Over about 3.5 billion years, evolution (descent of species over time, with genetic modification) has produced the astonishing variety and number of life forms found on Earth today. Punctuating this natural evolutionary process of speciation have been five mass extinctions – periods characterized by the rapid (compared to evolutionary processes) loss of over 75% of all species. Past causes of mass extinctions include major changes in ocean and atmospheric chemistry, changes in climate, periods of volcanic activity, and an impact with an asteroid.
According to a recent review article in Nature, we may be about to enter a sixth mass extinction, meaning that over the next 300 to several thousand years we can expect that over 75% of all current species will become extinct. Somewhat disturbing is the suggested cause – humans. Won’t THAT be an interesting and contentious debate over the next 300 years or so!
This is a well-referenced review in a high-quality journal. It’s worth reading if you’re interested in this subject. The notion that the next mass extinction may be caused by humans is only a small part of it.
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