HAINAN gibbons sing to each other every morning; but these days they do not have much to sing about. The species (pictured) is endemic to a Chinese island that is not just a fruitful producer of rice and rubber but also a golfer’s paradise. Most of its forests have been destroyed to accommodate these activities, and the gibbon population is down to a couple of dozen. If the species disappears, it will be the first ape to go extinct since the beginning of the Holocene era 12,000 years ago.

The Hainan gibbon is only one of 4,224 species listed as critically endangered by the International Union for the Conservation of Nature. Attention tends to focus on mammals and birds, but amphibia, such as frogs, are even more at risk.

Over the past few centuries mankind’s economic growth has caused many of the problems that other species face. But as our special report this week argues, greater human prosperity now offers other species their best chance of hanging on.

What did for the dinosaurs

There have been five great extinctions in the history of Earth. One killed off the dinosaurs; another wiped out up to 96% of species on Earth. All were probably caused by geological events or asteroids. Many scientists think a sixth is under way, this one caused by man.

From the time that he first sharpened a spear, technological progress and economic growth have allowed man to dominate the planet. He is reckoned to be responsible for wiping out much of the megafauna—giant elk, aurochs, marsupial lions—that once populated Earth. When he paddled across the Pacific he exterminated 50-90% of the bird life on the islands he colonised. Technology allowed him to kill creatures and chop down forests more efficiently and to produce enough food to sustain 7 billion people. As a result, over the past few centuries extinctions are thought to have been running at around 100 times the rate they would run at in his absence.

Yet when people start to reach middle-income level, other species start to benefit. That is partly because as people get richer, their interests begin to extend beyond necessities towards luxuries: for some people that means expensive shoes, for others a day’s bird-watching. Green pressure groups start leaning on government, and governments pass laws to constrain companies from damaging the environment. In the West, a posse of pressure groups such as Greenpeace and the Environmental Defence Fund started up in the 1960s and helped bring about legislation in the 1970s and 1980s.

Growth also has indirect benefits for biodiversity. People clean up their environment in ways that help other species: through building sewage-treatment plants, for instance, and banning factories from pouring effluent into rivers. Prosperity and peace tend to go together, and conflict hurts other creatures as well as man, as the wars in the Congo have shown. Richer countries generally have better governments, and conservation cannot work without an effective state. Agricultural yields rise, allowing more food to be produced on less land. Population growth rates fall: in East Asia, fertility has dropped from 5.3 children per woman in the 1960s to 1.6 now.

One consequence is that in rich countries conditions for other species are, by and large, improving, and endangered creatures are moving away from the edge of the cliff. America’s bald eagle, for instance, was down to 412 breeding pairs in the 1960s. There are now 7,066. Whale populations are mostly recovering thanks to a moratorium on commercial whaling. More broadly, the Living Planet Index, a compilation of a wide range of indicators of biodiversity produced by the Zoological Society of London and WWF, has risen over the past 40 years in temperate (generally rich) countries and fallen in tropical (generally poor) ones. This is not just because rich countries export their growth to emerging markets. Look, for instance, at the fate of the forests on the Korean peninsula: in South Korea, one of the world’s fastest-growing countries in recent decades, forest cover is stable, whereas North Korea has lost a third of its forests in the past 20 years. Nobody exported their growth to North Korea.

In emerging markets some indicators are improving as people press governments to look after the environment better. Deforestation in the Brazilian Amazon, for instance, has fallen from 28,000 sq km in 2004 to 5,000 sq km last year. From a standing start in 1982, China has given over three times as much land to national parks as America has.

Gee up GM

But the problem is by no means solved. Thousands of species are teetering on the edge of extinction. Whether or not they tip over depends in large part on two factors. One is climate change. If the temperature increase is at the medium to high end of the estimated range, then a biodiversity catastrophe is very likely. If it remains at the lower end—which the current hiatus in warming suggests is possible—then most species should not be too badly affected. The second is the demand for land. Habitat loss is the biggest threat to biodiversity. Mankind already cultivates around 40% of Earth’s land surface, and the demand for food is expected to double by 2050. If that demand is to be met without much more land being ploughed, yields will have to increase sharply. That means more fertiliser, pesticide and genetically modified (GM) seeds.

For this to happen, the green movement needs to change its attitude. It has helped other species by pressing governments for change, but some greens want growth to slow and most oppose intensive farming. They have made Europe a no-go zone for new GM crops, and have exported their damaging prejudices to Africa and Asia, to the detriment of biodiversity.

No doubt most of the planet’s other species would have been better off if mankind had never lifted that first spear. The technological progress and economic growth that followed have brought Earth to the edge of the sixth great extinction. But more progress not less offers the best chance of averting it. The Hainan gibbon’s current plight is an improvement on ten years ago, when the chorus was down to a dozen. With a great deal of care, it might just survive to sing for many years yet.