Human Change Over Time

Question 1

What are 4 key characteristics of primates?

Answer 1

relatively large brain size, opposable thumbs, forward facing eye, long gestation periods

Question 2

What are opposable thumbs good for?

Answer 2

enables a precision grip to do things like hold a pen

Question 3

What families do hominoids encompass?

Answer 3

Great apes and lesser apes

Question 4

What is a key characteristic of hominoids?

Answer 4

they do not have tails

Question 5

What is a key characteristic of hominins?

Answer 5

They are bipedal (walks on 2 legs)

Question 6

What is the name of the hole located at the bottom of your skull?

Answer 6

The foramen magnum

Question 7

How have our spines changed to allow for bipedalism?

Answer 7

Changed from a ‘C’ shaped spine to an ‘S’ shaped spine

Question 8

Why are S shaped spines better than C shaped spines for walking on 2 legs? list 2 benefits

Answer 8

1) The extra curve in an S shaped spine has a larger shock absorption capacity hence is stronger and can carry more weight
2) positions the center of gravity right beneath our feet so we can maintain balance when standing on 2 feet

Question 9

Why do C shaped spines promote quadrupedalism?

Answer 9

It forces the animal to naturally bend over

Question 10

How has the position of the foramen magnum changed over time?

Answer 10

Moved from the back of the skull towards the centre

Question 11

How does a central foramen magnum support bipedalism?

Answer 11

It enables the skull to be balanced directly on top of the spinal chord so we can walk with our head upright.

Question 12

What change has occurred to our big toe over time?

Answer 12

It has moved to become aligned with the rest of our toes

Question 13

How does having an aligned big toe support bipedalism?

Answer 13

It is the last toe to leave the ground when walking and gives us a forward thrust which makes walking easier

Question 14

What does having a big toe not aligned with the rest indicate about an animal’s lifestyle?

Answer 14

It lives an arboreal lifestyle (lives in trees)

Question 15

How has our pelvis changed over time?

Answer 15

It has become shorter and wider

Question 16

How do the changes to our pelvis support bipedalism?

Answer 16

It creates a bowl shape which supports the upper torso and makes it easier to walk.

Question 17

Why has the pelvis changed, other than to support bipedalism?

Answer 17

Has become rounder to enable babies with larger cranial sizes to pass through upon birth

Question 18

How has our leg changed over time?

Answer 18

Our femur has increased in length, and the angle it makes with the shin bone has increased

Question 19

How does a longer femur support bipedalism?

Answer 19

It allows for longer strides, so more distance can be covered with less energy

Question 20

How does the increased angle the femur makes with the shin bone support bipedalism?

Answer 20

allow for the center of gravity to be directly beneath us and gives us increased balance on 2 legs. Also enables us to fully extend our leg

Question 21

How has our jaw shape changed over time?

Answer 21

It has gone from box shaped to parabolic

Question 22

Why has our jaw changed over time?

Answer 22

Our diet has become less plant based and more meat based which requires less grinding and hence not needing as strong a jaw.

Question 23

How have our teeth changed over time?

Answer 23

They have become smaller

Question 24

Why have our teeth changed over time?

Answer 24

Large teeth are required for grinding plant matter and seeds, but humans started eating and cooking more meat which are easy to eat hence these larger teeth weren’t necessary

Question 25

How has our arm to leg length ratio changed over time?

Answer 25

Our arms have become shorter in comparison to our legs

Question 26

What does having relatively short arms indicate?

Answer 26

That we don’t live an arboreal lifestyle

Question 27

How have our brow ridges and skull slant changed over time?

Answer 27

they have both decreased

Question 28

Why have our brow ridges and skull slant changed over time?

Answer 28

Because our cranium size has increased and taken up more room.

Question 29

How and why have our zygomatic arches and chaw position changed over time?

Answer 29

Our Zygomatic arches have reduced in size and our jaw sticks out less due to the change in our diet that requires less grinding and hence we need a smaller jaw

Question 30

How and why has our cranial capacity changed?

Answer 30

Our cranial has increased in size and become more curved to allow for a larger brain

Question 31

How and why has our nose changed over time?

Answer 31

Our nose has become more protruding to increase thermoregulation as a result of the increase in surface area

Question 32

What are 5 selective advantages for bipedalism?

Answer 32

making it easier to cover long distances, enabling our hands to be free, to see predators/prey over long grass, easier thermoregulation, wind hits a greater surface area

Question 33

What is cultural evolution?

Answer 33

The progression of socially transmitting learned behaviors to other individuals

Question 34

How has biological evolution influenced biological evolution?

Answer 34

Increase in cranial capacity infers an increased brain size which has allowed our species to become more intelligent and communicate with one other which has enabled culture to flourish

Question 35

What are 4 differences between cultural and biological evolution?

Answer 35

Cultural evolution is much faster than biological evolution, it can be transmitted through unrelated individuals, there is a choice in the traits that are inherited, and traits aren’t just passed down from generation to the next