It is 'the fate of this organism' ... that the more that it learns about the nature of its being and the effect of that being upon its configuration space ... the more deliberatively it 'husbands the uncorrupted' for further discovery -the inevitability, therefore, of eventually least population of least population of least resource/environment corruption...
(-from The 'Black Box' Nature and Course of Human Existence)
September 2, 2005 Science Magazine
Perspectives
NATURAL HISTORY:
Beyond the Chimpanzee Genome: The Threat of Extinction

Marc D. Hauser*

I have had the privilege of watching chimpanzees for many hours in their natural habitat in Africa and in a variety of zoo settings. They are magnificent animals. Watching them is unlike watching any other nonhuman creature. When a chimp looks back at you, your soul has been penetrated. You feel as though your inquisitiveness has been volleyed back, no words or actions exchanged.
   The unveiling of the chimpanzee genome (1) presents a unique opportunity to systematically explore how and why we diverged from our closest living relatives. Perhaps, once and for all, we can begin to figure out the meaning of the tiny differences in DNA between our respective species. Perhaps we will learn how small differences in the code of life enabled us--but not chimpanzees--to cook soufflés, create symphonies, translate our own voyages into maps, build ever more complicated artifacts, and write plays that reflect the social intricacies of our lives. But none of this will have any meaning unless we understand what it is like to be a chimpanzee. Humans are unique, and so too is every other species on this planet. But characterizations of uniqueness only make sense in light of a comparative record, one that documents the anatomy, physiology, and behavior of other species.


Understanding our relatives. Jane Goodall observes a family of chimpanzees
CREDIT: KARL AMMANN/CORBIS

   A map of the genome provides one layer of description. It is a meaningless layer without equally rich descriptions of how genes enable each species to make a living, escape predators, fend off competitors, build allies, and produce babies. In this sense, my greediness to understand extends beyond the chimpanzee genome to that of its closest genetic relative, the bonobo. Although remarkably similar on many levels, bonobos differ from chimpanzees--and resemble humans--in important parts of their skeletal anatomy, brain physiology, sexual behavior, and temperament. In many ways we are "chimpobos," a hybrid ape.
   Thanks to the pioneering work of Jane Goodall [see the figure; (2)] and the many primatologists who have enriched her work since, we now have a detailed description of chimpanzee life. The general public's impression of this life is, however, highly colored by the documentaries presented on television. These focus on the brutality of their hunting and intercommunity killings, or on their exceptional talents with tools. But if you take a snapshot of chimpanzee life at a random moment, here's what you see: eating, sleeping, or grooming.
   Watching a chimpanzee eat may not be the most exhilarating experience for even the most die-hard field biologist, but by documenting what these animals eat, when, how, and for how long, scientists have unlocked some extraordinary mysteries. When chimpanzees are infected with certain pathogens, such as the nematodes that attack them in the Mahale Mountains of Tanzania, they consume plants that act as either chemical or physical defenses. For other ailments, including constipation, lethargy, and lack of hunger, they eat the bitter pith of a plant; this same plant is used across Africa as a local cure for humans infected with bilharzia and malaria. These discoveries, made possible by painstaking observations, have ignited an entire field of inquiry: searching for new remedies in the plant life that surrounds us (3).
   Detailed observations of their eating habits also reveal an exceptionally diverse tool technology (4). On the basis of studies spanning the natural range of chimpanzees in eastern and western Africa, we now know that different populations use different tools to gain access to their local resources. Some use sticks to extract termites, others use rocks to crack open hard nuts, and yet others use tree bark as sandals to climb over the thorny needles of trees that hold a delectable fruit. The variation among populations is not due to genes, but rather to the capacity for social learning that the genes have built. What we see when we watch a chimpanzee population is a microculture--one that has developed its own unique signature, evidenced by distinctive tool technologies and, in many cases, equally distinctive social gestures (5).
   When chimpanzees eat, sometimes they do so in the midst of several other community members, and sometimes they do so alone. Here, sex differences emerge. Males live in their natal groups for life, whereas females leave once they reach reproductive maturity. When you watch chimpanzees in the wild, it is not uncommon to find an adult female, either alone or with her offspring. Seeing a male alone is rare. Many of the males in a community are brothers. They hunt together, cooperate to form alliances against other members of the community, and often go off on patrols to defend their turf against often violent neighbors. Like our own species, but unlike their close relative the bonobo, chimpanzee males are extremely aggressive toward their neighbors. If members of one community have outnumbered a foe, they will attack and kill a member of another community who has wandered too far from home (6, 7); some of the calculations used in making such group decisions may be carried out with the chimps' exquisite mathematical prowess (5, 8). Watching such kills is chilling. It is too close for comfort.
   When chimpanzees cluster into social groups, the political strategizing that goes on reflects planning, power, and peace offerings (9). Studies in the wild and in captivity, especially the latter, have revealed that individuals both compete and cooperate by making inferences about what others know and intend (10, 11). These studies have revolutionized our understanding of what chimpanzees think and feel, raising profound philosophical questions about the nature of thought without language, as well as ethical questions concerning the rights and welfare of these animals (12).
   Constraining our continued understanding of this wonderful animal is one annoying hurdle: our own species. In the very near future, we may ironically face the possibility of having a detailed map of the chimpanzee genome, but no individuals to study. Illegal hunting, the bushmeat trade, and deforestation are destroying chimpanzee populations (see, for example, www.chimpcollaboratory.org). If the same amount of effort that is going into genetic analyses went into chimpanzee conservation and behavioral biology, not only would we save this species from extinction, but we would write the most detailed story of our past--as rich as the Bible, but grounded in science.
~~~~~~~~~~~~
References and Notes
1. The Chimpanzee Sequencing and Analysis Consortium, Nature 437, 69 (2005).
2. J. Goodall, The Chimpanzees of Gombe: Patterns of Behavior (Belknap/Harvard, Cambridge, MA, 1986).
3. M. A. Huffman, R. W. Wrangham, in Chimpanzee Cultures. R. W. Wrangham, W. C. McGrew, F. B. M. de Waal, P. G. Heltne, Eds. (Harvard Univ. Press, Cambridge, MA, 1994), pp. 129-148 [publisher's information].
4. A. Whiten et al., Nature 399, 682 (1999) [Medline].
5. T. Matsuzawa, Primate Origins of Human Cognition and Behavior (Springer-Verlag, Berlin, 2002) [publisher's information].
6. M. L. Wilson, M. D. Hauser, R. W. Wrangham, Anim. Behav. 61, 1203 (2001) [Abstract].
7. R. W. Wrangham, D. Peterson, Demonic Males (Houghton Mifflin, New York, 1996).
8. M. D. Hauser, Wild Minds: What Animals Really Think (Holt, New York, 2000).
9. F. B. M. de Waal, Chimpanzee Politics: Power and Sex Among Apes (Harper & Row, New York, 1982).
10. D. Premack, A. Premack, Original Intelligence (McGraw-Hill, New York, 2002).
11. M. Tomasello, J. Call, B. Hare, Trends Cognit. Sci. 7, 153 (2003) [Medline].
12. P. Cavalieri, P. Singer, The Great Ape Project: Equality Beyond Humanity (St. Martin's, New York, 1994) [publisher's information].
13. I thank three of my closest colleagues for comments on this essay: F. de Waal, B. Hare, and R. Wrangham.

   10.1126/science.1111421 The author is in the Departments of Psychology, Organismic and Evolutionary Biology, and Biological Anthropology, Harvard University, Cambridge, MA 02138, USA. E-mail: mdh@wjh.harvard.edu
   10.1126/science.1111421
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