The environment of this planet is the result of its distance from the sun, its size, and its chemical and biological composition. The earth has had different climates in the past. At one point in time there were little oxygen, and then it was almost frozen solid. During the age of dinosaurs, it was much hotter, and it was much colder (at least for areas near the north and south poles) during the last ice age that ended 13,000 years ago.
The planet is not designed by anyone. The planet just so happens to have the right stuff (including life forms) that helps it maintain an environment suitable for life. If photosynthetic organisms did not evolve, animals would not be able to evolve because animals need oxygen, and photosynthetic organisms such as bacteria, algae and plants are able to supply it. We are here because of a series of contingencies. If just some of these things failed to happen in the past, we would not be here. For example, if the dinosaurs were not wiped out by a giant meteor that struck the earth, our ancestors, the shrew-like mammals, would probably not be able to evolve beyond the shrew stage. If South America did not collide with North America, the climate in Africa may not have changed. We evolved on the African savanna, because the changing climate starting 5 million years ago dried up africa and turned many forests into savanna. The apes were running out of space, and some of them (our ancestors) were driven away from forests into the savanna. If our ancestors could not survive in the savanna, then we won't be here either.
In fact, monkeys and then apes evolved after Antarctica froze for the first time ever in the history of this planet, about 35 million years ago. Temperatures since then have been far below those during the age of dinosaurs. If global warming continues unchecked, and temperature reach the same high level as the age of dinosaurs, humans may not be able to survive except in the polar regions because the tropics are simply too hot to live for most of us.
· 1 month ago