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Human Evolution
Part II
Evolution of the Human Brain
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Intelligence is not just a function of brain size – it appears that what is more
important is the brain size compared to body size.
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Modern humans have brain volume three times larger than that predicted for an
average monkey or ape with our body size.
Another important factor is the way the
brain is organised – evident in the
development of the areas concerned with
spoken language.
Two areas of the brain have become highly
developed in modern humans – Broca’s
area concerned with speech and
Wernicke’s area concerned with
comprehension of language.
Selection pressures for increased brain size
must have been considerable given the
increasing brain volume evidenced
throughout hominin evolution.
Coupled with the brain’s evolutionary
development is the increasingly complex
behaviour exhibited by hominins
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Brain volume for hominins
Hominin Species
Millions of Years Ago
Average Brain Volume (mL)
Australopithecus afarensis
3.5
440
Australopithecus africanus
2.5
450
Paranthropus robustus
2.0
520
Paranthropus bosei
1.5
515
Homo rudolfensis
2.0
700
Homo habilis
1.8
575
Homo ergaster
1.8
800
Homo erectus
0.5
1,100
Homo heidelbergensis
0.2
1,250
Homo neanderthalensis
0.05
1,550
Early Homo sapiens
0.08
1,450
Changes in Brain Size
Evolution of Behaviour
• Coupled with the brain’s evolutionary development is the
increasingly complex behaviour exhibited by hominins
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Enhancing the natural
protection of rock
shelter
Caring for the elderly
Toolmaking using
bone and antler
Toolmaking using flint
Making clothes from
animal skins
Prolonged infant
dependency
Technical Intelligence
Producing and using artifacts required an
understanding of abstract ideas and physical
processes:
•The fracturing behaviour of stone
•Best angles of striking stone
•How hard to strike a stone
•Trajectory of a thrown projectile
The Modern Human Mind
Creating artifacts and images with symbolic meanings as a means of
communication
Using knowledge of animal habits, tools, advanced planning communication to
coordinate the hunting of large game
Natural History Intelligence
Predict the future by
understanding:
•The habits of game
•The rhythms of the seasons
•The geography of the landscape
Social Intelligence
Group bonding behaviour improves
survival opportunities for members.
Language allowed early humans to:
•Communicate ideas
•Plan survival strategies
•Coordinate hunting and gatherings
Paleolithic Tools
• The term paleolithic refers to a time period in the
development of human culture that means Old Stone
Age
• It spans the emergence of the first recognisable stone
tools until the development of sophisticated tool kits in
the mesolithic period (Middle Stone Age) about 10,000
years ago
• The earliest human tool cultures date from about 2.6
million years ago in eastern Africa and are known
mostly by their stone implements
• This does not mean that the associated hominins did not
use other , biodegradable materials (such as wood) –
they just did not preserve well,
Timeline of Stone Tool Technologies
Paleolithic Tool Use
• It is impossible to tell with certainty what a tool
recovered from an archaeological site was used
for
• By studying how similar tools have been used
by ‘recent’ stone age societies, it is possible to
guess at their likely function
• People using only stone-based technology were
still in existence well into the first half of the 20th
century
• Anthropologists studying these primitive
cultures gathered valuable insights into how our
ancestors may have lived
Paleolithic Tool Use
Tool Making Methods
• A variety of stone tool
manufacturing methods
have been used through
the history of tool making
• Some of these methods
(particularly hard
hammer and soft hammer
percussion) were
probably combined with
other methods in the
manufacturing process
Oldowan Tool Culture
First appeared: 2.5 Mya
Associated hominin: Homo habilis
• These tools were simple riverworn pebbles that were crudely
fashioned with a minimum of
flakes being removed
• These tools typically had flakes
knocked from several angles to
produce a core with a cutting
edge
• Although the cores may have
been used as tools, it is known
that the sharp flakes were also
useful in cutting
Acheulian Tool Culture
First appeared: 1.5 Mya
Associated hominin: Homo erectus
• These tools were typically ‘tear
drop’ in shape and were carefully
crafted with a slight bulge on each
broad surface (called a bi-face)
• They ranged greatly in their size
and are often referred to as ‘hand
axes’ although it is not clearly
understood how they were used
• They differ markedly from the
earlier pebble tools in that there
appears to be a standard “design”
and each tool is manufactured
using a great many more blows to
remove flakes
Mousterian Tool Culture
First appeared: 150,000 years ago
Associated hominin: homo neanderthalensis
• More refined tool culture than
the earlier Acheulian tool
culture
• Flint became a preferred
material to produce stone tools
because the very predictable
way in which it would chip
when struck with another hard
object (much finer
workmanship was possible)
• The Levallois tool making
method involved preparing a
core and striking off a large oval
flake which is then retouched
on one surface only
Neanderthal Culture
• The Neanderthals of Europe and
southwest Asia buried their dead
in a way that suggests they
practiced ritualised burial:
– The grave is usually characterised
by certain items found buried with
body (burnt animal bones, stone
tools and flowers)
– The position and orientation of the
body are also found consistently
the same (aligned east-west with
legs curled up)
• A flute-like piece of cave bear bone
has been found at a Neanderthal
hunting camp Slovenia (dated at
between 43,000 and 82,000 years
ago) suggesting that Neanderthals
may have made music
Upper Paleolithic Tool Culture
First appeared: 40,000 years ago
Associated hominin: Homo sapiens
• There was a rather sudden increase in the sophistication
of tool making about 35,000 to 40,000 years ago
• Both the modern homo sapiens and the last of the
Neanderthals produced flint tools of much finer
workmanship using a technique called punch blade, in
which long, thin flakes are removed and shaped into a
large number of different tool types
• European sub-cultures (traditions) include the
Magelanian, Solutrean and Aurignacian.
• Other material such as bone, ivory and antler became
increasing utilised to produce very fine tools such as
needles
Upper Paleolithic Tool Culture
Hunting Big Game
• The ability to hunt and kill large game (such as woolly mammoth
and woolly rhinoceros) was a triumph of human innovation
requiring:
– Well developed technology
to make effective weapons
– Cooperative behaviour
plans and coordination of
hunts
– Understanding of the habits
and behaviour of prey
animals
– A knowledge of the local
landscape to effect an
ambush
– An understanding of the
physical laws in order to use
weapons (e.g. gravity on the
trajectory of a thrown spear)
Paleolithic Art
• Modern humans
underwent a
cultural explosion
about 35,000 years
ago giving rise to
prehistoric art and
new kinds of tools
• The stimulus was
probably the need to
represent, in some
lasting way, ideas
concerned with the
unknown: death,
hunting success and
fertility
Mesolithic Cultures
Mesolithic Period:
Middle Stone Age
First appeared:
12-10,000 years ago
• Foraging and fishing economy
• Characterised by the use of small stone
tools (called microliths) and by a broadbased hunting and gathering economy
(including foraging for seeds from wild
cereal grasses).
Neolithic Cultures
Neolithic Period:
New Stone Age
First appeared:
10,000 ya in Middle East
• Plant cultivation and animal domestication
• The Neolithic culture is usually associated with
the beginnings of agriculture, pottery and
permanent settlements in the Old World
• This shift away from a hunter-gather economy,
to one which could provide surplus food, meant
greater population densities could be achieved
and allowed for the development of artisans.
Tools of
Mesolithic and Neolithic Cultures
The Beginning of Agriculture
• Farming began in parts of western Asia, the so-called
“Fertile Crescent” running from Egypt to the Persian
Gulf about 10,000 years ago
• By about 7,000 years ago, agriculture became established
in China, followed by Mesoamerica (Guatemala,
Honduras and southern Mexico) about 5,000 years ago
Summary of Crops
Fertile Crescent (10,000 years ago)
• Plants - barley, wheat, emmer, einkorn, lentils
• Animals - sheep, goats, cattle
Southeast Asia (>4,000 years ago)
• Plants - rice, bananas, sugar can, citrus fruits, coconuts, soya beans, yams, millet, tea,
taro
• Animals – pigs
Northern China (7,000 years ago)
• Plants – rice and millet
Mesoamerica (8,000 years ago)
• Plants – beans, maize, peppers, squash, gourds, cotton
• Animals – guinea pigs, llamas
South America (8,000 years ago)
• Plants – lima beans, potatoes, squash, beans, pumpkin
Africa (>4,000 years ago)
• Plants – millets, sorghum, groundnuts, yams, dates, coffee, melons
Domestication of Animals
Domesticated
Animal
Wild Ancestor
Region of Origin
Date
(Years ago)
Dog
Wolf
Many places?
13,000
Goat
Bezoar goat
Iraq
10,000
Sheep
Asiatic mouflon
Iran, Iraq, Levant
11,000
Cattle
Aurochs
Southwest Asia
8,500
Pig
Boar
Anatolia
9,000
Domestic fowl
Red jungle fowl
Indus Valley
4,000
Horse
Wild horse
Southern Ukraine
6,000
Arabian camel
Wild camel
Southern Arabia
5,000
Wild camel
Iran
4,500
Llama
Guanaco
Andean plateau
6,000
Water buffalo
Indian wild buffalo
Indus Valley
4,500
Ass
Wild ass
Northeast Africa
5,500
(one hump)
Bactrian camel
(two humps)
Bronze Age Cultures
Copper Usage
• 9,000 years ago in South-east Turkey native copper was worked by
cold-hammering
• 6,600 years ago saw the first smelting of copper
Bronze Age
• 5,000 years ago saw the first
bronze created by smelting
an alloy of tin and copper
• Bronze was used to make
implements, vessels and
weapons, although stone
implements continued in use
• Pottery (beakers) made from
fired clay pots became
valuable storage vessels
Evolutionary Trends
in Modern Humans
• Modern humans have to withstand selection pressures
that are quite different to those experienced by our
‘cave-dwelling’ ancestors
• New natural selection pressures resulting from our
modern culture and technology may be affecting our
evolution
• Modern humans have:
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Larger, more complex brain
Reduced face projection
Less broad nose
Reduced jaw robusticity
Reduced tooth size
Human pelvis has enlarged birth canal
Human femur better adapted for walking
Coarseness of body hair reduced
Anatomical Problems of
Modern Humans
• Hypothermia may occur in cooler climates if no clothing is worn (caused by
heat loss due to the lack of insulating hair covering the body)
• Teeth are overcrowded as a result of a general reduction in jaw size
• Slipped disks and other lower back troubles are compounded by the load
carried by two limbs instead of four
• Hernias occur because the gut is no longer hung from the spine and the
intestines may bulge out through a weakened abdominal wall
• Childbirth problems are caused by changes in the shape of the pelvis (a
response to bipedalism), together with babies born with larger skulls
• Skin cancer is more prevalent because a reduction of protective body hair
means the skin is exposed to more radiation from the sun
• Varicose veins are caused by an upright posture that allows blood to collect
in the veins of the thigh and leg (blood must overcome about 1.2 metres of
gravitational pressure to return to the heart).
• Feet may suffer strain because the body rests on just two limbs (the arches
of the feet collapse producing flat footedness, distorted bones, even
hammer toes and bunions)
Biological and Culture Evolution
• Phrases such as ‘biological evolution’ and ‘cultural evolution’ may
suggest that the two processes are similar.
• In reality, there are major differences between the two. The term
‘cultural change’ is preferable to the term ‘cultural evolution’.
• In contrast to biological evolution, cultural evolution or change,
often based on technological evolution, occurs very quickly in
human populations.
• For example, which of the following would occur more rapidly in a
human population immigrating to a cold climate:
1. evolving a stocky body shape through the processes of biological
evolution, or
2. learning how to control fire and make fur clothing from the pelts of
mammals through the processes of cultural evolution?
• Cultural evolution can occur in other primates. For example, a
female macaque monkey from a troop of monkeys living on a
Japanese island began to carry her food to a nearby stream and
washed the sand off it prior to eating. Eventually other monkeys
copied this behaviour until it spread through the entire troop.
Biological and Cultural Evolution
Biological evolution
Cultural evolution
•Traits can be transmitted to a person only
from parents.
•Transmission can occur only from one
generation to the next.
•Slow pace, with many generations
required to spread a trait widely in a
population
•Traits acquired during a person’s lifetime
cannot be transmitted through genetic
inheritance.
•People cannot choose which genetic traits
they will inherit.
•Data transmitted are encoded in the
genetic material.
•Biological evolution is unplanned and
results from random processes.
•Cultural traits can be transmitted to a
person by many unrelated persons.
•Transmission can be within or between
generations and can occur between people
widely separated in time and space.
•Fast pace, as the spread can be by
immediate learning and does not depend
on inheritance
•Cultural traits acquired during a person’s
lifetime can be transmitted through
processes such as teaching or imitation.
•People can choose to accept or reject some
cultural traits.
•Data transmitted are commonly in the
form of written, spoken or signed
language.
•Cultural change can be conscious and the
result of deliberate processes.
Technological Evolution
• Technology is the application of science by human beings in order to gain
better control of the material environment.
• Technology is expressed through objects, such as tools, machines and
automatons (self-controlled machines), and through complex processes,
such as medical procedures.
• Technological evolution refers to changes over time in technology that give
humans increased control over their environment, such as the change from
stone tools to metal tools, from steam power to electric power, from copper
to fibre-optic cables for data transmission, and from typewriters to word
processors.
• Historic examples of technological evolution include:
– the invention in 1456 of the printing press that enabled mass production of
written material to replace handwritten documents produced in small numbers
– the invention in 1895 of radio that enabled transmission of spoken language
across geographic space
– the invention in the 1930s of television that enabled images to be transmitted
across space
• In the second half of the twentieth century, technological evolution led to
many developments including fibre-optics, lasers and space travel.
Interaction between
different types of evolution
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Many of the cultural changes seen in human societies are based on technological
evolution. If we look at human pre-history, we can also see an example of a
profound cultural change that was based on technological evolution and on
biological evolution.
This cultural change in early human species was tool making and it first appeared in
the habilines (Homo habilis).
Initially, tool making developed through a technology that used stone tools to create
new tools that were also made of stone; for example, using a hammer stone to make
stone flakes to be used as cutting tools.
The significance of this cultural change is in the fact that tools, such as axes, enable
the power of the body to be concentrated on a small area of an object so that it can be
cut or otherwise manipulated and tools, such as levers, provide a mechanical
advantage.
The development of a tool-making culture by early human species depended on both
technological evolution and biological evolution.
Why? Tool making was possible only because, much earlier, biological evolution in
hominins had resulted in two important developments:
1. bipedal (two-footed) locomotion that freed the hands for other purposes
2. increased brain size that gave the capacity for greater problem-solving skills.
So, biological evolution provided the physical and cognitive framework in which
cultural change based on technology could take place in human species.
Interaction between
different types of evolution
Key Points:
• Biological evolution, cultural change and technological evolution
interact.
• Cultural change in many cases has been based on technological
evolution.
• Cultural change refers to changes in human societies transmitted by
social agents, such as imitation and teaching.
• Technological evolution refers to changes over time in technology
that give humans increased control over their environment.
• Biological evolution and cultural evolution differ in many ways.
• Technology extends human capabilities.