Leaving Lucy in the Dust—The Case of Kenyanthropus platyops
||Bert Thompson, Ph.D.
Brad Harrub, Ph.D.
“The first definite hominids, Australopithecus, appeared about 5 million years ago in Africa. They lived on the ground, weighed less than 20 kilograms, and were less than 1.3 meters tall. They disappeared about 1.3 million years ago” (Raven and Johnson, 1989, p. 437). This quote is from a textbook I was assigned in a general biology class during my undergraduate studies. While the name Australopithecus may not be familiar, the name that evolutionists gave to the creature supposedly responsible for human bipedal locomotion probably is one you have heard: Lucy. Lucy’s skeleton was discovered at Hadar, Ethiopia in 1974 by Donald C. Johanson, who at the time was the curator of physical anthropology at the Cleveland, Ohio Museum of Natural History. Described as “remarkably complete” in the Cambridge Encyclopedia of Human Evolution (see Jones, et al., 1992, p. 237), the skeleton (that of a female creature) is approximately 40% complete. In 1981, Dr. Johanson wrote, and Simon & Schuster published, Lucy: The Beginnings of Humankind. Johanson’s claim was that Lucy (Australopithecus afarensis) was a hominid on the road to becoming man. Johanson considered Lucy to have essentially the body of a human, but the head of an ape. One of the most interesting points regarding this find was that Lucy was assigned a date of about 3.5 million years. Of further interest is the fact that Johanson viewed Lucy as giving rise to both Australopithecus africanus and Australopithecus robustus (also known as A. boisei), which are evolutionary dead-ends, as well as to those creatures on the road to becoming human (Homo habilis and Homo erectus). Lucy’s headlining days, however are all but over.
The branch of the evolutionary tree that designated Lucy as the single ancestor of Australopithecus afarenis and Australopithecus anamenis (which were commonly thought to belong to the lineage ancestral to all later hominids) recently “broke off ” due to a recent fossil find. In the March 22, 2001 issue of Nature, a new hominid genus named Kenyanthropus platyops from eastern Africa was described (Leakey, et al., 2001). Using their new specimen to rework humanity’s pedigree, paleoanthropologist Meave Leakey (wife of famed paleontologist Richard Leakey) and her colleagues at the National Museums of Kenya in Nairobi argued that the small-brained creature is so unusual it belongs not just to a new species, but to an entirely new genus. This new species now is nestled firmly in the roots of the human family tree at a time when scientists thought only one ancestral species existed, leaving it unclear just which (if either!) was the direct forebear of modern humankind.
The authors named this new find Kenyanthropus platyops, which means flat-faced man of Kenya, “in recognition of Kenya’s contribution to the understanding of human evolution through the many specimens recovered from its fossil sites” (p. 433). However, an exhaustive study of the article reveals a list of 36 craniodental fossils from this site, of which only 5 contain bone fragments. The remaining 31 are fragments of teeth. Only two of these specimens, the skull and a partial upper jaw, are intact enough to be assigned to this new taxon. The authors described their new finds as “a well-preserved temporal bone, two partial maxillae, isolated teeth, and most importantly a largely complete, although distorted, cranium” (p. 433). Distorted indeed! Even an untrained eye can look at the figures provided in the article and see the extensive damage to this newly found fossil.
Additionally, the authors provided a table in which the derived cranial features of this new species are compared to other finds (p. 434). Out of the 21 characteristics listed, Kenyanthropus platyops differs from Homo rudolfensis (considered the most primitive species in our own genus, which also includes Homo erectus and Homo habilis) in only one area: the upper molar size. H. rudolfensis is listed as having a moderate upper molar, whereas K. platyops is listed as small. So, as a result of a very fragmented and “distorted” cranium that possesses “small” upper molars, we now have been graced with a new genus.
FRAGMENTS AND PIECES
Scattered throughout the text of the March 22 Nature article are hidden reminders that everything about this recent discovery is speculative and indefinite. Here are a few quotes that the authors used in describing this new find (also referred to as KNM-WT 40000):
“Most of the vault [cranial—BH/BT] is heavily distorted, both through post-mortem diploic expansion and compression from an inferposterior direction” (p. 434).
“The original shape of the severely distorted mastoids cannot be reconstructed, but other parts of the left temporal are well preserved” (p. 435).
“It is preserved in two main parts, the neurocranium with the superior and lateral orbital margins, but lacking most of the cranial base; and the face, lacking the premolar and anterior tooth crowns and the right incisor roots” (p. 433).
“Only the right M2 crown is sufficiently preserved to allow reliable metric dental comparisons. It is particularly small, falling below the known ranges of other early hominin species” (p. 434).
“Inability to distinguish between first and second molars makes meaningful intertaxon comparisons of these elements difficult” (p. 437).
“The sex of KNM-WT 40000 is difficult to infer. The small M2 crown size could suggest that the specimen is female” (p. 436).
HISTORY OF THE HOMINIDS
One quick and easy way for a paleontologist to get the public’s attention is to announce a find that is either: (1) very old; or (2) directly related to the ancestry of humans. With K. platyops, Leakey does both. And so the race for claim on the oldest “common” ancestor is on—again! In 1994, Tim White and colleagues described the new species Australopithecus ramidus (which they renamed in 1995 as Ardipithecus ramidus), dated at 4.4 million years old.
When first found (and still considered an australopithecine), morphologically this was the most ape-like australopithecine yet discovered (as well as the earliest), and seemed a good candidate for the most distant common ancestor of the hominids. A year later, Meave Leakey (author of the current Nature article) and colleagues described the 3.9-4.2 million year old Australopithecus anamensis. This taxon is slightly more similar to Ardipithecus and Pan (the chimpanzees) than the better known and slightly later A. afarensis, and stood for a while as the ancestor of the later hominids (or a close cousin to some unknown, ancestral taxon).
Some have argued that part or all of the material regarding K. platyops belongs more properly in the genus Australopithecus. If Leakey et al. are right in their assertion that facial flatness connects K. platyops and H. rudolfensis in a significant manner, then that implies that their lineage had an evolutionary history distinct from the australopithecines. Therefore, evolutionists would conclude that we are descended from Kenyanthropus by way of H. (or K.) rudolfensis, or that the latter species is completely distinct from us and does not belong in our genus at all.
PROBLEMS WITH K. PLATYOPS
Aside from the obvious concerns over the extrapolations made from this fossil find, there are two other issues with which the authors conveniently chose not to deal. (1) No remains have been recovered from the site in which the cranium was found, and as a result, we know nothing about K. platyops’ locomotory adaptation, particularly its degree of bipedality. Was this creature even able to walk upright as humans do? (2) Leakey placed a tremendous amount of importance on the flatness of the facial features of this fossil, due to the widely acknowledged fact that more modern creatures would possess an admittedly flatter facial structure than their older, more ape-like alleged ancestors. This is no small problem, because creatures younger than K. platyops, and therefore closer to Homo sapiens, have much more pronounced, ape-like facial features. K. platyops was dated at 3.5 million years, and yet has a much flatter face than any other hominid that old. Thus, the evolutionary scenario seems to be moving in the wrong direction. As Tim White (anthropologist of the University of California at Berkeley) put it: “If you think of a family tree with a trunk, we’re talking about two trunks, if they’re right” (as quoted in McCall, 2001, p. 4-A).
COMING TO A NATIONAL GEOGRAPHIC NEAR YOU!
In the “acknowledgments” section of her Nature article, Leakey thanked the National Geographic Society for funding fieldwork and laboratory studies. This simple “thank-you” likely indicates that the editors of National Geographic soon will be sending out a full-color, slick-paper, professionally produced, eye-catching magazine into our homes so that we, our children, and our grandchildren can read articles about this new species. National Geographic and others are quick to run cover stories featuring world-famous evolutionists such as Donald C. Johanson (discoverer of our alleged hominid ancestor, “Lucy”) or the late Louis and Mary Leakey (in-laws of Meave, both of whom spent their entire professional careers on the African continent searching for the ever-elusive “missing link” between humans and ape-like ancestors). However, when the issue hits newsstands near you, remember what Greg Kirby, senior lecturer in population biology at Flinders University, Adelaide, said in an address on the case for evolution in South Australia in 1976: “…not being a paleontologist, I don’t want to pour too much scorn on paleontologists, but if you were to spend your life picking up bones and finding little fragments of head and little fragments of jaw, there’s a very strong desire to exaggerate the importance of those fragments….”
Jones, S., R. Martin, and D. Pilbeam, eds. (1992), The Cambridge Encyclopedia of Human Evolution (Cambridge, United Kingdom: Cambridge University Press).
Leakey, M.G., F. Spoor, F.H. Brown, P.N. Gathogo, C. Kiarie, L.N. Leakey, and I. McDougall (2001), “New Hominin Genus from Eastern Africa Shows Diverse Middle Pliocene Lineages,” Nature, 410:433-440, March 22.
McCall, William (2001), “It’s Old, Unusual—Is It Us?,” Tallahassee Democrat, pp. 3A-4A, March 22.
Raven, P.H., and G.B. Johnson, eds. (1989), Biology (St. Louis, MO: Times Mirror/Mosby College Publishing), second edition.