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Biology U3/4 > Chapter 10: Human Change Over Time > Flashcards

Chapter 10: Human Change Over Time Flashcards

1
Q

State the characteristics of mammals

A
  • Fur or hair over their body
  • Milk-producing mammary glands
  • Teeth comprising of incisors, canines, premolars and molars
  • A lower jaw made of one bone
  • Breath using lungs
  • Three bones in the middle ear
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2
Q

State the characteristics of primates

A
  • Flattened face
  • Opposoable thumbs (allows for grip)
  • Binocular vision
  • Bicuspid teeth
  • Short nose
  • Large brain relative to body
  • Long gestational period
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3
Q

State the characteristics of hominoids/hominids

A
  • Large brain (cerebral cortex)
  • Characteristic teeth and skull bones
  • Absence of tail
  • Long upper limbs
  • Wide chest
  • Joints that allow arms to rotate
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4
Q

State the characteritics of hominins

A
  • Bipedalism (walking on two hind legs in a sustained fashion)
  • Large brain (allows for self awareness, use of complex language, writing and rituals)
  • Use of tools
  • Culture

NOTE: Hominins refer to modern human groups and their bipedal ancestors.

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5
Q

List the fossil evidence for bipedalism

A
  • Bowl-shaped pelvis and s-shaped spine
  • Central foramen magnum on the base of the skull
  • Larger feet and heel bone + more prominent foot arch
  • The femur and tibia arranged at an angle
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6
Q

List the effects of bipedalism on hominin behaviour

A
  • Enabled them to walk greater distances and migrate
  • Freed the hands for making tools and carrying young
  • Allowed them to reach for food (e.g. vegetation on trees)
  • Allowed them scan for predators by raising their head
  • Cultural behaviours such as ceremonies
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7
Q

List the trends in hominin evolution

A
  • An increase in the size of the cranium (indicates that brain size is increasing)
  • Longer feet with more developed arches
  • Longer legs (a larger leg to arm ratio)
  • Smaller teeth
  • Flattening and shortening of the face (making the face nearly vertical)
  • A more central foramen magnum
  • Smaller cheek bones (zygomatic arch)
  • Less prominent brow ridge
  • More V-shaped jaw (parabolic)
  • Development of an S-shaped spine
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8
Q

Outline the timeline of the hominin species

A
  • Australopithecus (A. afarensis and then A. africanus)
  • Homo habilis (first tool makers)
  • Homo ergaster (only found in Africa)
  • Homo erectus (first emigrants, migrated out of Africa)
  • Homo heidelbergensis (displays features between H. erectus and H. sapiens)
  • Homo floresiensis (the hobbit, small stature)
  • Homo neanderthalensis (all non-african humans have neanderthal DNA)
  • The denisovans (homo sapiens from oceania and mainland asia have denisovan DNA)
  • Homo sapiens (the only extant member of the human species)

NOTE: Homo neanderthalensis were NEVER in Africa.

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9
Q

Describe the features of early hominins (Australopithecines)

A
  • Bipedalism
  • Spine was between a c- and s-shape
  • Rounded but not parabolic jaw
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10
Q

State the difference between hominins and hominoids

A
  • Hominins refer to modern humans, extinct human species as well as immediate ancestors
    • This includes members of Homo, Australopithecus, Paranthropus and Ardipithecus
  • Hominoids refer to all modern and extinct Great Apes
    • This includes modern humans, chimpanzees, gorillas, and their immediate ancestors
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11
Q

Describe how brain size has changed in relation to hominin evolution

A
  • Brain size (relative to body) has increased from the Australopithecines to Homo sapiens
    • Homo neanderthalensis is the exception
  • Cerebral cortex and cerebellum (including other areas associated with language) expanded at higher rates compared to other brain regions
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12
Q

Explain the effect of increased brain size

A
  • Larger brains require a lot of energy
  • They allowed for tool use, travelling, the use of fire, systematic hunting, farming, caring for ill/elderly members of the species and enabled meat in the diet
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13
Q

Describe the trend in leg length and its relation to bipedalism

A
  • Longer leg to arm ratio
  • Longer legs allow for a more effective bipedal motion
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14
Q

Describe the trend in pelvis shape and its relation to bipedalism

A
  • Compared to chimpanzees, our pelvis is shorter and wider
    • Allows humans to walk and balance upright without having to shift our weight forwards and use our knuckles for stability
  • Compared to australopithecines, our pelvis is more bowl-shaped
    • Made the pelvis more stable to support weight (allowing for bipedalism)
    • Allows more surface area for muscle attachment
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15
Q

Describe the trend in foot shape and its relation to bipedalism

A
  • Larger heel and larger arch in the foot
    • Allows for even distribution of weight
  • Forward facing big toe
    • Allows us to use the big toe for propulsion (to move forward)
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16
Q

Describe the trend in leg angle and its relation to bipedalism

A
  • Compared to australopithecines, the angle between our femur and tibia is smaller
  • This is because australopithecines were shorter (large angle helped bring the centre of mass within the outline of the feet)
17
Q

Describe how and why the human fossil record has changed over time

A
  • The human fossil record is always changing
  • It is incomplete (compete fossils of incomplete specimens or incomplete fossils of complete specimens)
  • Classifications are not fixed and may change upon discovering new information
18
Q

Explain why the human fossil record is incomplete

A
  • Many species of hominins did not live in areas that are conducive to fossilisation
  • It is likely that many hominin species practiced burial rituals
  • Most hominin species only lived for a short period of geological time
19
Q

Explain why scientists can have different interpretations of the human family tree despite using the same evidence

A
  • Ancestral relationships are inferred based on limited fossil evidence
    • New evidence causes scientists to revise hypotheses
  • Dating methods tend to be imprecise
    • Some scientists consider genetic dating to have an error margin
  • The human fossil record is open to differing interpretations that are contested, refined and replaced when challenged with new evidence
20
Q

Explain how scientists used mtDNA to determine that Neanderthals were a different species to sapiens

A
  • mtDNA was extracted from Neanderthal fossils
  • The mtDNA was sequenced and compared to that of modern humans
  • It was found that Neanderthal mtDNA is distinct from modern humans indicating that they are two separate species
21
Q

Describe the evidence of the interbreeding between Denisovans, Neanderthals and Homo sapiens

A
  • Fossil evidence doesn’t provide a definitive answer of their interbreeding but genome sequencing has shown strong suggestions
  • Denisovan DNA accounts for 3-5% of DNA of Aboriginal Australians + Melanesian populations (e.g. Papua New Guinea)
  • All non-African modern humans have 1-4% of Neanderthal DNA (only native Africans have no Neanderthal DNA)
22
Q

State the evidence of the existence of Homo naledi

A
  • Fossilised remains were discovered in a South African cave in 2013
  • Showed characteristics between genus Homo and genus Australopithecus
  • Classified into a new species, Homo naledi
23
Q

State the evidence of the existence of Homo luzonensis

A
  • Fossilised teeth, finger bones, remains of a foot and a femur were discovered in the Philippines
  • Lived in luzon 50 000 to 67 000 years ago
  • Classified as Homo due to their cognitive ability to make and hunt with stone tools
24
Q

State the evidence of the existence of the Denisovans

A
  • Finger bone found in Siberian cave in 2008
  • Most closely related to Homo Neanderthalensis

NOTE: The Denisovans were a small population and only interacted to interbreed with Homo sapiens in the areas they inhabited.

25
Q

Explain the “out of Africa” hypothesis

A
  • The hypothesis states that Homo sapiens evolved in Africa and then left, replacing other human groups
  • It proposes that the migration of modern humans occurred in two waves
  • A first small-scale migration starting 120 000 years ago (into the Middle East)
  • A second large-scale migration starting 60 000 years ago (to Europe and Asia and then to all other regions)
  • Potential reasons for migration include availability of resources, environmental changes and curiosity

NOTE: This theory suggests that all modern humans are descendants of an African population of Homo sapiens.

26
Q

Explain how mtDNA provides evidence in support of the “out of Africa” hypothesis

A
  • There is higher genetic diversity in the mtDNA of modern African populations compared to the rest of the world
  • Homo sapiens have lived in Africa for 300 000 years which has allowed more mutations to accumulate overtime
  • Their later migration outside of Africa has left less time for mutations to occur which explains the less diverse mtDNA of modern non-African populations

NOTE: This is an example of the founder effect. New populations (outside of Africa) have a smaller gene pool compared to the original population.

27
Q

Explain the multiregional hypothesis

A
  • The Multiregional hypothesis states that Homo erectus left Africa and evolved into Homo sapiens in different locations
28
Q

State when and where the first fossils of Homo sapiens were found outside of Africa

A
  • When: 100,000 - 120,000 years ago
  • Where: Middle East
29
Q

State when Indigenous Australians arrived in Australia

A
  • 50 000 years ago
30
Q

Explain mitochondrial DNA (mtDNA)

A
  • mtDNA is present in all individuals
  • It is maternally inherited, so no recombination occurs
  • They contain a non-coding region known as the D-loop
  • The D-loop has two DNA sections that undergo mutation quicker than the rest of the molecule

NOTE: The greatest variation in mtDNA is observed within African populations.

31
Q

Define haplotypes and haplogroups

A
  • Haplotypes refer to the particular mtDNA sequence of an individual’s D-loop
  • Haplogroups are the various haplotypes worldwide that fall into a number of large clusters
  • Individuals in the same haplogroup share a common ancestor and have similar haplotypes
32
Q

State how mtDNA haplogroups can be used

A
  • Haplogroups can be used to track modern human migration across the world due to the lack of genetic recombination and high level of mutation in the D-loop
33
Q

Describe the difference between mtDNA and nucleur DNA

A
  • mtDNA is maternally inherited, so no recombination occurs
    • Have higher mutation rates due to lack of repair mechanisms
    • Provides evidence for maternal lineage and migration
    • Contains smaller amounts of genetic material
  • Nuclear DNA is inherited from both parents, so recombination occurs
    • Have lower mutation rates due to presence of repair mechanisms
    • Provides evidence for maternal and paternal lineages + interbreeding across species
    • Contains larger amounts of genetic material
34
Q

List the advantages of mtDNA and nuclear DNA analysis

A
  • mtDNA
    • Faster to sequence
    • Known or constant rate of mutation
    • Less likely to degrade compared to nuclear DNA
  • DNA
    • More genetic material (information) available
    • Can be used to determine interbreeding between species
    • Presence of introns can reveal more inherited mutations
35
Q

Outline the likely route that the ancestors of Indigenous Australians took to travel to Australia

A
  • It is proposed that their ancestors moved out of north-east Africa through the Middle East and Asia, and then travelled south to Sahul
  • From here, ancestors travelled east and west

NOTE: Sahul is a paleocontinent made up of the present-day landmasses of Australia, Tasmania, and New Guinea.

36
Q

Explain the importance of “Country” to Indigenous Australians

A
  • Aboriginal and Torres Strait Islander populations are part of the longest living cultures in the world
  • Due to the length of time they have lived in Australia, they have created strong and rich connections to their Country and Place
  • They exemplify their care for Country by traditional land management practices (e.g. traditional burning and fishing traps), allowing them to live sustainably in Australia
37
Q

List reasons for why DNA evidence for interbreeding may or may not be found

A
  • Reasons for DNA evidence being found
    • DNA has been obtained from older hominin fossils
    • Other hominin DNA has been found in the genomes of different hominin species, suggesting interbreeding occurred
  • Reasons for DNA evidence not being found
    • DNA degrades quickly and may not be found in very old fossils
    • Low chance that a fossil of an interbred individual will be found
38
Q

Explain how ancient cave drawings provide evidence of cultural evolution

A
  • Cave drawings show passing of information through generations
  • Cave drawings become more complex over time
  • Cave drawings show evidence of change in cultural practices, evidence of complex thought or evidence of symbolic representations
39
Q

Identify features of primates that distinguish them from other mammal groups

A
  • Prehensile/grasping hands
  • Forward facing eyes
  • Relatively large brain volume to body
  • Nails instead of claws

Biology U3/4 (12 decks)

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