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Posted on 24 May 2013 18:54

Johanson and Lucy’s Journey to the Past

Introduction of Johanson and Lucy
Dr. Johanson is famous for his discovery of Lucy, an ancient bipedal species that holds the title as our oldest human ancestor with the age of 3.2 million years. However, it is quite debatable whether Johanson’s assumptions on Lucy are accurate. Given that his work is magnificent and deserves recognition, I will be examining his evidence to verify Lucy’s bipedal capabilities and its ancestry connection to us. By analyzing not only his evidence but also Mary Leakey’s, it is possible to confirm Johanson’s results.

The Initial Findings of the Knee Joint
Initial discovery of a hominid’s knee joint can probably mark the beginning of Johanson’s great discovery of Lucy. It was November of 1973, near the end of the first field season, when Johanson discovered the femur and the tibia . After combining them with the condyles found nearby, he was able to recognize it as a human knee joint combination. While an ape’s femur and tibia join in a straight line, these joined in an angled manner and were able to “lock”, resembling more of that of a human . Moreover, the knee joint of a human is oval and that of an ape is round, and this ancient knee joint was much more oval than round. What was also important was the age of the knee joint. His geologist Maurice Taieb took a sample of a layer of basalt around the knee joint to date it biostratigraphically, and it came out to be about three million years old, which at the time was the oldest known evidence for human bipedalism. Moreover, in order to make sure of its bipedalism Johanson consulted his right-hand anatomist, Owen Lovejoy , and he find out that the creature was bipedal indeed. Therefore, Johanson was able to conclude that the owner of the knee joint was nevertheless capable of manlike walking .

The Remains of Lucy and Her Habitat
Discovery of the knee joint was only the start of what came to be Johanson’s greatest find. In order to establish a valid connection between Lucy and humans, Johanson needed much more than a bipedal knee joint. So he ventured back to Hadar for a second field season.

Tom Gray and Johanson discovered the remains of Lucy at Locality 162 on November 24, 1974, almost a year after the knee joint discovery. They found a plethora of bones that belonged to a species. When the team put together the puzzle to form a probable skeletal structure, they found the specie to be less than 3ft 6 in. tall, have a tiny brain and possess a V-shaped jaw . The species was then named Lucy. The skull was a marvelous discovery because it proved a widely believed theory at the time to be completely wrong. It was the definitive answer to whether human ancestors developed large brains before bipedality or vice versa . Johanson and Gray uncovered one of the greatest ancient artifacts in just one sitting, and it certainly was magnificent.

What also comes into question is Lucy’s habitat. Now that Johanson had in his hands the bones of Lucy, his next step was to figure out where Lucy lived and how she might’ve died. Johanson and his crew excavated animal fossils from rodents to elephants, showing where Lucy lived was a very different place from what it seems now. Then, Johanson reconstructs the past by referring to the reduction of dense forests and relating it to Lucy and her kind’s survivability . Around the time of Lucy’s existence, there was a gradual decline of forests. Lucy and her kind were bipedal even during their prosperous forest life, so when forests started to decline, they were still able to look for the same food in different locations . In addition, the bipedality and the need to range far to search for food implied that the males could not have absolute control over the females like the gorillas had. In the end, Johanson was able to map out Lucy’s environment at the time by analyzing both the past and the current geology of Hadar. It is surprising how modern archaeology is able to delineate a part of Lucy’s life in such a precise manner.

Unfortunately Lucy had another thing in common with humans, an inevitable death. Her death was discovered Johanson decisively concludes that she died of a natural death and not from her enemies. Therefore, her corpse was kept nearly intact and covert from scavengers underneath the soft sediments of the lake. As time passed, the flesh rotted away and heavy rains constantly washed sediments over Lucy, placing her even closer to the Earth’s core. However, with the enlargement of the Great Rift caused by movements of the Earth’s crust, and constant rains that washed down the sediments, Lucy was finally able to see light and Johanson’s crew .

The Evidence for Lucy’s Inclusion into the Human Family
As aforementioned, the discovery of Lucy’s knee joint was crucial to Johanson’s project. In fact, Johanson utilizes the knee joint to prove its bipedality, and ultimately its validity of belonging to the human family.

Fairly recently, there has been an article in support of Johanson’s speculation that Australopithecus Afarensis was a bipedal human ancestor. Unlike Johanson however, this article utilizes the discovery of a foot arch to bolster the hominid’s bipedal capabilities. Foot arches in humans are one of the reasons they are able to walk upright, and the arch’s existence in Lucy confirms that its species abandoned climbing trees and picked up ground life . The foot arches therefore assure Johanson that Lucy truly belongs to the human family with its foot arches which since then have been crucial to human locomotion.

Another component of bipedality is the structure of the pelvis. Johanson consulted his anatomist Owen Lovejoy for the evaluation of the pelvis discovered at Hadar. The unearthed pelvis proposed some problems at first. Johanson found the pelvis to resemble a chimpanzee’s and was quite frustrated. However, Lovejoy proceeded to create a plaster copy and reconstruct it and the angle of the hip looked much more like humans indeed .Lovejoy points out the ilium of the chimpanzee pelvis which sticks out sideways, which is perfectly placed for a knuckle walker . Lovejoy also stated that in order to allow the abductor muscles to function smoothly and walk upright for an indefinite amount of time, the ilium needs to be rotated forward so that it forms sort of a girdle . Interestingly, the exact case is true for both human pelvis and Lucy’s pelvis. Her pelvic structure resembles a human’s which bolster its bipedality for sure. In short, Lovejoy concluded for Johanson that Lucy was the connection between apes and humans by saying that her pelvis may have evolved enough to allow her bipedality, but she hasn’t yet, at the time, developed a more evolved pelvic structure that would allow offspring with larger brains .

Emergence of hominids does not stop here. At a good distance from Hadar, footprints of hominids were discovered by Mary Leakey and her crew in Laetoli. These footprints were delicately preserved under volcanic ash in an unbelievably good condition. Moreover, these footprints were not of apes but of hominids that walked erect . Tim White is positive of the bipedality as he states, “The external morphology is the same. There is a well-shaped modern heel with a strong arch and a good ball of the foot in front of it. The big toe is straight in line. It doesn’t stick out to the side like an ape toe…” In addition, there are, at least not visible, no knuckle prints where they should be if these footprints didn’t belong to a bipedal species. Surprisingly, these footprints outdate Lucy by a couple hundreds of thousands of years as they are 3.5-3.7 million years old . Thus, the footprints provided crucial information that our ancestors actually walked upright even earlier than we thought. Unfortunately, Marly Leakey chose to acknowledge Johanson’s conclusion and to not use the term Australopithecus Afarensis in her article by saying, “there is some doubt as to its validity.”

Johanson’s Conclusions: Valid or Invalid?

After examining Johanson’s evidence and trying to think coherently and logically, I see Johanson’s conclusion as valid as it can be. The most convincing and compelling argument Johanson proposed concerns the knee joint. The knee joint presents a bipedal species old as 3.2 million years old. However, at the time, the dating method by Taieb was erroneous due to the uncertainty of the exact location and time the layer of basalt. Nevertheless, the fact that this species walked upright also corrected the order of evolution, bipedality to larger brain and not larger brain to bipedality. Lucy’s knee joint is oval and her angled position of the femur both resemble our own skeletal structure and are completely different from those of apes. In addition, the pelvic structure further bolsters Lucy’s position in the human ancestry because it possesses both an evolved portion and a stagnant portion. Lovejoy claimed that the ilium of Lucy’s pelvis was positioned in the manner of facilitating bipedality, but it hasn’t adapted to giving birth to large skulled infants. Thus its unique pelvis suggested that it has evolved from apes but has not yet reached the homo-specie. All in all, Lucy is the bridge between apes and humans; the long lost connection that finally emerged to answer our question, what happened in between?

Moreover, I’d like to evaluate Mary Leakey’s great discovery in order to somewhat buttress Lucy’s spot in human ancestry. Mary Leakey’s hominid footprints in Laetoli were marvelous. She and the crew were able to uncover delicate footprints and find out that they were hominids. The footprints exhibited human-like features such as the strong arch and the frontal ball of the foot. These footprints clearly represent a bipedal species when comparing our own footprints. However, her disproval of Johanson’s connection of Lucy to the Laetoli footprints seemed more as a matter of personal emotions than a matter of scientific validity. There is of course no substantial amount of evidence to point these footprints directly at Lucy. However, it is not difficult to perceive that the bipedality prior to the development of larger brain can help classify the species as Australopithecus Afarensis. It is therefore, possible that Leakey’s argument with Tim White could have incurred her rejection of White’s and Johanson’s assertions . Although it may not be true, there’s more reason to think this way when the footprints dated to be 3.7 million years. When we are talking about a species that is capable of bipedality after the gradual disappearance and dispersion of forests, we have to instinctively think infer that they will walk in order to gather food.
In sum, there is no doubt about Lucy’s bipedality when looking at solid evidence of her skeletal structure which empowers it. Johanson was clear in his research and paleoanthropology, and his discoveries make his argument almost infallible. On a side note, I feel that it is unappreciative and unprofessional for Leakey to simply reject Johanson’s idea without considering further research to test his validity or to discover more evidence around the footprints. It seems best for paleoanthropologists to work together when flagrantly searching for the same reason, to find the ancestor of humans.

The Conclusion and My Comments on Johanson

Dr. Johanson uncovered a crucial veil that blurred the connection between apes and humans. For millennia, we were frantically delving into our ancestry to find our oldest relatives. Johanson finally found Lucy, our oldest ancestor, and established groundbreaking researches. His most essential implication derived from his findings has to be the corrected sequence of erect locomotion then larger cranium capacity. Many at the time believed the reverse to be true and Johanson basically killed nearly three birds with one Lucy. Moreover, Johanson’s fervor for finding our oldest ancestor is more than commendable. He completed a total of four field seasons, each with more passion than the previous. Mary Leakey, too, is an excellent expert, but I find it quite unfortunate that she necessarily cut ties with Johanson and some of his best partners. There are some criticisms present to attack Johanson’s discoveries, but I find them pointless and weak when initially encountering Johanson’s solid and ameliorated arguments. My wishes are that Johanson and Leakey together work towards further strengthening Lucy’s existence, and I hope to see their collaborative work soon.

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