Some learned, authoritative commentary pertaining to the Dikika find -
Quote:Expert Commentary on Lucy's Baby: Ralph Holloway
As part of our publishing experiment, I invited paleoneurologist Ralph Holloway of Columbia University to comment on the recently announced Australopithecus afarensis child from Dikika, Ethiopia. Here's his response:
My first reaction to the article was really one of excitement at learning about the mix of rimitive and derived characters, and how that really brought into better focus the mosaic nature of hominid evolution. I believe there will be on-going controversies regarding the adaptive balance between upright bipedal locomotion, knuckle-walking, and retaining arboreal adaptations such as sleeping in trees at night ...
Quote:Expert Commentary on Lucy's Baby: C. Owen Lovejoy
I invited Owen Lovejoy of Kent State University, a leading authority on hominid locomotion, to send in his thoughts on the recently unveiled skeleton of an Australopithecus afarensis youngster. Here's what he has to say:
"The authors are to be congratulated for an obviously important and fascinating contribution to our knowledge of Australopithecus afarensis and human evolution in general ...
... While the scapula does appear, at this stage in its preparation, to have some similarities with those of gorillas, it differs markedly from that of the chimpanzee, and shows some rather striking similarities with the human scapula (which the authors also note). Several of its metrics are clearly already intermediate between apes and modern humans, even at its geological age of more than 3 MYA ...
... A. afarensis already exhibits every fundamental hallmark of upright walking and running that is exhibited by modern humans! The lumbar spine of A. afarensis has 5-6 vertebrae which are all free to lordose, whereas apes have only 3-4 lumbars of which either one or two are "trapped" by their elongated pelvic bones. This makes their lumbar spine almost entirely immobile--indeed this is the reason why they must walk with a "bent-kneed" gait when bipedal and, incidentally, lordosis is also a trait that would imperil the australopithecine spine during arboreal travel--look what apes have done to their pelves and spines!). A. afarensis also has an entirely remodeled pelvis with a fully established abductor apparatus to control pelvic tilt--functionally equivalent to those of modern humans save for a small birth canal, a non-grasping foot with a longitudinal arch, a completely extended knee that maximizes cartilage contact only in full extension (i.e., during propulsion and impact loading at heel strike) and reduces it in flexion, an inflated calcaneus or heel bone for energy absorption at heel strike, and so on (reviewed in Gait and Posture, 21: 95-124, and in press: No.51 of papers available online). Even the internal structure of the thigh bone is identical to that of modern humans and entirely unlike that of any arboreal ape or monkey. Indeed the lower limb skeleton of A. afarensis is so remarkably similar to that of modern humans that I find the intent of the comment in the Nature "News and Views" incomprehensible. That review claimed that the "limb bones [of A. afarensis] are much more ape-like than those of later taxa that are rightly included in our own genus, Homo." Surely this comment was intended to refer only to the forelimb?
A little evolutionary biology seems to be in order here rather than just rote comparison of specimens. Most importantly, there would have been no biological reason for A. afarensis to alter its primitive forelimb morphology unless and until some positive selective force was imposed on it. Yet, as the authors describing this new specimen note, it already does show novel morphology with respect to such important features as partial reorientation of the scapular spine and reduction of the size and proportion of the suprascapular fossa. What positive selective force might have caused these changes away from the primitive state? As just noted, and as the authors emphasize, the hindlimb of this specimen is so highly derived for specialized bipedality that it has lost virtually all of any agility and grasping capacity (the absence of which is known from other specimens) that figure so prominently in the climbing of apes ...
... set the stage for the late Pliocene technological advances that eventually provided hominids with the broad adaptive plateau that in turn paved the way for emergence of the genus Homo."
OK - Now, lets take a look at gunga's Dr. David Menton, who's video gunga offers as evidence. A search of Accreditted Scientific/Academic Journal Publications turns up
18 articles Dr. David Menton has authored or co-authored. Not one pertains to paleobiology, anthropology, archaeology, or any other discipline relevant thereto. Dr. Menton has no peer-reviewed, accepted, published articles relevant to his ID-iot bullshit; the only publications featuring his fantasies are to be found exclusively in the Creationist/ID-iot publishing world, most notably, as is the case with the video gunga introduced,
Penfold Book & Bible House - "
Serving the whole English speaking world with a huge selection of Christian books, videos, and DVDs, proudly featuring a selection of "
Over 50 Creation/Evolution Titles". Also available through Penfold Book & Bible House, btw, are those hard-to-find, but indispensible
Bible Pens -"
Fine Bible Pens that don't leak or run ... which are excellent Bible Pens that will serve you faithfully over the long term"
Anyone delusional enough to introduce Dr. Menton's out-of-his-field, over-his-head ID-iot fantasies as evidence counter to evolutionary theory is functionally brain dead.
Now lets tackle rl's "The hole in Lucy's foot" straw man. ID-iots, seeking to make much of what little they have to hand, typically pervert scientific method in order to purport to have "found" that which in fact was not there to be found, and this case is no exception. The basics of the actual science from which rl's current specious objection proceeds is discussed objectively in this article:
Quote:Footprints to Fill
Flat feet and doubts about makers of the Laetoli tracks
By Kate Wong
It is one of the most evocative traces of humanity's ancestors ever found, a trail of footprints pressed into new fallen volcanic ash some 3.6 million years ago in what is now Laetoli, Tanzania. Discovered in 1978 by a team headed by Mary Leakey, the Laetoli footprints led to the stunning revelation that humans walked upright well before they made stone tools or evolved large brains. They also engendered controversy: scientists have debated everything from how many individuals made the prints to how best to protect them for posterity. Experts have generally come to agree, however, that the tracks probably belong to members of the species Australopithecus afarensis, the hominid most famously represented by the Lucy fossil. Now new research is calling even that conclusion into question.
The case for A. afarensis as the Laetoli trailblazer hinges on the fact that fossils of the species are known from the site and that the only available reconstruction of what this hominid's foot looked like is compatible with the morphology evident in the footprints. But in a presentation given at the American Association of Physical Anthropologists meeting in April, William E. H. Harcourt-Smith of the American Museum of Natural History and Charles E. Hilton of Western Michigan University took issue with the latter assertion.
The prints show that whoever made them had a humanlike foot arch, and the reconstructed A. afarensis foot exhibits just such an arch. So far, so good. The problem, Harcourt-Smith and Hilton say, is that the reconstruction is actually based on a patchwork of bones from 3.2-million-year-old afarensis and 1.8-million-year-old Homo habilis. And one of the bones used to determine whether the foot was in fact arched--the so-called navicular--is from H. habilis, not A. afarensis.
To get a toehold on the Laetoli problem, the researchers first compared the gaits of modern humans walking on sand with two sets of the fossil tracks. This analysis confirmed that the ancient footprints were left by individuals who had a striding bipedal gait very much like that of people today. The team then scrutinized naviculars of A. afarensis, H. habilis, chimpanzees and gorillas. The dimensions of the H. habilis navicular fell within the modern human range. In contrast, the A. afarensis bone resembled that of the flat-footed apes, making it improbable that its foot had an arch like our own.
As such, the researchers report, A. afarensis almost certainly did not walk like us or, by extension, like the hominids at Laetoli.
But according to bipedalism expert C. Owen Lovejoy of Kent State University, other features of the australopithecine foot, such as a big toe that lines up with, rather than opposes, the other toes, indicate that it did have an arch. Even if it did not, Lovejoy contends, that would not mean A. afarensis was incapable of humanlike walking. "Lots of modern humans are flat-footed," he observes. "They are more prone to injury, because they lack the energy-absorptive capacities of the arch, but they walk in a perfectly normal way."
For their part, Harcourt-Smith and Hilton note that a new reconstruction of the A. afarensis foot built exclusively from A. afarensis remains is needed to confirm these preliminary findings. As for identifying the real culprit, if A. afarensis did not make the prints, that would put the poorly known A. anamensis in the running. But just as likely, speculates Harcourt-Smith, an as yet undiscovered species left the prints. That is to say, consider the world's oldest whodunit an unsolved mystery.
Note that Harcourt-Smith and Hilton do not claim their work disproves anything, note they acknowledge further work - work in progress - may either confirm or refute their hypothesis, and note that other expert opinion discounts the significance of the Harcout-Smith and Hilton findings relevant to the bipedalism of A. Afarensus.
Now, consider rl's implication the whole Laetoli Footprint/A. Afarensus/Bipedalism deal falls apart on the basis of one particular mis-constructed bit of fossil restoration - Johanson's Lucy. That too is a typical ID-iot ploy, and it is typically ID-iotically dishonest.
Quote:Austalopithecus Afarensis
Inhabiting eastern Africa between four and three million years ago, Australopithecus afarensis was a long-lived species that may have given rise to the several lineages of early human that appeared in both eastern and southern Africa between two and three million years ago.
For its antiquity, A. afarensis is one of the better known species of early human, with specimens collected from over 300 individuals. It is a species that exhibits many cranial features which are reminiscent of our ape ancestry, such as a forward protruding (prognathic) face, a "U-shaped" palate (with the cheek teeth
parallel in rows to each other similar to an ape) and not the parabolic shape of a modern human, and a small neurocranium (brain case) that averages only 430cc in size (not significantly larger than a modern chimpanzee).
The specimens recovered have given representative examples of almost all of the bones of the A. afarensis skeleton.
From this, it is clear that there are many significant difference between A. afarensis and its ape predecessors, one of which is crucial to later human evolution, bipedality.
Quote:How do we know Lucy walked upright?
As in a modern human's skeleton, Lucy's bones are rife with evidence clearly pointing to bipedality. Her distal femur shows several traits unique to bipedality. The shaft is angled relative to the condyles (knee joint surfaces) which allows bipeds to balance on one leg at a time during locomotion. There is a prominent patellar lip to keep the patella (knee cap) from dislocating due to this angle. Her condyles are large, and are thus adapted to handling the added weight which results from shifting from four limbs to two. The pelvis exhibits a number of adaptations to bipedality. The entire structure has been remodeled to accommodate an
upright stance and the need to balance the trunk on only one limb with each stride. The talus, in her ankle, shows evidence for a convergent big toe, sacrificing manipulative abilities for efficiency in bipedal locomotion. The vertebrae show evidence of the spinal curvatures necessitated by a permanent upright stance.
Quote:How do we know (Lucy's) skeleton is from a single individual?
Although several hundred fragments of hominid bone were found at the Lucy site, there was no duplication of bones. A single duplication of even the most modest of bone fragments would have disproved the single skeleton claim, but no such duplication is seen in Lucy. The bones all come from an individual of a single species, a single size, and a single
developmental age. In life, she would have stood about three-and-a-half feet tall, and weighed about 60 to 65 pounds.
Quote:Laetoli Footprints
(A)ccording to most creationists, these are modern human footprints that are dated at 3.7 million years ago, long before humans were meant to exist. Creationists emphasize the close resemblance between these and modern human footprints, but often neglect to mention their extremely small size and the fact they may also be similar to the feet of the australopithecines living at the same time. Exactly how similar they are is a matter of some debate.
Tuttle (1990) thinks the footprints are too human-like to belong to A. afarensis, and suggests they may belong to another species of australopithecine, or an early species of Homo. Johanson, who has often said that Lucy was fully adapted to a modern style of bipedality, claims (Johanson and Edgar 1996) that the A. afarensis foot bones found at Hadar, when scaled down to an individual of Lucy's size, fit the prints perfectly. Stern and Susman (1983), who have argued that Lucy's foot and locomotion were bipedal but not yet fully human-like, believe that the footprints show subtle differences from human prints and could have been made by afarensis. Clarke (1999) believes that the Laetoli tracks could have been made by feet very similar to those of the new australopithecine fossil Stw 573.
In short, there is a wide range of opinions about the nature of the footprints and whether A. afarensis could have made them. Most creationists usually cite only Tuttle, whose conclusions they find most convenient. The most honest conclusion, for now, is to admit that although no-one can be entirely sure what made the Laetoli footprints, it seems quite likely that they belonged to australopithecines.
Quote:STW 573 (Little Foot)
In 1995, Ronald Clarke and Phillip Tobias announced the discovery of the fossil Stw 573, nicknamed Little Foot, consisting of four articulating foot bones from an australopithecine. These bones were actually discovered in Sterkfontein Cave in the late 1970's, but were only recognized as hominid when Ronald Clarke found them while looking through a box of miscellaneous bones in 1994. The bones had human features in the hindfoot, while the forefoot was very apelike. Although adapted to bipedalism, the big toe could spread out sideways from the rest of the foot, like chimpanzees but unlike humans. Clarke and Tobias interpreted this as evidence that Little Foot had walked bipedally, but also spent a significant amount of time climbing in trees (Clarke and Tobias 1995, Oliwenstein 1995). Other scientists, most notably Owen Lovejoy, disagreed, arguing that the australopithecine hip, knee and spine are all adapted for bipedality, and that it is "mechanically and developmentally naive" to ignore all this evidence in favor of one foot joint.
In 1997, while examining more boxes of bones from Sterkfontein, Clarke found, over the space of about two weeks, another 8 leg and foot bones from the same individual...
... The skeleton was originally thought to be between 3.0 and 3.5 million years old, but a more recent paper has claimed an age of just over 4 million years (Partridge et al. 2003). If this age is correct, it would make Stw 573 one of the oldest known australopithecine fossils, and easily the oldest from South Africa ...
... Additionally, Clarke considers that the feet of Stw 573 are a very good match for the 3.7 million year old footprint trails discovered at Laetoli by Mary Leakey's team.
Clarke points out (1998) that not only has this fossil yielded the most complete australopithecine skull yet found, it has been found in association with the most complete set of foot and leg bones known so far, with more probably still to be extracted from the rock (and since then, the arm and hand has been discovered.) In addition, the preservation of the skeleton is extraordinary, with most of the bones intact and joined together in their natural position (it is usual for fossil bones to be broken, often into small pieces, and for bones to get separated and scattered) ...
Assorted Other ID-iot lies pertaining to Lucy/A. Afarensis
Once again, the hole is in the ID-iot's foot.
