It should be no secret that all living things adapt to their environment in some way. If the environment changes over a long period of time, so do the species living in it. Those that cannot adapt die off, those that adapt best carry on their genes to future generations because there are more of them. These future generations then take on new traits (beginning as genetic abnormalities) which, if favorable to the environment, will spread, and eventually the "abnormal" trait will become the dominant trait, because the creatures with these creatures with the favorable traits will outlast those without and pass on their genes.
This is the process of evolution, and natural selection. Dinosaurs for instance did not just magically begin as these giant dominant creatures, they began as tiny reptiles that gained an advantage over other forms of life by their speed and being able to walk on two legs, which eventually mushroomed into them becoming the dominant life form and becoming these gargantuan beasts. This seems like a relatively obvious scientific concept, yet some people still refuse to believe it, for religious reasons or whatever else.. The fact is, species are always evolving, either in response to a changing environment, or in gaining favorable traits that give them an advantage in the existing environment.
Of course, this is a process that extends over tens, even hundreds of thousands of years, so the idea that we could be witnessing a species beginning to take on a new trait in response to a new environment in our very short lifetime is very spectacular.
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