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EVOOOO > Human evolution > Flashcards

Human evolution Flashcards

1
Q

q

What class are humans, and what are the characteristics of that class

A

Mammalia,
1.Fur or hair
2.Milk producing mammary glands
3.three bones in the middle ear
4.teeth compromising of incisors ,canines,molars and premolars
5.Lower jaw made of a single bone.

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2
Q

What are order are humans, and what are the characterisitics of it

A

Primates
1.Body features
2.Skull features
3.Functional features

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3
Q

What super family does humans classify into, and what are its characteristics

A

HominOIDS
1. Lack of tail
2. Shorter spine
3. Broader ribcage and pelvis to help them sit upright
4. Y5 molar pattern
5. Larger and more complex brain
6. Typically longer amrs than legs EXCEPT HUMANS
7. Distinctive molar teeth in lower jaw.

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4
Q

What tribe is homo sapiens from, and what are its characteristics

A

Hominins
1. Bipedalism
2. Communication and formation of complex social groups

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5
Q

What are the body features of a primate

A
  1. A flexible skeleton, with arm that can rotate in the shoulder socket to allow to reach behind their body
  2. Prehensile hands/feet that can grasp objects and have 5 fingers/toes in each limb
  3. Large number of sensitive touch receptors in fingers
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6
Q

What are the skull feautes

A

1.Binocular vision due to possessing large,front facing eyes that give 3d vision making depth of perception possible.
2.Larger cranium for their body size
3.Relatively long gestation periods to accomodate for brain development

( gestation means how long u been preggy for)

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7
Q

What are functional features

A

Strong social mammals that live in groups

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8
Q

Hominins include homo sapiens and all of our extinct ancestors that could walk in a bipedal locomotion? True or false

A

True

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9
Q

What does bipedalism mean

A

A form locomotion where it involves using only two legs for walking upright

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10
Q

What is evidence of bipedalism in a hominin?

A
  1. Centralised foramen magnum
  2. Bowl shaped pelvis
  3. S shaped spine
  4. Broader ripcage
  5. Increased carrying angle of the femur
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11
Q

Overtime what happened to Hominins brain size over time and what happened cause of it

A

Increased in brain size which resulting in higher cognitive processes that developed
Speech
Complex emotions
High order desicion making
Abstract thinking and planning

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12
Q

Does the biggest brain in primates mean the smartest?

A

No, neanderthals had bigger brains than humans but we predcit they used it for superior vision and thermorgulation whereas humans instead evolved extensive networks to promote socialisation.

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13
Q

Due to the brain size increased what happened to the brain that resulted in higher cognitive function

A

The CEBRUM became more folded which increased SA and** increased in neural connections.**

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14
Q

What are the cons of having a larger brain and link it to the mortalityu and dietary requirments

A

When a brain is larger, that means more mutations occured resulting in a high morphological change, this is energy costing , therefore high morality rates and a higher dietary requirements.

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15
Q

What are the cons of having a larger brain and link it to the mortality and dietary requirments

A

Having a larger brain means higher cognitive abilities, which meanst they had lower predator vunerbilities, more group caring, better cooking production. This meant lower mortality and lower dietary requirements.

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16
Q

List the structural changes in the skull over time in hominins

A

1.More centrralised foramagnum
2.Lessing of the brow ridge
3.Shrinking of the saggital crest
4.Flattening of the face
5.More domed skull
6.Smaller teeth
7.Less of a protruding chin

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17
Q

What is the foramen magnum and what happened over time

A

The hole in the base of the skull through where the spinal cord passes.
It became more central as hominins became more upright, maintaining balance of the head.

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18
Q

What is the saggital crest and what does having a big one mean and what happened for it to reduce

A

Saggital crest is present on the top of the skull running lengtwise along the midline where Jaw muscles attach.
Having a bigg saggital crest would mean large muscles can attach and increase jaw strength (they ate a lot of meat) .
In humans, saggital crest reduced as brain size increased and teeth became smaller. ( as we started cooking food)

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19
Q

What is brow ridge

A

Crest of the bone situated on the frontal bone of the skull.

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20
Q

Why did the face get flatter over time?

A

AS the envviorment got more drier and homo sapiens developed tools and relyed more on them to break and cut foods. The jaws and teeth became less demanding and therefore the face became more delicate, flatter look. Allowing for more complex communication and expression of emotion.

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21
Q

Why the skull became more domed?

A

To faccilaitate the increased brain size

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22
Q

Whats a feature that primates possed to order to live an arboreal lifestyle?

aboreal means living in trees

A

3D colour vision
High rotational movement in the hip and shoulders
Some posses tailsTails

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22
Q

Why the teeth became smaller?

A

Tool reliance meant no need for big teeth and jaw, this increased evolutionary pressure to spend less energy making large teeth.

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23
Q

What strucutural changes that was vital for bipedalism

A
  1. Shape of spine
  2. Shape of pelvis
  3. shape of ribcage
  4. Arrangement of femur and tibia
  5. Leg to arm ratio
  6. Size of heel bone and subsequent heel arch
  7. Wrists and hands that allow for manipulation of objects and tools.
24
Q

What changes in spine structure over time

A

Changed from a C shaped to a S shaped, providing flexibility for walking, acting as a weight distributor and shock absorber.

25
Q

Structure of pelvis change compared to hominins and hominoids.

A

To help hominins the pelvis is more bowl shaped and a much narrower

26
Q

What changed in rib cage overtime?

A

The rib cage changed from funnel shaped to barrel shaped to help maintain upright posture for a long period of time.

27
Q

What happened to the femur and tibia arrangement?

A

A larger carrying angle occured, this made our knees and feet lie below the centre of the body and majority of the weight fall outside of the knee joints.

This therefore allowed us to stand upright and walk upright as your body weight can be supported by one lef as the other leg steps foward.

28
Q

What happened to leg to arm ratio

A

Hominins had a greater leg to arm ratio compared to hominoids ( which needed it for tree dwelling and standing on all fours)

29
Q

What happened to the feet of the hominins comapred to hominoids

A
  1. Size of heel bone is larger than hominoids heel
  2. Arch size is larger than hominoids heel
  3. Big toe became more inline with other toes than opposed in hominoids
    This is was benefical to bipedalism as the feet was better suported for weight/weight distribution.
30
Q

What happened to the hands of hominids.

A

There was more of a reliance of hand use for manipulatin of objects and tools, mosiac pattern in the humans allowed for greater manual dexterity especially for the thumb.

31
Q

What happened to the hands of hominioids.

A

They had long curved fingers as it provided strong grip for grasping.

32
Q

How did hominins culturally evolve

A

Cultural information written and verbally trnasmitted
Increasingly complex tools
Complex societies
Wider acess to food sources as hominins were now in groups together
Increasingly detailed art

33
Q

What two grips occured in humans

A

Prescion grip- which was used for precise manipulation of objects
Power grip- generates more force due to the use of the palm to grasp objects.

34
Q

What are the benifits of Bipedalism

A
  1. Creation and use of tools
  2. Tools gave acess to new foods
  3. Extra energy from cooked foods were provided, increasing cognitive function
  4. Can carry younng and reach for foods
  5. Arts and culture
  6. Can raise head high to scan for prey and predators.
35
Q

Why is it so hard to find fossil evidence

A
  1. Not all individuals die in eviroments/conditions that promote fossilation
  2. Rock layers containing fossils can erode and disappear overtime
  3. Many rock layers are inaccessible to palentoligists
36
Q

Where did Homo Neanderthals habit and when

A

Europe and Asia and 40,000-400,000 yrs ago.

37
Q

How could you differentiate between species of homo sapiens and neanderthals

A

Usage of mtDNA from neanderthal fossils.

38
Q

Did or did not homo sapiens and neanderthals have a common ancesotr

A

Yes blud

39
Q

which of the two neanderthals and homo sapiens are better adapted to the cold

A

Homo neanderthals, a they have a broad build that minimises skin surface area, therefore conserving heat.

40
Q

Did Homo S and Neanderthals interbreed

A

They may have interbred as they coexisted in the same reigions 80,000-100,000 years ago. The Interbreeding maybe happned with humans that left africe around 65,000 years ago but not with african humans. This is evidenced by the neanderthal DNA (1-4%) found in the genomes of non-african population but not in sub saharan african genoms

41
Q

What was the second interbreeding event with neanderthals

A

Siberian neanderthal population may have interbreed with early form of humans 100,000 years ago as there was an significant amount of ancient human dna found in only neanderthals siberian fossil

42
Q

What are the two other new types of hominins

A

Homo denisovans and Homo luzonesis

43
Q

Is denisovans a member of h sapiens and h neanderthals

A

DNA analysis of bones were found that it was not a memeber of H.sapiens and Hneanderrthals but more closer to neanderthals.

44
Q

Did denisovans ever interbreeed

A

Yes 4-6% shared DNA with Melanesian H Sapiens.

45
Q

How old are H. denisovans

A

40,000 years old

46
Q

What is H.Luzonesis, where it live and when

A

A small bodied hominin lived in Luzon island around 50-67,000 years ago.

47
Q

Why was Homo Luzonesis classfied as Homo genus

A

It had signs of stone tool marks which is an characteristic of Homo genus.

48
Q

What are the two methods used as evidence for migration

A
  1. Fossil usage for relatedness by comparing anatomy, particulary homolgous structures.
  2. Molecular homology, compares similarties in DNA or Amino acid sequences in protiens as evidence for relatedness.
49
Q

Wht are the two hypothesis for migration

A
  1. Multiregional
  2. Out of Africa
50
Q

What is the Out of Africa hypothesis

A

A model that siggests that modern homo sapiens first developed and evolved in Africa before migrating outwards in colonies, taking over the other hominins that spread earlier.

51
Q

What is the multiregional hypothesis

A

A model that suggests that seperate human populations evolved independantly from another hominin species( Homo erectus) that spread earlier throughout Europe and Asia, and allowed the occurance of gene flow between populations.

52
Q

Whats the evidence of out of africa

A

1.Mitrochondrial DNA analysis show that modern human mitochondrial lineages trace back to a common ancerstor that lived in Africa, often named the mitochondrial eve 140,000 - 290,000 years.
2. Modern day humans have low genetic diversity compared to other species given that we only have existed around 200,000 years, the greatest genetic diversity is occured in African population, where Homo Sapiens first appeared, this meant that if there was more genetic diversity it suggests that there was more time for spontaneous mutations to accumalate in mTDNA there.
3. Oldest Homo sapiend fossils were found in east africa then later found in middle east, suggesting migration in and out of africa.
4. Artifacts have been dated to provide evidence for cultural evolution and map migration patterns.

53
Q

Evidence for mutlireigonal hypothesis

A

There is based of limited fossil evidence and anatomical characterisitics of modern populations

54
Q

What were the migration of aborignal and torres strait populations

A

Most modern genomes of aboriginals and torrest strait islanders trace back to the original Out of africa event 50,000-65,000 years ago, where Homo spaiens reached a super contininent called SAHUL. Which got seperated by high sea levels, makingthem the first modern human population to become genetically and geographically isolated.

55
Q

What is SAHUL and and what happened to it

A

Consisted of tasmania, australia and New guniea.
Sahul got seperated by sea levels rising 10,000 years ago.

56
Q

why is mtDNA good?

A

inherited via maternal line (mother only)
any changes that arise are from mutations ; does not undergo recombination

**MTDNA is present in high numbers of copies
hence, can be recovered from ancient specimens
**

57
Q
A

EVOOOO (4 decks)

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