This summary written in March 1999, with latest additions in May 2002.
Most North Americans seem to hold to the romantic belief that the tropical rain forest is an idyllic place to live, with an abundance of natural wild foods that provide primitive peoples with all they can eat with less than two hours of work a day. Perhaps the major source of this myth comes from Hollywood’s Tarzan movies: hero Tarzan swings out on a vine, picks a few bananas, swings back and hands them to Jane to eat, and then they go into their tree house and make love for the rest of the day.
For some of us who have left the movie theater and actually gone out and lived with human foragers in a tropical forest, sooner or later we come to realize just how difficult it is for native peoples to live and to find wild foods in such environments. After I had lived for most of a quarter century in the Sierra Madre, the largest rain forest in the Philippines, I wrote an essay to dispel this myth of such forests being a cornucopia of foods. In fact, I argued, it would have been impossible for any human group to have survived for long in tropical rain forests without at least some access to cultivated starch foods. I first proposed this hypothesis in my dissertation, Why Foragers Do Not Become Farmers (Headland 1986:178-184). A year later I refined the argument and published it as an article in the journal Human Ecology titled "The Wild Yam Question." The core of the hypothesis was this:
It has been generally assumed until recently that tropical rain forests are food-rich biomes for human foragers, and that prehistoric hunter-gatherers once lived completely independent of cultivated foods in such environments. An alternative hypothesis that such forests are actually food-poor for humans is proposed here. Specifically, that wild starch foods such as yams were so scarce and so hard to extract that human foragers could not have lived in such biomes without recourse to cultivated foods.... [Headland 1987:463]
Interestingly, another anthropologist, Robert Bailey, was at the same time developing the same argument, based on his many years of studies of Pygmies in the rain forests of central Africa. His seminal article was published in American Anthropologist in 1989. Bailey’s abstract summarized it this way:
Studies of tropical forest hunting and gathering peoples have contributed to our perceptions of the foraging way of life. Yet no peoples have ever been directly observed living independently of agriculture in tropical rain forest. This article tests the hypothesis that humans do not exist nor have ever existed independently of agriculture in tropical rain forest. We find no convincing ... evidence ... for pure foragers in undisturbed tropical rain forests.... [Bailey et al. 1989:59]
Bailey was developing his argument completely independent of me, and I of him. Indeed, we had never heard of each other until our papers were in press. The thesis, probably poorly named "the wild yam question," soon attracted a good deal of interest. At the 1991 annual meeting of the American Anthropological Association there were four different symposia that focused on the topic. (The names of the organizers and titles of those sessions are listed on page 261 of volume 19 of the journal Human Ecology.) And all of the articles in the special June issue of Human Ecology that year were dedicated to the topic (Headland and Bailey 1991). Both of the original essays are cited frequently in the literature, and at least a dozen researchers have gone into the field to gather data for testing the hypothesis. One doctoral dissertation came out in 1996 subtitled "A Reply to the Wild Yam Question" (Stark 1996). Another dissertation (Mercader 1997) came out a year later also contradicting the hypothesis. The opening sentence of Hiroaki Sato's 2001 article on "The potential of edible wild yams as a staple food in the rain forest" says,
My study was greatly stimulated by the hypothesis proposed by Headland (1987) and Bailey et al. (1989), that human beings could never have led a life independent of agriculture in tropical rain forests. [p. 123]The most sophisticated research that has been done on the question is that by Edmond Dounias from the Laboratoire Ermes Institute in France (e-mail email@example.com). He published a very valuable paper on the topic in 2001 (Dounias 2001). It is no surprise to read that Central African Pygmies exploit forest yams. But it is important to understand that although these appear to be wild yams, Dounias's research shows that many of them are actually "paracultivated" (his term). That is, the Baka manipulate forest yams, but do not fully domesticate them (p.136). Individual Baka own certain wild yam plots in the forest, with exclusive rights to harvest what they own. When they harvest these yams, they do it in a way that encourages their reproduction so they can come back later and reharvest the same plants. "Paracultivation" means that when the Baka dig up yams, they protect and replant the head of the tuber so it regrows. They leave the terminal part of the tuber in the ground, and refill the hole with organic humus so the plant will produce more tubers (p.144). "Wild yams occupy an intermediate position between wild resources ... and crops" (p.140). Dounias’s years of research on the human use of wild yams in a tropical forest is superior to any other work on the topic, to my knowledge.
Two of the earliest critiques of the Bailey/Headland hypothesis appeared in American Anthropologist (Townsend 1990; Colinvaux and Bush 1991). Bailey (1990, 1991) responded to both of those criticisms. A substantial examination on the subject was posted on the Internet (Barkin 1998). While this author makes some legitimate criticisms of what he calls "the green-desert hypothesis," he errs in confusing main points of the original thesis. Barkin misunderstands the hypothesis when he makes the incorrect claim that "Headland ... hypothesizes that wild yams are the only real way to acquire starches in tropical forests." And again on another page where he states, "Headland ... supposes that wild yams are the only significant source of starch in the rain forest." Later he says, referring to palms, "How could such an obvious ... source of rain forest starch [palms] have escaped Headland and Bailey’s analyses?" In fact, I stated in my articles that yams are only one of several types of edible wild carbohydrates in such forests; and I described both palm pith and palm hearts as another such source. Barkin apparently failed to read our articles carefully.
Still, Barkin and others have found serious deficiencies with the wild yam hypothesis, at least as we originally proposed it in the late 1980s. Solid criticisms have been put forth in the 1990s that bring the hypothesis into question. While the argument fits well for Philippine rain forests (where I did my research), there are other types of tropical forests in other countries that appear to be exceptions to the argument. Roosevelt et al.’s (1996) archaeological report seems to checkmate the Bailey/Headland hypothesis for at least one early Holocene tropical forest area in the Amazon. (But see the three articles by Haynes, Reanier, and Barse (1997) that disagree with Roosevelt et al.’s argument.). Kenneth Good (1995) disagrees with the hypothesis, saying that he is "convinced that hunters and gatherers could have subsisted in Amazonia ... without domesticated plants" in his research area among the Yanomami. Brosius (1991) has pointed out another exception to the hypothesis: sago palm forests in central Borneo which seem to supply sufficient year around starch for the Penan foragers he lived with there. Townsend (1990) and Stark (1996) make the same points for the Sepik in New Guinea, and for Maluku, Indonesia, where sago groves are also found. And there is some evidence that humans were living thousands of years ago in West Malaysia independently of cultivated plant foods (Endicott and Bellwood 1991). The abstracts of several of the arguments appear on another page on this website titled "Human Foragers in Tropical Rain Forests." Sato's (2001) study in the African rain forest also contradicts the hypothesis, leading him to conclude, "I cannot agree with ... Headland's assertion (1987) that it is impossible for hunter-gatherers in the tropical rain forests to lead a life independent of agriculture" (p.133).
Some who have attempted to contradict the hypothesis, however, have drawn their examples not from evergreen nonseasonal rain forests, but from seasonal monsoon forests or dry subtropical deciduous forests (e.g., Gardner 1993). And because we now recognize that most, if not all forests today are anthropogenic (modified by humans), and because many important plants in such forests are neither 'wild' or 'domesticated' (some are in between: 'semicultivated' or what Dounias (above) calls 'paracultivated'), the original hypothesis is no longer as simple as it once seemed. (For example, most of the sago forests in Borneo and Maluku are anthropogenic, with many of the "wild" sago palms actually planted by man.) The best review of the controversy is summarized in an encyclopedia article by Doyle McKey (1996).
Archaeologist Peter Bellwood, the leading authority on the prehistory of the Indo-Malaysian Archipelago, addresses "the empty rain forest theory" (his term) in the second edition of his classic book Prehistory of the Indo-Malaysian Archipelago (1997). He refers to the theory as a recent "important international debate," saying it "concerns the question of whether or not hunters and gatherers could ever have lived in interior equatorial rain forest without regular access to agricultural foodstuffs via trade. According to Headland ... they could not. The debate has been given worldwide significance by [Robert] Bailey et al. (1989), who suggest that interior wet rain forests in Africa, Asia, and America were generally uninhabited before agriculture began. However," says Bellwood, "the archaeological record for Peninsular Malaysia indicates that foragers did inhabit such regions (as accepted by Bailey et al.), albeit in small numbers and probably not everywhere, and have done so for at least 10,000 years.... On the other hand, much of interior Borneo has evidently never supported human populations ... so the hypothesis may work in part for the Punan [people there]. This presents one of the great mysteries of Borneo," continues Bellwood. "Why were there ... no Negritos in the interior here--no apparently autochthonous foragers? Did the Borneo rain forests really keep them out, as suggested by the proponents of the empty rain forest theory? I confess to not knowing the answer" (pp. 133-134).
Bellwood is convinced that the early forest peoples of southern regions of Mainland Southeast Asia "had no true agricultural status" (p. 162). Referring to the Hoabinhian archaeological site at Spirit Cave in northwestern Thailand, Bellwood says that "current opinions ... regard it as part of a foraging lifestyle." Bellwood notes, on the other hand, the contrary results of Y. Kuchikura (1993): "studies of wild yam densities in Peninsular Malaysian rain forests lead him [Kuchikura] to suggest that inland hunter-gatherers there could not have existed in completely undisturbed environments without access to agricultural foods" (p. 162).
The controversy has been recently popularized for undergrad students with a chapter in a textbook on "clashing views on controversial issues in anthropology" edited by Kirk Endicott and Robert Welsch (2001).
- Bailey, Robert C.
- 1990. Exciting Opportunities in Tropical Rain Forests: A Reply to Townsend. American Anthropologist 92:747-748.
- Bailey, Robert C., Mark Jenike, and Robert Rechtman.
- 1991. Reply to Colinvaux and Bush. American Anthropologist 93:160-162.
- Bailey, Robert C., G. Head, M. Jenike, B. Owen, R. Rechtman, and E. Zechenter.
- 1989. Hunting and Gathering in Tropical Rain Forest; Is It Possible? American Anthropologist 91:59-82.
- Barkin, Gareth.
- 1998 [September]. Surviving the Green Desert: The Headland/Bailey Hypothesis and the Penan Foragers. On the Internet at http://www.artsci.wustl.edu/~anthro/courses/361/barkin.html.
- Bellwood, Peter.
- 1997. Prehistory of the Indo-Malaysian Archipelago, Revised Edition. Honolulu, University of Hawaii Press.
- Brosius, J. Peter.
- 1991. Foraging in Tropical Rain Forests: The Case of the Penan of Sarawak. Human Ecology 19:123-150.
- Colinvaux, Paul A., and Mark B. Bush.
- 1991. The Rain-Forest Ecosystem as a Resource for Hunting and Gathering. American Anthropologist 93:153-160.
- Dounias, Edmond.
- 2001. The Management of Wild Yam Tubers by the Baka Pygmies in Southern Cameroon. African Study Monographs, Suppl. 26:135-156. [March].
- Endicott, Kirk, and Peter Bellwood.
- 1991. The Possibility of Independent Foraging in the Rain Forest of Peninsular Malaysia. Human Ecology 19:151-185.
- Endicott, Kirk M., and Robert Welsch, eds.
- 2001. Do Hunter-Gatherers Need Supplemental Food Sources to Live in Tropical Rain Forests? Yes: T. Headland. No: S. Bahuchet, et al. In Taking Sides: Clashing Views on Controversial Issues in Anthropology. Kirk Endicott and R. Welsch, eds. Pp. 226-249. Guilford, CT: McGraw-Hill/Dushkin.
- Gardner, Peter M.
- 1993. Dimensions of Subsistence Foraging in South India. Ethnology 32:109-144.
- Good, Kenneth.
- 1995. "Yanomami of Venezuela: Foragers or Farmers, Which Came First?" In Indigenous Peoples and the Future of Amazonia. Leslie E. Sponsel, ed. Pp. 113-118. Tucson: U of Arizona Press.
- Haynes, C. Vance, et al.
- 1997. Dating a Paleoindian Site in the Amazon in Comparison with Clovis Cuture. Science 275: 1948-1952.
- Headland, Thomas N.
- 1986. Why Foragers Do Not Become Farmers: A Historical Study of a Changing Ecosystem and Its Effect on a Negrito Hunter-Gatherer Group in the Philippines. Ann Arbor: University Microfilms International.
- Headland, Thomas N.
- 1987. The Wild Yam Question: How Well Could Independent Hunter-Gatherers Live in a Tropical Rain Forest Ecosystem? Human Ecology 15:463-491.
- Headland, Thomas N., and Robert C. Bailey, editors.
- 1991. Human Foragers in Tropical Rain Forests. New York: Plenum. [A special issue of the journal Human Ecology, vol. 19, no. 2, June.]
- Kuchikura, Y.
- 1993. Wild yams in the tropical rain forest. Man and Culture in Oceania 9:103-126.
- McKey, Doyle B.
- 1996. Wild Yam Question. In Encyclopedia of Cultural Anthropology. Volume 4. D. Levinson and M. Ember, editors. Pp. 1363-1366. [HRAF]. New York: Henry Holt.
- Mercader JF.
- 1997. Bajo el Techo Forestal: la Evolución del Poblamiento en el Bosque Ecuatorial del Ituri, Zaire. Tésis Doctoral, Facultad de Historia, Universidad Computense de Madrid: Madrid.
- Roosevelt, Anna, et al.
- 1996. Cave Dwellers In the Amazon. Science 272:373-384.
- Sato, Hiroaki
- 2001. The Potential of Edible Wild Yams and Yam-like Plants as a Staple Food Resource in the African Tropical Rain Forest. African Study Monographs, Suppl. 26:123-134. [March].
- Stark, Kenneth J.
- 1996. Alternative Rainforest Economies of Maluku, Indonesia: A Reply to the "Wild Yam Hypothesis." Ann Arbor: University Microfilms International. [Order no. 9629856.]
- Townsend, Patricia K.
- 1990. On the Possibility/Impossibility of Tropical Forest Hunting and Gathering. American Anthropology 92:745-747.