(I don't know whether this is a genuine "linguistics" problem as of how "linguistics" is defined, but it has bothered my curiosity for so long I have to ask it somewhere.)
When we scientifically study something, we almost always try to come up with a hypothesis which states what kind of factors made this thing the way it is today. An example: The fact that the majority of creatures breathe oxygen, and have water as the basic medium for metabolism, is explained by the factors that for billions of years on earth, oxygen and water have been the dominant elements in the environment. On the contrary, some creatures live without oxygen, because where they live another resource is dominant instead of oxygen. According to the same logic, we could reasonably(though not 100% surely) infer that on a planet where CO is the dominant gas, the creatures, if already formed, will very probably be using CO as an important part for metabolism. By this way, we are constructing a reproducible prediction of how things are formed, based on some observable factors. We are providing an explanation “why” things are the way they are.
Another more relevant example: A popular hypothesis states that Northern European people generally have pale skin, because pale skin absorbs Vitamin D better than dark skin. Another hypothesis states that an agricultural & centralized society formed in China & Egypt because of the closed & fertile nature of their land, while the island/sea conditions of ancient Greece contributed to its commercialism & openness. These are not as easy to attest to as the above hypothesis of why creatures breathe oxygen. But they're still reasonable hypotheses.
I don’t know whether we can apply the same logic to the formation of languages. Languages around the world are very distinct. However I do not believe they just became the way they are today totally out of random. That is to say, for example, while some languages are synthetic, some others are analytic. While some are tonal, some others are not. These are classifications comparable to the dark/pale skin colors, differences in torso lengths etc among different races. As I have seen, linguistics has largely been about studying what are the differences between these different languages, but I haven’t been able to find any study about why these differences were formed in the first place, or, put it another way, what (practical) factores could have contributed to the different characteristics of different languages. which to me appears to be a fascinating topic.
My questions are:
Does any relevant concentrated study exist on this topic?(I don’t believe such study doesn’t exist at all...)
If so, what do they propose? Does any of you have a reasonable hypothesis about it?
If not, why? Is it because of the sheer difficulty in realizing such a study, because of our limitation on historical knowledge as well as tools and methods available to conducting such a study?
Or is it that I am just talking nonsense and the formation of languages is a totally distinct process, different in nature, that cannot be compared to the examples I proposed? Or is it really just a very random process which cannot be analyzed and attributed to factors as such?(i.e. even given the same environmental/societal conditions, totally different languages characteristics would have been formed).