Evolution 280 Exam 3 Questions and Answers Fully Solved Latest Version 2025-2026
What larger clades contain hominins? Which species is the sister taxon of hominins? When did
this diverge? Evidence? - Answers -Great African Apple Clade = larger clade that contains
humans
-Chimps are the sister taxon
-Early molecular clock said human/chimp split was 5 mya, but fossils and genome analysis
show it was 7 mya
Who was sahelanthropus tchacensis? - Answers -6-7 mya
-oldest hominid fossil, with brow ridge but face more flat like a human, and that spine connected
to a the skull on a lower spot, suggesting the beginnings of upright posture
Who was aridipithecus radius? (Ardi) - Answers -4.4 mya
-Upright posture is introduced, a shorter pelvis, but feet of not show strong weight bearing
structures
-Both hands and feet can grasp things, good for climbing along branches and trees, a
combination of bipedal and tree dwelling features. Could potentially walk upright hanging
between branches
Australopithecus afrensis (lucy) - Answers -3.2 MYA,
-lucy has knees for upright walking
Australopithecu sediba - Answers -2 MYA
--had some older features (brow like ridge, small teeth)
-has a pelvis that was short from top to bottom and larger from side to side
-Features larger space in the middle of their pelvis ---was this adaption for larger brains in
humans????
-Had anatomy to make and use tools but we aren't sure
Paranthropus and Homo Ergaster - Answers -1.7 MYA
-Pelvis, knees and arrangement of the leg bones re perfectly suited for bipedal posture, should
pride representative o less raking through trees
-used tools
Homo Erectus - Answers -1.5 MYA
, -found in china, southeast asia, etc.
-Big brains? Yes, but not as a big as homo genus, used tools
-first hominin to leave africa
Homo sapiens - Answers -195,000
-ethopia (africa)
-had big brains, small teeth, and upright posture
Homo neanderthalensis - Answers -400,000 YA suggested by molecular clock
-250,000 YA suggested by fossils
-had big brains, used tools, has small teeth and upright posture
-Found in the middle east
Homo floresiensis "hobbit" - Answers -18,000 YA
-small creatures with small brains but they used tools
-found on island in indonesia
-near them found small elephant skeletons (animals on island can evolve to be extra small)
What are the two theories describing how homo sapiens came to have a world wide distribution?
- Answers 1-African replacement hypothesis
2 - multirgional hypothesis
What is the african replacement hypothesis? - Answers Homo erectus let and then homo
sapiens replaced them when they died off
What is the multi regional hypothesis? - Answers Homo erectus let, and then all the homo
erectus start evolving secretly (through normal speciation) and they acquired difference but not
enough to become different species because there was enough gene flow to prevent it
What hypothesis is support more? What evidence? - Answers The african replacement
hypothesis: found fossils of homo sapiens in africa, very unlikely that separate populations
evolved into the same species EVERYWHERE
What are the major findings and conclusions of efforts to sequence Neanderthal DNA? -
Answers -Found that 2% modern humans contain neanderthal DNA
-Therefore homo spaiens and neanderthals must have hybridized in Europe to give rise to
modern humans
What larger clades contain hominins? Which species is the sister taxon of hominins? When did
this diverge? Evidence? - Answers -Great African Apple Clade = larger clade that contains
humans
-Chimps are the sister taxon
-Early molecular clock said human/chimp split was 5 mya, but fossils and genome analysis
show it was 7 mya
Who was sahelanthropus tchacensis? - Answers -6-7 mya
-oldest hominid fossil, with brow ridge but face more flat like a human, and that spine connected
to a the skull on a lower spot, suggesting the beginnings of upright posture
Who was aridipithecus radius? (Ardi) - Answers -4.4 mya
-Upright posture is introduced, a shorter pelvis, but feet of not show strong weight bearing
structures
-Both hands and feet can grasp things, good for climbing along branches and trees, a
combination of bipedal and tree dwelling features. Could potentially walk upright hanging
between branches
Australopithecus afrensis (lucy) - Answers -3.2 MYA,
-lucy has knees for upright walking
Australopithecu sediba - Answers -2 MYA
--had some older features (brow like ridge, small teeth)
-has a pelvis that was short from top to bottom and larger from side to side
-Features larger space in the middle of their pelvis ---was this adaption for larger brains in
humans????
-Had anatomy to make and use tools but we aren't sure
Paranthropus and Homo Ergaster - Answers -1.7 MYA
-Pelvis, knees and arrangement of the leg bones re perfectly suited for bipedal posture, should
pride representative o less raking through trees
-used tools
Homo Erectus - Answers -1.5 MYA
, -found in china, southeast asia, etc.
-Big brains? Yes, but not as a big as homo genus, used tools
-first hominin to leave africa
Homo sapiens - Answers -195,000
-ethopia (africa)
-had big brains, small teeth, and upright posture
Homo neanderthalensis - Answers -400,000 YA suggested by molecular clock
-250,000 YA suggested by fossils
-had big brains, used tools, has small teeth and upright posture
-Found in the middle east
Homo floresiensis "hobbit" - Answers -18,000 YA
-small creatures with small brains but they used tools
-found on island in indonesia
-near them found small elephant skeletons (animals on island can evolve to be extra small)
What are the two theories describing how homo sapiens came to have a world wide distribution?
- Answers 1-African replacement hypothesis
2 - multirgional hypothesis
What is the african replacement hypothesis? - Answers Homo erectus let and then homo
sapiens replaced them when they died off
What is the multi regional hypothesis? - Answers Homo erectus let, and then all the homo
erectus start evolving secretly (through normal speciation) and they acquired difference but not
enough to become different species because there was enough gene flow to prevent it
What hypothesis is support more? What evidence? - Answers The african replacement
hypothesis: found fossils of homo sapiens in africa, very unlikely that separate populations
evolved into the same species EVERYWHERE
What are the major findings and conclusions of efforts to sequence Neanderthal DNA? -
Answers -Found that 2% modern humans contain neanderthal DNA
-Therefore homo spaiens and neanderthals must have hybridized in Europe to give rise to
modern humans
