10. Human evolution

Question 1

List some of the features which characterise primates:

Answer 1

• Hands and feet that have five digits including an innermost, opposable digit which enables primates to grasp, climb or manipulate objects
• Forward-facing eyes enabling stereoscopic (3D) vision and colour photoreceptors - assists in arboreal lifestyle, as most primates live in trees and hang from limbs
• Less reliant on a sense of smell
• Enlarged cranium compared to body weight and expended cerebral cortex – responsible for higher functions of the brain
• Flexible spines and can rotate about their hips and shoulders
• Primates are social creatures with single offspring requiring intense care for an extended period of time

Question 2

Flexible spines and being able to rotate about their hips and shoulders enable primates to be able to move using:

Answer 2

• Brachiation: Swinging through the air between branch
• Suspensory locomotion: Using all fours to amble which hanging
• Quadrupedalism: Moving on all four limbs
• Bipedalism: Moving on hind limbs

Question 3

What do hominids comprise?

Answer 3

• Gibbons
• Orangutans
• Gorillas
• Chimpanzees
• Humans

Question 4

List the features that characterise hominids:

Answer 4

• Curvature of the spine, to bear weight better when standing
• Shorter and broader pelvis
• Longer legs and shorter arms
• The position of the foramen magnum (the hole in the skull for the spinal cord) at the base of the skull, rather than in the back
• Alignment of the big toe with the other toes

Question 5

List 3 anatomical features that allow humans to stand upright and walk (bipedal) with a full striding gait:

Answer 5

• Position of foramen magnum – in vertebrate animals the spinal cord fees through the foramen magnum hole to connect with the brain – in full bipedal humans it is positioned centrally and therefore vertically over the spinal cord.
• S-bend in human spine supports weight vertically. Gorillas and chimps have a spine that curves forward to that their body weight is evenly supported from the forelimbs during quadrupedal locomotion
• Human pelvis is comparatively shallow and bowl-shaped which creates a basin that sustains the weight of the abdomen and supports the upper body. It also provides attachment sites for muscles of larger buttocks of humans

Question 6

List some features of human behaviour:

Answer 6

• Complex language
• Aptitude for manipulating and interpreting symbols
• Personal ornamentation, art and music
• Establishment of extensive communities and observance of societal conventions
• Advanced cognitive capacity is credited to relatively enlarged brain – particularly the cerebral cortex (outermost region of brain)

Question 7

List 3 ways humans can communicate:

Answer 7

• Communicate complex abstract ideas
• Vocalise and talk using language
• Manipulate and interpret symbols (Eg. Music and mathematics, preserve ideas by using written language, and develop scientific models)

Question 8

What is cultural evolution?

Answer 8

Describes the way human beliefs, social practices, skills and technology change over time.
-Occurs rapidly within the lifetime of the individual

Question 9

Describe the 3 major advances that have driven human evolution:

Answer 9

• The development of nomadic hunter-gatherer societies in which knowledge about the environment, seasons, food and social traditions are passed from generation to generation
• The development of agricultural societies in which production of food no longer involves the whole population, freeing the society to develop arts, writing, music, crafts, mathematics and other areas of knowledge. Food supplies are more reliable than in hunter-gatherer societies
• The development of technological societies, which began with the Industrial Revolution in the 18th century. This development has led to greater urbanisation, specialisation of roles in society and rapid technological change.

Question 10

What are hominins?

Answer 10

Modern humans and their extinct bipedal ancestors.

Question 11

What are Oldowan tools?

Answer 11

Are the simplest recognised tools – rocks that have had bits chipped off to make sharp edges.

Question 12

Describe the Multiregional origin hypothesis:

Answer 12

Modern humans evolved simultaneously across all colonised continents from local H. erectus populations through genetic drift.

Question 13

Describe the Out of Africa hypothesis (or Recent Single Origin hypothesis):

Answer 13

Modern humans evolved initially in Africa and then migrated across the world, displacing earlier hominins as they advanced.
-Based on evidence of fossil, molecular and cultural evidence, such as artefacts, the Out-of-Africa hypothesis is more widely accepted

Question 14

List 2 hypotheses for the evolution of modern humans:

Answer 14

• Multiregional origin hypothesis

- Out of Africa hypothesis (or Recent Single Origin hypothesis)

Question 15

Describe the relationship between modern humans and Neanderthals:

Answer 15

• Neanderthals coexisted for a time with modern humans. They demonstrated cultural and technological evolution, but little symbolic expression of art.
• Debate about whether Neanderthals should be classified as own species or as a subspecies of H. sapiens.
• Proposed that humans encountered and interbred with Neanderthals as they migrated out of Africa and through Middle East. Explains why Neanderthal DNA is found mainly in descendants of Europeans and Asians and not African populations.

Question 16

Describe the relationship between modern humans, Neanderthals, and the Denisova:

Answer 16

• In 2010, fragments of a new hominin known as the Denisova was found in Siberia.
• Mitochondrial DNA and nuclear DNA indicate Denisovans were related to Neanderthals, but as a separate branch in the evolutionary tree.

Question 17

Describe the evolution of domestication and civilisation:

Answer 17

• The Fertile Crescent in the Middle East was the location of a variety of species that were suitable for domestication and artificial selection, including wild wheat, barley, peas, cows, sheep, pigs, and goats.
• This led to the most significant advances in the last 10,000 years as moving from the traditional hunter-gatherer, nomadic lifestyle to a settled one enabled the development and specialisation of advanced technology.
• Just as humans selected for favourable traits in other species, the new sources of nutrition applied selection pressures on humans (Eg. Higher allele frequencies for gene lactase to break down the lactose in sugar in milk derived from cattle or goats in populations with a dairying history.)
• Humans and their domesticated species have essentially co-evolved and become interdependent.
• Growing crops at higher densities than would occur in the wild have driven the increase in human population
• Human population has been able to reach 7 billion because of technological innovation and industrialisation
• Impacts of human activities included depletion of wild species, habitat destruction, widespread pollution, spread of invasive species, and accelerated climate change.

Question 18

Describe 2 general changes in the skull that occurred during the evolution of modern humans:

Answer 18

• Reduction in the size of the front teeth, especially the canines
• Larger cranial capacity
• Flatter face

Question 19

Describe 2 general changes in the skeleton that occurred during the evolution of modern humans:

Answer 19

• Curvature of the spine, to bear weight better when standing
• Shorter and broader pelvis
• Longer legs and shorter arms