Bipedalism Theories

Theory Problems
Ecology (Woodland to Savanna) Occurred later (1)
Thermoregulation (2) Occurred later (1)
Enhanced vision Wrong habitat (1)
Hunting and tools Occurred much later
Male provider (3) hominids reproductively disadvantaged (4)
Scarce dietary resources Not fully supported by the data
Next Last Origin of Mankind and the Races Home
First | Previous | Next | Last |        | Index | Home

Slide 76 of 109


Bipedalism uses twice the energy as mammalian quadrupedalism. Therefore, one would expect to find a fairly robust theory to explain why hominids opted to use so much energy to get around.

Most evolutionary theories constructed to account for the appearance of bipedalism have serious problems, since they rely upon the change from woodland to savanna habitat, which occurred after bipedalism arose. This eliminates the ecology, the thermoregulation, and the enhanced vision hypotheses. The original hunting hypothesis (proposed by Charles Darwin) has been invalidated, since the appearance of hunting tools were much later than the appearance of bipedalism.

The male provider model states that monogamous males provided for pregnant/nursing mates and their offspring. All available evidence indicates that early hominids were polygynous and not monogamous and that male provisioning of immobile females and offspring was unlikely. No monogamous An order of mammals including man, apes, monkeys, etc., often characterized by large brains and flexible hands and feet.primate species is known to have a male who provides food for the female and her offspring. Even so, in hunter/gatherer societies, the average human female gathers an estimated 12,000 calories per day in food while the male averages only about 7,230 calories. So much for male provisioning!

The final explanation was that scarce dietary resources required an efficient means of travel. In the late Miocene, hominid dietary resources become thinly dispersed in some areas, requiring possible extensive travel to exploit those resources. Why energy-consuming bipedalism, as opposed to quadrupedalism, would be chosen as the means of travel, remains a question.


References Top of page

  1. Reed, Kaye E., 1997. Early hominid evolution and ecological change through the African Plio-Pleistocene. Journal of Human Evolution 32: 289-322.

  2. Wheeler, P. E., 1991. The thermoregulatory advantages of hominid bipedalism in open equatorial environments: the contribution of increased convective heat loss and cutaneous evaporative cooling. Journal of Human Evolution 21: 107-115.

  3. Hunt, Kevin D., 1996. The postural feeding hypothesis: an ecological model for the evolution of bipedalism. South African Journal of Science 92:77-90.

  4. McHenry, H.M. 1982. The pattern of human evolution: Studies on bipedalism, mastication, and encephalization. Annual Review of Anthropology 11: 151-173.

  5. ANTh101

http://godandscience.org/evolution/sld076.html
Last Modified June 21, 2006

 

Rich's Blog