What are the different ways a body can adapt?

What are some of the ways the human body adapts to hardships, resulting in a more efficient body, theoretically speaking?

I’ll start us off: Don’t family doctors, and people who are subjected to sicknesses all the time, have better immune systems? Their immune system has seen many more strains of viruses and bacteria than mine, so they are more equipped to fight illness, right?

Is lifting weights and getting stronger/raising testosterone levels one?

Is sun exposure one? Mild exposure over a length of time produces a more protective layer of skin against UV?

Maybe small amounts of carbon monoxide exposure twice a week could cause your body to start expecting it and “prepare” somehow?

The reason I ask is that my brother is always saying that if you treat your body bad sometimes, it will be a better body than if you treat it good and pamper it all the time (always good sleep, diet, exercise, clean air). He’s a cute kid, and has no scientific evidence to back this up, but he swears he’s right. So, let’s give him a chance and provide some examples, or maybe refuting evidence to stifle him.


I’m going to be lazy with the sites on this one so if anyone wants to back me up or disagree please feel free.

  1. Yes and no, exposure to viruses early in life do strengthen the immune system. (I’m remembering a study about farm kids versus city kids. Can’t find the site though.) But viruses are mutating all the time so this strengthening is always mitigated when encountering a new mutation of the same virus.
  2. Yes. Weightlifting does change the body in the way you are describing. Interestingly the muscles in the upper legs tend to have the most effect on increasing testosterone.
    3.Yes and No. What you are talking bout is melamine. It is the substance within the cells that makes skin darker and blocks UV. There was an interesting story about skin color and geographic location in Scientific American last month. The darker the skin the less Vitamin D it produces but the more B12 it retains (It was either b12 or b6, I can’t remember right now) They concluded that the major cause of darker skin wasn’t cancer prevention, but this balance of Vitamin D and B12./ All exposure to the sun is cumulative and increases your chance of skin cancer. Regular exposure just increases your chance of getting cancer.
    4.NO, Don’t expose yourself to any Carbon Monoxide. It bonds to the iron in hemoglobin and destroys the red blood cells. Not to mention that it will impair your judgment and you will not be able to regulate your exposure to it after a certain point, which could result ion serious, permanent brain damage or death. I think what you are looking for is acclimatization. This is the process in which the body adapts to higher altitude and less dense air. It can have dramatic effects on athletic performance, but the only practical way to expose your self to it in a beneficial is to build a house at high altitude and do your physical training at a lower altitude. Many cross-country skiers and professional cyclist do this.

As an overall theory it has a lot of holes in it. But if you want a dramatic example of instance where it is true just do a yahoo search on free diving.

Generally, that “that which doesn’t kill you makes your stronger” stuff is bunk. No, it brings you closer to death. Not usually a good thing.

Certain systems adapt to relatively harmless things. People living a hard life, physical work, pre-industrial age, developed differently than we do. Starts with thicker skin where needed, stronger & bigger tendons, then your bones actually take on a different shape. You can tell what social level a 2 thousand year old skeleton was at by the attachment points of tendons to the bones. (Teeth would also “adapt” to coarsely ground flour by wearing away quicker. Not a good thing. Some parts can build back up, many can’t.)

You can also adapt to dietary changes (usually). People get used to spicier foods all the time. But if you’re lactose intolerant, that’s it.

If you want to see a great example of fairly rapid adaptation, check out mountain climbers on Everest. By stopping at base camps for extended periods of time, they can condition their bodies to allow them to function and stay concious at altitudes that would knock them cold in seconds if they weren’t acclimated.