I’ve been wondering what the creationist response to the new Dmanisi article in Nature would be. The Discovery Institute’s decrepit Ford Pinto gets pushed to the podium (sans muffler, a few wheels and a bumper or two). I say decrepit because Luskin’s post is, to put it charitably, pitiful. Finds at Dmanisi have been cropping up since sometime in the early 1990′s. The site itself dates to around 1.77 MYA based on 40Ar-39Ar dating as well as geomagnetic polarity studies. The site contains stone tools similar to the Oldowan core and flake industry found in East Africa. Skeletal material from a number of hominins have also been found there.
Creationists have a hard time dealing with the crania found at Dmanisi and Luskin’s new post continues that trend. Lusken is taking umbrage at a new paper, published in Nature, concerning the postcranial skeletal material found at Dmanisi. In the process of whining about Daniel Lieberman and John Noble Wilford manages to pretty much bungle both the new Nature article on Dmanisi and the recent article on Ileret.
The postcranial material has been attributed to four individuals (one adolescent and three adults) by Lordkipanidze et al. The adolescent material is associated with the D2700 crania. Some elements, representing a large individual, are associated with the D2600 mandible and some elements (from a smaller individual) are associated with the D3444/D3900 crania. The crania were evaluated in a previous paper by Rightmire et al – published in The Journal of Human Evolution in 2006. In that paper, the authors point out similarities to Australopithecus afarensis, Homo habilis and H. erectus. Most of the traits relating the Dmanisi material to A. afarensis or H. habilis were considered to be either size related or primitive retentions. Similarly, a number of the traits shared by the Dmanisi material and H. erectus are either primitive retentions or are variable in H. erectus and early Homo. Rightmire et al make the case that the Dmanisi material is, indeed, H. erectus by noting a number of traits shared with Asian H. erectus. If the Dmanisi material is H. erectus then there are a number of interesting implications relating to the variability of the H. erectus taxon (in cranial capacity, size, and the completeness of the postcranial adaptation to bipedal walking, or more specifically, long distance walking/running). In their summary Rightmire et al make six points. The last is the most interesting:
On morphological grounds, it can be argued that the group from which the skulls are drawn is close to a stem from which later more derived populations are evolved. As further comparative work is carried out, several hypotheses must be considered. One is that an early Homo population left Africa and settled in the Caucasus, where it was ancestral to the Dmanisi hominins. Dating does not presently rule out the possibility that H. erectus originated in Eurasia and that some groups then returned to Africa, where they evolved toward H. erectus ergaster. Also, both geographic considerations and the anatomy of the Dmanisi fossils are consistent
with the hypothesis that hominins reaching the Caucasus early in the Pleistocene are closely linked to the first inhabitants of Java and/or China.
It is in this context that the Ileret finds were announced and the Dmanisi material makes a brief appearance in the Spoor et al paper. In that paper Spoor et al argue that the Dmanisi material can not be considered transitional based on size or size related traits. In other words, H. erectus is more than an allometrically scaled up version of H. habilis.
This brings us back to the Dmanisi postcranial material. In summarizing their results Lordkipanidze et al state:
The following preliminary conclusions can be drawn: the morphology of the upper and lower limbs from Dmanisi exhibits a mosaic of traits reflecting both selection for improved terrestrial locomotor performance and the retention of primitive characters absent in later hominins (Supplementary Table 8). The length and morphology of the hindlimb is essentially modern, and the presence of an adducted hallux and plantar arch indicate that the salient aspects of performance in the leg and foot, such as biomechanical efficiency during long-range walking and energy storage/return during running, were equivalent to modern humans. However, plesiomorphic features such as a more medial orientation of the foot, absence of humeral torsion, small body size and low encephalization quotient suggest that the Dmanisi hominins are postcranially largely comparable to earliest Homo (cf. H. habilis). Hence, the first hominin species currently known from outside Africa did not possess the full suite of derived locomotor traits apparent in African H. erectus and later hominins.
Last month I discussed the fact that newly reported Homo erectus fossils predated fossils of “Homo” habilis, meaning that habilis could not possibly have been an evolutionary link between the Australopithecine apes and our genus Homo.
Luskin is misinterpreting the Ileret paper. In that paper a right maxilla, referable to H. habilis was announced. The maxilla was dated to 1.44 MYA and indicates that as there was some temporal overlap between H. habilis and H. erectus. The paper does not indicate that H. erectus predates H. habilis as a species. Luskin is flat out wrong on this.
I can imagine that both Wilford and Lieberman have subsequently received possibly non-fictitious memos [emphasis mine - afarensis] reminding them “Don’t question evolution to the public, plug evolution to the public!”, because both are now defending our knowledge of human evolution in articles that just came out this week.
Apparently, Dembski and Luskin have been sharing Cliff Notes on how to invent fake emails and memos.
According to Wilford’s NY Times article, these newly reported fossils, “had brains not much larger than those of a chimpanzee” and “[t]he small body size and small craniums, the upper limbs, elbows and shoulders were more like the earliest habilis specimens.” Of course habilis’s skeleton has been recognized as highly ape-like, so these features all appear very ape-like. Why do they claim this species is transitional? Supposedly, it’s all in the legs.
According to the Figure 3 in the Nature report, the femoral length is like that of a human or a gorilla (Fig. 3b). The tibial mediolateral distal width is like that of a chimp, human, or bonobo. Figure 3a reports that the tibia length is quite similar to that of a gorilla but different from that of humans. (Figure 3 also reports the length of an arm bone, as the humeral length resembles that of a human or perhaps a chimp (Fig. 3b).) Finally, the fossil footbones that were discovered are reported have some features that are like human feet, and others that are closer to the feet of modern apes.
In some ways, this is kind of correct. Unfortunately for Luskin, the correct part is what Wilford had to say. There are some primitive retentions in the Dmanisi upper limbs. For example, in the cranial orientation of the glenoid cavity (part of the scapula) and in the lack of humeral torsion (from Lordkipanidze et al):
Following this line of argument, the Dmanisi hominins would have had a more australopith-like than human-like upper limb morphology, and absence of humeral torsion in H. floresiensis would provide support for the hypothesis of long-term continuity of this plesiomorphic trait in Homo.
What about the lower limbs? Lordkipanidze et al measured the femurs and tibias of 22 humans, 30 chimps and 30 gorillas. The measurements are below. For the femur:
Humans: mean 381.9±22.9, range 337.0 – 434.0.
Chimps: mean 290.2±15.9, range 252 – 318.
Gorilla: mean 350.1±40.8, range 294.0 – 423.
For the Tibia:
Humans: mean 318.9±20.5, range 290.0 – 374.0
Chimps: mean 242.2±14.3, range 207.0 – 266.0
Gorillas: mean 281.5±29.7, range 241.0 – 334.0
They also took measurements on orangs, but those figures don’t seem to be reported in the supplemental results. Incidentally, for the Dmanisi material the numbers are femur length 386, tibia length 306. Clearly, there is some overlap between humans and gorillas in terms of the size of the femur and tibia. Simple linear measures are taxonomically uninformative – for the most part – something more, namely an analysis of the morphology, is needed. So either Luskin really doesn’t understand the material he is dealing with or he is deliberately obfuscating the issue. The figure 3 referred to occurs in a discussion of limb length proportions and body mass estimates. Here is what Lordkipanidze et al conclude based on that:
Limb proportions of the Dmanisi hominins, measured by femoral/tibial and humeral/femoral ratios (Fig. 3b, c and Table 1), were similar to those of modern humans, but also to those of earliest African Homo and to the BOU-VP-12/1 specimen dated to 2.5 Myr ago. Absolute hindlimb length of the Dmanisi hominins is greater than in australopiths and close to that of later Homo including modern humans. This may reflect selection for improved locomotor energy efficiency, as the cost of transport is inversely proportional to hindlimb length for terrestrial animals including bipeds.
Is anyone really surprised that hindlimbs were responding more quickly to demands on locomotion, while the forelimbs, freed from locomotory demands, were changing at a slower pace? Luskin makes a lot out of the overlap in dimensions (length, width, etc.) for the next couple of paragraphs clearly demonstrating he doesn’t understand the material.
Yet these leg and foot bones in many respects resemble modern apes as much as they resemble modern humans.
I’ve already addressed the femur and the tibia so let’s look at the foot:
D4110 is a well-preserved left talus. The neck is stout and expanded transversely but elongated compared to modern humans. The neck (horizontal) angle is small and similar to modern humans. The medial tubercle is strong and projecting, and the groove for the tendon of flexor hallucis longus is deep. This groove has a slightly oblique orientation, which is similar to great apes, whereas humans exhibit a more vertical orientation. D2671 and D3442 are subadult and adult right first metatarsals, respectively, with lengths at the lower end of modern human variation and elevated robusticity indices. The morphology of the head deviates from that known from apes and humans. It is spherical and exhibits a narrowing of the dorsal breadth of the articular surface. Head torsion is in the range of variation of subadult and adult modern humans and of OH8 (H. habilis). Two adult metatarsals III (D2021 and D3479) have a straight shaft, exhibit a high degree of torsion and have a dorsoventrally elongated cross-sectional shape, as in modern humans. Metatarsals IV (adult D4165 and subadult D2669) exhibit an elevated degree of torsion and dorso-ventral elongation. Adult metatarsal V (D4508) is short and at the lower end of modern human variation for its mid-shaft dimensions.
That is, verbatim (except for references), the entire section on the feet. There is only one trait that in the Dmanisi foot shows any similarity to the apes. That is in the orientation of the groove on the talus for the flexor hallucis longus. In the chimp and gorilla the flexor hallucis longus flexes the big toe and toes three and four. In humans the groove for this muscle is vertical while in apes it is more oblique. Otherwise, the foot displays the tranverse and longitudinal arches and adducted big toe characteristic of humans. So much for apelike feet.
In short, these are interesting new finds: Above the waist, they appear to be extremely ape-like. Below the waist, they seem to resemble modern apes as well as resembling modern humans. Yet this species post-dates the human-ape split and is being touted as a species that was evolving into a modern human, not a modern ape. What’s going on here?
What’s going on here is that you clearly do not know what the heck you are talking about.
Postcranial evidence from early Homo from
David Lordkipanidze, Tea Jashashvili1, Abesalom Vekua, Marcia S. Ponce de Leo´n, Christoph P. E. Zollikofer, G. Philip Rightmire, Herman Pontzer, Reid Ferring, Oriol Oms, Martha Tappen, Maia Bukhsianidze, Jordi Agusti, Ralf Kahlke, Gocha Kiladze, Bienvenido Martinez-Navarro, Alexander Mouskhelishvili, Medea Nioradze & Lorenzo Rook
Vol 449|20 September 2007| doi:10.1038/nature06134
Anatomical descriptions, comparative studies and evolutionary
significance of the hominin skulls from Dmanisi, Republic of Georgia
G. Philip Rightmire , David Lordkipanidze , Abesalom Vekua
Journal of Human Evolution 50 (2006) 115-141
Implications of new early Homo fossils from Ileret,
east of Lake Turkana, Kenya
F. Spoor, M. G. Leakey, P. N. Gathogo, F. H. Brown, S. C. Anto´n, I. McDougall, C. Kiarie, F. K. Manthi & L. N. Leakey
Vol 448|9 August 2007| doi:10.1038/nature05986