Part A.
There has been at least a dozen various human like species since the earliest homid species split from the ancestral line the humans shared with the apes. This was approximately 6 to 8 million years ago. Most of these homid human like creatures are just relatives to the human beings and are not their ancestors. Humans are more closely related to modern apes like gorillas and chimps more they are to the monkeys. It is believed that humankind shares a common ancestry line with the African apes, like chimps and gorillas. And it is believed that this common line of ancestry existed 5 to 8 million years back. Shortly after, these two lines of species separated into two different lineages. Ultimately, one of these lineages evolved into the modern chimpanzees and gorillas, and the other lineage evolved into homids, the early ancestors of man. There are a few hypotheses on how these two relate. One is that these three species are very close relatives. Another hypothesis is that man, gorillas, and chimpanzees branched from one ancestor. One of the other hypotheses is that man is more closely related to chimpanzees than they are to gorillas.
The second cladistic is the correct one. The blue line represents the chimpanzees, the red line represents humans, and the black line shows the gorillas. This is the correct diagram because it shows how the humans and chimps branched from a common ancestry line, after the branching of the human kind’s clade from the lineage that man shared with gorillas.
Part B.
1. How do the gorilla DNA and the chimpanzee DNA compare with the human DNA?
There are various differences in the chromosome numbers of humans and modern apes. These differences either resulted from two chromosomes fusing in humans or from chromosome fission in the modern apes. Human telomeres are composed of repeats of bases 5’TTAGGG which run towards the chromosome’s end. In addition to this, the pre- telomeric region of the chromosome also contains a characteristic base pair. This region is located in the area of the chromosome just before the telomere. The sequences of the genomes of both chimps and humans that can be aligned differ by more than 35 million substitutions in their single nucleotides. More over, more or less of their genomes differ by about 3 percent in insertions, deletions, and duplications. About one and half of these changes occurred in the lineage of humans, mostly because the rate of mutation is constant.
2. What do these data suggest about the relationship between humans, gorillas, and chimpanzees?
The above data further justifies the fact that man and modern apes share a common ancestor and lineage, and that at some point this lineage became separated to give forth three different lineages; man, gorillas, and chimps. However, as shown by the many matches between the DNA of man chimps, humans seem to be the very closest relatives of chimps more than they are to the gorillas. This is because the human and chimpanzee DNA matches with five bases and, there are only two nucleotide bases that do not match between the DNA of the two species. Gorillas and humans seem to be far relatives when compared to chimpanzees, because the number of nucleotide mismatches, 4, is more than the matches, 3.
3. Do the data support any of your Part a hypotheses about the evolutionary relationships between humans, gorillas, and chimpanzees? Why or why not?
The data provided by these DNA comparisons does support the hypothesis on evolutionary relationships among chimpanzees, gorillas and man; and especially the cladograms where by we saw that humans and gorillas branched from the same lineage, after they had diverged from the lineage they both shared with the gorillas, and later on diverging into two different lineages; the chimpanzees and humans. It further supports the hypothesis that these three species shared a common ancestor once. It also supports the hypothesis that man and chimps are very close relatives, more than gorillas are close relatives to man.
4. What kinds of data might provide additional support for your hypotheses?
There are various data that can provide additional materials to support the above hypothesis. One of this is the genealogical relationship data for man, gorillas, and chimps, which mostly involves the differences and similarities in the genomes of these species. DNA sequence data is another useful source of information in addition to evolutionary history data; divergent times data, taxonomic history, classification, chromosomal evidence, and cladistics.
Part C.
1. Which DNA is most similar to the common-ancestor DNA?
After comparing these four DNA samples, it was found that the gorilla DNA was the one closest to the DNA of the common ancestor of the three species more than the DNAs of both man and chimpanzee. The only two nucleotides that did not match with the DNA of the ancestor were the second and the third base pairs. These two base pairs however, matched with the same positioned DNAs of the chimpanzee DNA. They did not match with the base pairs in the same position in the human DNA.
2. Which two DNAs were most similar in the way that they compared to the common-ancestor DNA?
Also, after comparing the genomes of man, gorilla, and chimp, with the DNA of the common ancestor, two DNAs were found to be very similar in the way they differed from the genome of the common ancestor. These two are the chimpanzee and man. They differed from the DNA of the common ancestor in 4 base pairs. The only matches found were in three base pairs. This was so for the two species. This further show how closely related these two species are.
3. Which of the hypotheses developed in Part I do the data best support?
Of the various hypotheses formulated above about these species, the above data on the relations of man, gorilla, and chimpanzee, mostly supports two hypotheses. The hypotheses that man, gorilla, and chimpanzee branched from the same ancestor, and the hypothesis that man is much more closely related to chimps than he is to the gorillas. This is because the three species have some common nucleotides with the genome of the ancestor. The hypothesis, that chimps and humans are closely related is proved by the fact that they have the exact same genome matches and mismatches with the genome sample of the common ancestor.
4. Proving of the hypothesis
The above data proves that these hypotheses are true because of the presence of matches in the DNA base pairs of all the three species and also because of the fact that chimpanzees and humans have the same number of mismatches and matches with the common ancestor DNA.
5. Humans and apes have a common ancestor.
This is the most accurate statement of the both, according to the data provided above. This is because there is no enough evidence given by the data to show that humans evolved from apes. But there is enough evidence to show that apes and man have a common ancestor or lineage; and especially chimps. This is proved by the presence of similar base pairs in the genomes of apes and humans. The similarities are much more pronounced between humans and chimps. And therefore we can conclude that these three species evolved or diverged from the same lineage or ancestor.
6. Chimpanzees and humans have a common ancestor.
This is the most accurate conclusion of the two statements. This is because there is no enough prove to support the statement that claims that humans evolved directly from the chimps. Another reason why the second statement is incorrect is the numerous differences in the nucleotides of the two species. However, it is correct to claim that humans and chimpanzees are very close relatives who share a common lineage. This is because of the number of matches in the DNA of both species. If they were not from the same ancestor, then they would have no similarities in their genome.
7. Human DNA and chimpanzee DNA are 98.8 percent identical
It is true that the genomes of these two species are almost 100 percent identical. In fact the above data shows that the genomes of a human and a chimp only differ at two positions, the second and the third positions. All the other base pairs in their genomes match 100 percent. This is farther indicates the very close relations the two share.
8. Methods of science
There were various scientific methods used in this class activity. Some of them included taxonomy, cladistics, genetics, classification, evolution, dating methods, taxonomic classification, sequence divergence, and cladograms.
