MISTERIES OF HUMAN
EVOLUTION
POSSIBLE REASONS
FOR THE EMERGENCE OF MODERN HUMANS
HUMAN EVOLUTION
•  About 5-6 M years ago, the genus Homo
diverged from our closest cousin, the genus Pan
e.i. the chimpanzee.
•  2 M years ago, several proto human linage lived
side by side in Africa and only Homo Habilis
survided.
•  40,000 - 30,000 T years ago only CroMagnons were able to survide where
Neanderthals became extinct. • 
• 
• 
• 
• 
• 
• 
• 
Who was the first hominid?
Why do we walk upright?
Why our brains so big?
When did we first use tools?
How did we get modern minds?
Why did we outlive our relatives?
What genes make us human?
Have we stopped evolving?
•  Evolution means some organisms
become increasingly better adapted to
particular environment.
•  Extinction represents inability to
undergo further change fast enough as
the environment changes.
•  Body size is argued to be a major
parameter in genetic evolution
BODY SIZE & ENVIRONMENTAL
ADAPTATION
•  Bigger the species (large body size), slower is its rate of reproduc9on and less quickly it can evolve and respond to environmental change. Whales, elephants, rhinocerus are some of the species under great thread of ex9nc9on. •  Body size of early hominids were determined by measuring the thickness of the thigh bone. BODY SIZE AND GENETIC EVOLUTION
• 
• 
• 
• 
• 
• 
• 
Birth rate
Longevity
Brain size
Age at sexual maturity
Lenght of gestation
Weight at birth
Interval between births
BODY WEIGHTS OF HOMINIDS
GROWTH RATE & ENVIRONMENTAL
ADAPTATION
•  Rapid growth rate and earlier sexual maturity
will make a species adapt to an unstable
environment.
•  Growth rate of earlier hominids were
determined by studying their teeth enamel.
•  Study showed that early hominids in general
developed faster than modern humans
BRAIN SIZE & GROWTH RATE
•  In mammals the size of brain depends on
how fast the animal develops especially
before birth.
•  Generally as the brain size increases,
growth rate decrease.
•  Encephalisation Quotient (EQ) is an index
of relative brain size.
Increments are added to teeth enamel in
every 7-8 days. Comparing the same
number of growth lines with body weight
gives the rate of growth.
Rapid growth and earlier sexual maturity
is just what ecological theory would
predict for a species adapted to an
unpredictable environment.
ENCEPHALISATION QUOTIENT OF
HOMINIDS
•  Early hominids had brain size not
much different than the great apes.
•  The real increase in brain size
happened possibly as recently as
100,000 years ago with the
appearance of anatomically modern
humans
CLIMATE AND HUMAN EVOLUTION
Reconstruction of evolutionary past
must start with the ecological
context of the hominids. It is the
relationship between the organism
and it s environment that shapes
evolution. POSSIBLE REASONS FOR
BIPEDALITY
CLIMATE IN AFRICA
•  About 6-­‐5 M years ago, the world become cooler and more arid (dry). •  This caused tropical forests to decline and grasslands to expand. •  2.5 M years ago, permanent grasslands took hold in Africa and the habitat shiIed from wooded to more scrub-­‐like environment. CLIMATE DURING PLEISTOCENE
RIFT VALLEY
•  About 8 M years ago, tectonic activities created
the rift valley which divided East Africa from
West Africa.
•  This distrupted climatic circulations in Central
Africa.
•  Pandidae families continued their life in the
humid arboreal West side.
•  Hominidae, however, had to adapt to an arid
savanna environment of the East side.
PHYSIOLOGICAL FACTORS FOR
BIPEDALITY
HOMONID
SITES IN
AFRICA
BIPED vs QUADRUPED
Savanna mammals cool their
Brain either by:
1.  Panting which increases the
air circulation and the base
of the brain.
2.  Heat exchange by caroit rete.
Primates have neither.
1.  Upright walking exposes as
much as 60% less heat.
2.  Upright posture keeps the
body further away from the
hot surface of the ground.
3.  Humans have hair to act as a
shield to reflect radiation.
4.  Naked body allows cooling
by evaporation.
EFFECTS OF GEOMAGNETIC CHANGES
ON HUMAN EVOLUTION
•  Increase in ionizing radiation
•  Increase in UV radiation.
•  Disturbe biomagnetic systems
•  Cause climatic changes
SOLAR WIND
GEOMAGNETIC EXCURSIONS AND
HOMINID EVOLUTION
•  Date (BP)
1,790,000
299,000
111,000
32,000
Physical Change
Homo Erectus Homo Sapiens Neandertalensis
Homo sapiens Journal of Field Archaeology, 5,1978 pp. 445
Reversal
Olduvia
Biwa 2
Blake
Mungo
1.  14 pole reversals occured during
the last 2 M years.
2.  During the reversals earth s
magnetic field strength decreased, which caused an
increase the amounts of ionizin
radiation.
3.  Increase in ionizing radiation could have trigerred biological
mutation. NEANDERTHALS DISSAPEARING
ACT!
Jared Diamond (Discover, May 1898) claims
that the Neanderthals could not talk. Over 100,000 years, they showed no intelectual capacity for
symbolic thought or language. They lacked
inventiveness. With the appearence of Cromagnon s, however, art and technological
innovations suddenly bloomed. This is because the
anatomically modern humans were capable of
speech. Abrupt human physical
changes (Fossils) and
cultural changes (tools)
correlate with the
blake and mungo excursions.
EVIDENCE FOR ABILITY TO
TALK
COMPARISON OF HUMAN
vs CHIMPANZEE LARYNX
•  Marks left by brain on the inside of
fossil skulls.
•  Study of the jaw and skull base as an
index to speech ability
•  Comparison of brain-cell circuits
controlling modern human language
with those of monkeys
POSITION OF LARYNX FOR TALKING
When basicrania is unflexed and larynx is positioned
high in the neck, it is impossible to talk.
1. Infants have high larynx up to 18 months.
2. Australopithacus has high larynx.
3. Homo erectus is believed to have the ability of flexing at the same level of 6 years old child. 4. Fully flexed adult basicrania first appeared on Homo sapiens between 300,000 - 400,000 years ago. COULD HOMO NEANDERTHALS
TALK?
MIGRATIONS
•  Between 100,000 and 15,000 years ago, modern
humans migrated all of the known world today.
•  Australia 80 Km from Southeast Asia was
occupied 40,000 years ago by sailing with boats
or rafts.
•  North America was occupied about 15,000 years
ago when Asians crossed the Bering Strait. Due
to Ice Ages, sea levels were low and there was a
land bridge.
•  First American created the Clovis culture. 15,000 years old dwelling
Made out of mammoth
Bones inMazhirich, Ukraine. TRACING HUMAN LINAGE USING
MALE Y-CHROMOSOMES
Distinctive tools of the first residents of the New World
known as the Clovis culture. GENETIC DNA MUTATIONS MARK THE PLACE
AND TIME OF Y-CHROMOSAL LINAGE
M168 50,000 years ago (Africa) M130 50,000 years ago (Africa) M89 45,000 years ago (Near East) M9 45,000 years ago (Near East) M175 35,000 years ago (India) M45 35,000 years ago (North Asia) M173 30,000 years ago (North Europe) M20 30,000 years ago M242 20,000 years ago (Siberia M3 10,000 years ago (Alaska) M172 10,000 years ago (Southern Europe) M17 10,000 years ago (Central Europe) M122 10,000 years ago (South east Asia) DISTRIBUTION OF MALE YCHROMOSOME MUTATIONS •  M45 is originated about 35,000 to 40,000 years ago in Central Asia and is
the major branching point
•  M173 is shared by Western European decent
•  M3 is shared most Native Americans
•  Central Asian men also have M45 but not the M173 and M3.
•  European marker M173 happened about 30,000 years ago.
•  M3 is present only in Native Americans and is believed to have occurred
13,000 to 14,000 years ago.
•  Marker M242 arose after M45 but before M3. Both Native Americans and
Asians have M242. The genetic separation of Asians and Native Americans
occurred no earlier than 17,000 years ago.
•  After 1492 the groups that diverged 30,000 years ago began to converge
again in Americas. •  It is estimated that 17 % of Native Americans man today have YChromosomes inherited from Europeans.
GENETICS & ARCHAEOLOGY
• 
Isolation of ancient DNA is difficult mainly due to
extensive degradation and contamination, however,
two important developmentswas very critical:
• 
Polymerase Chain Reaction (PCR) allowed the
enzymatic synthesis of unlimited copies of any DNA
fragment.
DNA could be recovered from hard tissues such as
bone and teeth that may be more than 100,000 years
old.
• 
STUDIES ON MITOCHONDRIAL DNA
•  Mitochondria are organelles that produce
energy in cells
•  It has the same structure throughout the
organisms.
•  Mamalian mitochondrial DNA (mtDNA) is
only maternally inherited.
•  Thus maternal line can be followed for
many generations.
HOMO SAPIENS
(MAN THE THINKER)
•  Human beeings had to survive in a hostile world.
He had to find food. He had to use his
intelligence to observe, to understand and to
control the forces of nature in order to survive.
•  Even most primitive societies today have:
a) Material factors such as food, shelter,
warfare, population density, climate, treasures
b) Spiritual factors such as prevailing religion,
philosophy and art.
mtDNA AS MOLECULAR CLOCKS
•  Study of human mtDNA showed that genome now
present evolved from a single ancestral mtDNA in subSaharan Africa known as mitochondrial Eve •  2-4 of human mt DNA are calculated to mutate every
million years.
•  The mtDNA linage that diverged from Eve has changed
on average 0.57% implying ancester of all our mtDNA
types lived between 140,000-290,000 years ago. MESOLITHIC AGE
11,000-8,000 BC
•  End of the third phase of fourth Glaciation.
Climate becoming warmer and humid.
•  Stone implements were about 2.5 cm tall chipped
into geometric shapes.
•  Mesolithic Man probably were:
a. descendants of the Cro-Magnon
b. longheaded variety from Africa
c. broadheaded group migrating from
Central Asia
NEOLITHIC REVOLUTION
•  Beginning of agriculture
•  Domestication of animals
•  Invention of pottery
•  Beginning of settlements
•  Use of new stone implement
REASONS FOR NEOLITHIC
REVOLUTION
•  Demographic stress
•  Proper environment
•  Exploitative technology DIFFUSION OF AGRICULTURE
SPREAD OF MAIN GRAINS IN
THE WORLD
Domestication of goat
Domestication of pig
Domestication ofcattle
Domestication of sheep