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Primates: Missing Our Relatives

Why are humans so bent on destroying primates’ habitats?

July 14, 2002

Why are humans so bent on destroying primates' habitats?

When the last Ice Age ended 10,000 years ago, baboons outnumbered humans by at least two to one. In fact, back then non-human primate populations literally dwarfed the world's human population.

All of that has changed, of course. The development of agriculture allowed for rapid human population growth.

About 2,000 years ago, humans — at that time numbering 300 million — became the most abundant of the primates.

And by 1930, the human population of 2 billion likely outnumbered all other primates combined.

Today, however, at 6.1 billion and climbing, we are threatening the survival of many of our primate cousins — including our closest living relatives, the chimpanzees and bonobos.

The other ape species are also quite close to us as well — not only genetically, but also in observed behavior. And yet, the 300,000 human babies born each day exceed the total population of the great apes at present. Thus, even our evolutionary proximity may not prevent us from eradicating our near-kin.

While humans now inhabit every corner of the earth, almost three quarters of all primates live in just four countries: Brazil, the Democratic Republic of the Congo (formerly Zaire), Indonesia and Madagascar.

In each of these countries, forest cover is decreasing. Because habitat loss is a danger to 90% of threatened primates, their concentration in a few countries greatly increases their vulnerability.

Take, for example, the case of bonobos, a species of great apes that closely resembles the chimpanzee — that live mostly in the Congo.

Scientists have found that the DNA of bonobos and humans differs by only 1.4% — making the bonobo our closest living relative.

But along with many other primates in the region, the slow-breeding bonobo has seen a rapid decline. In 1980, there were close to 100,000 bonobos. Now, there may be fewer than 10,000.

For years, the Congo has been plagued by civil war and occupation by foreign military and rebel groups. This turmoil has created millions of human refugees — and may have elevated the demand for meat from wild animals (bushmeat).

Yet, the war-induced sluggish economic development — quite logically, yet perversely — may have slowed logging in the Congo, which contains half of Africa’s remaining tropical moist forests.

By the same token, the desirable return of political stability might trigger an unfortunate effect: Tree-cutting could increase several-fold in the next few years, accelerating what could be the first great ape extinction.

Gorilla populations have also dropped to dangerously low levels, largely from illegal commercial bushmeat hunting. Fewer than 325 mountain gorillas exist — and all of them reside in one subpopulation spanning Rwanda, the Congo and Uganda.

The Cross River Gorilla is the most endangered subspecies of gorilla, with only 150 to 200 individuals remaining in the world.

In parts of West and Central Africa, hunting is an even greater threat than forest loss. There, the bushmeat trade — consisting primarily of forest antelope, pigs and primates — is worth over $1 billion a year.

In areas where social turmoil has ravaged traditional economic activities, and the average annual family income is less than $100, the lure of earning $300 to $1,000 each year as a hunter has enticed many to turn to this devastating occupation.

Exploitative hunting is not profitable in the long term, however. Wild populations, especially those of the large and slow-reproducing apes, are soon decimated by it.

Over one million tons of wild meat is consumed annually in the Congo Basin — almost six times more than the forests’ sustainable yield. Commercial hunting has emptied forests that were once full of animals.

As cities grow and bushmeat hunting accelerates to meet rising demand, it is estimated that hunting could eliminate all viable African ape populations in fewer than 20 years — eradicating a valuable link to knowledge about our own species.

To save other primates from being lost in what is considered the earth’s sixth major extinction event, more resources are needed to curb illegal logging and hunting, especially in Africa. Illegal logging has ruined vast stretches of original primate habitat.

Much of the bushmeat hunted comes from protected areas and international trade in primates is already unlawful under the Convention on International Trade in Endangered Species.

Large wilderness blocks of biologically rich areas could be converted to new parks that take into account the needs of wildlife and human populations.

Ecotourism endeavors can be used to support primate conservation.

And hunters can find alternative income in park protection work once they realize that live animals can be much more valuable than dead ones.

Certainly, the extinction of our closest relatives would be an ecological disaster. It would be a biological disaster as well — in the most intimate sense.

Understanding ourselves better — our biology, psychology and sociology — depends in part on understanding our closest living relatives better. Thus, if we do not act to prevent their destruction, we may never fully understand ourselves.