Ergaster

While I was working on a long reply to Bait (deep in the "care and feeding of the kitty" thread), it became very clear that he has either failed to understand the nature of the debate regarding australopithecine bipedalism, or is willfully ignoring it. I decided therefore to do something I almost never do: post a series of quotes. But I'm doing it now for a very specific reason: Bait is using quotes to try and show that professionals dispute the fact of australopithecine bipedalism. I will show that this simply is not true, using their own words.

Each quote has a number after it: these refer to the sources at the end. They are roughly in chronological order. This is adapted from a longer essay I am working on, so some numbers will be skipped (the ones referring to specific creationist sources). I have retained my interspersed commentary, for context.

Essentially, the debate is about just how australos walked (like modern humans? Different from modern humans?), and to what degree arboreality was important in their locomotor repertoire. There is zero debate about the fact that, while on the ground, they were bipedal.

-------Start quotes----------------------

The following quotes were taken directly from the primary professional literature, and in some cases from the very papers that creationists themselves cite to support their contention that australopithecines were not bipeds (these will be marked with an asterisk). Most of the references to the literature from the creationists come via secondary or popular sources; however, since most of these are based upon the primary literature, these should suffice. Some of the papers reflect the results of detailed morphological and functional analyses on various australo body parts; others were written in context of the debate over the degree of terrestriality vs arboreality. They are arranged in roughly chronological order.

It should be noted that many more analyses on hominid locomotion than these have been undertaken, of course, but the fact of australo bipedality is so firmly established and universally understood that most researchers feel no need to explicitly state it in their papers.

Charles Oxnard* (3), a fave of the creationists, says this:

"Their locomotion may not have been like that of modern man, and may, though including a form or forms of bipedality, have been different enough to allow for marked abilities for climbing." (p. 389).

"They may have been bipedal in a way that is no longer seen, but have retained abilities for climbing..." (p. 394).

At times, creationists have made the claim that the orang is the functional model for australo locomotion; Oxnard says this:

"...it is clear that the overall mode of locomotion of the orang-utan is not the model for these creatures." (p. 394).

We can see that while Oxnard may doubt the ancestral position of the australos, he did not question their bipedal locomotion. Much of the information that Oxnard used to come to his conclusion in 1975 is now outdated.

Stern and Susman* (4) say this:

"That bipedality was a more fundamental part of australopithecine behavior than in any other living or extinct nonhuman primate is not in serious dispute." (p. 279)

"Finally, we must emphasize that in no way do we dispute the claim that terrestrial bipedality was a far more significant component of the behavior of A. afarensis than in any living nonhuman primate." (p. 281).

They (5) also say this:

"The most reasonable conclusion to be drawn from a study of the Hadar calcanei is that the structure of this bone is fully concordant with the other evidence that Australopithecus afarensis walked bipedally with a valgus knee." (p. 108).

Although Paranthropus (the robust australopithecines) do not come in for as much comment as the more gracile australos (probably because the former are not though to be on the human lineage), Randall Susman (6) notes:

"It would thus appear that Paranthropus was essentially bipedal but with a nonhumanlike mode of toe-off." (p. 472).

Bruce Latimer (7) says this:

"The Hadar postcrania demonstrates clear anatomical alterations in its lower limb directly related to the mechanical requirements of bipedality." (p. 169).

And this:

"It is clear that by the late Pliocene habitual terrestrial bipedality was the primary locomotor form of the earliest hominids...[D]emonstrable specializations for bipedality are present throughout the postcranial fossils represented in the Hadar collection and these, in combination with what are unequivocally bipedal footprints at Laetoli, must be seen as overwhelming evidence in favor of habitual bipedality at Hadar." (p. 170).

After analyzing the sacrum of Australopithecus africanus, Walter Leutenegger (8) concluded:

"The broadening of the sacrum in A. africanus should be viewed in terms of a reduction of stress at the pubic symphysis as an adaptation to erect posture and bipedal gait." (p. 310).

C. Owen Lovejoy (9) says this:

"When the lower limb sample of Australopithecus (including both South and East African samples described to date) are analyzed with regard to morphological features of biomechanical significance, it is found that only minor differences exist with respect to the lower limb skeleton of modern man and these differences indicate no difference in gait pattern but only one of response to encephalization...[I]n summary, the lower limb skeleton of Australopithecus points to a long history of bipedalism among hominids." (pp. 325-326).

And this (10)*:

"The close resemblance of Lucy's pelvis to that of a modern human and its dramatic contrast to the pelvis of a chimpanzee make it clear that she walked fully upright...[A] review of the rest of her skeleton and that of other Australopithecus skeletons would reveal equally dramatic modifications that favor bipedality...[T]he knee, for example, is adapted for withstanding greater stress during complete extension than the knee of other primates, and its design brings the femur and the tibia together at a slight angle, so that the foot can easily be planted directly under the body's center of mass when the body weight is supported on one leg. The ankle is also modified for supporting the entire body weight, and a shock-absorbing arch helps the foot to cope with the added load. The great toe is no longer opposable...the foot is now a propulsive lever for upright walking rather than a grasping device..." (p. 125).

(...)

John Robinson (11) undertook an extensive (two books in length) review of the anatomy of australopithecines based upon the fossil material available before 1972. He says this:

"It [A. africanus] had essentially the same body proportions as has modern man and evidently was, for all practical purposes, basically as well adapted to erect bipedal posture and locomotion as we are, although some slight improvements in efficiency still had to be made here and there." (p.245)

Kevin D. Hunt (12) has this to say:

"In both general morphology and detail, the pelvis and the lower body morphology of Australopithecus afarensis and later hominids unambiguously indicate bipedalism." (p. 86),

and

"Australopithecine anatomy of the lower body suggests a striding bipedalism less adapted to endurance than that of modern humans, but still hardly distinguishable kinematically from our own." (p. 88).

Christine Berge (13) concludes, after using multivariate analyses on australopithecine pelvic bones:

"The functional interpretation of the results indicates that the australopithecines appear as bipedal as Homo regarding the innominate bone specializations." (p.559).

(Another Berge source was used by Bait to try and show precisely the opposite of what she claims here).

From Ronald J. Clarke (14), on the discovery of "Little Foot":

"Bipedalism was attained early in hominid evolution. Skeletal adaptations for this form of stance and gait are apparent in the pelvic girdle, hip complex, knee joint, and foot of the African apemen, the australopithecines." (p. 521)

From Robin Huw Crompton et al. (15):

"It is universally accepted that the postcranial skeleton of the early hominid Australopithecus afarensis shows adaptations, or exaptations, towards bipedalism." (p. 55)

Henry McHenry, one of the top functional anatomists in the business, has this (16) to say:

"In many respects, the postcranium of A. africanus is like that of A. afarensis...[B]oth species had a postcranium fundamentally reorganized from the common pattern of the Hominoidea to the bipedal pattern unique to the Hominidae." (p.255)

And this (17), which sheds light upon the terrestrial/arboreal debate:

"3. The host of "ape-like" traits seen in these early hominids probably implies that their bipedality was kinematically and energetically different than modern humans and may imply that they were more efficient tree-climbers than are modern humans. This arborealism was different from ape-like tree climbing, however, because the hindlimb was specialized for bipedality and had lost essential climbing adaptations such as hallucial divergence." (p. 133).

"These results [a multi-trait comparison of early hominids] seem to imply that Australopithecus afarensis is indeed intermediate in its postcranial anatomy between modern humans and apes. But in the key characteristics that are essential for human-like bipedality, the earliest known hominids are not at all intermediate." (p.134)

(...)

McHenry performed a multivariate analysis (18) of hominid pelvic bones and concluded the following:

"One result is quite clear from the similarity coefficients: none of the fossil hominids shows a close relationship with any extant ape...[T]he results of the principle coordinates analysis are eminently interpretable in terms of function of the hip joint. The first principle coordinate accounts for about half of the total variance. Homo and the fossil hominids are widely separated from the rest of the hominoids...[I]n sum, in the traits that best distinguish the human and ape acetabulum and ilium, the fossil hominids are distinctly human except in being intermediate in the size of the acetabulum and in the size of the sacral articular surface." (pp.266-267)

The following (19) is an excellent paragraph, that sums up the excitement over debates like this one, and in science in general:

"Agreement abounds on what is most important about Australopithecus but disagreement inevitably arises about interpretation of the finer points. To an interested layman, the squabbles over femoral neck shape and glenoaxillary angulation must seem very odd. The same oddity afflicts theorists of the evolutionary process. If the experts summed up all the points upon which they agree, the point of disagreement would seem much less important.

But disagreements are real, important, interesting, and healthy for the science of human evolution studies. I must emphasize the healthy aspects of scientific competition. When two competing geological dating laboratories that are bent on proving the superiority of their procedures come out with the same potassium-argon date, for example, one can feel more confident of the date's validity. When disagreement arises, evidence and logic have to be very sharply honed." (p.177)

The third paragraph from the same article identifies the fallacy of creationist reasoning on this particular matter of australopithecine bipedality:

"Before launching into detailed analysis of the australopithecine locomotor anatomy and behavior, one must see the forest and not just the trees. A strictly inductive approach going from minute detail up to generalization too easily misses fundamentally important generalizations. No serious student of evolution doubts that Australopithecus had a revolutionary new adaptation: the greater-than-average mammal intelligence of an anthropoid primate, the wonderfully manipulative dexterity of the primate hand, and a means of getting about on the ground that kept the hand free of any duty to body support. This is such an obvious generalization to those of us acquainted with the fossil record, that we do not say it enough."(pp. 177-178).

(...)

(3) Oxnard, C. 1975. The place of the australopithecines in human evolution: grounds for doubt? Nature 258:389-395.

(4) Stern JT & Susman RL. 1983. The locomotor anatomy of Australopithecus afarensis. American Journal of Physical Anthropology 60:279-317.

(5) Stern JT & Susman RL. 1991. "Total morphological pattern" versus the "magic trait": conflicting approaches to the study of early hominid bipedalism. In Y. Coppens &
B. Senut (eds.), Origine(s) de la Bipédie chez les Hominidés. Paris: CNRS, pp. 99-111.

(6) Susman, RL. 1989. New hominid fossils from the Swartkrans Formation (1979-1986) excavations: postcranial specimens. American Journal of Physical Anthropology 79:451-474.

(7) Latimer B. 1991. Locomotor adaptations in Australopithecus afarensis: the issue of arboreality. In Y. Coppens & B. Senut (eds.), Origine(s) de la Bipédie chez les Hominidés. Paris: CNRS, pp. 169-174.

(8) Leutenegger, W. 1977. A functional interpretation of the sacrum of Australopithecus africanus. South African Journal of Science 73:308-310.

(9) Lovejoy, C. Owen. 1975. Biomechanical perspectives on the lower limb of early hominids. In R. H. Tuttle, (ed), Primate Function, Morphology and Evolution. The Hague: Mouton, pp.291-326.

(10) Lovejoy, C. Owen. 1988. Evolution of human walking. Scientific American November:119 - 125

(11) Robinson, John T. 1972. Early Hominid Posture and Locomotion. Chicago: University of Chicago Press.

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

(13) Berge, Christine. 1984. Multivariate analysis of the pelvis for hominids and other extant primates: implications for the locomotion and systematics of the different species of australopithecines. Journal of Human Evolution 13: 555-562.

(14) Clarke, Ronald J. & Tobias, Phillip V. 1995. Sterkfontein Member 2 foot bones of the oldest South African hominid. Science 269:521-524

(15) Crompton, Robin Huw, Yu Li, Weijie Wang, Gunther, Michael & Savage, Russel. 1998. The mechanical effectiveness of erect and "bent-hip, bent knee" bipedal walking in Australopithecus afarensis. Journal of Human Evolution 35:55-74.

(16) McHenry, H. M. 1994. Early hominid postcrania: phylogeny and function. In R. S. Corruccini & R. L. Ciochon (eds), Integrative Paths to the Past: Paleoanthropological Advances in Honor of F. Clark Howell. Englewood Cliffs: Prentice Hall pp. 251-268.

(17) McHenry, H. M. 1991. First steps? Analyses of the postcranium of early hominids. In In Y. Coppens & B. Senut (eds.), Origine(s) de la Bipédie chez les Hominidés. Paris: CNRS, pp. 133-141.

(18) McHenry, H. M. 1975. Multivariate analysis of early hominid pelvic bones. American Journal of Physical Anthropology 42:263-270

(19) McHenry, H. M. 1986. The first bipeds: a comparison of the A. afarensis and A. africanus postcranium and implication for the evolution of bipedalism. Journal of Human Evolution 15:177-191.

-----------End quotes---------------------

Deb

Valentine Pontifex

You might want to post these quotes to the following talk.origins <a href="http://groups.google.com/groups?selm=01c1b686%2440155fa0%24d0aa5f80%40myhos t.u.washington.edu" target="_blank">thread</a>.

Dr.GH

Thanks for the information Deb. Will there be illustrations in the article you are planning?

Ergaster

Boy, everyone wants pictures!

To tell the truth, I hadn't thought about it. I hadn't planned on going into anatomy in much detail, just how creationists misinterpret professional debates. I'm not sure what sort of illustrations would be appropriate for something like that.

Deb

kwigibo

[ April 01, 2002: Message edited by: kwigibo ]</p>

Dr.GH

Great cartoon.

Deb, I was thinking that if there were some illustrated examples of what physical features the textusal material was refering to, readers would gain the understanding of the technical nature of the discussion. Not every point would need to be illustrated. Say, how the angle of the femoral head is measured could be one example.

Just an idea. It is easy for me to suggest because I'm not doing the work.

ps418

This popped up in the Geological Society of America press release:

<a href="http://www.geosociety.org/news/pr/02-18.htm" target="_blank">Human Ancestor Australopithecus Did Indeed Walk Upright</a>

Ergaster

Yeah, we're scratching our heads over that one on a paleoanthro mailing list I'm on...like, this is news??

Oh well....