→ Using comparative morphologies limits our ability in determining relationships between humans and other primates. Sometimes morphologies seem very different, yet the changes or modifications required to achieve those differences might be small in number or too simple. 

→ Using genetic evidence gives a much more accurate picture.

DNA-DNA Hybridisation

→ Can be used to show how genetically similar two species are.

→ DNA from a human and a chimpanzee (other primate) can be tested for melting point. Then it can be melted into single strands. The single strands are combined into hybrid DNA, in which some hydrogen bonding between base pairs does not happen because they are not complementary.

→ The lower the hybrid DNA M.P. is compared to the original DNA is a measure of how similar the original DNA was.

→ When the DNA is similar the two species are seen to be close in evolutionary terms.

Karyotype Analysis

→ Involves using a chemical to kill a cell during cell division when the chromosomes can be seen individually.

→ Photos are taken and the chromosome pictures arranged in pairs of increasing size. This picture of all the chromosomes in the genome is a karyotype.

→ Comparing the number, size, shape and banding pattern of chromosomes allows scientists to observe differences between species.

→ The fewer differences between karyotypes, the closer the species are in evolutionary terms.

→ People are interested to study our closest living relatives, as it helps us to understand where we have come from. It helps us to understand ourselves as a species when we can identify our closest living relatives and see our unique or common features and behaviours. DNA-DNA hybridisation and karyotype analysis help scientists to accurately achieve this knowledge.

i.     Figure 1: Prehensile

Figure 2: Non-prehensile
 

ii.   → Classification will be identical in higher levels, not necessarily the same in the lower levels.

→ Since phylum is above order in the classification system, these two animals in the same order will be in the same phylum.

→ Genus is below order in the classification system, so these animals are not necessarily in the same genus.

i.     → Genus Homo: the fossil should indicate an upright stance.

→ Genus Australopithecus: the fossil should indicate a stooped stance.
 

ii.   DNA sequencing

→ Mitochondrial DNA sequences of the fossil and a modern Homo species (eg Homo sapiens) could be compared to determine time since a common ancestor.

→ If the time since a common ancestor is less than 2 MYA, the fossil is likely to be of the Homo genus.

→ If it is greater than 2MYA since a common ancestor, it is likely that this fossil is either Australopithecus or another species.

→ The amino acid data set shows that chimpanzees and humans have identical amino acids in this protein.

→ Gorillas show one amino acid difference, new world monkeys show three amino acid differences and prosimians show four amino acid differences.

→ On the basis of this data, it can be assessed that chimpanzees and humans are identical, followed by gorillas then new world monkeys and then prosimians.
 

→ The morphological characteristics outlined in the table would rank the organisms in evolutionary proximity as chimpanzees most closely related to humans but different species, followed by gorillas then new world monkeys and then prosimians.

→ Both data sets correlate and therefore the estimates of evolutionary proximity to humans can be considered to be more reliable.