Savanna theory
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The savanna theory is the term used by those in favour of the aquatic ape hypothesis for an old conventional understanding of how humans acquired bipedalism (walking on two feet) and other human aspects. The savanna theory, as opposed to the aquatic ape hypothesis, does not involve aquatic or littoral environments as an important element in developing the distinct traits of the human. Some of the more modern conventional ideas on the environments that influenced human evolution might be better described as mosaic theory, with humans evolving in a sparse mosaic forest. However mosaic theory also does not involve water as a major environmental influence on human evolution. As savanna theory is a term mostly used by those who favour the aquatic ape theory to denote what some of them consider the main opposing theory, most of this page concerns the arguments made against the savanna theory. For an overview of human evolution in general see the human evolution page.
The origins of savanna theory are linked with Professor Raymond Dart, a South African paleoanthropologist credited with the discovery of the Taung skull in 1925. The Taung skull was the first recognized link between man and the great apes, and Prof. Dart based his theory on the modern location of the discovered fossils. Despite now knowing that the conditions under which the Taung skull was deposited were much wetter than currently, the savanna theory remains a linchpin of modern anthropology (Cf., e.g., Scientific American, April 2006, "Why Are Some Animal So Smart?", pg. 71).
The savanna theory paradigm posits that the early hominids or proto-people were faced with shrinking forests and in order to survive took to bipedalism, venturing out into the savanna, a dry, open grass/woodland environment, in search of game. Humans, the theory goes, were able to do this because they are generalist animals and could adapt to many different circumstances.
"Generalist" is not a scientific term, but like the other great apes, humans are omnivores with a fairly restricted range. Their unique daily water requirements, until the discovery of water portability, limited the amount of time they could spend away from a potable water source. There is strong evidence that the first domesticated plant was the bottle gourd (Cf: The Gourd Book; Charles Bixler Heiser, 1979).
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[edit] Problems with the theory
The savanna theory has been cited for many problems, foremost among them tying it to an unlikely event: changing one's natural habitat. It has not been established that this is possible; at least in the circumstances given. Two of the major factors combining to hinder habitat transference are the slow regularity at which mutations take place compared to the swiftness of environmental collapse, which can occur in anything from a matter of seconds to some hundreds or thousands of years. The current phase of massive environmental collapse (global warming, etc.) is being accompanied by massive extinctions, not massive adaptations. The rule of thumb is: by the time one needs evolutionary change to survive, it's too late.
Another major factor affecting habitat transference is opportunity. Evolution is governed by opportunity, not necessity. Successfully using evolution to survive, even given sufficient time, is only possible if there is an available biological niche into which to evolve, which only happens under rare circumstances.
A further problem with the savanna theory is the timing and location of the disappearing forests as new discoveries constantly push back the earliest date of bipedalism.
Further timing problems of the savanna theory are related to cultural adaptations necessary for savanna habitation aside from water portability, such as tool development; for example, sufficiently effective offensive and defensive weaponry wasn't developed until millions of years after the advent of bipedalism.
Perhaps the greatest obstacle to the savanna theory derives from human anatomy, which is ill-suited for life in open countryside without protective weaponry and clothing, and it's hard to see how humans could have survived in the savannas prior to their invention.
The last serious challenge to the savanna theory is demographic. It is tautological that a species cannot live outside its natural habitat, therefore, where a species does live is, by definition, its natural habitat. Human demographics establish that the vast majority of people live within a few miles of a navigable waterway. Furthermore, all people either have water piped into their homes or live within a few hundred yards of potable water. If humans' natural habitat were the savanna, then the vast majority of us would still be inhabiting the savannas, and Nebraska would be teeming with people and New York a minor port town. That Nebraska is not teeming with people means either that people changed their natural habitat again (no more likely a second time around), this time from savanna to shoreline, or that there was never a savanna phase to begin with.
The earliest objections to the savanna theory came from the works of Alistir Hardy and Elaine Morgan who popularized the aquatic ape theory (AAT), which recognizes that many features of human anatomy and physiology must have been shaped by association with an aquatic environment; work being currently furthered by the Dutch physician Marc Verhaegen. Of the various objections to the savanna theory, this is the most technical and the most difficult to prove. AAT proponents have also required shifts in natural habitat as severe or more so than that of the savanna proponents. In the past decade or so, partly through dialogues carries out in the Yahoo AAT Group (in which Verhaegen participated), a littoral interpretation of human's aquatic past has begun to gain ascendance.
Opponents of the savannah theory, typically proponents of the aquatic ape theory, suggest that the evidence and Occam's Razor indicate that the current human abode, at the water's edge, is where we've always lived, and that if there was a savanna phase in human history, it has yet to be demonstrated.
[edit] References
- Bender, Renato; Verhaegen, Marc & Oser, Nicole (1997): Der Erwerb menschlicher Bipedie aus der Sicht der Aquatic Ape Theory. Anthropologischer Anzeiger 55 (1), 1-14.
- Bender, Renato and Oser, Nicole (1997): Gottesanbeterinnen, Maulwürfe und Menschen. Unipress 95, 20-26.
- Bender, Renato (1999): Die evolutionsbiologische Grundlage des menschlichen Schwimmens, Tauchens und Watens: Konvergenzforschung in den Terrestrisierungshypothesen und in der Aquatic Ape Theory. Diploma Thesis; Institut of Sport and Sport Science, University of Bern.
- Bender-Oser, Nicole: Die Aquatile Hypothese zum Ursprung des Menschen: Max Westenhöfer's Theorie und ihre Bedeutung für die Anthropologie (2004). - Medical Dissertation, Institut of History of Medicine, University of Bern.
- Heiser, Charles Bixler (1979). The Gourd Book.
- Morgan, Elaine (1997). The Aquatic Ape Hypothesis. Souvenir Press (London)
- Verhaegen, Marc (1993). Aquatic versus Savannah: Comparative and Paleo-environmental Evidence. Nutrition and Health 9: 165-191.
