Earth isn’t really that big, if you think about it. Biodiversity on Earth is really a wide span.
In: Biology
I’m reading all these with great interest. Thanks everyone who has answered!! I value knowledge above almost anything else 🙂
While it doesn’t seem that big we actually have a very wide range in terms of habitable territory, all the way from above the Arctic Circle through to the Sahara Desert, the Amazon rainforest, and all sorts of habitats in between. When we were less technologically adept than we are in modern day, evolution had a greater role in selecting beneficial traits: ability to block solar radiation, conserve/shed body heat, handle higher or lower altitudes, etc.
On top of this, we are learning that the legacies of at least (and possibly more) *three* humanities that contribute to what we now know as humanity: the “standard” Homo sapiens model that came out of Africa last, which comprises the majority of our DNA, Homo neanderthalensis, which was found in Eurasia, and Homo denisova. There could be even more humanities that contributed to our current gene pool and heritage. This to me is incredibly fascinating and exciting news!
That said…and this might address some of the context of your question…we are now driving our own evolution and acting on our environment to shape it for our purposes, more than it acts upon us. We are also becoming more cosmopolitan with ever-accelerating technological, cultural, and genetic interchange. Based on this, barring divergences that could be triggered in the future by deliberate genetic engineering, or long-term genetic drift as a result of a population leaving Earth, there is really not so much of an evolutionary “need” for us to continue diverging from each other…and indeed, as technology and medicine make our environments more and more comparable to each other over time, some of those differences could come to moderate/lessen over time.
Because of evolutionary adaptation.
People with darker skin have more melanin to protect them from the sun. The opposite goes for very light skinned people in cold countries, where as much sun should be absorbed by the skin as possible. Facial features like thin/full lips for heat regulation. Usually a mass of people who all evolved in the same way due to their environment look similar and continue to evolve more in this direction, whereas people from other parts of the world evolved in a different way.
The world is very big. How far is the longest you’ve walked in a day? For me it’s about 15 miles. Almost all of these different people were separated by hundreds of miles with no roads in between. Today with cars and planes we can move much easier, and as a result people are mixing much more, but back then people didn’t want to just spend 3 months walking through a forest to see if other people were there.
They aren’t, it is just that humans are good at spotting the rather minor differences in the species rather like how penguins can tell each other apart. The one major easy difference is skin colour which is due to solar radiation being greater near the equator so darker skins are more useful to prevent sunburn and skin cancer and towards the poles lighter skin is useful to convert sunlight into vitamin D.
Humans are more similar to each other than other animals of other species who can still interbreed. Take dogs for example. Most if not all dogs can still interbreed and yet the variety amongst them is absurdly large.
Yes, some people are of different sizes or have different features but it is at worst on par with the diversity of other animals and realistically much less so.
You recognize more differences between people because you look at more people than you do birds or dogs.
Earth is plenty big enough for biodiversity. Forget the past 200 years. Before vehicles, it was incredibly time consuming to travel long distances. Population Centers developed in relatively isolation for tens of thousands of years. Only recently has modern technology made the planet feel smaller.
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