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BIOLOGY, M4 2016 HSC 35d

A new fossil form was recently found in South Africa. This fossil shares characteristics with both the genus Australopithecus and the genus Homo.

There has been debate as to whether this new fossil form should be classified in the genus Australopithecus or in the genus Homo.

  1. Describe a key difference between fossils classified as the genus Australopithecus and those classified as the genus Homo.   (2 marks)

  2. Explain how DNA sequencing technology could be used to determine which genus the new fossil belongs to. In your answer, refer to relevant hominid species.   (4 marks)

Show Answers Only

i.     → If the fossil is to be classified as the genus Homo, then the fossil should indicate an upright stance.

→ Alternatively, if the fossil is to be classified as the genus Australopithecus, then the fossil should indicate a stooped stance.
 

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

Show Worked Solution

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.