Category Archives: Evolution

The Ability to Drink Milk is an Evolutionary Advantage

There is an interesting article making its way around the interwebs these days telling you to throw away the milk ‘cuz it’s baaad for you ‘cuz lotsa folks got the lactose intolerance.

This is inaccurate and misleading information.  It’s really a vegetarian activist and animal rights argument masquerading as a health warning, making use of fake science in an attempt to add credence to a false premise that milk is bad for us.  They probably made up their statistics, but only about 10% of Americans are lactose intolerant, though virtually all Chinese and “full-blood” Native Americans are.

In reality there is a fascinating evolutionary story in play here.  You see, most humans can only digest lactose (milk sugar) as infants and young children by producing an enzyme called lactase.  At a certain age after childhood the gene that promotes lactase production switches off.  There is no scientific evidence that this is because milk is bad for the adult human.  It’s just generally unnecessary and does not provide any benefit in pre-agricultural societies since their dietary requirements can be met with meats and other resources found in the environment.

Milk consumption was only necessary to keep the child alive long enough to begin eating the bodies of animals rather than from the body of their mother.  Since there is apparently not any need or benefit to be able to digest lactose beyond childhood, there was never a need or function for an adaptation that allows humans to produce lactase beyond childhood.  It didn’t help us live longer or have more sex in our nomadic hunter-gatherer environment.

That’s just kind of the way evolutionary adaptations work.  They typically only serve the function that is needed to keep the individual alive long enough to procreate as often as possible and create as many genetic replications as possible (also called babies).

Probably around 7,000 years ago amongst European and African cattle-herding populations there occurred in an individual a genetic mutation.  No big deal; everything that makes any life-form different from a single-celled organism is the result of a genetic mutation.  This particular mutation allowed for our bodies to continue producing lactase as adults.

This mutation provided an evolutionary advantage by increasing the “fitness” of the individual so that he lived longer than most others and produced more progeny than those without this mutation.  Since they were now herding cattle they had access to milk in proportions unlike you’d find while chasing wild antelope.  It is plausible that there may have been food shortages of some sort that helped these milk-drinkers to outlive and outbreed less healthy people without the mutation.  It could have just provided for a healthier person in general, without any starvation drama.  Regardless, the ability to derive nutrition from more places is an advantage that can increase the evolutionary fitness of the species.

All the numbers disparities and mumbo jumbo of the vegetarians is not so cleverly presented to look like drinking milk is some freakish and “unnatural” thing because most humans do not have the genetic adaptation to produce lactase beyond childhood.  In reality, people of European and African descent have a somewhat unique genetic adaptation that allows us to derive nutritional benefit from milk well past our childhood, and this is an evolutionary advantage.   Enjoy it.

Quick Reference: Berkley

cow photo: Moo moo.jpg

Note: I will give the author at “I waste so much time” credit for one thing: growth hormones in milk are a genuine concern, but then again harmful chemical additives in our food is a problem even when discussing Brussels sprouts.  Let’s not throw the baby out with the bathwater.

The Selfish Gene, Book Review

Dawkins, Richard (2006) The Selfish Gene, 30th Anniversary edition, New York: Oxford University Press

The Selfish Gene by Richard Dawkins is a remarkable and engaging journey through evolutionary theory.  Dawkins’ “selfish gene theory” challenges what he considers common and incorrect notions that the “important thing in evolution is the good of the species.”  Dawkins asserts that evolution is in fact a survival and replication strategy of the gene.  Written most especially for the layperson, Dawkins’ prose abandons much of the technical jargon of science and replaces it with an informal and metaphorical language designed to be read with the same enthusiasm and comfort as science-fiction.

Setting the backdrop for the “selfish gene” theory, the first four chapters cover basic molecular and biological science as Dawkins postulates the possible chemical origins of life and the gene.  Once the gene-centered concept of evolution is thoroughly introduced, Dawkins changes gears and begins to discuss the influence natural selection may have on animal behavior.  This is the basis for the selfish gene theory in which he asserts that the pressures of natural selection which favor the most survivable genes are a catalyst for the evolution of the selfish gene which in turn produces certain behaviors in the individual.  Dawkins says that the individual body of an organism is a “survival machine” created by its genes throughout millions of often violent evolutionary years.  The primary purpose of this survival machine is to provide a protective environment where genes can more efficiently survive and replicate themselves.  Dawkins argues that because these survival machines are essentially programmed with the information carried in their genes, the drive to survive and replicate is thus manifest in a myriad of selfish behavioral characteristics.  In short, the theory states that genes and therefore the species in which they reside evolve behaviors that cause them to act selfishly for their own benefit.  Natural selection favors selfishness.

Altruism represents a possible contradiction to the selfish gene theory, so Dawkins spends much of the early portion of the book addressing this idea. Altruism is a behavior in which an individual acts in a manner that benefits its kin group at the possible expense or sacrifice of its own life.  An example of altruistic behavior in the animal world is when a certain bird gives an alarm call, warning those animals nearby of an approaching predator and thereby drawing attention to itself and exposing itself to a higher degree of danger. Dawkins explains that altruism may actually have a selfish component on the genetic level in its evolutionary function.  If evolution is about “the good of the gene” it is therefore beneficial to sacrifice an individual life in order to protect those same genes existing within the kin group.

Dawkins’ language is constantly peppered with analogies and metaphors which assign many conscious attributes to the genes as they interact with the world.  Such examples are indicative of the title itself; the “selfish” gene.  Dawkins acknowledges that experts in the biological fields are likely to be displeased with his informal, non-technical, and anthropomorphic literary style but he assures us that he speaks only figuratively, that these terms are not meant to convey any truly subjective or moral qualities upon genes or natural selection.  Metaphor is merely his tool in translating scientific jargon and complex equations into the language of the layman.

In the second portion of the book, Dawkins stretches his metaphorical translation to include a cultural concept he calls a meme, from the Greek root mimeme.  He describes the meme as “a unit of cultural transmission, or a unit of imitation.”  It is essentially a segment of idea and it functions on a cerebral level, replicating, gene-like as it passes from mind to mind. The uniqueness of the gene and therefore life itself is in their functions as replicators. Dawkins argues that memes are also significant in their function of replicating themselves through culture. Memes, Dawkins asserts, should be regarded as just as much alive as genes.  He seems to use this theory as a means to challenge not only the established perspective on evolution but certainly to challenge the more religiously minded reader with an often fiercely combative tone regarding the “god meme.”

The meme theory or memetics is a very interesting idea on a philosophical level, but at this point the book almost seems as if it has crossed over from science to fiction or perhaps some form of religious atheism.  The analogy breaks down under more empirical scrutiny, but Dawkins speaks about the subject as if he is presenting more than just a metaphor. Comparing memetics to genetics, though entertaining in an analogous context is not a very practical or empirically oriented theory.  The concrete existence of a gene makes for a much more scientifically sound study than the esoteric nature of a thought.

The Selfish Gene is a thought-provoking book, relevant beyond the fields of zoology, and biology.  Students of psychology, sociology, and philosophy would also find this book of interest.  Dawkins’ flowing prose is engrossing and it does in fact read more like good fiction than dry science.  Many of Dawkins’ points are openly intended to challenge people of faith.  This is especially remarkable due to the manner in which he uses metaphor to symbolize complex theory, attributing conscious strategies, personalities and plans to genes.  This technique is ironically reminiscent of the esoteric and hermetic symbolism found in the world’s religions which use similar techniques to symbolize philosophical ideals and translate often ancient esoteric information into popular language and culture.  In doing this I think Dawkins may have found a way to speak the same or a similar language to that of the religious whom he intends to confront and educate.