Download Ch. 15 Hominin Evolution

Definitions
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Hominin – term that refers to humans and
their extinct erect-walking ancestors. They
belong to the tribe homini.
Sometimes the word ‘hominid’ is used
instead of hominin but this term refers to
outdated classification so hominin is the
preferred term.
Hominoid – term that refers to any member
of the superfamily ‘hominoidae’
Humans are both hominins and hominoids
Classification of Humans
Kingdom
Animal
Chordata
(vertebrates)
Mammalia
Eutheria
(placental)
Primates
Marsupialia
Chiroptera
Phylum
Aves
Monotremes
Class
Sub-Class
Order
Primates
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Primate – name of a
taxonomic group to
which humans, monkeys
and apes belong. They
have certain features in
common:
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Five digits on hands and
feet that can curl/bend
around objects
Thumbs are ‘opposable’
meaning that they can be
brought into contact with
other digits
Flat nails on their digits
with tips of their digits
used for sensing touch
Primate features
5 Digits
Opposable
Thumb
Flat nails
Classification of Humans
Primates
Order
Sub-order
Anthropoidea
Super-family
Hominoidae
Family
Hominidae
Homininae
Hominini
Homo
Gorillinae
Cercopithecoida
Prosimii
Ceboidea
Hylobatidae
Ponginae
Sub-family
Panini
Tribe
Pan
Genus
Evolution of Primates
5 MYR
Classificatio
n reflects the
predicted
evolutionary
history
7 MYR
15 MYR
17 MYR
40 MYR
30 MYR
Hominidae skulls
From left to right: The skulls of a Gorrilla, Chimp, Orang-utan, and a
common ancestor to humans and chimps
Hominins
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Humans are the only living members of the
tribe ‘homini’
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Hominins are distinguished from other
members of the family hominidae because
they are able to walk upright (bi-pedalism)
The foramen magnum
1. Chimpanzee 2. Australopithecus africanus 3. Homo erectus 4. Homo
sapiens
The foramen magnum
Hominin Pelvis Structure
Hominin Evolution
Hominins
Hominin Evolution
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Oldest fossils found in Africa – hominins
originated in Africa
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Earliest evidence of hominins are 6 million
years old
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No evidence for genus Homo before 2.4
million years ago
Hominin Evolution
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Several different hominin species existed over
certain time-frames for reasonably lengthy periods
suggesting:
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Different niches occupied
Probably did not compete for food
Possibly were able to interbreed for some of the time
Eventually some of the co-existing species may
have begun to compete for food and/or habitat,
leading to the extinction of some species
The genus Australopithecus
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Small- brained
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Large-toothed and large protruding jaws
Walked upright – bi-pedal
Two types:
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Graciles (slender)
Robusts (heavy build) – now separate genus Paranthropus
The graciles are possibly ancestral to the human line
Tool use limited – evidence has been found which
suggests they may have used rocks to kill other
animals and break bones to extract marrow
The genus Australopithecus
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Sexual dimorphism- differences in body structure
and specifically body mass of adult males and
females
Zygomatic arches (cheekbones) – more pronounced
– probably large cheek muscles for chewing
suggests high fibrous content in diet
Larger waistline – longer digestive tract due to
herbivorous diet
Habitats can be inferred from fossil evidence –
varied amongst species – again suggesting different
niches
The genus Homo
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Evidence found of
more complex tools
being made and used
Diet changed –
smaller
teeth
fossil evidence of animal
remains near human fossils
larger brain size
change in rib-cage size and
shape
Suggests that meat
became part of the
diet
Australopithecus Vs. Homo
The genus Homo
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Compared to Australopithecus species
Homo species have:
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Larger brains (larger cranium size):
A. aferensis had a brain size of ~400-500mL
 H. habilis had a brain size of ~600-700mL
 H. sapiens has a brain size of ~1300-1400mL
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Smaller teeth
 Larger skull – increased height and width,
straight forehead instead of sloping like the
ancestral skulls
 Smaller brow-ridge
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http://www.amnh.org/exhibitions/permanent/humanorigins/meettherelatives/w5i1.html
Homo Erectus
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H. erectus probably
evolved from H.habilis
or H.ergaster around 2
million years ago
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First hominin fossils
to be found on
continents other than
Africa - emigrants
Homo heidelbergensis
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Considered to be an intermediary or
transitional form between Homo erectus and
Homo sapiens
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Fossils are dated between 400,000 to as
recent as 40,000 years ago
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Located in Africa, Asia and Europe
Homo neanderthalensis
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Strongly built
Evidence has been found to suggest that
they:
Made sophisticated tools
 Built shelters
 Sometimes buried their dead
 Made clothing from animal skins
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Fossils date between 150,000 to 35,000 years
ago
Homo neanderthalensis
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Existence overlaps with the earliest Homo
sapiens
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Therefore not likely to be an ancestor but a
cousin of the modern human
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Neanderthals are thought to have become
extinct through competition with H. sapiens
or disease
Homo Sapiens
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Earliest H. sapiens existed in Africa around
130,000 years ago
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Thought to have migrated North to Asia and
Europe
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Probably the first human species to use
complex speech
Cro-Magnon Man
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Considered to be a ‘modern’ H. sapiens
Produced art in caves depicting hunting
Found in regions of France and Spain
Produced very sophisticated tools such as
needles, fish hooks, chisels etc.
Tools and figurines made of bone have been
found
Buried their dead with objects such as
figurines and necklaces
Cro-Magnon Cave Art
1. HOMO HABILIS ~ LIVED: 2.4 to 1.6 million years ago HABITAT: Tropical Africa
DIET: Omnivorous – nuts, seeds, tubers, fruits, some meat
BEHAVIOUR: inquisitive, tool makers, cooperative
2. HOMO SAPIEN ~ LIVED: 200,000 years ago to present HABITAT: All DIET:
Omnivorous - meat, vegetables, tubers, nuts, complex foods BEHAVIOUR: complex
3. HOMO FLORESIENSIS ~ LIVED: 95,000 to 13,000 years ago HABITAT: Flores,
Indonesia (tropical). Not a direct ancestor
4. HOMO ERECTUS ~ LIVED: 1.8 million years to 100,000 years ago HABITAT:
Tropical to temperate - Africa, Asia, Europe DIET: Omnivorous - meat, tubers, fruits,
nuts BEHAVIOUR: migrated, social relationships, used fire
5. PARANTHROPUS BOISEI ~ LIVED: 2.3 to 1.4 million years ago HABITAT: Tropical
Africa DIET: Omnivorous - nuts, seeds, leaves, tubers, fruits, maybe some meat
Not a direct ancestor
6. HOMO HEIDELBERGENSIS ~ LIVED: 700,000 to 300,000 years ago HABITAT:
Temperate and tropical, Africa and Europe DIET: Omnivorous - meat, vegetables,
tubers, nuts BEHAVIOUR: creative/imaginitive
7. HOMO NEANDERTHALENSIS ~ LIVED: 250,000 to 30,000 years ago HABITAT:
Europe and Western Asia DIET: Relied heavily on meat, such as bison, deer and
musk ox BEHAVIOUR: tough, stoic, used animal skins for warmth
Comparing H. erectus, H.
heidelbergensis & H. sapiens
Feature
H. erectus
H. heidelbergensis
H. sapiens
Prominent brow
ridges
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Rounded skull
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Big teeth
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Sloping forehead
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Large Brain
(1200mL +)
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Small Face
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Pointed Chin
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Differing Hypotheses for the Human
Evolution Story
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Out-of-Africa: Modern humans originated in
Africa and then migrated to other continents
where they competed with and out-lived
more primitive populations
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Regional continuity hypothesis: Modern
humans evolved in different regions from
existing H. erectus populations in each
region
Early Human Migrations
based on mtDNA haplogroups
Differences in modern human
populations
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Differences in modern human populations
result from:
Biological evolution through natural selection
resulting in physical, biochemical and behavioural
differences between populations (driven by
adaptations which are genetically determined)
 Cultural evolution – changes in human society –
passed on to people that are not genetically related
 Technological evolution – expressed through
production and use of tools
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Questions to complete
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All Quickcheck
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Biochallenge Page 617 (need internet access)
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Chapter Review: 2, 3, 4, 5, 7, 8, 9