Survival of the Sickest, Part II-Diabetes

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The Younger Dryas period of extreme cold, coming just at the end of our last ice age, began in less than 10 years and ended in less than 3 years. That is what is called sudden onset of climate change. This was proven using ice cores and other methods. The present 'stable' climate of the last 11000 years is the exception in our climate history, not the rule. Change happens quickly, so how did humans adapt in such a short period of time? If human evolution takes millions of years, how has our species survived series after series of sudden climate change when grasslands turned into glaciers in a matter of a few years. The answer could be simple: Diabetes mellitis.

In diabetes, the body excretes water and dumps sugar into the blood, exactly the response seen in nature by plants and animals who are attempting to survive the cold. Grapes do it, Frogs do it, and humans do it. Almost everyone has the urge to pee when they have to go out in the cold. That's the body's way of reducing water, because water freezes and destroys cells. Less water, less ice crystals. Also, sugar lowers the freezing point of blood. Saline also lowers the freezing point.

When you are faced with abrupt cold, you shiver. The body robs the muscles of stored sugars and the friction generates heat, then capillaries restrict blood flow to the extremities, reserving the blood for the body core. Certain ethnic groups who live near the poles, like the Inuit and the Sami, have adapted and developed what is called a Hunters response, meaning that every few minutes, the capillaries dilate and allow the blood to flow to the extremities to prevent frostbite and damage, then restrict themselves again. These groups of people have adapted so that their capillary response is much quicker than those peoples who live in more temperate zones. Those who hail from more equatorial zones lack the response entirely. Polar peoples also have a larger quantity of brown fat cells, cells that don't store fat, but burn it to generate heat. The combination of these small adaptions could allow a human to hunt and forage longer in the cold, a skill that might allow survival to reproductive age.

Maybe, just maybe, those who are genetically predisposed to diabetes are those descended from places where there was a sudden advance of the ice sheets in the Younger Dryas period 13000 years ago? Diabetes may have helped certain groups survive the last ice age. There is definitely a cold link to the disease. More diabetes is diagnosed in the colder months-between November and February in the northern hemisphere. Children with Type I are usually diagnosed when the temps drop in the Fall of the year.

Adaption is a two way street. Natural selection chooses a technique that will allow the organism to survive an immediate threat, BUT, the adaption may weaken the organism in other areas. For example, peacock feathers make him more attractive to females, but also make him more obvious to predators.