Scientists have estimated that over the course of Earth's history, anywhere between 1 and 4 billion species have existed on this planet. Be it through disease, genetic obsolescence, over-predation or any number of other factors, the overwhelming majority of these species are now extinct. Of these billions of species, roughly 50 million still survive into the modern era. While these numbers are certainly extreme at first glance, it serves as proof that extinction, while a sad occurrence, is a part of life for all living things.
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