These days, few environmentalists talk about "overpopulation" as a problem, the way they used to in the 1970s.

But that may be changing, as global population is on course to reaching 8 billion (from today's 6.8) by 2020.

As the graph above show, there's definitely a strong link between human population increase and species extinction.

Should "overpopulation" be put back on the table?

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