals without the adaptation had to die in greater numbers, leaving the individuals with the adaptation to survive and reproduce.

Now you must ask yourself, do you really think people were dying because of an alternative diet? (like the Tibetan children without the genetic adaptation to hypoxia were dying due to hypoxia).

I'm not convinced from the facts provided so far that the mortality factor with alternative diets is sufficient to result in evolution like the evolution we see in the human Tibetan population, for example. Humans can survive pretty well on a broad variety of diets and as long as they are able to survive and reproduce on whatever they are eating, how are you going to get natural selection and evolution like we see in the Tibeten population's evolutionary response to hypoxia?

I don't think it's very plausible unless there is some evidence of higher mortality with the alternative diets, which hasn't been mentioned.

reply to post by Astrocyte

Omega 3, EPA and DHA. These are the fats that my genetic structure is suited to having.

Or, more precisely, your ancestors genetic structure. We're talking, I believe, more about metabolism than genetics.

having been born in Suburban Toronto, Canada, and from a young age, taken a particular dislike to the taste of sea food,

This article from the National Center for Biotechnology Information should be useful for you understanding your dilemma.

the most palatable foods are those that are both energy-dense and high in fat content (Drewnowski, 1997a,b). The taste, smell, mouthfeel, and hedonic properties of fat all contribute to the popular concept of fat “taste” (Drewnowski, 1997a).

Sensory preference for sweet taste is present at birth, and the “sweet tooth” of early childhood helps to introduce new foods into the children’s diet (Birch, 1999). Children learn quickly to prefer flavors associated with high-energy content and begin to select high-fat foods early in life (Johnson et al., 1991; Birch, 1992). Genetic predisposition, metabolic needs, and behavioral or emotional factors can influence the liking for fats. Human preferences for fat-rich foods may also be influenced by economic factors and sociocultural values (Drewnowski, 1995; Drewnowski, 1997a; Tuorila and Pangborn, 1988).

No doubt, if you had been born, and still reside, on a remote island in the Atlantic, you would be happily gorging yourself on plenty of fish. Since you were raised in an environ where your dietary needs were met, your taste preferences have varied from those of your ancestors.

It's no so much the seafood, but the fact that your metabolic needs are being met by your current diet. I really see no genetically based reason for the need to consume seafood, but do follow the implications of a healthy diet.

reply to post by Druid42


Appreciate the reply.

I believe, more about metabolism than genetics.

Isn't metabolism somewhat based in genetics?

That's the tricky thing. I have a physical body, and I live in a particular environment. My physical body is an inheritance conditioned by a few hundred years of fish eating. Eating the same food in high amounts for such a long period of time would create adaptations in your physical anatomy to this particular food. Whatever we eat, the molecules which make up the food interact with processes that occur within our brain and body. A diet that provides a certain type of food - like omega 3 rich Fish - would create a brain that functions "normally" when it is interacting with nutrients derived from fish.

This is the logic of my thinking. I feel, my physical body is primed to eat fish. True, I've been relocated, but why would me living in Toronto Canada cause immediate changes in a physical anatomy that has been conditioned by 20 or 30 generations by a particular diet?

reply to post by Astrocyte


Interesting question

You might be interested in a study of Japanese gut bacteria. There appears to have been a gene transfer from marine bacterium to human gut microbes.
This allowed the Japanese with these novel genes to extract nutrition from seaweed; something that those without the genes cannot do. A distinct advantage to have.

Western sushi eaters are unlikely to harbour nori-digesting bacteria, says Michel.
Gene-transfer events are extremely rare, and there would be little need for bacteria exposed to a Western diet to hang on to such genes, he adds.
"The biggest difference in Japan is the quantity of seaweed that is eaten every day," he says. "It is far higher than just eating sushi once a week.
I don't think the pressure is high enough to keep the genes in our gut."

source: Nature.com

reply to post by Astrocyte


Curiously, if your ancestors had experienced periodic famines; you may have been healthier.


A Swedish study examined a couple of hundred years worth of records from a small Swedish community. The scientists had access to well-kept, and practically complete historical records of annual harvests, births deaths, causes of death etc etc.

What did they find ?

These records showed that food availability between the ages of nine and twelve for the paternal grandfather affected the lifespan of his grandchildren

The article goes on to explain:

Shortage of food for the grandfather was associated with extended lifespan of his grandchildren. Food abundance, on the other hand, was associated with a greatly shortened lifespan of the grandchildren. Early death was the result of either diabetes or heart disease. Could it be that during this critical period of development for the grandfather, epigenetic mechanisms are "capturing" nutritional information about the environment to pass on to the next generation?

Nutrition and the Epigenome


Very interesting findings ..... worth a read.