Read the following passage, which contains some underlined or numbered words or phrases.
Each of the answer choices contains alternatives for the underlines; choose the one that fits best grammatically or stylistically. If you think the original is the best answer, choose Choice ‘A’, or NO CHANGE.
Questions about specific parts of the passage or about the passage as a whole are identified by numbers only, not underlines. These will be associated with specific questions.
Can We Turn a Chimp into a Man?
The similarity among the DNA genomes of humans and chimpanzees ranges from a low of 90% to almost 99%,
depending upon which source is examined. Assuming that the higher estimate is correct, would it be possible to
genetically engineer the remainder of chimp DNA to make it human? As gene manipulation and DNA re-sequencing
techniques are becoming more sophisticated every day, so would it be out of the realm of science fiction to manipulate
the germ plasm of a chimpanzee, replacing the sequences that make it a chimp, with those sequences which make us
human? Stefan Lovgren for National Geographic News states, “The number of genetic differences between humans
and chimps is ten times smaller than that between mice and rats.”
Though the percentage of shared DNA sounds as although the difference between man and chimp is small, scientists
have identified more than 40 million sequences that differ between the two species out of 3 billion DNA nucleotides in
each genome. Evan Eichler, a genome specialist at the University of Washington in Seattle, said, “The goal is to
answer the basic question: What makes us human?” Eichler’s team found that a scant 1.2% of the single-nucleotide
sequences differ between a humans and a chimps genome, and 2.7% of the genetic differences between the species are
duplications, repeated many times in the genome. What does this mean? It suggests that when chimps and humans
diverged from a common ancestor some six million years ago, it is probable that only a few important mutations are
responsible for the morphological and behavioral differences between them. "Darwin wasn't just provocative in
saying that we descend from the apes—he didn't go far enough," said Frans de Waal, a primatologist from Emory
University in Atlanta, Georgia. "We are apes in every way, from our long arms and tailless bodies to our habits and
temperament." So, what does this have to say about our big question? If the differences between man and chimpanzee
is identifiable and quantifiable, why can’t we tweak the DNA of one to become the other?
The answer might lie in the kinds of differences in DNA sequences between the species, more than just the
number of them. According to Wen-Hsiung Li, a molecular evolutionist at the University of Chicago, the difference
might be in the parts of the genome that regulate other gene activity, since we still have very little knowledge of how
our genome actually works to create proteins and other life-sustaining chemicals in humans, these differences are
significant. If DNA is just a set of instructions, informing cells how to make proteins, small differences make a great deal
of difference between species, or even between different members of the same species turn out. Look at the difference
between a Chihuahua and a Saint Bernard, which are both the same species, but have vastly different physical and
So, putting aside for the moment the ethical considerations of whether we should attempt to turn a chimpanzee into a
human, the astonishing complexity of these tasks are still well beyond our wildest capabilities at present. What is
intriguing about the comparison between man and chimp isn’t in the possibility of tinkering with one species or
another, but with finding out more about ourselves. "If genetic code is a book, what we found is that (14) entire pages
of the book duplicated in one species but not the other," said Evan Eichler. "This gives us some insight into the
genetic diversity that's going on between chimp and human and identifies regions that contain genes that have
undergone very rapid genomic changes." These discreet regions of DNA sequences might give us clues about
what it really means to be Homo sapien sapiens.
Created for Albert.io. September 2014
"If genetic code is a book, what we found is that (14) entire pages of the book duplicated in one species but not the other," said Evan Eichler.