Based on the evidence in the passage, which of the following would be supported by Scientist #2, but not by Scientist #1?
Is Lucy a Human or an Ape
Who was the first human? Scientists have long debated this question as they have searched for evidence of our first
ancestors. Many believed (and still do) that the search ended with the discovery of fossil AL 288-1. This fossil,
nicknamed “Lucy,” is of a skeleton that is 40% complete. It consists of skull fragments, a lower jaw, ribs, an arm bone,
part of the pelvis, a thighbone, and some shin bone fragments.
This fossil was one of the most complete primate fossils ever found. It was believed to walk in an upright fashion and
has been designated as the first and oldest known human ancestor. Recently however, a new group of researchers has
collected evidence that points to Lucy merely being another in a long line of apes. Let’s hear from two researchers
concerning the world’s most famous fossil.
Of course Lucy is the earliest human ancestor. There is lots of evidence that leads us to draw this conclusion. First of all
there is the ribs that were found. We had an anatomy expert put the ribs together and they fit in a way that created a
barrel shaped chest, just like the barrel shape we have in humans today. More evidence comes from Lucy’s arm bone.
Its length and shape point toward a creature that walked upright and gently swung its arms, just like modern humans.
It has a smaller brain, but we calculated the ratio between skull size and body height for both Lucy and a modern
human, and the numbers came out very favorably.
There is more evidence as well. Her sharp teeth and the wearing pattern of the enamel indicate a diet similar to other
lines of ancient humans, one that includes meat and vegetables. Collectively, this is quite a bit of evidence that Lucy is
our ancient cousin.
Since Lucy was first discovered, new methods of research have allowed us to look at the remains much more carefully.
We had our own researchers re-create the rib cage, and we found that they had to be forced into the barrel shape. This
is because the bones are more rounded in cross section than that of a human, which are flat in cross section. Instead
the bones formed a conical rib cage, which is the shape you find with an ape.
We also did a detailed analysis of the arm and hand bone of the Lucy fossil. We found that she has a “stiff” wrist, not a
flexible one. This is definitely a feature of knuckle walking apes, not of bipedal humans. Still more evidence comes from
Lucy’s teeth. We used image enhancement and other optical techniques to show that Lucy’s diet consisted of quite a
bit of fruit. This is not something a ground dwelling human would eat on a regular basis, as this is a diet staple of a tree