Transcript Life: The Science of Biology, 8e

David Sadava H. Craig Heller Gordon H. Orians
William K. Purves David M. Hillis
Biologia.blu
B – Le basi molecolari della vita e
dell’evoluzione
The Evolution of the
Human Species
The Evolution of the Human Species
•Who were the first humans?
•When and where did they live?
•What makes us human?
The Evolution of the Human Species - Who were the first humans?
Human appearance on Earth
The Evolution of the Human Species - Who were the first humans?
Human taxonomy
Domain
Kingdom
Phylum
Subphylum
Class
Order
Superfamily
Family
Genus
Species
Subspecies
Eukaryota
Animalia
Chordata
Vertebrata
Mammalia
Primates
Hominoidea
Hominidae
Homo
Homo sapiens
Homo sapiens sapiens
The Evolution of the Human Species - Who were the first humans?
Primate evolutionary trends
• Digit mobility (grasping and opposability)
• Optical shift
• Bipedalims
• Relative size of the cerebral cortex
• Parental care
The Evolution of the Human Species - Who were the first humans?
Close relatives
Human species and anthropomorphic apes
(gorilla, gibbon, orangutan, chimpanzee) belong
to the superfamily of the Hominoidea, primates
without tails.
The Evolution of the Human Species - What makes us humans?
Hominidae
characteristics
The spine meets
the skull in the
back
The face
shows a
relative
degree of
prognation
Quadrupedal gait
(knuckle-walking)
The face is
straight
The spine meets
the skull,
balancing the
head in a vertical
position
Bipedal gait
(man is truly
vertical)
Short pelvis allows
bipedalism
Femoral shaft
angle,(feet
directly below
the center of
gravity)
Femur
almost vertical
within a horizontal
plane
Opposability
of big toe
Plantar arch
missing
Non-opposability
of big toe
Plantar arch and a
more robust
calcaneus
The Evolution of the Human Species - Where did the first humans live?
A common ancestor
Different climates in the
two areas of the Eastern
African Rift Valley are
thought to have caused
the evolutionary
divergence between
Hominidae and
anthropomorphic
apes.pes
Atlantic ocean
Indian ocean
The Evolution of the Human Species - Who were the first humans?
Early hominid characteristics
• Bipedalism
• Brain size grew larger (genus Homo)
• Reduction of sexual dimorphism (Homo erectus)
The Evolution of the Human Species - When did the first humans live?
Date
(thousand years)
Body
weight
(kg)
Mean cranial
capacity (cm3)
Cephalic
index*
To present
58
1349
5.3
Homo sapiens
35-10
65
1492
5.4
Homo neandertaliensis
75-35
76
1498
4.8
Late Homo erectus
600-400
68
1090
3.8
Early Homo erectus
1800-600
60
885
3.4
Homo habilis
2400-1600
42
631
3.3
Australopithecus africanus
3000-2300
36
470
2.7
Australopithecus afarensis
4000-2800
37
420
2.4
Chimpanzee
To present
45
395
2.0
Gorilla
To present
105
505
1.7
Species
Homo s. sapiens
*ratio of the maximum width of the head multiplied by 100 divided by its maximum length
The first members of the genus Homo appeared around
2.5 million years in Africa.
The Evolution of the Human Species - Who were the first humans?
Turkana Boy (Homo erectus)
Homo erectus is generally
considered to have been
the first species to have
expanded beyond Africa,
and related fossils are
spread over two
continents.
A nearly complete 1.6million-year-old skeleton,
found near Lake Turkana,
Kenya, belonged to an
eight-year-old boy.
The Evolution of the Human Species - Who were the first humans?
Professor Svante Pääbo holding the
skull of a Homo neandertaliensis
An international consortium of
researchers has sequenced the
genome of our closest relative,
the Neandertal.
Results indicate that
Neandertals are slightly more
closely related to modern
humans outside Africa. The
team also identified several
genomic regions that appear to
have played an important role
during human evolution.
(Science on May 7, 2010)
The Evolution of the Human Species - What makes us humans?
Two possible models
Out-of-Africa model
Multiregional model
Europe
Africa
Asia
Europe
(present)
Africa
Asia
Interbreeding between
people living in Europe,
Asia, and Africa
(gene flow)
Homo sapiens
evolved from
Homo erectus in
Africa
0.5 million
years ago
Modern humans
evolved more or less
simultaneously in all
major regions of the
Old World from local
archaic humans.
Humans with
modern traits left
Africa from 50,000
to 60,000 years ago
to settle the world
(1.8 million
years ago)
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The Evolution of the Human Species - What makes us humans?
Cultural evolution
• Worked stone tools
• Evolution of language
• Cave art, burials
• Domestic animals
and agriculture
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