The Lactose Tolerance Mutation

I’ve been meaning to write about lactose tolerance for a while now. Consistently I see this brought up as an example of a beneficial mutation. Superficially it would seem that it is the case. After all, people who are lactose intolerant miss out on some very tasty foods, that are also beneficial, or so we have been told. However, the standard idea leaves out some key details which undermine the evolutionary story.  This article will attempt to clear up the misconceptions and present evidence that is not well known but overturns the expected evolutionary story.

In order to understand why evolutionists milk this lactose tolerance mutation so much, a little background is needed.  Beneficial mutations are a key piece of neo-Darwinian dogma. They postulate that all the variety we observe in the world can, in one way or another, be traced back to a beneficial mutation that arose at some point in the past.  This being the case, they are always looking for examples of mutations they can call beneficial, to provide some shred of evidence for their dogma.

In order for a mutation to be beneficial, it must have no drawbacks, no negatives. Tradeoff mutations do not advance the cause of evolution. For evolution to proceed on its upward trajectory, it requires completely beneficial mutations. Lactose tolerance is proposed as one such mutation. Lactose is a sugar found naturally in milk and some other dairy-based products.  Digesting this sugar requires a special enzyme called lactase. Since milk tends to be an important part of our diet, this mutation seems incredibly beneficial.  However, this is where the story falls apart.

Babies, when they are born, have a gene that causes them to naturally produce lactase. Thus a baby can nurse freely from its mother in the overwhelming majority of cases with no issues. However, as we age, that gene turns off and the production of lactase stops. At least, it used to be that way, thus this article will solely discuss lactose tolerance in adults.  In the European population in particular and their descendants, a mutation occurred which turned off the regulation of the lactase gene. This permits people of European ancestry, among others, to eat milk and other dairy products freely. In context, this mutation likely occurred prior to Babel, but post-Flood since a few members of most of the world’s ethnic groups have it, but it is primarily concentrated in Europeans.

Evolutionists postulate that this ability to eat dairy allowed early European settlers to farm more easily as they could rely on dairy products as well as traditional crops for food. While this may be true, it does little to answer the question of whether this mutation is beneficial.  In fact, there is some evidence that, in adults, large amounts of lactose consumption in milk and other dairy products can be detrimental. Milk has been cited as a potential cause of reproductive cancer in both men and women. It has also been linked to a higher incidence of multiple sclerosis, type one diabetes, high cholesterol, and some other negative medical effects.

Now obviously one glass of milk or cone of ice cream is not going to give you all those terrible medical problems. Nor is it firmly established that all of those disorders are directly caused by milk. However, the fact that this is being discussed in the peer-reviewed literature, tells us that not all is well in the evolutionary story. Lactose tolerance in adults appears to be a mixed bag.

Evolutionists are largely ignorant of the potential harms milk and other dairy products can cause.  While I am not advocating abandoning dairy products in any way, I think it is interesting that a twenty-second google search permitted me to find this information, yet evolutionists insist that lactose tolerance is a beneficial mutation.  At best, lactose tolerance in adults is neutral. It does seem to provide some health benefits, such as reducing the risk of some cancers, but it also has negative effects that are either forgotten or not mentioned in the rush to declare lactose tolerance a beneficial mutation.  It tends to be this way with much of the evolutionary dogma. Once you dig into their claims a little, you tend to find that they have either exaggerated their data, ignored inconvenient facts, or simply lied about what they actually know. Obviously, the people likely to quote lactose tolerance to you are likely to be simply misinformed about the data, but the professional scientists selling it as a beneficial mutation ought to know better.


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  1. I am still wondering how can any variant of any gene possibly be considered beneficial according to this definition: “In order for a mutation to be beneficial, it must have no drawbacks, no negatives. Tradeoff mutations do not advance the cause of evolution. For evolution to proceed on its upward trajectory, it requires completely beneficial mutations.”
    This is a strange definition of beneficial mutation. Can you point me to any literature where this is how beneficial mutations are defined? I’m looking through my evolutionary biology textbook and can find no such description.

    All you have to do is back up and ask, is there any variant of any gene that could possibly be all beneficial without any trade-off. I can’t think of one. The gene variant that results in lactose intolerance has negative trade-offs to so how could it be said to be the original condition with the implication that it is beneficial?

    Your statement that “trade-off mutations do not advance the cause of evolution” is about 100% percent wrong since very single variant of every gene in involved in a trade-off situation. The question is the overall balance, if drinking milk has more benefits than negatives then natural selection will favor that variant even if there are some negatives (also note that selective sweeps of SNPs come into play here too) that come along with it. Of course drinking milk has some negatives, there isn’t a single type of food that doesn’t come with a negative but fortunately many food have positives that far outweigh the negatives. Once again, context is critical for how natural selection may effect the fate of a particular mutation. If you live in an environment in which you have plenty of food and clean water drinking lots of milk won’t help survival and will probably lower an individual’s overall fitness. However, if you live in an environment in which you have dirty water to drink, drinking milk will prevent you from getting a huge number of different water-born disease, not to mention the protein value in that same environment, and thus your chance of surviving to reproductive age is greatly enhanced. That mutation comes with a greater benefit for a population than the negatives which will be barely perceptible given the massive positive value. Therefore natural selection is going to pull population genetics in different directly depending on the environment. Hence, we can’t say that one allele or the other is “beneficial” apart from the context but within one context the allele is no doubt beneficial. Trade-offs are part of every single genetic interaction in every single cell and organism on earth so defining evolution as requiring beneficial mutation that have no trade-offs is to define it out of existence without considering the evidence.


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