Lucy Australopithecus Afarensis and The Evolutionary Controversy

It was November 24th, of 1974 when Donald Johanson and Tom Gray discovered Lucy’s remains. According to The Institute of Human Origins, they were scavenging for bones and fossils in Hadar, Ethiopia. As the end of the day neared and they started to head back, they decided to take a different route and that is when Johanson saw the right proximal ulna which would become one of many bones that belonged to Lucy (4).

The search for Lucy didn’t come easy. In the fall of 1973 and for four years following, Johanson and his team dug for fossils in Ethiopia (1). It was during that time that Lucy was discovered. While searching and digging, armed tribesmen protected them from rebels and thieves. After finding the first fossil, Johanson wanted to compare his findings to a modern bone so badly that he took a human bone from a nearby grave. After doing so, one of Johansson’s colleagues accused him of stealing fossils and Ethiopian officials almost ended the digging. Johanson said “not every expedition is like Raiders of the Lost Ark but they have their moments” (4).

Lucy’s species is classified as being Australopithecus Afarensis. Australopithecus Afarensis is a species of hominid that lived in eastern Africa between four and three million years ago (3). It is a species that exhibits many cranial features which are similar of our ape ancestry, such as a prognathic face, a "U-shaped" palate not the parabolic shape of modern humans, and a small neurocranium that is not significantly larger than a modern chimpanzee (3).

So how did Lucy get her name? That first evening after discovering the bones, the researchers celebrated at the camp, staying up all night, and at some stage during the evening the fossil AL 288-1 was nicknamed Lucy, after the Beatles song "Lucy in the Sky with Diamonds”, which was being played loudly and repeatedly on a tape recorder in the camp. She has been referred to as “Lucy” ever since (4). Researchers found that it was only fitting for her to receive an Ethiopian name as well so they named her Dinkenesh which means “a wonderful thing” (10).

For three weeks after the initial discovery they continued to collect bones in the same location. Several hundreds of pieces or fragments of bone were found, with no duplication, confirming their original speculation that they were from the one skeleton. As the team analyzed the fossil further, they calculated that an estimated 40% of a hominid skeleton had been recovered, an amazing accomplishment in the world of anthropology. Usually, only fossil fragments are discovered; rarely are skulls or ribs found intact (4).

There are many controversies surrounding Lucy and one includes whether or not she was actually female. Johanson concluded that the skeleton was female based on the one complete pelvic bone and sacrum indicating the width of the pelvic opening. Lucy clearly fits into the female category because in Hadar the size differences between males and females are very clear. (9) Since the females in Hadar are very small and Lucy is also small then the obvious choice is that Lucy is also female. Hadar may have been the archaeological site but, it is modern. People there today follow in the growth patterns of all other humans. The growth and bone sizes in Lucy’s day were due to the time and not the location. Other fossils have been found in that area and they all follow the same guides of sizes and growth patterns that other parts of the world fall into. Even today, males are still larger than females all over the world and this pattern has been very consistent since the beginning of time.

Another common controversy was whether or not Lucy was bipedal. Chimpanzees and apes split off from hominids 6-7 million years ago. Lucy was only 3 feet 8 inches tall, weighed 65 lb and looked somewhat like a Common Chimpanzee. Her cranial cavity was small and indicated that her brain size was also small. Although it can be said that she had a smaller brain, her pelvis and leg bones were almost identical in function to modern humans, showing with certainty that she walked upright. When asked a question about Lucy walking upright, Dr. Johanson said, “The difference between an ape's skeleton, a creature that walks on all fours, and a human ancestor that walked on only two legs is very obvious in the anatomy of the knee and the hip. Lucy's hip, or pelvis, was wide and short from top to bottom resembling a modern human pelvis, very different from the pelvis of a four-legged animal like an ape that is very narrow and high from top to bottom.” (9) Another difference between Lucy and a chimpanzee is that a chimpanzee has a foramen magnum that is positioned more toward the back side of the cranium, Lucy’s foramen magnum was positioned at the base and more like a humans. If the foramen magnum is located at the rear of the cranium like a chimpanzee then it prevents the head from being held upright like a human. (10)

The other side of the controversy is that perhaps Lucy was a quadruped or walked on her knuckles. Researchers have discovered new evidence that the earliest humans that walked upright descended from ancestors that walked on their knuckles. Lucy would have been a descendent of the knuckle walkers and able to choose which type she preferred but science lends us to believe that she walked upright most of the time. Lucy was found to have a wrist locking mechanism that was found only on knuckle walkers and that’s where the controversy stems from but there is too much other evidence that shows that she walked upright. Now it is thought that she did in fact walk upright but had the ability to walk on her knuckles if she needed to and the wrist locking mechanism was just a component that was left over from adaptation in earlier species (2).

So what came first, brain size or walking upright? This has been a debate among scientists for quite some time. When Lucy was found, they noticed that her skull was very small and that her brain was not much larger than that of a chimpanzee yet she showed characteristics of walking upright. After much studying it is believed that being bipedal came first. (5) The two reasons were that her brain size was still very small and that she was several years older than the first stone tools that were ever made. Lucy’s brain was about 380-430cm³ and a modern human is about 1350-1400 cm³ (6).

Among some of the bones that were found were a humerus, some ribs, a lower jaw, sacrum, femur, the right ulna and some vertebrae along with an almost fully intact pelvic bone (7, 8). Her pelvis looked more like a modern woman's than an ape. It had broad, fan-shaped bones called iliac blades on both sides. These iliac blades curved to form a pelvic basin which helped to support her internal organs and entire upper body as she moved (6). This would be characteristic of a species that walked upright. Her long arm bones are consistent with a species that would be able to climb in trees and because the bones in her hand were curved, it supports the belief that she was a very skillful climber. Her vertebrae and femur have muscle attachment scars and show that she must have been very powerfully built. Also her lower jaw showed that her mandibular region was built more forward than that of a modern human and was more consistent with an ape. (6) (7)

The real Lucy is actually traveling to Houston, Texas to be on display at the Houston Museum of Natural Science. She has traveled a few times throughout the years but it doesn’t happen very often. You can view Lucy’s remains at many museums around the globe but if you do happen to see them, they’ll most likely be castings of the real thing. The bones that are on display at museums are actually replicas that are developed in the Institute of Human Origins. The real Lucy is usually protected in a safe that was specially constructed in the Paleoanthropology Laboratories of the National Museum of Ethiopia in Addis Ababa, Ethiopia. The reason for this is because the bones are so old and fragile that they might break upon transport from location to location. (4)

Evolution works through mutations that occur over time. If a mutation happens often enough then as time goes on, everyone will carry the gene for that specific mutation and it will become normal. We all have mutations of some kind but when the population starts to all carry the same mutation is when evolution will occur.

The debates and controversies among anthropologists have been on going for a very long time and they’re sure to continue, but the reputation of A. afarensis as "the ape that walked upright" makes it a celebrity species in the story of human evolution.


Sources

1. Can, Rebecca L. “In Search of Eve” The Sciences Sept / Oct 1987
EBSCOhost. TexShare. San Jacinto Coll. Lib., Pasadena. 22 October 2007http://web.ebscohost.com/ehost/pdf?vid=2&hid=106&sid=26f0e284-d14b-44dab156-4cc212b7515b%40sessionmgr104

2. Reynolds, Cynthia (2000, March 22). "Did Lucy walk on her knuckles?".
Retrieved November 23, 2007, from Discovery - Science
Today Web site: http://www.exn.ca/Templates/Story.cfm?ID 2000032251

3. (Unknown).Smithsonian Institute, "Australopithecus afarensis". Retrieved
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http://anthropology.si.edu/humanorigins/ha/afar.html

4. (Unknown). Arizona State University, "Lucy's Story". Retrieved November
22, 2007, from Institute of Human Origins Web site:
http://www.asu.edu/clas/iho/lucy.html#female

5. (Unknown). "Mother of man - 3.2 million years ago". Retrieved
November 23, 2007, from Science & Nature - Prehistoric
Life Web site: http://www.bbc.co.uk/sn/prehistoric_life/
human/human_evolution/mother_of_man1.shtml

6. (Unknown). Australopithecus Afarensis. Retrieved December 12, 2007, from Wikipedia Web site: http://en.wikipedia.org/wiki/Australopithecus_Afarensis

7. (2001). "Finding Lucy" Retrieved October 20, 2007, from PBS -
Evolution Web site: http://www.pbs.org/wgbh/evolution/
library/07/1/l_071_01.html

8. (2001). "Riddle of the bones". Retrieved October 30, 2007, from
PBS - Evolution: Humans Web site: http://www.pbs.org/wgbh/
evolution/humans/riddle/move.html

9. (2002). Educational Broadcasting Corporation, "Search for the
First Human". Retrieved November 20, 2007, from Secretes
of the Dead Web site: http://www.pbs.org/wnet/secrets/
case_firsthuman/chat.html

10. Houston Museum of Natural Science