THE EVOLUTION DIET

THE EVOLUTION DIET

Or, more accurately, what evolution can tell us about diet, started in my mind as a semi-humorous post that soon evolved into one with some serious messages.  It was triggered by a conversation I overheard discussing someones weight problem and the persons lack of knowledge of what I thought were bits of information one could not overlook if they kept up with the news and opinion over the past few dozen years.

The evolutionary aspects of diet

We are a product of a long evolutionary history.  One would think our more recent ancestors had a more direct impact on our genetic heritage.  That is probably true, but more remote ones often leave their imprint on our genetic code.  Many fundamentals of our biochemistry go back to one-celled ancestors common to both plants and animals.  So it is not surprising that vegetation has a store of nutrients useful for a healthy diet.

We may worry about exposure to foreign organisms, especially bacteria.  When our ancestors left that primordial soup in which they evolved they were accompanied by a varied flora and fauna.  So today, after a course of antibiotics that kill off useful members of those organism inhabiting our gut, it is a good idea to eat yogurt and perhaps other things that will reintroduce those useful organisms back in to the gut.  Doing so can lead to rapid return of comfortable intestinal function.

Even our skin may benefit from the presence of useful organisms that compete with pathogens trying to establish themselves on or in our skin.

Fast forward to the present and we see diets that rely on excessive distortion, not truly natural diets based on our evolutionary history.

A fatal diet

A few decades ago, a liquid protein diet worked wonders in providing rapid weight loss.  But some died when they reached their desired weight and tried to resume a normal diet to prevent further weight loss.  It was thought the lack of carbohydrates and/or fats in their diet had fostered the deterioration of the parts of their biochemical cellular features which could not be retooled quickly enough to preserve life.

A balanced diet

Is balanced on a tray carried by the waitperson?  No, it is one that should contain all needed nutrients such as vitamins, minerals, proteins, fats, carbohydrates as well as fiber and some less easily characterized nutrients.  Would an egg diet be a balanced diet, it has all the nutrients needed to form the systems of a bird?  No, most adults need a larger supply of energy. But some eggs are probably beneficial.  Fats are food having the most calories (stored energy), about 9 calories per gram, carbohydrates and proteins each have about 4 or 4 1/2 calories per gram, and alcohol has about 9 calories per gram.  So, if you are serious about a diet, reduce the alcohol consumption to the equivalent of a small glass of wine; none is far better than too much.

Nutrients do not all provide energy.  For example-  Our need for vitamin C in our diet is almost certainly a result of having tree-dwelling primate ancestors that had so much vitamin C laden fruit in their diet that random mutations destroying the ability to make vitamin C did not get eliminated by natural selection.  Non-primates ancestors such as your pets retained the ability to make vitamin C from earlier common ancestors we share.

Fat was the most efficient material to use for storing energy.  Not only for its high energy content, but it has very low impact on the aqueous based metabolic processes of cells.  Thus enough can be more easily stored to get an animal through seasons of low food supply.  We don't have that need now so our natural tendency to stock up does not get followed by a season to use up the excess reserves.  We still need fats and/or oils in our diet to aid uptake of fat soluble vitamins in our food.

Because we cannot digest fiber it does not provide dietary calories.  We lost that ability sometime way back in our evolutionary history.  Our appendix is thought to be a vestigial organ representing the cecal sac of an ancestor that could use it as a location to use microorganisms to break down fiber and otherwise indigestible plant parts, like cellulose, into usable carbohydrates.

High protein diets may put an excessive load of breakdown products on the excretory system.  More details of protein metabolism can be found in [ http://evolutioninsights.blogspot.com/2014/04/evolution-of-proteins.html ] a post which also indicates the important role protein break-down products had in adaptation for animals emerging from water to occupy terrestrial habitats.  The views count for the protein post is zero.  The views count for carbohydrates [  http://evolutioninsights.blogspot.com/2014/04/evolution-of-carbohydrates.html ] was one.  The views count for fats [  http://evolutioninsights.blogspot.com/2014/04/evolution-and-fats.html ] was two.  But the next post on macromolecules was more than an order of magnitude more popular [ http://evolutioninsights.blogspot.com/2014/05/evolution-of-macromolecules.html ].

Teeth

Our teeth include biting (incisors), piercing and tearing (canines), and chewing or grinding (molars), a combination of forms characteristic of omnivores.  That could suggest that our transition from one diet to another was fairly rapid in an evolutionary sense; it also makes us more adaptable to a variety of diets.

Evolution of diet

Our earliest animal like ancestors fed on small microorganisms like bacteria.  That method of nutrition can still be seen in us as the white blood cells that go around ingesting bacteria that invade our body.  Things go awry when disease causing bacteria get too good a start in our body.

The large eggs, part of the diet of many of us, developed in part because birds and reptiles were able to form them with a shell because the waste products of protein metabolism could be largely in the form of nearly insoluble uric acid.  Before that ammonia that was the first nitrogenous waste product of protein metabolism could diffuse in to the water.  We have partially gotten away from uric acid by using urea as a soluble nearly non-toxic alternative.  But for most of us, too much protein can lead to gout and other problems of excess uric acid accumulation.  Egg, dairy, and meat eaters face other problems from cholesterol and saturated fats although most of us can use moderate amounts if adequate vegetable, fruits, and whole grain fiber gets to our diet.  Some fish, not all types of fish, each week seems to have a beneficial role in nutrition.

Trans-fats, refined sugars and refined grains were not part of our remote ancestors diets, and we would probably be better off without them.  But even if we could study middens or other evidence of diet of distant ancestors it does not necessarily mean that roots, leaves, fruits, and berries form an essential diet.  We do not know the health and disease problems of those ancestors in sufficient detail to know that we should try to be like them.

My wife tells me that if I eat like my grandparents did on the farm, then I should work like them too.

An important consequence of a vegetarian diet is better avoidance of toxic chemicals we have introduced into our environment.  Animal protein can accumulate heavy metals, the animal fats can accumulate organic toxins when animals get food or medicines that contain those compounds.  Fortunately, the scary numbers are partly due to our ability to often identify pollutants in parts per billion amounts, a few generations ago when tests identified parts per million amounts, we didn't know they were there.  The bad thing is that some can poison at extremely low concentrations if they mimic or interfere with hormones or their functions.

Part of the bureaucracy many complain about is doing its best to see that we get safe food, drugs, air, and water.  That is not to say that improvements cannot be made.

Joe Engemann    Kalamazoo, Michigan       July 21, 2015

EVOLUTION OF MACROMOLECULES

Natural Selection and Macromolecules

DNA

The larger organic molecules found in living organisms are called macromolecules because of their large size.  They are primarily proteins, carbohydrates, and nucleic acids.  Many of them function within the cells where they were formed.  But the most important or central one to biology and evolution is DNA, a nucleic acid.

The long, linear double-stranded molecules of DNA are coiled in helices of chromosomes enclosed within the nucleus of animal and plant cells.  How the purine and pyrimidine base combinations along the molecule function, to duplicate the DNA sequence and form RNA and proteins to do the work of the cell, was a mystery until the code units were first determined by Watson and Crick in the mid 1950’s.

Determining the DNA code of humans then became a major priority for geneticists and molecular biologists throughout the world.  Francis Collins was a leader among those heading the Human Genome Project, which with others determined the sequence.  Along the way of his scientific journey he made a transition from atheism to belief in God.  He describes many aspects of the journey in his 2006 book, The Language of God*.

When I read the book in 2007 I thought he had written the book I was trying to write.  He also finds evolution by means of natural selection a basically true scientific explanation.  He does a good job of refuting creationist arguments.  He does a much better job explaining the molecular side of evolution in the genetics area than I could possibly do.  If you want to know that, please read his book.  If you don’t want the details, please read the introduction and first chapter of his book.  It is great food for thought.

Macromolecules in cells

Some macromolecules have an important structural function outside of cells.  The protein, collagen, functions as a connective tissue fiber in tendons, ligaments, and separate fibers of  loose connective tissue of many animals such as ourselves.  It, and the spongin fibers in sponge tissue, are similar proteins and are the only proteins that release the amino acid hydroxyproline when hydrolyzed.  The collagen fiber networks in bone are the primary protein portion strengthening the crystallized calcium compounds of mineralized bone.

Keratin is a protein important in hair, nails, and horns of some mammals.  Chitin is a polymer of acetyl glucosamine, the structural protein of insect and other arthropod exoskeletons.

Within the cells, DNA has functions demonstrating many of the potential functions cell molecules may have.  Slight changes in function can be eliminated or incorporated in subsequent generations depending on accompanying rates of survival.

            Localization.  The DNA can keep functional parts (genes) in close association.  Then necessary interactions can be accomplished efficiently.  It provides a better opportunity for functional clusters to be passed on to offspring during reproduction.

            Retention.  They are easily retained by the cell as well as by the nucleus.

            Storage.  The information coded can be kept and then passed on to subsequent generations.  The individual’s DNA cannot be effectively built up and depleted, like carbohydrate and fat nutrient reserves, except through cell division or cell death.

            Reduced osmotic impact.  The approximately four dozen molecules of DNA in each human cell have less osmotic impact than most other major components of the fluid portion of the cell that do not readily permeate the cell membrane.

            Reduced chemical reactivity.  Relative to size, reactivity of DNA is far below that of most small organic compounds.

            Diversity.  We are each unique in our DNA, as are most species.

            Reproduction.  DNA contains the information needed to develop within a functioning cell the machinery to duplicate itself and make the other changes necessary for reproduction of the species.  The plan is there.  All it needs is a functioning organism and a favorable environment.

Evolution

A variety of glitches in the mechanism for duplicating itself can rearrange one or more portions of the DNA molecule.  If it is a serious enough change the organism or the offspring getting the change may die or be incapable of reproduction.  A minor change will usually be passed on with little effect if it is a region of the DNA not active in producing necessary products.

But those changes or rearrangements of sequences may in rare instances be beneficial to survival of the offspring.  Over time, it may contribute to better reproductive and survival success and the new form will eventually replace the original form.  That is the simplified version of the development of the diverse community of species living on earth.

So what is good for survival?  Whatever works best!  A heavy fur coat if you live in the arctic, a skimpy or missing coat of fur if you live in the tropics.  A trim body may help if food is abundant and the environment is comfortable.  Abundant fat may help you survive if you face long winters or times without food.  Migrate to another environment and your offspring will eventually be quite different from those that didn’t migrate.

The story of evolution is in the DNA.  But it is often easier to find the story in conjunction with the details of the organisms when the intermediate forms are extinct.

*Collins, Francis S.  2006. The Language of God – A Scientist Presents Evidence for Belief.  Free Press, New York.  294 pp.

Joseph G. Engemann        May 2, 2014