Lucy

Donald Johanson, at one time an assistant professor of anthropology at Case Western Reserve University and curator of Physical Anthropology at the Cleveland Natural History Museum, is one of those lesser-known anthropologists who became famous overnight thanks to sensational claims regarding the discovery of fossil remains of presumed human ancestors. While working in 1973 near Hadar in the Afar Triangle of Ethiopia with a team led by Johanson, Maurice Taieb, a French geologist, and Alemayehu Asfaw from the Ethiopian Antiquities Administration, Johanson discovered a knee joint of a small primate that he initially thought belonged to a monkey. After assembling the parts and adjusting the angle at which the joint should be positioned, he concluded that it was a hominid knee joint, meaning a creature that was an intermediary between monkeys and humans. Furthermore, he believed, based on the animal fossils found nearby, that the joint was three million years old. Thus, from this small piece, he concluded that he had discovered a three-million-year-old human ancestor.

On his way back to the U.S. after the fossil hunting season, Johanson stopped in Nairobi to show his knee joint fossil to Richard Leakey and Mary Leakey, the son and widow of Louis Leakey. Both agreed that it was a hominid. On his return to the U.S., Johanson showed the joint to C. Owen Lovejoy, a professor of anthropology at Kent State University and an authority on locomotion. After a brief examination of the fossil, Lovejoy stated that it belonged to a fully bipedal creature, a “modern knee joint.”

During the second season in Hadar in October 1974, Asfaw discovered a lower jaw that he thought came from a baboon. Johanson, however, claimed that it was from a hominid. Two days later, Asfaw found two additional similar jaws. One was a palate (upper jaw) with all the teeth. Johanson’s announcement of the significance of this material at a press conference in Addis Ababa on October 25, 1974, included the following statement:

“These specimens clearly show features that must be considered as indicators of the Homo genus. Taken together, they represent the most complete remains of this genus in the world.”

All previous theories of human origin that linearly led to modern humans must be revised. We must discard many theories and consider the possibility that human ancestry goes back over four million years.”

A similar confident and imaginative language was used by Richard Leakey when presenting his discoveries of Skull 1470, as we will see later.

In November of the same year, while researching fossils several miles from camp with graduate student Tom Gray, Johanson found a bone fragment, based on which he concluded it was “part of a hominid’s hand.” Soon, they discovered other remains, including a spine, ribs, and parts of the skull and pelvis, all classified as hominid. After three weeks of gathering in the area, about 40% of the fossilized skeleton was collected. It was a female fossil, named “Lucy.” This creature was only about three and a half feet tall and had a very small brain, between 380 and 450 cm³. Johanson announced at a press conference that his Lucy was a three and a half million-year-old hominid that walked upright, just like modern humans. This brought instant fame to Lucy and her discoverer. The National Geographic Society promised funding and assigned a photographer to Johanson’s team. The money came from several sources. Johanson’s future was secure.

In papers prepared for publication in September 1975 and published in March 1976, Johanson and Taieb attempted to assign the material found by Asfaw to the genus Homo and suggested that Lucy showed similarities to Australopithecus africanus, while other fragments (the right proximal femur and temporal fragment) showed similarities to Australopithecus robustus.

By the end of 1975, during the third season in Hadar, members of Johanson’s team discovered a group of fossils, including fragments of at least thirteen individuals, including four young and nine adults. The discovery of so many fossilized primates of all kinds in such a small area had never occurred before. As with all earlier discoveries of primates remaining in Hadar, Johanson immediately classified them as hominids, attributing them to the Homo genus. Johanson called them the “First Family.” The use of terms like “human,” Lucy, “first family,” “child,” and similar anthropomorphic expressions helped convey the idea that the hominid status of these fossils was already widely accepted.

Johanson enlisted the help of Tim White, at the time a post-doctoral anthropology student at the University of Michigan, to assist in the work on the Hadar fossils. White had worked with Richard Leakey at Lake Turkana in Kenya and with Mary Leakey at Laetoli in Tanzania. From the beginning of their discussions, Johanson argued that there were two species in Hadar, including one that should be classified in the Homo genus, while White argued for individual species. White’s viewpoint prevailed, and their final decision was that the Hadar fossils represented a very primitive species of Australopithecus, which they named Australopithecus afarensis.

According to Johanson’s and White’s analyses, with the assistance of Owen Lovejoy in determining bipedal locomotion, as well as full support from others, Lucy and other accompanying creatures that walked upright in a human-like manner, though they were quite monkey-like from the neck up, were portrayed as creatures with small, strong, human-like bodies and monkey heads. This view, supported by evolutionary anthropologists regarding Australopithecus for several decades, became entrenched in textbooks and widely disseminated through scientific literature, as it was in all forms of mass media.

Johanson’s fame rests not only on the large number of individuals of his fossils, of which, in fact, only one (Lucy) was presented and was 40% complete, but also on the age attributed to these fossils, around three and a half million years, making them the oldest candidates for human ancestors. The family tree that Johanson and White constructed places A. afarensis at the base of the tree. Its branches then split into one leading to A. africanus and A. robustus, and another that splits into Homo habilis, Homo erectus, and Homo sapiens.

Referencing Johanson-White’s Interpretation of the Hadar Fossils Chapter 14 of the book Lucy, The Beginnings of Humankind by Johanson and Edey is titled “The Analysis is Complete.” That title reflects Johanson’s confidence that his analysis of the Hadar fossils, as creatures that are essentially monkeys from the neck up but walk exactly like humans, was entirely correct and would stand the test of time. This confidence, however, was somewhat premature, to say the least. First, it directly contradicts the claims of Lord Zuckerman and Charles Oxnard regarding the status of Australopithecus. Lord Zuckerman and Charles Oxnard worked on fossils of Australopithecus that were two million years younger than Lucy and the other fossils from Hadar. So, if nothing else, the fossils they studied were far “more advanced,” much more human-like, than the creatures discovered by Johanson. Certainly, if the Hadar creatures were walking upright, then so must the ones studied by Zuckerman and Oxnard. As noted earlier, however, Lord Zuckerman and Oxnard agreed that the Australopithecus they studied did not walk like humans.

Furthermore, many scientists disagree with the assessment that the Hadar creatures were capable of walking bipedally and question Johanson, White, and Lovejoy’s claims that these creatures were fully bipedal in a human-like manner. Our attempt to analyze and assess the various researchers’ analyses ended in the conclusion that it was a true “jungle” of opinions.

First, nearly all researchers have changed their minds once or more, and no consensus is in sight. Richard Leakey was the most honest regarding his claims. In an article published in March 1982 in New Scientist, he stated, “I am uncertain about the claims I made less than a year ago.” Although there is little doubt in Leakey’s belief that Australopithecus walked upright, in the same article he says: “Paleontologists do not know whether Australopithecus walked upright. No one has yet discovered a complete skeleton with a skull.” We must remember that this statement followed all the claims of recent major discoveries, including those from teams led by Johanson, Mary Leakey, and Richard Leakey. In his 1981 book The Making of Mankind, Leakey states (p.71) that: “Now we can say that Australopithecus definitely walked upright.”

As previously published in this section, Johanson initially believed that the Hadar specimens included those with similarities to Australopithecus robustus and Australopithecus africanus, and that some were definitely of the Homo genus. Later, he changed his mind and did not group them all into a new species, Australopithecus afarensis, but decided that his afarensis creatures were the most primitive of all Australopithecus species, in fact, the most primitive of all known hominids. If these creatures were truly so primitive, how then, in his earlier discussions with White and after many months of studying these fossils, did Johanson still insist that some might be included in the Homo genus, the most advanced of all species?

Jack T. Stern and Randal Susman, anatomists at the State University of New York at Stony Brook, published a detailed study on the postcranial skeletons of Johanson’s Hadars examples .51 In that journal, they suggest that larger specimens were male, and smaller specimens were female. Detailing further in the newspapers the debate among evolutionists regarding the status of Lucy and other Hadar specimens, published on July 2, 1983, a year after Stern and Susman submitted their statements to the American Journal of Physical Anthropology, Stern stated that he had changed his mind and now believed that the Hadar specimens represented two species. In the same issue of Science News, it was published that Yves Coppens, curator at the Musee de l’Homme in Paris, and one of the co-authors of the article publishing Johanson’s identification of the Hadar specimens as a distinct species, now, based on the premolars found in those specimens, suggested that there were two species. Also in the same journal, it was published that Phillip Tobias from the University of Witwatersrand in Johannesburg, South Africa, based on comparative studies of Hadar specimens with nearly 100 new specimens found over the last few years in Sterkfontein, South Africa, where Raymond Dart discovered the first Australopithecus africanus in 1924, claimed that certain types of afarensis should be abandoned, and all of Johanson’s Hadar specimens should be included in A. africanus. This was also recommended by Noel T. Boaz, an anthropologist from New York University.

As already mentioned, Stern and Susman published detailed analyses of the postcranial material of the Hadar specimens.51-54 Although these researchers believe that their studies reveal that the Hadar creatures were adept at climbing trees and were thus fully or partially adapted to that way of life, they also believe that these creatures also possessed some form of bipedal movement. They thus claim the following:

“We must emphasize that there is no way to discuss the claim that bipedal terrestrial movement was a significant component of A. afarensis behavior, and therefore, no living nonhuman primate.” (p. 280)

Stern and Susman highlight many ape-like features of the Hadar specimens. Referring to the hands, which were long and curved, they say:

“A brief review of the morphological and functional similarities of the Hadar fossils’ hands leads inexorably to the image of hands adapted for climbing, surprisingly similar to the hands found at the very end of the chimpanzee family — in the pygmy chimpanzee.” (p. 158)

Observing the feet, which were long, curved, and very muscular, they state:

“The foot and ankle reveal an animal that was bipedal, but also good at climbing trees… There is no evidence that any existing primate has long, curved, extremely muscular hands and legs for any purpose other than occasionally or permanently living in trees.” (p. 308)

Referring to the scapula, they say:

“We concluded that the glenoid cavity of A. afarensis was cranially oriented much more than is typical for modern humans, and that this feature arose from adaptation to using the upper limbs for lifting, which is typical of behavior during climbing.” (p. 284)

In an unnamed section, after drawing attention to the unnamed Lucy showing:

“Obvious human traits such as the low, wide femoral neck, the deep notch in the iliac, the protruding lower anterior spur of the femoral neck, and the surface of the iliac for tendon muscle origin…”

They then continue by describing numerous ape-like features (p. 284-290), and by pointing to the possibility of a weak or absent nuchal ligament, they say: “The only possible explanation is that bipedal walking was similar to that of chimpanzees or monkeys that walked like spiders…” Later they state:

“The possibility that the nuchal ligament of A. afarensis was not fully developed as in humans suggests either less frequency or a different mode of terrestrial bipedality than typical for modern humans.” (p. 290)

Regarding the sacrum, Stern and Susman state: “The sacrum of AL 288-1 is different from that of modern humans, in that the first segment does not have well-developed transverse processes.” (p. 291) Referring to the pelvis, after noting that the anterior part of the iliac of Lucy (AL 288-1) does not stand laterally like in humans, but by centering the iliac, it seems that it would be even more cranial than in chimpanzees, they say:

“The fact that the anterior part of the iliac of Lucy stands laterally in humans, but not in chimpanzees, is obvious. The similarity of AL 288-1 to chimpanzees is also obvious.”

Later, referring to this fact, they say: “This indicates that the lateral pelvic balance mechanism during bipedal walking was closer to that of monkeys than humans.” (p. 292)

For Stern and Susman, the proximal femur of one of the largest individuals (AL 333-3) is much more similar to humans than it is for the smaller individuals (AL 288-1 ap). They conclude:

“The general impression, raised after studying the well-preserved large proximal femur (AL 333-3), is that the specimen is very similar to the modern condition… On the other hand, the joint cap of the femoral head in AL 288-1 ap suggests the conclusion that the hip excursion of that small representative of A. afarensis was much more ape-like than human.” (p. 295)

Later (p. 296) they claim:

“The small proximal femur is much less human-like, globally speaking, and probably comes from individuals of pongid (ape-like) species, which had the ability to retract the hip.”

Regarding the distal tibia of smaller specimens, Stern and Susman say:

“Preuschoft’s analyses suggest that AL 288-1, as nonhuman primates with an anterior center of gravity for the body, had difficulty maintaining the vertical orientation of the body and could progress in movement more like African monkeys, and less like humans.” (p. 300)

They conclude:

“Data on the distal tibia from Hadar indicate that the small-bodied individual moved differently than modern humans, while larger specimens did not show signs of diversity.” (p. 301)

Their study of the femur led to the claim:

“We can summarize the morphological status of the Hadar femur by stating that it came from a population with an average structure different from that typical for humans.”

After studying numerous traits, they say:

“Each of these traits is structurally similar to pongids. The overall configuration of the distal femur of AL 288-1 is more similar to that of monkeys than humans.” (p. 305)

Their analyses of the knee joint are particularly interesting since Johanson, White, and Lovejoy described the knee joint structure as particularly significant in determining the fully human mode of movement in Lucy and other Hadar creatures. Stern and Susman state:

“In short, the knee of the small Hadar hominid shares with other australopithecines a significant angle of the femoral neck in relation to the bicondylar plane, but in all other respects, it falls either outside the range of modern human variation (Tardieu, 1979) or barely within it (our analysis). Therefore, except for the degree of valgus, the knee of the small Hadar hominid does not possess modern features in a pronounced degree, and since many of these features cannot serve to specify the exact nature of bipedality practiced, we must agree with Tardieu that the overall structure of the knee is compatible with significant arboreal activity.” (p. 298)

Furthermore, the degree of valgus in Lucy’s knee joint cannot be a human trait. The angle of valgus is a measure of how much the leg above the knee bends outward or laterally (so in humans, a larger valgus angle than normal results in knock-knees). In chimpanzees and gorillas, the angle is around zero. The upper and lower parts of the leg of these great apes form a straight line, and the body’s center of gravity falls within the legs. In humans, the degree of valgus is about nine degrees, and the upper part of the leg is angled outward or laterally from the knee. This places the lower leg and foot more directly under the body’s center of gravity. Lucy and South African australopithecines have a high degree of valgus, about 15 degrees.

If we recall, the knee joint angle was what led Johanson to state on the spot that the knee joint he found in 1973 was that of a hominid. As Stern and Susman (p. 298) and Cherfas have mentioned, Jack Prost from the University of Illinois at Chicago Circle takes exactly the opposite stance. He supports the fact that the high degree of valgus displayed by australopithecines supports the idea that they were skilled tree climbers.55 In support of this theory is the fact that among monkeys and great apes, the highest degree of valgus (equal to that in humans) is found in orangutans and monkeys that walk like spiders, both of which are extremely skilled at climbing trees. On page 313 of their work, Stern and Susman present their overall conclusions:

“We have discovered significant evidence that arboreal activities were so important for A. afarensis that the morphological adaptations that allowed skilled movement in trees were maintained. This conclusion does not necessarily lead to the further deduction that the nature of terrestrial bipedality, when it was practiced, was different from that of modern humans. However, we believe that this second conclusion is reasonable, although the evidence in its favor is much less convincing than that indicating a significant degree of arboreality.”

Earlier, on that same page where they discuss the nature of the bipedal stance of these creatures, they do, however, state that:

Finally, if the deductions about the poorly developed sacroiliac and knobby sacral ligaments in the Hadar hominids are correct, then the only possible explanation is that their bipedal stance was similar to that of chimpanzees and monkeys that walked like spiders, where the maximum vertical force, on average, is a smaller part of body weight than that which characterizes humans.”

Thus, while maintaining the idea that Lucy and other A. afarensis creatures walked upright, though not necessarily in a completely human way, Stern and Susman support the idea that these creatures were highly adapted to an arboreal or “tree-climbing” mode of movement. In light of many characteristics of anthropoid apes described by Stern and Susman, and considering the conclusions of Oxnard and Zuckerman and their colleagues regarding the movement of Australopithecus, it may be that A. afarensis and other Australopithecines were not actually more adapted to bipedal movement than chimpanzees and gorillas, who sometimes walk bipedally.

There is even a case where an anthropoid ape permanently adopted upright bipedal movement. A black anthropoid ape from Celebes (Cyanopithecus niger), kept separate from other primates in the Hong Kong Botanical and Zoological Garden, mimicked human movement at a very early age and moved in a very human-like way, quite different from the way Old World monkeys walk when they do so upright.

We have quoted Stern and Susman extensively to emphasize that even those who believe that, contrary to the conclusions of Lord Zuckerman and Oxnard, the Australopithecines achieved a certain model of bipedal movement still discover anthropoid-monkey features in the postcranial anatomy of these primates. Furthermore, Stern and Susman’s conclusions are in sharp contrast with those of Johanson and Owen Lovejoy, the latter of whom is quoted as claiming that A. afarensis was fully adapted to bipedal movement in painful detail.

Russell Tuttle, an anthropologist from the University of Chicago, leans toward Johanson and his followers regarding the manner of Lucy’s bipedal movement, as opposed to Stern and Susman’s views, but agrees with Stern and Susman that Lucy must have been arboreal.

By professional agreement and media promotion, Lucy and other A. afarensis creatures achieved a high status on the human family tree. However, it seems that Lucy and her cohorts had already started sliding down the family tree, and we predict that they will ultimately have the same fate as many other missing links that fell off the human family tree and are now simply missing. While cautious about Johanson’s Hadar specimens, Oxnard’s notes regarding these creatures seem particularly appropriate. He says:

“But because a new discovery that was not a human ancestor has never been welcomed, and because no new discovery has ever been published that was not bipedal, we can assume that we should be extremely cautious until these fossils are widely accessible for study using the full range of methods and research of today’s science.

• Literature
• 32. C. E. Oxnard, Homo 30:243 (1976).
• D. Johanson and M. A. Edey, Lucy the Beginnings of Humankind, Simon and Schuster, New York 1981, p. 155-156.
• Johanson and Edey Ref. 40, p. 163.
• Anonymous Correspondent, Nature 253:232 (1975).
• Johanson, Ref. 40, p. 16.
• Johanson, Ref. 40, p. 271.
• D. Johanson and M. Taieb, Nature 260:293 (1976).
• Johanson, Ref. 40, p. 213, 223.
• D. Johanson and T. D. White, Science 203:321 (1979); 207:1104 (1980).
• Johanson, Ref. 40, p. 352.
• J. Cherfas, New Scientist 93:695 (1982).
• R. E. F. Leakey, The Making of Mankind, E. P. Dutton, New York, 1981.
• J. T. Stern, Jr. and L. R. Susman, Am. J. Phy. Anthropol. 60:279 (1983).
• W. Herbert, Science News 124:8 (1983).
• R. H. Tuttle, Science 220:833 (1983).
• For a description of the analysis of Stern and Susman in layman’s terms see J. Cherfas, New Scientist 97:172 (1983).
• J. Prost, Am. J. Phys. Anthropol. 52:175 (1980).
• Oxnard and Lisowski, Ref. 33, p. 116.
• I. Anderson, New Scientist 98:373 (1983).
• W. Herbert, Science News 122:116 (1982).
• Oxnard, Ref. 32, p. 243.