Human Change over time

Question 1

Classification through the taxonomic series ( a hierarchy based on sims and diffs)

Answer 1

Domain ( Eukarya) ( very general) > kingdom ( Animalia)> phylum(chordata) >class (mammals)>order( primates) >family (hominidae) > genus(homo) >species (homo sapiens) (very specific)

Question 2

The two most specific levels of the hierarchical system

Answer 2

> Genus: Is a group of closely related organisms that share a very recent common ancestor
Species: Is a particular group of organism within a genus. A group of individuals that are capable of interbreeding to produce viable fertile offspring

Question 3

Characteristics all mammals share

Answer 3

> Warm blooded
Bear live young
Females have mammary glands to produce milk
Specialised teeth (4 types)
Three middle ear bones
Lower jaw consists of a single bone
Have fur, hair or hair folliciles

Question 4

Characteristics of a primate

Answer 4

> Dextrous five digit hands with opposable thumb or big toe
Flexible shoulder and high joints
Flattened nails which are sensitive to touch
Forward facing eyes
Large regions brain for hand eye coord and 3d colour vision
Social animals

Question 5

Superfamily: Hominoid

Answer 5

> Apes
No tail
Molars with 5 cusps (not four)
Broad and flattened fib cage
Longer arms than legs
Increased cranium size

Question 6

Subfamily: Hominin

Answer 6

> Includes only humans, both current species and ancestral species that were bipedal.
Note that the great apes are not hominins.
Three major genera of hominins:
early hominins (7 - 4.4 mya)
Australopithecus( 4.4-1.4 mya)
Homo (2 mya - current)

Question 7

Hominin Evolution:

Answer 7

> Over time there have been changes in limb structure and the shape of the skull.

Question 8

Bipedalism

Answer 8

> The development of bipedalism in humans is what distinguishes us from other primates that are not able to permanently walk upright and instead are quadrupedal.

Question 9

Crucial structural changes have occurred that aid in bipedalism:

Answer 9

> Position of foramen magnum
Spine curve
Shape of Rib cage
Structure of pelvis
femur angle
big toe alignment
foot arch
heel size
arm to leg ratio

Question 10

What happens to the Foramen Magnum

Answer 10

> It gradually becomes more central throughout hominin evolution and it happens due to the hominin species becoming increasingly upright

Question 11

What happens to the spine curve?

Answer 11

> The spine hominins changes from C-shaped to S-shaped with curves in both the upper and lower spine
These curves help support weight vertically and aid with upright mobility

Question 12

What happens to the shape of the rib cage?

Answer 12

> Change over time from funnel-shaped to barrel-shaped
Helped later hominins to maintain an upright posture for lengthy period of time

Question 13

What happens to the structure of pelvis?

Answer 13

> As time progresses, hominin pelvis becomes shorter and more bowl-shaped
This shape provides hominins with more support for the upper body while standing and walking upright

Question 14

What happens to the femur angle?

Answer 14

> The legs of earlier hominin species attached the the pelvis in more of a straight line having to swing their legs wide when walking, making them slower.
In later hominin species, the leg attaches to the pelvis at an angle, allowing them to walk upright more easily.

Question 15

What happens to the big toe alignment?

Answer 15

> The big toes of hominins become more protruding over time.
Over time, other toes of the foot become increasingly aligned (not opposable) because there was no longer a need to grasp.
Provides greater balance when walking on two legs.

Question 16

What happens to the foot arch?

Answer 16

> Over time, the foot arch of hominins increases, making bipedal locomotion more efficient.

Question 17

What happens to the heel size?

Answer 17

> Heel size increases in hominins throughout time.
Making bipedalism more energy efficient and less impactful to the foot.

Question 18

What happens to the arm to leg ratio?

Answer 18

> Arm to leg ratio decreases.
Due to legs becoming used for bipedal locomotion.

Question 19

Advantages of Bipedalism

Answer 19

> The structural changes leading to bipedalism occurred in the evolution of the Homo genus over several million years.
These changes resulted in significant advantages in their survival in different environments and with changing selection pressures.

Question 20

What happens to the change in brain volume?

Answer 20

> Over time, the size of the brain has increased.
Observed when looking at the average volume in cubic centimetres.
Estimated based on internal casts of the skulls uncovered, given that brain tissue would not have fossilised.

Question 21

What happens to the bow ridge?

Answer 21

> Over time, the brow ridge decreases in size.
Possibly due to the increasing size of the cranium, or that as cooking made food easier to chew there was less mechanical stress generated by jaw muscles.

Question 22

What happens to the face angle?

Answer 22

> Hominin faces become flatter over time.
Due to jaw size decreasing and becoming less protruding.

Question 23

What happens to the jaw shape and the canine teeth?

Answer 23

> The dental arch changes from a U-shape to a shorter V shape or parabolic arch.
Canine and molar teeth size also tended to decrease through time.
These trends are linked to the changing hominin diet, which became more based on softer, cooked foods.

Question 24

What happens to the chin?

Answer 24

> Homo sapiens are the only hominin species to have evolved a chin.
Scientists are unsure why this has occurred.

Question 25

What happens to the finger toes?

Answer 25

> Finger and toe length have shortened over time.
Fingers have lost their curvature.
Modern humans however have a much larger thumb.

Question 26

Human Fossil Record

Answer 26

> The human fossil record is like a puzzle that is slowly being filled in as new fossils are discovered.
Ultimately it is still incomplete and different interpretations can be made from the few pieces of evidence we have.

Question 27

Out of Africa Theory

Answer 27

> Analysis of DNA indicates that interbreeding occurred between some hominin species.
> This challenges our understanding that different species were able to produce fertile and viable offspring.
The ability of different hominin species being able to interbreed may be explained by their genetic similarities.

Question 28

Homo Neanderthalensis

Answer 28

> Fossilised remains of Neanderthals uncovered in Europe and the south-west regions of Asia indicate that they lived in these locations.
No fossil shave been uncovered in Africa.