Requirements for adaptation?

Question

The topic probably sounds wrong or something but I'm only 14 so forgive me if I'm asking stupid questions.

Okay, according to my teacher, humans actually didn't look like what we look like now and one piece of evidence is our tail bones. According to her, we stopped using our "tails" and because of that, they got in the way and to adapt (am I using he right term in the first place?) our tails slowly disappeared. She mentioned other examples but I was already confused with this one.

What confused me was, if the tails disappeared just because we found no use for them, then, let's say, mosquito bites annoy us too, so would we in the future not itch anymore or something?

So what exactly causes us to adapt and change physically?

Answer 1

What biologists theorize caused all of the complex and diverse life on this planet is what is known as the theory of evolution. At the center of this theory is something called natural selection. It is kind of like survival of the fittest. The simplest example is of a herd of gazelle's being hunted by a cheetah. The cheetah will catch the slowest of the gazelles, while the fastest ones will escape. When the faster gazelles reproduce, they pass on their genes to their offspring who will also tend to be fast. You may have also heard your teacher talk about genes, the stuff that stores all the information about us (like eye color, gender, hair color, etc). These genes are passed on from generation to generation. However, sometimes, something will go wrong when the genes are being copied and they will not be copied exactly. This is known as a mutation and they occur randomly. While mutations are usually not good for an organism, they are beneficial in some cases. So, it is theorized that the first life on this planet were tiny bacteria and over a couple of billion years these tiny bacteria evolved (through natural selection and random mutations) into the diverse life we see today. You can learn a lot about evolution here:

http://en.wikipedia.org/wiki/Evolution

Wikipedia is not always reliable, but the information on evolution looks to be pretty solid.

Answer 2

You teacher was probably just trying to make a point and used a bad example. Adaptation is not purposeful, it is the result of random genetic change and natural selection. If tails got in the way of an animal, then those individuals with long tails would have a lower survival rate than their short-tailed friends. Over many generations, animals with shorter tails or no tails at all would increase in number at a much higher rate than long-tailed animals, and if the difference in survival is large enough, long-tail individuals would disappear entirely.

Answer 3

We dont actually "adapt" so much as you think of the word as it means. What we do is develop mutations, some are bad some are good. The good mutation, say in this case having no tail, leads that being to strive and is more likely to reproduce. Thus he will introduce the "no tail" gene into his kids who will introduce it into theirs and so on. Eventually the whole race developed with this no tail gene and it was ridden from the population because it was simply better. That is adaptation, which happens over great periods of timel.