Carlie asked:
I have a question: I have heard that it is not actually possible for a human to adapt to a certain type of weather. My roommate was saying this after she learned it in a class (she is pre-med). But apparently, if you live in a warm place all of your life, you do not become more adapted to it in any way. Same goes with extreme cold. Is it just that we are mentally better to deal with it? Or what?
Phrased as it is, that's a difficult question to answer. I'm going to assume that by 'adaptation' one means '
hysiological' adaptation, because from my classes, I figured that patterned behavioral changes are also adaptations- that there's not much point to arbitrarily dividing behavioral and physical attributes.
I'm not sure how correct I am, but I'm under the impression that as far as preserving the balance in bodily processes, certain things are more important than others. Specifically, temperature, fluid balance and the concentration of various ions/electrolytes in the blood must be kept fairly constant by the body otherwise certain things simply don't work. Enzymes that are crucial to our metabolic processes only work within a narrow pH and temperature range, for example- otherwise they denature and fall apart and, well, you die.
With this in mind, the body prioritises its functions. Longterm exposure to extremes of temperature will have your body responding accordingly with its default physiological mechanisms (shivering in cold, sweating when hot) but since certain metabolic processes are consistent in their output and others parameters must be kept constant, I'm guessing that the only actual 'adaptations' would be the physiological changes that come incidentally with the behavioral ones.
For example, if I was in a cold environment, I'd probably be inclined to eat more because more insulation is good and I'll also be burning more energy just to keep the body's core temperature constant. However, my body couldn't somehow regulate my temperature by burning more energy on its own- you can't get something for nothing and the byproducts of a process isn't something your body can change in the short term. Likewise, humidity would be another factor that your body cannot adapt to in that way.
One of the major factors that defines how you react to climate conditions as a whole would be endocrine function as that would largely dictate the parameters of your metabolic functioning. I won't go into the details of it as it's much too complicated and what little I learnt of it I've kinda forgotten anyway :P But I am under the impression that our endocrine system doesn't react to changes in temperature/humidity trends- it's governed by the signals it gets from its own internal messengers: hormones.
One 'climate' variable that I can think of that the body adapts to would be altitude and therefore air pressure. Seeing as oxygen is kinda important to us, if there's less of it in the air, the heart will raise its output accordingly to make sure that the tissues are still getting the required amount, and over time the muscle will thicken. The blood also thickens as more RBCs are produced, and the efficiency of delivery of oxygen to tissues and tolerance of by-product buildup is increased.
This doesn't come for free, either. Thicker blood makes it harder on the heart, and the body, being more stressed, is susceptible to pathology. Furthermore the body starts consuming muscle at high altitudes in order to provide energy just to keep going.
The object lesson really is that optimal conditions are just that. Your body will try to cope with everything it can but nothing comes for free.
