Transcript The Human Species

HUMAN EVOLUTION - the
process by which human
beings developed on Earth
from now-extinct
primates.
 Evolution
refers to change over time, or
transformation over time.
 Evolution assumes that all natural forms
arose from their ancestors and adapted over
time to their environments.
 There are numerous ways in which evolution
occurs, the most noted are Natural Selection
and Adaptation.
 Charles
Darwin (1809 - 1882) – the one everyone
knows for the theory of evolution; gradual change
over generations and survival of the fittest
(natural selection) - when his works were first
published they created a huge controversy “is it
from your mother’s side or your father’s side that
you are descended from apes”
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Darwin's Theory of Evolution - all life is related and
has descended from a common ancestor: the birds
and the bananas, the fishes and the flowers -- all
related.
In a nutshell, as random genetic mutations occur
within an organism's genetic code, the beneficial
mutations are preserved because they aid survival -a process known as "natural selection." These
beneficial mutations are passed on to the next
generation. Over time, beneficial mutations
accumulate and the result is an entirely different
organism (not just a variation of the original, but an
entirely different creature).
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“Natural selection acts only by taking advantage of slight successive variations; she
can never take a great and sudden leap, but must advance by short and sure, though
slow steps.“ – Charles Darwin
Natural selection acts to preserve and accumulate minor
advantageous genetic mutations.
Suppose a member of a species developed a functional advantage (it grew wings and
learned to fly). Its offspring would inherit that advantage and pass it on to their
offspring. The inferior (disadvantaged) members of the same species would
gradually die out, leaving only the superior (advantaged) members of the species.
Natural selection is the preservation of a functional
advantage that enables a species to compete better in the
wild. Natural selection is the naturalistic equivalent to
domestic breeding. Over the centuries, human breeders
have produced dramatic changes in domestic animal
populations by selecting individuals to breed. Breeders
eliminate undesirable traits gradually over time. Similarly,
natural selection eliminates inferior species gradually over
time.
 Fossil
- The mineralized bone of an extinct
animal. The remains of past life-forms.
 Primate - Large-brained, mostly treedwelling mammals with three-dimensional
color vision and grasping hands. Humans are
primates.
 Hominid - Modern human beings and our
ancestors, generally defined as the primates
who habitually walk erect. Technically, the
members of the family Hominoidea.
 Australopithecus
afarensis
 Australopithecus
africanus
 Australopithecus
robustus
 Australopithecus
boisei
 1.5
– 4 million years ago
 First fossils found in 1924, a young child
 Small brain capacity 450 - 500 cm3
 Large brows and flat forehead
 Mary Leakey discovered a complete skull
1959 in Tanzania
 Donald Johanson in 1974 discovered the
remains of the most complete specimen ever
found – known as “Lucy”
 They may have used primitive tools, but little
evidence
 Our
most ancient ancestor is
Australopithecus afarensis.
They lived roughly 4 - 2.75
million years ago. " Lucy" is the
skeleton remains of an
Australopithecus afarensis
which has made us aware of
this species.
 Males and females show a
considerable difference in size,
varying from 1 - 1.7 m in height
and from 25 - 50 kg in weight.
This bipedal ancestor had a
brain capacity that fluctuated
from 380 - 450 cc.
(below) A single footprint of
Australopithecus afarensis
(above) A single footprint of
Australopithecus afarensis (top), left some
3.5 million years ago at Laetoli, Tanzania,
shows a striking similarity to a single
footprint of a habitually barefoot modern
human being from Peru
Australopithecus africanus inhabited the
earth roughly 3 - 1.6 million years ago.
 The characteristic difference between
the Ausrtalopithicus afarenis and
africanus is the height and brain
capacity.
 The height of the africanus is 1.4 m and
the brain capacity is approximately 400 600 cc. Smaller incisor teeth and a
slightly flatter face are also noted.
 The afarensis has a height of 1.2 m and a
cranial capacity of 380 - 450 cc.
 Sticks, and stones were most likely used
to gather food by the Australopithecus
africanus.
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One of the earliest of modern
man's ancestors, Australopithecus
afarensis lived between 4 million
and 3.2 million years ago in
eastern Africa.
Australopithecus africanus lived
between 3 and 2.3 million years
ago mostly in South Africa
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The Australopithecus robustus dates from
approximately 2.3 - 1.3 million years ago.
The difference between Ausrtalopithecus
robustus and both afarensis and africanus
becomes apparent in the comparison of
their structure.
Australopithecus robustus had an average
height of 1.5 m and weighed 45 kg on
average (much larger then both
Australopithecus afarenis and africanus).
As well as a larger bone structure, the
Australopithecus robustus also had a
larger cranium capacity ranging from 500
- 600 cc, housed by an large skull.
As is characteristic of most of the
Australopithecus, robustus had a flat face.
It's muscular jaw and flat, almost molarlike teeth seemed to imply that the
Australopithecus was likely a vegetarian
Australopithecus boisei
inhabited eastern Africa
approximately 2.5 - 1.2 million
years ago.
 The Australopithecus boisei's
skull is similar to that of the
Australopithecus robustus, in
which they both have a distinct
ridge on the top of their skulls.
 Australopithecus boisei has a
relatively level face and
possesses an extremely large
jaw which coincides with their
wide teeth.
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 Homo
Habilis
 Homo
Erectus
 Neanderthals
 Cro-Magnons
 Homo
Sapiens
1.75 million years ago
 The handy human being first discovered by Louis
Leakey in 1964 in Tanzania
 Had a larger brain Australopithecus about
capacity
750 - 1225 cm3
 Had large, sharp canine teeth and smaller rear teeth
than Australopithecus
 An "apelike" (long arms and a small body) body
structure was characteristic of the Homo habilis.
 It probably used tools for skinning animals and
powerful arms suggest some time spend living in
trees
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 300,000
-1.5 million years ago
 Eugene Dubois discovered homo erectus on the
island of Java
 At first he thought it was an “upright ape” but
later changed because of human similarities
 Remains have been found in China
(called Peking), Tanzania and Algeria
 Fair sized brain about capacity 750 - 1225 cm3
 This species learned to use fire for warmth, how
to co-operate with others to hunt animals and
how to design stone tools such as axes
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The first species to migrate from Africa
during the Pleistocene glacial period was
Homo erectus.
They inhabited the regions of
southeastern and eastern Asia until
approximately 300 000 years ago.
Europe, India, China and Indonesia have
all yielded evidence of Homo erectus.
"Turkana Boy" was an African discovery,
which shows that Homo erectus had a
similar body size to humans. The period
that this boy lived in was 1.6 million
years ago. Homo erectus, according to
some studies, made use of fire and
occupied caves.
 35,000
– 85,000 years ago
 Discovered accidentally by quarry workers in
Germany 1856
 Thomas Huxley used the discovery to support
Charles Darwin’s Theories
 Neanderthalis has a similar brain to ours a
capacity 1400 - 1600 cm3
 It may have been possible for it communicate
through speech
 Practiced many social behaviours such as burying
its dead in graves
 Produced a wide variety of
tools such as knifes,
scrapers and chisels
 Made
clothes
from animal
skins
 First
humans to
bury their dead
 Lived
in caves
and tents
 10,000-
35,000 years ago
 Again by accident in 1868 in France by road
workers
 The site not only had fossils but the artifacts
of a community, including tools and shelters
 Later remains were discovered in Italy,
France and Czech Rep.
 Highly developed culture, decorated hand
tools, ornaments and cave paintings
 Very good hunters, worked in teams
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Approximately 35 000 years ago, Cro-Magnons, moved into
the Neanderthal region of what is today known as France.
Within the time from 35 000 - 10 000 years ago the
evolution of art and technological innovations becomes
apparent.
Cro-Magnons used paints composed from manganese and
iron oxides to paint the walls and ceilings of their caves
through-out what is today called France and Spain.
Many of these beautiful paintings have been preserved and
can still be seen.
During the seasonal migration of herds, the Cro-Magnons
used cunning hunting skills and tools to kill their prey.
They managed to develop extremely advanced tools for
hunting (possibly even a bow and arrow).
The Cro-Magnon dwelled primarily in caves or rock shelters
in groups.
 10,000
years ago - present
 Homo sapiens named “wise humankind” – yet
to be proven
 Large brain capacity 1450-1600 cm3 , power of
communication through speech
 Developed sophisticated tools of stone and
iron
 Also advanced cave painting to new levels
 Stonehenge a prehistoric monument in southern
England originates from this period – sense of
religion & supernatural
 Species has continued to change from nomadic to
settlement/agricultural life around 5000 years ago
 Bipedalism
(moving/walking on 2 legs)
 Hand Functions
 Cranial Capacity (size of skull – determines
brain size)
 Tool Design
 Tooth Size
 Communication - Speech, Language, Art
Several differences allow the human being to walk erect on two legs with a
striding gait rather than move in a knuckle-walking fashion like the gorilla –
one example includes: in the legs the femurs (thighbones) are relatively long
and are set farther apart at the hips than they are at the knees.
The increase in hominin cranial capacity over time.
Stone tools of the Acheulean industry, used by Homo erectus and early
modern humans, and of the Mousterian industry, used by Neanderthals.
(Top, left to right) Mid-Acheulean bifacial hand ax and Acheulean bandedflint hand ax. (Centre) Acheulean hand tool. (Bottom, left to right)
Mousterian bifacial hand ax, scraper, and bifacial point.
Dagger Carvings –
Stonehenge
Horse in world's oldest painted
prehistoric cave, 15,000-10,000
BC Lascaux, France
 http://www.pbs.org/wnet/humanspark/epis
odes/program-two-so-human-sochimp/video-full-episode/407/
 http://www.pbs.org/wnet/humanspark/epis
odes/program-one-becoming-us/video-fullepisode/395/
 http://video.pbs.org/video/1312522241/