HUMAN EVOLUTION.pptx

Perfection
EVOLUTION OF
MAN
Presented By
Dr.Mahesh.Pandit B.N.Y.S
Evolution of Man Part II - Dr.Mahesh.Pandit 1

Classification Hierarchy
Kingdom Animal
Phylum Chordate
Class Mammal
Order Primates
Family Hominid
Genus Homo
Species Sapiens

Evolution of Primates
The evolution of primates is characterized by
trends towards:
1. Mobile limbs
2. Grasping hands (with opposable thumbs)
3. Flattened face
4. Binocular vision
5. Large, complex brain (for learned behavior)
6. Reduced reproductive rate

Evolution of Primates -Mobile Limbs
• Most primates have flat nails as well as
sensitive pads on the undersides of fingers
and toes.
– Many also have both an opposable big toe and
thumb.
• Mobile limbs and clawless opposable digits
allow primates to freely grasp and release tree
limbs.
Evolution Part II - Dr.Mahesh.Pandit 4

Evolution of Primates - Primate Hands

Stereoscopic vision and resultant depth
perception allows primates to make accurate
judgments about distance and position of
adjoining tree limbs.
Evolution of Primates - Binocular Vision

• Story of human evolution begins around 65
mya with explosive radiation of a group of
small, aboreal mammals (Archonta).
– Insectivorous nocturnal mammals.
Evolutionary Path to Apes

• Earliest Primates
– Two distinct features that allowed them to
succeed in aboreal environment:
• Grasping fingers and toes
• Binocular vision
• Evolution of Prosimians - “Before Monkeys”
– Earliest primates split into prosimians and
anthropoids about 40 mya.

Origin of Anthropoids
– Higher primates - Includes apes, monkeys, and
humans.
• One of most contentious issues in primate biology is
identity of first anthropoid.
Direct Descendents:
– New World monkeys
– Old World monkeys

Old World Monkeys:
•They are diurnal.
•Narrow and down pointing nostrils.
•Longer hind legs than forearms.
•Flattened nails on fingers and toes.
•Prominent buttock pads to sit on.
•Tails.
•Larger than the New World monkeys.

New World Monkeys:
•Wide nostrils which are circular and spaced apart.
•They are small to medium sized.
•Long tails which are sometimes prehensile.
•No buttock pads.
•No cheek pouches.

• Hominoids (apes and human)
evolved from anthropoid
ancestors.
• First Hominoid
– Current attention is centered
around a Miocene ape Proconsul
which has many characteristics of
Old World Monkeys, but lacks tail
and has apelike hands, feet, and
pelvis.
How Apes Evolved

• Comparing Apes to Hominoids
– Common ancestor of apes and hominids is thought to
have been aboreal climber.
• Hominids became bipedal.
• Apes evolved knuckle-walking.
– Multiple anatomy differences related to bipedal
locomotion.
How Apes Evolved

–Asian apes evolved first.
• Gibbons 15 mya - Orangutans
10 mya
–African apes evolved 6-10
mya.
Closest living relative to humans.
• Chimpanzees and humans share
98.4% of nuclear DNA.
• Gorilla DNA differs from human
DNA by about 2.3%.
How Apes Evolved

Proconsul is believed ancestral to hominids.
Hominoid Evolution

Human-like ancestors that
walked upright on 2 legs
Similar to chimps and
gorillas but bigger brains
Hominoids

Human and Gorilla skeletons

• Modern human first appeared in Africa about
600,000 years ago.
– Three species of modern humans:
• H. heidelbergensis
• H. neanderthalensis
• H. sapiens
Last Stage of Hominid Evolution

• Bipedalism seems to have evolved as our
ancestors left dense forests for grasslands and
open woodlands.
• Bipedalism Appears in the Fossil Record 5-7
Million Years Ago
• Reason why bipedalism evolved is still
controversial.
• Preceded large brains.
Origins of Bi-pedalism

The process of becoming bipedal creatures had
taken millions of years.
Bipedalism affected the neck, skull, rib cage, pelvis,
and limbs & many parts of the body.
The rib cage has to be reshaped into a cone-like
shape, the pelvis bone becomes shaped like a
basin to hold and support all of the internal
organs, and the lower limbs lengthen and angle
inwards.
Origins of Bi-pedalism

Australopithecus
Homo erectus
Homo sapiens
Evolutionary Tree With Many Branches

• The 1960s and 1970s
were a fertile period for
fossil hunting in Africa
• The idea developed that
more than one hominid
species existed at the
same time developed
Homo sapiens
Homo erectus
Homo habilis
Australopithecus
africanus
A. robustus
A. boisei
Australopithecus afarensis
“Lucy”
Added
1974

1991
As more specimens
were found a clearer
idea developed of the
relationships
between them
Homo sapiens
Homo erectus
Homo habilis
A. africanus
A. robustus
A. boisei

2001
?
?
?
1 Ma
2 Ma
3 Ma
4 Ma
Homo sapiens
Homo
erectus
Homo habilis
A. africanus
P. robustus
Paranthropus boisei
Australopithecus anemensis
Ardipithecus ramidus
P. aethiopicus
Homo rudolfensis
H. ergaster
H. heidelbergensis
Homo neanderthalensis
A. garhi
?
?
?

?
?
?
?
?
?
?
?
1 Ma
2 Ma
3 Ma
4 Ma
5 Ma
6 Ma
7 Ma
Homo sapiens
Homo
erectus
Homo
habilis
A. africanus
Paranthropus
robustus
Paranthropus. boisei
Australopithecus anemensis
Ardipithecus ramidus
P. aethiopicus
Homo rudolfensis
H. ergaster
H. heidelbergensis
Homo neanderthalensis
A. garhi
Orrorin tugensis
Gorilla gorilla
Sahelanthropus tchadensis
“Toumai”
Pan trogolodites
2003

• An estimated number of 16 hominid species is
thought to have existed
• This is based on the evolutionary patterns of
other primates
• Our family tree is similar to other species
• Periods of radiation
• Separated by periods of extinction
How many more?

Migration of human Populations

Pangaea brought together terrestrial species that had
evolved separately from one another. This created intense
competition and some extinction. Geographic isolation as
continents drifted apart and environmental conditions
became different on each land mass.
Continental Drift

1. Fossil record
2. Anatomical Evidence
Homologous Structures
Analogous Structures
Vestigial Organs and Structures
3. Developmental Evidence
4. Molecular Evidence
Evidence for evolutionary change

• The remains or traces
of organisms left in
sedimentary rock
• Sediment (pebbles,
sand, silt, or clay)
accumulate over time
and exhibit distinct
layers
• Oldest (bottom),
youngest (top)
How are Fossils formed

1. Hard body parts
2. Bones and Teeth
3. Shells
• Over 300,000 fossil
species have been
described and named!
Types of Fossils

4. Impression or
imprint
5. Mineralization
(petrified wood)
6. Casts and Molds
Dinosaur footprints
Cast of Echinoderms
Leaf Impression Petrified Wood Human hand imprint
Sponge imprint
Types of Fossils

7. Ice is an excellent preservative
– Mammoth preserved in ice for over
25,000 years
– Allows for DNA analysis
8. Amber: 2 mya mosquito in amber
Types of Fossils

1. Relative Dating
– Relative position in sedimentary - Most fossils are
dated by their relative position in
sedimentary layers
– Rocks - Rock formation occurs in a time ordered
sequence
– Index fossils - Index Fossils occur in specific layers
of rock over a large geographical range
2. Absolute dating
– radioisotopes
Fossil Dating

The Hominid fossil evidence is Fragmented,
incomplete, Widely debated .Despite all this
we have a wealth of fossil collections
Just have a look
Evidence
- Fossil record

• Homology: a fundamental
similarity that occurs due
to descent from a
common ancestor
• Homologous structures:
Structures that are similar
to each other because
they are derived from the
same common ancestor.
Homologous structures
Leaping
Swimming
Running
Grasping
Flying

Analogous structures are fundamentally different
structures adapted to the same ecological niche
Analogous structures

Vestigial Structures are things that have no current use
to an organism. They show evolution because before
the organism changed they were useful.
Vestigial Structures

The appendix is a narrow, muscular tube attached to the
large intestine. It would aid in the digestion of cellulose in
our plant chewing days. As the human diet changed, this
organ stopped functioning, as it was no longer used.
- The Appendix
1

Sinus cavities do make our heads weigh less ,adds warmth and
moisture to the air we breathe. In animals with an heightened
sense of smell the sinus cavities are lined with olfactory tissues.
Some scientists believe that our
ancestors had a much better
sense of smell (our DNA contains
broken genes for additional
odour receptors)
- Para nasal Sinuses
2

A tiny pit on each side of the septum is lined with non
functioning chemo-receptors. They may be all that
remains of a once extensive pheromone-detecting
ability.
-Vomeronasal /Jacobson’s organ
3

The coccyx is a set of fused vertebrae at the bottom of the
spinal column. It’s all that’s left of our tails, which
disappeared from hominids as they began walking upright.
The coccyx does serve as somewhat of
a shock absorber, though that was not
it’s original function.The coccyx has nine
muscles attached to it, such as the
muscle that is necessary for defecation.
- The coccyx
4

Our toes were most likely
used at one point for
grasping on to things and
climbing. While losing
ones toes would cause
problems with walking for
awhile, we technically only
need our big toe as a
function to help keep our
balance.
- Toes
5

This is a set of cervical ribs
commonly thought to be
leftovers from the age of
reptiles. They still appear in
less than 1% (about 1 in 200)
of humans, and in rarer cases a
person may not just have one
but have two neck ribs.
Unfortunately, these can cause
nerve and artery problems.
- Cervical ribs
6

Darwin’s point is found in the
majority of mammals, and humans
are no exception. It is most likely
used to help focus sounds in animals,
but it no longer has a function in
humans. Only 10.4% of the human
population still has this visible left-
over mark of our past
– Darwin’s Point
7

Somewhere along the evolutionary journey we actually had
a third eye lid, much like you se on a frogs, for example.
Humans retain a tiny fold in the inner corner of the eye.
– 3rd Eyelid
8

Palmaris Longus is a muscle that has
a long tendon and a short belly, runs
from the elbow to the wrist. It is
believed to be an important muscle
for hanging and climbing. It is now
seen in about 10% of population.
– Climbing muscle
9

These three muscles most likely
made it possible for prehominids
to move their ears independently
of their heads (again, like a cat or
dog). We still have these muscles
which is why most people can
learn how to wiggle their ears
- Extrinsic Ear Muscles
10

The Subclavius muscle
stretches under our shoulder
from the first rib to the
collarbone. It would still be a
useful part if humans still
walked on all fours. Not all
humans have one and a small
number of us actually have two.
– Knuckle walk muscle
11

The plantaris muscle is used by
animals in gripping and
manipulating objects
with their feet – something you
see with apes who seem to be
able to use their feet as well as
their hands. Humans have this
muscle as well, but it is now so
underdeveloped
– Plantaris Muscle
12

Wisdom teeth are vestigial third molars that human
ancestors used to help in grinding down plant tissue.
Human ancestors had larger jaws with
more teeth, which were possibly used to
help chew down foliage to compensate
for a lack of ability to efficiently
digest the cellulose that makes up a
plant cell wall.
– Wisdom teeth
13

These are bundles of smooth
muscle fibres that allow animals
to puff up their fur to intimidate
others. They also served the
function of insulation when we
had more body hair. While we
still retain this ability our lack of
body hair makes them useless.
– Erector Pili Muscle
14

Most of your body hair serves no function (though some
think otherwise). Eyebrows keep sweat from going into
your eyes, and male facial hair may play a role in sexual
selection. Armpit and pubic hair help deal with moisture
but beyond that it does us no good. Your arm and leg hair
are just the remains of a once fully
covered body of hair.
– Body Hair
15

While our closest cousins
(chimps and gorillas) still
retain this extra set of ribs,
most humans have 12 ribs.
Additionally, about 8% of
humans are born with extra
ribs.
– Thirteenth Rib
16

Evidence
DENTAL FORMULA – 2-1-2-3

Comparison of human (left) and gorilla hand bones. The
gorilla hand is shown from a palmar perspective. Note the
similarity of metacarpals with regard to the relative
diameters of the shafts and the heads, as well as overall
similarity of bone structure
Evidence

• Species that differ as adults often bear striking similarities during
embryonic stages
• Presence of gill ridges in human embryos indicates that humans
evolved from an aquatic animal with gill slits
• Human embryos have long bony tails
Developmental Evidence

Lemur
Pig
Human
Developmental Evidence

Molecular evidence for evolution includes similarities at
the gene, protein, chromosomal, and genome levels.
Evolutionary relationships can be elucidated by
comparing:
1. Chromosomes
2. Protein sequences
3. DNA sequences
4. Molecular clocks
Molecular evidence

1.Karyotypes can provides clues to evolutionary
histories between various groups of organisms.
2.Chromosomes vary in size and banding pattern.
3.Similarities in both size and banding pattern in the
chromosomes between two species indicates that
the two species shared a very recent common
ancestor and are closely related.
4.The chromosomes of humans, chimps, gorillas and
organgutans are extremely similar.
Molecular evidence
- Chromosomes

1. All cells rely on DNA to make protein, suggesting
that this has been passed down from an ancient
common ancestor.
2. Using new technologies, biologists are able to
determine the amino acid sequences in proteins of
various species of organisms.
3. Biologists have found that the more closely related
two species are, the greater the similarity in amino
acid sequences of their proteins.
4. Such comparisons allow scientists to deduce
evolutionary relationships between various
organisms
Molecular evidence
- Protein sequences

Molecular evidence
- Protein sequences

1. Since DNA molecules are highly conserved and passed from
one generation to the next, base sequence pattern should
indicate evolutionary relationships.
2. Via the process of DNA hybridization, scientists can
accurately determine the degree of relatedness between
various groups of species.
3. Matches in base sequence between species indicate a high
degree of relatedness. The figure on the right you can see
that more matches are made between a human and a chimp
than between a human and a chicken. This indicates that the
human and the chimp shared a more recent common
ancestor than the human and the chicken and are closely
related.
Molecular evidence
- DNA

In any two species, the number of molecular differences in a
common molecule is proportional to the time since divergence of
the two species. This concept is termed the molecular clock and it
allows scientists to determine the amount of time that has
elapsed since the two species diverged from one another.
According to this concept, the greater the number of differences,
the greater the amount of time since divergence of the two
species
Molecular evidence
- Molecular Clock

Human Brain capacity

Evidence
- Comparative Intelligence

• Frontal lobe, associated with synthesizing
information from other areas and inhibiting
action.
• Volume of white matter, brain
interconnections, grows faster than neocortex,
eventually constituting 34% of human brain.
• Differentiation of tissue (but only through
development).
Brain areas that grew

• Rapid human brain growth may have resulted from
tool use, language, social behavior and learning to
plan for the future.
• However, agriculture, urbanization and literacy have
not produced additional changes in brain size.
• The advantages of further increases in brain size may
be offset by:
– childbirth difficulties.
– the large amount of resources required by the nervous
system.
Evolution of the Human Brain

With Due apologies to Mr. Andrew Symonds
Man and apes
99% common genes (really??)

And more similarities??
And…many more!!!
With Due apologies to President Bush

For those of
you who still
refuse to
believe…..

HUMAN EVOLUTION.pptx

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