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Response to Chapter 9 of The Evolution Deceit

'The Scenario of Human Evolution'

Part 2: Sahelanthropus 

(unreviewed version)

Andya Primanda
Laboratory of Animal Taxonomy, Dept. of Biology
Univerity of Indonesia
2002

The Turkish creationist Harun Yahya (HY) is among the first ones to comment the recent discovery of Sahelanthropus, even before scientists start debating over it. In the article 'New Fossil Discovery Sinks Evolutionary Theories' HY said that 'Darwinist scientists confess that this fossil has rocked the very foundations of the theory of evolution' and concluded that Sahelanthropus does not fit with the model of human evolution he refers to as 'the evolutionary chain stretching from ape to man.' 

However, HY based his statements on the assumption that Sahelanthropus displayed 'more human-like attributes' than australopiths (Australopithecus, Paranthropus, Ardipithecus), yet living before them. HY considered australopiths as strictly apes (as if humans were not apes), based on outdated claims by Lord Solly Zuckerman and Charles Oxnard (Yahya 2001: 88) and newer studies of Fred Spoor et al. (1994) which suggested that australopiths did not walk upright, based on inner ear morphology. HY apparently dismissed the overall morphological evidence (foramen magnum, spinal column, pelvis shape, foot) which points to the conclusion that australopiths were bipedal (see for example McHenry 1994, Wood & Richmond 2000) in favor of one evolutionary aspect, semicircular canal morphology, which apparently was in intermediate stage due to mosaic evolution of bipedality. Recently Spoor had reconsidered his claims (Spoor & Zonneveld 1998) and stated that semicircular canal morphology might not be directly associated to ape quadrupedality vs human bipedality, because Neanderthals, which were clearly bipedal, have smaller vertical semicircular canals than modern humans (primitive-like but considered a derived condition from the humanlike Homo erectus semicircular canal). Spoor & Zonneveld's revised conclusion therefore undermined HY's claims. 

HY did left another claims to be tested scientifically, that is, about the more humanlike traits of Sahelanthropus. The discoverers (Brunet et al. 2002) considered Sahelanthropus to have a unique mosaic of primitive and derived characters. The primitive characters include small brain size and thick supraorbital torus, whereas the derived characters consist of weak prognathism, foramen magnum position, and small canine. Three characters will be examined here: brain size, prognathism, and foramen magnum position. 

Brain size 

Brunet et al. (2002: 146) estimated that the cranial capacity of Sahelanthropus is 320--380cm3.  When plotted against other hominids' brain size (data from McHenry (1994: 6781)), Sahelanthropus falls into an uncomfortable place for HY: between extant apes' (bonobo & chimp) brain size range, and smaller than australopiths (Australopithecus & Paranthropus--no cranial capacity data available for Ardipithecus).

Table adapted from McHenry (1994: 6781). Following recent taxonomical conxiderations, McHenry's  'early H. erectus' is replaced by its current name H. ergaster.  Sahelanthropus data from Brunet et al. (2002: 146).

 
The data translates into this chart, showing that Sahelanthropus have smaller brain size than Australopithecus and Paranthropus, therefore not more humanlike in that aspect as alleged.

Prognathism 

Using hominid cranium fossil images (due to lack of access to actual specimens), I have done a comparison of prognathism by superimposing crania outlines of various hominids on Sahelanthropus.

Materials for the comparison are taken from the Smithsonian Human Ancestors Hall, The eSkeletons Project, and Brunet et al.(2002).  Specimens chosen for the comparison are: Female Gorilla (eSkeletons), STS-5 'Mrs. Ples' for A. africanus, SK 48 for Paranthropus robustus, ER 406 for Paranthropus boisei, KNM-ER 1813 for Homo habilis, ER 3733 for Homo ergaster, Shanidar 1 for H. neanderthalensis and typical Homo sapiens (eSkeletons).

The result suggests that the Sahelanthropus face is not as humanlike as HY wished; its facial prognathism falls within australopithecine range (facial protrusion is comparable to boisei and afarensis, but less pronounced than africanus).  However, its comparison with Homo species is rather problematic, due to a different facial profile.

As a caveat: This method of comparison may be flawed, because it was done indirectly and without proper equipment. Therefore the results may not be of high value. It is advisable to repeat the measurement directly using actual material and better equipment. 

Foramen magnum 

Comparative observation of foramen magnum position in gorilla, Australopithecus africanus, Homo sapiens and Sahelanthropus shows that Sahelanthropus falls nicely in an intermediate position, between ape and human positions.

(Gorilla and human skull images from The eSkeletons Project.  A. africanus & H.ergaster from Australian National Museum.  Sahelanthropus from Brunet et al. (2002))

Discussion 

HY claimed that '…Sahelanthropus…is actually more humanlike according to the evolutionary criteria." He is hard-pressed to do so because he wants to show that evolutionists try to put fossils according to their scheme, the 'ladder from ape to man'. Therefore, if,  Sahelanthropus is more humanlike than the australopiths which lived after it, that particular fossil would demolish the evolutionist scheme. HY failed on two counts: 1) As shown before, Sahelanthropus does not show more humanlike characteristics than australopithecines; 2) 'The evolutionist scheme', 'the ladder from ape to man' is a strawman.  The prevailing scientific view is currently shifting to another perspective.

HY quotes Bernard Wood, which said that '...human evolutionary history was a ladder in the 1960s...but it looks like a bush now'.  As a matter of fact, this change of evolutionary thought was due to the ever-expanding human fossil record, with new and unexpected discoveries pouring in every few years.  And paleoanthropology had just seen some spectacular discoveries recently; the discoveries of Ardipithecus, Orrorin, Kenyanthropus and Sahelanthropus expanded the human fossil record to previously blank periods (7--2 million years ago).  This influx of new material certainly begs the reassessment of human evolution hypotheses.  'The evolutionary ladder from ape to man' of the early 20th century has been abandoned by most.  It is now accepted that the human evolutionary lineage, just as other lineages, is not just one straight line, but a tree with many branches, which only one survived until today.  Some (perhaps many) paleoanthropologists now entertain the view that human evolution, like most other evolutionary lineages, should include an adaptive radiation at every stage (Tattersall 2000: 14; Wood 2002: 134).  This adaptive radiation may be the 'bush' he referred to, which means that the discovery of various hominids with strange mixtures of primitive and derived characteristics is expected.

HY also misquoted Henry Gee, which said that 'The idea of the missing link … is now completely untenable.' Of course there is no such thing as 'the' missing link. Every organism, living or fossil, is a link between those which existed before and those which existed after. Each one is a transitional form; there is not one which can be assigned as the missing link, the turning point, the mark of change from one type to another. Evolutionary change is gradual. 

HY's conclusion, that Sahelanthropus' discovery demolishes evolution and proves that man emerged suddenly, with no evolutionary process behind him, would seem far-fetched. As a statement of faith, I do not question his claim that man is created by God; after all, I share the same faith with him. However his claim that man has no evolutionary history is clearly refuted, not by words of man, but by the existence of hominin fossils such as archaic Homo sapiens, H. erectus, australopiths, and Sahelanthropus, as well as molecular and comparative evidence. To deny such evidence would make God seem like a deceiver of humankind, as He had put those as signs for humans to contemplate: 

And on earth there are signs of [Allah's existence, visible] to all who are endowed with inner certainty, just as [there are signs thereof] within your own selves. Can you not, then see?

(Al-Quran, 51:20-21)

Postscript 

As a final note, there is at least one man whose prediction was partly confirmed by the discovery of Sahelanthropus and other central African hominids. None other than the old master of evolution himself, Ernst Mayr: 

"…[Homo] rudolfensis does not seem to have descended from any known species of Australopithecus in eastern or southern Africa. Rather, it seems to have invaded eastern Africa from somewhere else in Africa. Surely, there must have been australopithecine subspecies or allospecies in the tree savannas of western and northern Africa, but no fossils have been found so far. Yet Homo must have evolved from some of these peripheral populations. This would explain why Homo, a far more advanced hominid, appears in eastern Africa so suddenly." (Mayr 2001:246, emphasis added)

If Sahelanthropus may be assigned as an australopithecine allospecies or a sister group to them, then Mayr's prediction is confirmed. 

REFERENCES 

Brunet, M., F. Guy, D. Pilbeam, H.T. Mackaye, A. Likius, Dj. Ahounta, A. Beauvilain, C. Blondel, H. Bocherens, J.-R. Boisserie, L. De Bonis, Y. Coppens, J. Dejax, C. Denys, Ph. Duringer, V. Eisenmann, G. Fanone, P. Fronty, D. Geraads, T. Lehmann, F. Lihoreau, A. Louchart, A. Mahamat, G. Merceron. G. Mouchelin, O. Otero, P. Pelaez Campomanes, M. Ponce De Leon, J.-C. Rage, M. Sapanet, M. Schuster, J. Sudre, P. Tassy, X. Valentin, P. Vignaud, L. Viriot, A. Zazzo & C. Zollikofer. 2002. A hew hominid from the upper Miocene of Chad, central Africa. Nature 418: 145--151 

Mayr, E. 2001. What evolution is. Basic Books, New York. 

McHenry, H.M. 1994. Tempo and mode in human evolution. PNAS 1994: 6780--6786.

Nelson, H. & R. Jurmain. 1988. Introduction to physical anthropology. 4th ed. West Publ. Co., St. Paul. 

Spoor, F., B. Wood & F. Zonneveld. 1994. Implications of early hominid labyrinthine morphology for evolution of human bipedal locomotion. Nature 369: 645--648. 

Spoor, F. & F. Zonneveld. 1998. Comparative review of the human bony labyrinth. Yearbook of Physical Anthropology 41: 211--251. 

Tattersall, I. 2000. Paleoanthropology: The last half-century. Evolutionary Anthropology 9: 2--16.

Wood, B. 2002. Hominid revelations from Chad. Nature 418: 133--135. 

Wood, B. & B.G. Richmond. 2000. Human evolution: Taxonomy and paleobiology. J. Anat. 196: 19--40.

Yahya, H. 2001. The evolution deceit. 6th ed. Kültür Publishing, Istanbul. (Online pdf version at www.harunyahya.com) 

Yahya, H. 2002. New fossil dicovery sinks evolutionary theories. www.harunyahya.com

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