Australopithecus sediba revisited
Published: 20 September 2011 (GMT+10)
National Geographic Daily News
A reanalysis of Australopithecus sediba still shows that it is not an apeman or missing link but likely to be another variety of australopithecine.
In 2010 a media frenzy over the fossilized bones of Australopithecus sediba occurred in conjunction with the publishing of the find in Science by a team of researchers led by Lee Berger.1 As background familiarization for this next installment in the Australopithecus sediba saga, the reader is referred to Australopithecus sediba no human ancestor.2 In the 9 September 2011 issue of Science a series of five articles on Australopithecus sediba was published, elaborating in more detail on specific aspects of last year’s study. Four of the papers dealt with anatomy, and a brief comment on each of these papers is included sequentially below. The other paper reported on the “refined dating” of sediments associated with the fossils, where the previous age estimate of the fossils (1.78 to 1.95 million years ago (Ma)) was conveniently replaced by an older date of 1.977 ± 0.002 Ma.3 The older date makes it more tenable from an evolutionary point of view to hold the position that Australopithecus sediba was the direct ancestor of the genus Homo. Whilst most evolutionists will no doubt accept this date, other creationists who have examined the method described in the paper to obtain the revised date note that “the whole process is quite circular, producing an attractive ‘precise’ date of completely unknown accuracy.”4
The endocast of MH1
The orbitofrontal cortex generally refers to the inferior surface of the frontal lobe of the brain. One of the most significant features of the virtual endocast of MH1 is that the shape of its orbitofrontal region is said to align more closely with human endocasts than comparison Australopithecus africanus endocasts, and so this is suggested as being indicative of neural reorganization towards the human condition.5 It should be pointed out that this suggested neural reorganization had nothing to do with brain size, as with a cranial capacity of about 420 cm3 the brain of Australopithecus sediba was at the low end of the australopithecine range, and only slightly larger than the mean chimpanzee brain.
One problem with reading too much into the shape and sulci pattern of the orbitofrontal region is the considerable variability of this region in humans.6,7 If similar variation existed in extinct apes, like the australopithecines, then differences in the orbitofrontal region between Australopithecus sediba and the other two comparative australopithecine endocasts (Sts 5, Sts 60) may just reflect individual variability. More australopithecine endocasts need to be examined in order to get a better idea of the variability of the orbitofrontal region within this group.
Ultimately, the shape and pattern of gyri and sulci of the cerebral cortex, whilst useful surface markers, do not give information about the neural architecture of brain tissue, and so cannot answer questions concerning neural organization. Whilst one can make certain inferences based on bulging gyri and/or the location of certain sulci, they can only be speculative, particularly so in poorly understood regions of the human brain, such as the orbitofrontal region. Any neural reorganization towards the human condition would require the information content of the genome to increase which, as pointed out in the earlier article,2 is what makes evolution impossible, and is the reason why there are no apemen.
The pelvis of Australopithecus sediba
A detailed analysis of the juvenile male (MH1) and female (MH2) Australopithecus sediba pelvic remains is presented in the 9 September 2011 issue of Science.8 Although some of the interpretation about the ilia may be questioned due to the incompleteness of the pelvic remains, for example, the degree of reduced lateral flare of the iliac blades, one can accept the general conclusions about the shape of the Australopithecus sediba pelvis without buying into the evolutionary interpretation of its pelvic form. In short the pelvis displays traits that are typical of australopiths and some that are more human-like. However, when comparing the reconstructed pelvis of Australopithecus sediba with a reconstructed pelvis of Australopithecus africanus (Sts 14) and Australopithecus afarensis (AL 288-1: Lucy)9 the forms do not visibly appear so different that they could not be accommodated within the same created kind, which would not include extant apes. Hence, this latest report on the Australopithecus sediba remains helps indicate the diversity of skeletal form within the australopithecines.
In a sense, the pelvic remains of all known australopithecines may in some aspects be more human-like than chimpanzee-like, for a reason. As suggested by David DeWitt, some of the bipedal features of the pelvis and lower limbs may indicate that these creatures were specifically designed to live in trees, and as such “would require a more upright posture than a creature that knuckle walks.”10 As pointed out in my earlier article (but re-emphasized here), according to evolutionist authority Charles Oxnard, certain features (humeri, ankle bones, and metacarpals) of the australopithecines “clearly differ more from both humans and African apes, than do these two living groups from each other. The australopithecines are unique.”11 He further states on the same page that “though bipedal, it is likely that their bipedality was mechanically different from that of humans. Though terrestrial, it is further likely that these fossils were accomplished arborealists [i.e. suited to living in the trees].” The form of the australopithecine pelvis, as indicated by Australopithecus sediba, along with other features (up next), does not contradict the above assessment by Oxnard.
The hand of Australopithecus sediba
Another paper in the Australopithecus sediba collection is about the hand, and the authors conclude from their analysis of the nearly complete hand and wrist fossil bones of the adult female (MH2) “that Au. sediba may represent a basal condition associated with early stone tool use and production.”12 As no stone tools have been reported associated with Australopithecus sediba, this statement illustrates how evolutionary bias influences interpretation of these fossils. Even if stone tools were associated with the finds, it wouldn’t necessarily mean that they were made by Australopithecus sediba, as the latter may simply have been the victim of humans living in the area—who left their tools behind.
Like the pelvis, the hand of Australopithecus sediba, according to the authors, presents a suite of both australopithecine-like features and human-like features. The main human-like feature is said to be “a long thumb and short fingers associated with precision gripping and possibly stone tool production.”12 The stone tool production issue has already been addressed above, being based on evolutionary interpretations, as stone tools have not been associated with the find. That its hand was capable of precisely gripping objects such as stone tools, because of its short fingers and long thumb, is also open to debate. Paleoanthropologist William Jungers “thinks it’s ‘an australopithecine hand in essentially all relevant respects’ and didn’t manipulate objects in an advanced, humanlike way.”13 The hand also “appears to have possessed powerful muscles for grasping, suggesting A. sediba spent a lot of time clambering through the branches of trees.”14 According to the authors “the retention of arboreal features in MH2, together with its primitive australopith-like upper limb, suggest that Au. sediba still regularly engaged in arboreal behavior.”15 Hence, like the pelvis, the hand of Australopithecus sediba perhaps shows some variation (or curiosities at best) from other australopithecines examined, but still remains an australopithecine hand.
The foot and ankle of Australopithecus sediba
The last of the anatomical papers on Australopithecus sediba was about its foot and ankle, and according to the authors:
“These fossils reveal a mosaic of primitive and derived features that are distinct from those seen in other hominins. The ankle (talocrural) joint is mostly humanlike in form and inferred function, and there is some evidence for a humanlike arch and Achilles tendon. However, Au.sediba is apelike in possessing a more gracile calcaneal body and a more robust medial malleolus than expected. These observations suggest, if present models of foot function are correct, that Au. sediba may have practiced a unique form of bipedalism and some degree of arboreality.”16
This mixed bag of human-like and ape-like anatomy in the foot and ankle of Australopithecus sediba may at first glance seem to support evolution, but it actually only brings confusion to any evolutionary tale. This is because, for example, parts of the calcaneus (heel bone), such as the position of the lateral plantar process (LPP), are ape-like in Australopithecus sediba, but human-like in Australopithecus afarensis, making it almost untenable to suggest that Australopithecus sediba descended from Australopithecus afarensis, as this implies the more ‘modern’ calcaneal body arrived before the ‘primitive’ form. Hence, one of them has to drop out of any alleged hominid lineage leading to humans or, as suggested by the authors, evolutionary reversal would have to occur in “calcaneal and distal tibial morphology, despite habitual bipedal locomotion in both species.”17
Findings such as the above bring up the issue of homoplasy18 to these and other paleoanthropologists. According to Chris Stringer, from London’s Natural History Museum, “What may be happening is that there were several australopithecine forms all evolving human-like features in parallel as they turned to meat-eating and tool-making and moving greater distances. The question now is to pull out of this mess which one is really the ancestor of the genus Homo.”19 When evolutionists invoke parallel evolution they are effectively invoking parallel miracles of nature, as apish creatures evolving human-like features once is difficult enough to believe or imagine; that it must have happened independently multiple times shows evolution to be a collection of just-so stories that can be accommodated to almost any scenario, no matter how unlikely.
The suggestion from the Science paper that “if present models of foot function are correct, that Au. Sediba may have practiced a unique form of bipedalism and some degree of arboreality”,16 fits the conclusion from Oxnard’s analysis (see above) that the australopithecines are unique.
One thing to come out of these series of papers on Australopithecus sediba is that there is considerable variability within the australopithecines—the latter considered a created kind by many creationists. However, some of the features exhibited in Australopithecus sediba, when compared to other australopithecines, leave room for debate on whether the australopithecines represent just one created kind or several, particularly given the already known difference in cranial morphology between some of the robust and gracile australopithecines.
Last year a particularly contentious idea was the interpretation of Australopithecus sediba by creationist Todd Wood, following baraminological analysis of craniodental character states, which led him to conclude that “the present results indicate that Homo habilis, Homo rudolfensis, and—most surprisingly—Australopithecus sediba belong in the human holobaramin.”20 Putting Australopithecus sediba into the human kind led to strong criticism from both me and others.21,22,23 Subsequent analysis on postcranial characters by Wood found “that the postcranial characteristics of A. sediba do not favor a classification as Homo or Australopithecus.”24 More recently Wood published an article addressing some of the criticism from his critics, and whilst our differences in interpretation of Australopithecus sediba still remain, I do agree with his statement that “many fossils are inherently difficult to classify because they are partial, fragmentary remains and because there are very few of them.”25
Whilst I disagree with the evolutionist’s interpretation of Australopithecus sediba as a hominid (ape-man), the finds in themselves are very interesting, and can ultimately only lead to a better understanding of what constitutes a created kind—in this case the australopithecines. What will be most interesting next is the publication of the “Little Foot”26 skeleton next year, where one suspects current theories of human evolution will again be under the spotlight. There is also a report from the Australopithecus sediba Malapa fossil site where Berger’s team have “recovered material surrounding some of the fossils that may represent preserved skin and soft tissue, something never before seen in human fossils this old.”27 A project has begun amongst researchers to determine whether skin is really present, which would be a significant finding indeed.
- Berger, L.R., de Ruiter, D.J., Churchill, S.E., Schmid, P., Carlson, K.J., Dirks, P.H.G.M. and Kibii, J.M., Austalopithecussediba: A new species of Homo-Like Australopith from South Africa, Science 328:195–204, 2010. Return to text.
- Line, P., Australopithecus sediba—no human ancestor: new alleged hominid ignites debate, but is no missing link, 15 April 2010. Return to text.
- Pickering, R., Dirks, P.H.G.M., Jinnah, Z., de Ruiter, D. J., Churchill, S.E., Herries, A.I.R., Woodhead, J.D., Hellstrom, J.C. and Berger, L.R., Australopithecus sediba at 1.977 Ma and implications for the origins of the genus Homo, Science 333:1421–1423, 2011. Return to text.
- Mitchell, E., Menton, D. and Snelling, A., Sediba with a little sleight of hand, answersingenesis.org, accessed 15 September 2011. Return to text.
- Carlson, K.J., Stout, D., Jashashvili, T., de Ruiter, D. J., Tafforeau, P., Carlson, K. and Berger, L. R., The endocast of MH1, Australopithecus sediba, Science 333:1402, 2011. Return to text.
- Kringelbach, M.L., The human orbitofrontal cortex: linking reward to hedonic experience, Nature Reviews Neuroscience 6:693, 2005. Return to text.
- Chiavaras, M.M., LeGoualher, G., Evans, A. and Petrides, M., Three-dimensional probabilistic atlas of the human orbitofrontal sulci in standardized stereotaxic space, Neuroimage 13:486, 2001. Return to text.
- Kibii, J.M., Churchill, S.E., Schmid, P., Carlson, K.J., Reed, N.D., de Ruiter, D. J. and Berger, L. R., A partial pelvis of Australopithecus sediba, Science 333:1407–1411, 2011. Return to text.
- Kibii, et al., ref. 8, p. 1410; see also Supporting Online Material, Figure S7, p.10. Return to text.
- DeWitt, D.A., It’s an ape … It’s a human … It’s … It’s … a missing link! Detailed analysis of Australopithecus sediba presents problems for evolution, answersingenesis.org, accessed 14 September 2011. Return to text.
- Oxnard, C., Fossils, Teeth and Sex: New Perspectives on Human Evolution, Hong Kong University Press, Hong Kong, p. 227, 1987. Return to text.
- Kivell, T.L., Kibii, J.M., Churchill, S.E., Schmid, P. and Berger, L. R., Australopithecus sediba hand demonstrates mosaic evolution of locomotor and manipulative abilities, Science 333:1411, 2011. Return to text.
- Gibbons, A., Skeletons present an exquisite paleo-puzzle, Science 333:1371, 2011. Return to text.
- Amos, J., African fossils put new spin on human origins story, bbc.co.uk, accessed 9 September 2011. Return to text.
- Kibii, et al., ref. 8, p. 1416. Return to text.
- Zipfel, B., DeSilva, J.M., Kidd, R.S., Carlson, K.J., Churchill, S.E., and Berger, L. R., The foot and ankle of Australopithecus sediba, Science 333:1417, 2011. Return to text.
- Kibii, et al., ref. 8, p. 1420. Return to text.
- Resemblances not due to inheritance from a common ancestor. Return to text.
- Amos, J., African fossils put new spin on human origins story, bbc.co.uk, accessed 9 September 2011. Return to text.
- Wood, T.C., Baraminological Analysis Places Homo habilis, Homo rudolfensis, and Australopithecus sedibain the Human Holobaramin, Answers Research Journal 3:71, 2010. Return to text.
- Line, P., Gautengensis vs sediba: A battle for supremacy amongst apeman contenders, but neither descended from Adam, 17 June 2010. Return to text.
- Menton, D.N., Habermehl, A. and DeWitt, D.A., Baraminological analysis places Homo habilis, Homo rudolfensis, and Australopithecus sediba in the human holobaramin: discussion, Answers Research Journal, 3:153–158, 2010. Return to text.
- Lubenow, M., The problem with Australopithecus sediba, answersingenesis.org, accessed 13 August 2010. Return to text.
- Wood, T.C., A re-evaluation of the baraminic status of Australopithecus sediba using cranial and postcranial characters, Proceedings of the Ninth BSG Conference, p. 8, 2010. Return to text.
- Wood, T.C., Baraminology, the image of God, and Australopithecus sediba, Journal of Creation Theology and Science Series B: Life Sciences 1:13, 2011. Return to text.
- Balter, M., Little Foot, Big Mystery, Science 333:1374, 2011. Return to text.
- Callaway, E., Fossils raise questions about human ancestry: Australopithecus sediba is a mosaic of modern and primitive traits, nature.com, accessed 15 September 2011. Return to text.