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IN THE once-seedy district of Soho, about 10 minutes’ walk from New Scientist‘s London offices, a pump, a plaque and a pub commemorate one of the greatest ever breakthroughs in human history: a decisive step made almost 200 years ago towards conquering infectious disease.

Our current global health crisis is a reminder of how little we want to return to the days when deadly infections carried away most of us. Yet also in some way, advances back then were a first step on a path towards planetary perdition. The success against infectious disease, alongside other major developments, dramatically improved our survival and set humanity’s numbers soaring, from little more than 1.25 billion people back then to 7.7 billion now.

Now, climate change, biodiversity loss, the degradation of the biosphere and, yes, coronavirus are forcing us to consider the legacy of that success. The pandemic is becoming the latest focus for an old, uniquely contentious question: are there just too many of us on the planet?

The basic argument is hard to deny. With fewer of us around, there would be fewer greenhouse gas emissions, less pollution and waste, more space for both us and the rest of the natural world to survive and thrive.

So let’s bite the bullet. Let’s talk about population – where it is heading globally, what that means for the planet, and what, if anything, we should be doing to limit its growth. Be warned, however: finding answers isn’t nearly as easy as posing questions. And with scenes of sexism, racism, nationalism, misogyny and eugenics, what follows at times makes for uncomfortable viewing. …