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Evolution/Evolution and Human diet? Adaptation?

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Question
Are we more adapted to African fruits and plants?  I am not good at explaining my thought process but here it goes. :-)

We spent a long part of our history evolving and,  eating plants and fruits on the continent of Africa.. Could it be that our bodies obtain nutrients and digest the plants and fruits of Africa better?  Or another specific part of the world we evolved in?   There are all these various African fruits and greens we don't eat because we don't have access!   I mean our closest relatives the chimps and bonobos eat figs and nuts and various African vegetation in the form of leaves, nuts,berries, etc... Would we as humans be better suited to eating these foods? Or maybe the specific type of foods of the African Savannah?   We then moved out Africa and starting eating diets of the local foods that were available to us in various places?  Did we start finding better foods and more nutritious foods all over the world and that's why we now incorporate them into our diets? I know we can survive anywhere obviously as we have been doing it since we left Africa....but  are we still more adapted to these African foods?  Or is it the all about being able to obtain nutrients from any plants and fruits regardless of where they are from?   I could be eating blueberries and wild dandelions right now in North America, or I could be eating an African wild Fruit with African greens...Or since white people are European is it that they would be more adapted to eaten European vegetation?  Or once again does it not matter....  Is it all the same as long as we digest and obtain nutrients regardless of where they come from.?

Answer
Dear Eric,

The short answer to your question is:  It all depends on natural selection.


The long answer is:

Any trait an organism has--such as particular enzymes to digest particular types of food--can be classified in one of three ways:

adaptive - increases the organism's likelihood of survival and reproduction
maladaptive - decreases the organism's likelihood of survival and reproduction
neutral - does not affect the organism's likelihood of survival and reproduction

Natural selection will favor adaptive traits, and those with adaptive traits are more likely to out-reproduce their conspecifics (members of the same species), and thus leave more of their genes to the next generation, including those coding for adaptive traits.

Natural selection can act slowly or quickly, depending on environment and all the circumstances facing the population under selective pressure.

When it comes to diet and the ability to digest certain foods, the same thing is true.  

Since European-ancestry humans have been out of Africa for thousands of years, there's no reason to think that they would be better adapted to digesting African food items than the more northern food items they found along the way as they migrated north.  Those better at getting energy from those new food sources would leave more offspring than those who were not as good at same.

Natural selection (and genetic drift) might help explain why certain human populations tend to have more individuals who are lactose intolerant than others.  Humans whose populations relied significantly on the milk of other mammals for sustenance would not have an adaptive advantage if they were lactose intolerant, and so would probably leave fewer offspring to the next generation.

On the other hand, in populations where milk was not a major food source, lactose intolerance was probably a neutral trait (or even adaptive, if making the enzymes required for digesting milk sugars were an unnecessary metabolic expense that took away from reproductive output).

So there's no really good reason to think that human populations that have been evolving outside of Africa for thousands of years are still better adapted to eating African foods.  It's all about evolution.

Hope that helps.

Dana

Evolution

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Dana Krempels

Expertise

I can answer questions about evolutionary mechanisms and theory, including genetic drift, mutation, natural selection, etc. I also can clear up misconceptions about evolution as it's sometimes talked about by those not well-versed in the subject (e.g., some politicians and many religious fundamentalists).

Experience

I have a Ph.D. in Biology, and presently teach Evolution and Biodiversity, Genetics, Botany, and Zoology at the University of Miami.

Organizations
House Rabbit Society Beta Beta Beta Biological Honor Society

Publications
Exotic DVM Magazine (veterinary journal)

Education/Credentials
B.S. in Biology B.A. in English Ph.D. in Biology

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