The loss of other animal species bodes badly for human beings. A Sumatran orangutan at the MetroZoo in Miami.

Editorial Observer/VERLYN KLINKENBORG

Like everyone, I have been reading the graphs and looking at the numbers that measure the convulsions in the global financial markets. And as I do, I keep hearing the echo of another frightening set of numbers - the ones that gauge the precipitous declines in the species that surround us. The financial markets will eventually come back, but not the species we are squandering.
Last month in Barcelona, Spain, the International Union for the Conservation of Nature released results of a global survey of mammal populations. It concluded that at least a quarter of mammal species are headed toward extinction in the near future. Don’t think of this as an across-the-board culling of mammals, of everything from elephants to the minutest of shrews. The first ones to go will be the big ones. And among the big ones, the first to go will be primates, which are already grievously threatened. Nearly 80 percent of the primate species in southern and southeastern Asia are immediately threatened.
The causes are almost all directly related to human activity, including, for marine mammals, the growing threat of ocean acidification, as the oceans absorb the carbon dioxide we emit.
The numbers are not much better for other categories of life. At least 22 percent of reptile species are at risk of extinction. Perhaps 40 percent of North American freshwater fish are threatened. In Europe, 45 percent of the most common bird species are rapidly declining in numbers, and so are the most common bird species in North America. Similar losses are expected among plants. What is especially worrying is how much the rate of decline has increased over the past half-century as the human population has increased.
These numbers are shocking in their own right. But they don’t begin to tell the whole story. These are projections for the most familiar, best studied, most easily counted plants and animals, which, all told, make up less than 4 percent of the species on Earth. It is only reasonable to assume that many, if not most, of the legions of uncounted species are doing as poorly.
What complicates matters further is a simple lesson we might also draw from the present financial crisis: everything is connected. No species goes down on its own, not without affecting the larger biological community. We emerged, as a species, from the very biodiversity we are destroying. At times it seems as though the human experiment is to see how many species we can do without. As experiments go, it is morally untenable and will end badly for us.
The good news here is the same good news as always - the resilience of nature. Given even the slightest chance, declining species often find a way to recover. But the bad news is also the same bad news - human irresponsibility. In our myopic pursuits, we characteristically overlook the possibility of giving species the chance to recover.
We are watching a global, international effort to stabilize the financial markets. It will take a similar effort to begin to slow the rate at which species are declining. The bottom line is that what is good for biodiversity is also good for humanity. This includes protecting habitat and finding ways to reduce human pressure on other species. It also includes a concerted effort to slow climate change, which, unchecked, could have a devastating impact on the entire planet.
What we need, really, is a new ability to think selfishly in a slightly different way. Instead of saving the Sumatran orangutan or the Iberian lynx for itself, it may make more sense to think of saving them for ourselves - not as resources to be harvested somewhere down the road or even as repositories of genetic difference, but as essential elements in the biological complexity from which we arose and in which we thrive.
Without them, we are diminished.