The world population has just hit a new record: 8 billion. As is often the case, there are heated debates about the planet's so-called "carrying capacity" – the total number of people who can live on Earth sustainably. Experts are generally divided into two camps. There are those who argue that we need to drastically reduce the human population to avoid ecological catastrophe. And then there are those who believe that technology will find smart solutions without any need to actively tackle the issue head-on. Scientists have been debating such demographic issues at least since the 18th century, when Thomas…