Becoming human 14

Question 1

Define Primate and it’s characteristics

Answer 1

• a member of the order Primates that’s comprised of about 400 different living species and that share a number of features including opposable digits and
  binocular vision

• Prehensile(grasp)hands and/or feet with
five digits, flatten nails rather than claws
• Opposable thumb
• Binocular colour 3D vision
• Social animals
•Sensitive touch receptors
• Relative large cranium for the body -

Question 2

Define Hominoids and it’s characteristics

Answer 2

a member of the superfamily Hominoidea that includes apes and humans.( no monkey)

• Broad rib cage
• No tail
• Long arms
• Y5–shaped molar teeth
• Large cranium

Question 3

Define Hominins and it’s characteristics

Answer 3

• upright walking ancestral and modern humans (the key difference is bipedalism). (no chimps and gorillas)

• Bipedalism
• Communication and formation of complex social groups
•Structural consequences of bipedalism – centralized foramen magnum, S-shaped
spine, broader rib cage, bowl-shaped pelvis, increased carrying angle of the femur

Question 4

Mammals:

Answer 4

Warm-blooded vertebrates, they have 
 • mammary glands(e.g. milk produce),
 • hair/fur, 
• three middle ear bones(help with hearing), and
•  one lower jawbone( powerful bite)

Question 5

Who are Homo Heidelbergensis?

Answer 5

• an extinct hominin species that existesd around 500,00 years ago and was the common ancestor of Neanderthals and modern humans
• Note that Homo neanderthalensis and Homo sapiens share a common ancestor( Homo heidelbergensis-but aren’t directly related)

Question 6

Sturctual Changes

Answer 6

1. Cranial capacity: increases
2. Brow Ridge: decreases due to increasing size of cranium
3. Face shape: flatter due to jaw size decrease + less protruding due to reduction in teeth size
4. Chin: Only Homeo sapiens have
5. Teeth: arch changes from u-shape-> v-shape, Canine+molar teeth decrease in size due to softer and cooked food diet.
6. Foramen Mangum: more center because hominin become upright
7. Spine curve: shape change from c-s shape to support weight vertically
8. Rib cage: from funnel-shape->barrel-shaped to maintain upright posture for long time
9. Arm to leg ratio: decreases for bipedal locomotion
10. Pelvis: shorter+more bowl-shaped for upper body support whilst standing + walking
11. Big toe: more protruding, other toes increasingly aligned as no longer a need to grasp.

12 .Foot arch: increases for more efficient bipedal locomotion
Heel size: Foot arch: increases for more efficient bipedal locomotion

Question 7

Functional changes: Bipedal benefits

Answer 7

1. Flexible, precise hand
2. can raise head and scan for predator and prey
3. walking on two legs is more energy efficient

Question 8

Cognitive changes

Answer 8

• Neanderthals had larger brains than humans, they used it for superior vision, maintain large, stocky body for cold climate
• Human brain increased in complexity in structure of brain, cerebrum became more folded= increased TSA –> enchnced cognitive ability . Human brain evolved to promote socialisation.

Question 9

The consequence for cultural evolution

Answer 9

1. Tool used: became more complex –> increased intelligence
2. Fires: used of fire-> intricate, for warmth, making tools and cooking
3. Social organisation: social groups increased in size, governments created to maintain order and peace
4. Food sources: worked together to hunt, but hunting become no longer necessary due to increased knowledge w/ farming-> constant food supply
5. Art: increasingly more detailed
   * With all, knowledge and skills have been passed on generations-> improved ways were done-> increased knowledge, skills and intelligence

Question 10

Check Rosies note of evidence of interbreeding

Answer 10

got it thanks rosie

Question 11

interbreeding and cross-breeding

Answer 11

refers to the mating
between different species

(e.g.
between Homo sapiens and other
closely related species such as
Neanderthals and Denisovans).
Also known as crossbreeding

Question 12

Homo neanderthalensis

Answer 12

commonly
called Neanderthals, they are
an extinct hominin species that
lived in cold climates alongside
Homo sapiens with whom they are
believed to have interbred

Question 13

Homo denisova

Answer 13

commonly
called Denisovans, they are an
extinct hominin species that lived
alongside Homo sapiens with whom
they are believed to have interbred.
Their status as a distinct species or
subspecies of Homo sapiens is
still debated

Question 14

Describe two other structural features (other than skull features) of hominoids that indicate they are more closely related to Homo sapiens than other primates.

Answer 14

• Hominoids have a broad rib cage and do not have a tail.

- These features indicate they are more closely related to Homo sapiens. than other primate species.

Question 15

describe how hominin differ from the same structure in the hominoid, and state the functional significance of these differences.

Answer 15

Pelvis

• Hominins have more bowl-shaped pelvis compared to hominoids.
• This provides support for the upper body of hominins while walking upright.

Spine

• Hominins have an S-shaped whereas hominoids have a C-shaped spine.
• This allows hominins to stay upright for extended periods of time.

Foot

• Hominin feet have two arches and a larger heel compared to hominoids.
• This makes upright locomotion more energy-efficient for hominins.

Rib-cage

• Hominins have a more barrel-shaped rib cage compared to hominoids.
• This allows hominins to remain upright for longer periods of time.

Angle of femur

• Hominins have a greater angle of femur compared to hominoids.
• This increases stability when walking and standing upright for hominins.

Question 16

Personal error

Answer 16

mistakes/ miscalculation due to human error

Question 17

Random error

Answer 17

Variation caused by uncontrolled conditions

Question 18

Systematic error

Answer 18

faults causing measurements to differ consistently

Question 19

The oldest hominin genus that was bipedal?

Answer 19

Australopithecus ( 2 million years ago)

Question 20

The process of passing on and refining knowledge through time

Answer 20

Cultural evolution

Question 21

When did bipedalism evolve in hominin

Answer 21

4 million years ago

Question 22

Describe two features the scientists would need to find on the skeleton to prove that the species was bipedal and explain how these helped with bipedal locomotion.

SOLUTION

Answer 22

• Short arm to leg ratio, as less time was spent in trees and more time walking/running.
• The femur set at a valgus angle between the knee and hip, to help with balance and support as the feet are in the middle of the body.
• An S-shaped spine, to support upright walking.
• Larger heel, to make bipedalism less impactful to the foot.
• Toes aligned, as no longer need to grasp branches.
  Non-grasping feet, as no longer need to grasp branches.
• A bowl-shaped pelvis is a structural that provides upright hominins with more support whilst walking on two legs.
• central foramen magnum is also a structural feature of bipedalism, d made it easier for hominins to hold their heads upright and look forwards whilst walking upright on two legs.

Question 23

Describe two effects of bipedalism on hominin behavior.

Answer 23

• Carry young.
• Reach higher food.
• Engage in cultural activities and rituals.
• bipedalism freed the hands for toolmaking and enabled individuals to see above vegetation to scan for predators.

Question 24

Evolution of behavior

Answer 24

Natural history intelligence:

• predict habits
• rhythms of seasons
• geographic of the landscape

Social intelligence

• communicate ideals
• coordinate survival strategies
• plan survival

Technical intelligence
- knowing how to make tools ( on particular angles will result in different shape)

Question 25

What is the out of Africa hypothesis and key evidence that supports the hypothesis

Answer 25

• helps explain how modern humans came to be so widespread across the globe.
• It states that early Homo sapiens lived solely in Africa and spread out across the world later in time.

key evidence that supports:
• Majority of older hominin fossils are found in Africa
• Use of the molecular clock to deduce divergences between human populations points to Africa as the origin of humans
• Neanderthals in Eurasia interbred with European and Asian Homo sapiens but not African Homo sapiens.

Question 26

What is the multiregional hypothesis?

Answer 26

• Proposes that an ancestor of modern humans such as Homo erectus became widespread across the globe first
• and evolved into Homo sapiens independently in several different human populations

This hypothesis is quite controversial due to racial and scientific implications.
Two pieces of evidence supporting the multiregional hypothesis include:
• Low genetic diversity in modern humans
suggests gene flow between populations
• Phenotypic variation between groups of modern humans suggests a long time since a common ancestor.

Question 27

The fossils of H. floresiensis showed that they had opposable thumbs. Explain why developing opposable thumbs was an important step in primate evolution.

Answer 27

• opposable thumbs allow primates to make grasping movements and hold both ‘precision’ and ‘power’ grips.1
• Furthermore, opposable thumbs enabled hominins to develop fine motor skills and make tools.

Question 28

Read:
H. floresiensis are unusually small for such a recent hominin species. Using the theory of natural selection, describe how this species evolved to be so small compared to Homo sapiens and Homo neanderthalensis.

SOLUTION

Answer 28

• Among the ancestors of 𝘏𝘰𝘮𝘰 𝘧𝘭𝘰𝘳𝘦𝘴𝘪𝘦𝘯𝘴𝘪𝘴, variation in height would have existed.
  -Moreover, height would have been a heritable trait.
• On the Indonesian island where they lived, there would have been a selection pressure that made it advantageous for 𝘏. 𝘧𝘭𝘰𝘳𝘦𝘴𝘪𝘦𝘯𝘴𝘪𝘴 to be short.
  !
• Perhaps the selection pressure was that they used less energy with smaller bodies, so didn’t need to eat as much when food was limited.
• Over time, shorter 𝘏. 𝘧𝘭𝘰𝘳𝘦𝘴𝘪𝘦𝘯𝘴𝘪𝘴 would have had more offspring than taller 𝘏. 𝘧𝘭𝘰𝘳𝘦𝘴𝘪𝘦𝘯𝘴𝘪𝘴, leading to an overall smaller population.
• In comparison, 𝘏. 𝘴𝘢𝘱𝘪𝘦𝘯𝘴 and 𝘏. 𝘯𝘦𝘢𝘯𝘥𝘦𝘳𝘵𝘩𝘢𝘭𝘦𝘯𝘴𝘪𝘴 would have been exposed to different selection pressures that made it advantageous to be taller.

Question 29

Explain how scientists could construct this tree from DNA samples of Neanderthals and modern humans.

Answer 29

• Scientists could have used the mitochondrial DNA (mtDNA) molecular clock to construct this phylogenetic tree.
• The mtDNA sequence between Neanderthals, African humans, and non-African humans could be compared.
• More differences in mtDNA sequences indicate more distant relatedness, so humans would have fewer mtDNA differences between each other than with Neanderthals, showing they are more closely related.

Question 30

Homo neanderthalensis 

Answer 30

extinct hominin species that
lived in cold climates alongside
Homo sapiens with whom they are
believed to have interbred

Question 31

Evidence that suggest first interbreeding between Humans and Neanderthals

Answer 31

-Suggests Neanderthals may have interbred with
humans as they left Africa somewhere in the
Middle East around 65 000 years ago and did
not interbreed with African humans.

-  Nuclear DNA studies in 2010 show around 1–4%
of the(non-african genome) human genome is identical to DNA found in Neanderthals.

Question 32

Evidence that suggest second interbreeding between Humans and Neanderthals

Answer 32

-Suggests a population of Neanderthals in Siberia
may have interbred with an early form of humans
around 100 000 years ago. This suggests a
second interbreeding event with humans.

• 100 000 year old DNA from Neanderthal fossils found in Siberia in 2016 found that it contained a significant amount of ancient human DNA not found in other Neanderthal populations.

Question 33

a hominin species that interbred with Homo sapiens, sharing 4–6% of their DNA with some Melanesian humans.

Answer 33

Homo denisova.

Question 34

What are two features that the fossil skull would need to have in order to be classified in the genus Australopithecus and not in the genus Homo?

Answer 34

A more sloped face.
A larger brow ridge.
More prognathic/protruding jaw.
A less parabolic jaw (U-shaped jaw).
Larger teeth.
No chin.
less central foramen magnum
and smaller braincase

Question 35

What two skeletal features would indicate the species lived primarily in trees?

Answer 35

Longer arms and prehensile feet.

Question 36

Additionally, scientists were attempting to indicate whether the species would have had a culture. What feature of the fossil could be used to determine this, and how could it suggest that the species was capable of cultural evolution?

Answer 36

• The cranial capacity of the fossil’s skull.
• This suggests that the species would have had a large brain and would have been capable of language,
• which is a key component of cultural evolution

Question 37

Identify two methods that could be used to calculate the relatedness between humans, bonobos, and common chimpanzees.

Answer 37

• Using the molecular clock model to compare amino acid sequences/ nucleotide sequence between the species would indicate their relatedness.
• Comparing homologous or vestigial structures may give an indication of their relatedness.
• Finding fossil evidence of a common ancestor and dating it would give an indication of the relationship between the three species.
• Comparing the genomes of each species with each other using DNA hybridisation would also indicate their relatedness through melting temperature