1. EVIDENCES OF
ORGANIC
EVOLUTION

2. INTRODUCTION
The only thing that goes up and never
down is time or age. With time and age,
many things change including new
constructions, modification as needed to be
fittest, destruction of unfit ones and even
extinction. All these things are under
evolution.
Evidences are substances that tell, the
incident may have happened but they are
not proofs which means the incident must
have happened.

3. TYPES OF EVIDENCES FROM
Morphology and anatomy
Embryology
Palaentology
Taxonomy
Physiology & Biochemistry
Bio-geographical distribution
Connecting links
Genetics
Camouflage

4. FROM MORPHOLOGY & ANATOMY
Homologous organs and
Divergent evolution
Coevolution
Analogous organs and
Convergent evolution
Vestigial organs

5. Homologous Organs
They are organs of different species having
similar structure (built on same fundamental
plan but may appear different) and
embryonic origins but different functions.
They show divergent evolution.
Divergent evolution is origin of two or more
species from a common ancestor and later
gradually became different species. They are
more related.
Ex- flipper of seal, wings of bat, wings of
birds, foreleg of horse, human hand.

6. Homologous Organs

7. Coevolution
It is the mutual evolution or adaptation of
two species to each other due to their
relationship in food chain, habitat or other.
e. g. Sphinx moth (Xanthopan morganii
praedicta) and Orchid flower (Angraecum
sesquipedale). Darwin observed 11 inch long
nectar receptacle of this Medagascar Orchid
and predicted, there must be an insect with
11 inch long proboscis in Medagascar. He
never visited Medagascar before. 40 years
later two enthomologists discovered Sphinx.

8. Analogous Organs
They are organs of different species
having different structure and embryonic
origins but similar functions.
They show convergent evolution.
Convergent evolution means origin of
different species from different ancestors
and adapted for similar mode of life. It is
also called as parallel evolution.
Ex- wings of insects, butterfly, birds &
bat.

9. Analogous Organs

10. Vestigial Organs
They are organs functional in ancestors
but function less in present forms.
Ex. In human :- Third eyelid, muscles of
ear pinna, body hair, appendix, coccyx,
wisdom teeth, of human beings.
Ex. in other animals :- rudimentary pelvic
girdles in python and boas snake,
rudimentary external ear in whale.
Ex. In plants :- scale leaves of Ruscus and
Asparagus.

11. Vestigial Organs in Human

12. FROM EMBRYOLOGY
All multicellular animals are formed by a
single celled zygote, comparable to
unicellulars.
Early stages of developments up to origin of
three germ layers are strikingly similar in all
metazoans (multicellulars).
Division of zygote by cleavage can be
compared to porifera.
Double layered gastrula is similar to
coelenterates. (Diploblastic animals).
Origin of three germ layers are similar to
Platyhelminthes. (triploblastic animals).

13. EXAMPLES
Development of frog tadpole :- During
development, frog tadpole shows fish like
characters as fish like body, gills, tail with tail
fins, lateral line system, it means frog evolved
from fish like ancestor.

14. EVIDENCES FROM EMBRYOLOGY

15. PALAENTOLOGY / FOSSILS
Study of fossils is called as palaentology.
Fossils are the remains of past animals or plants.
They provide direct evidence for evolution being
the geological records.
Fossils are formed by natural events.
Mainly hard parts of animals and plants are
preserved by natural events in rocks or softer
sediments.
With years, gradual chemical changes occur in
both rocks and preserved parts.
Fossils are recovered on excavation of such
rocks.

16. TYPES OF FOSSILS
Petrified fossils :- These are burial of hard parts
of animals. With years their organic contents are
gradually replaced by silica, lime and minerals.
Mould fossils :- It is the preservation of only
impression of external structure and no original
parts of an animal in wet soil, that has gradually
hardened.
Unaltered fossils :- Original hard parts or
complete animal may be found in ice, amber etc..
Cast fossils :- Sometimes the animal is burried,
gradually it is destroyed leaving a cast. This cast
is filled by different minerals giving impression of
external structure of animal.

17. TYPES OF FOSSILS
Print fossils :- These are footprints of animals on
wet soil, that has gradually hardened and
preserved.
Coprolite :- These are the remain of faeces and
body parts of animals, giving idea on its feeding.
AGE OF FOSSILS
Radio – carbon dating :- It was given by E. F.
Libby (1949). Gradually C14 is converted into C12.
Its half life is 5568 years. By this fossils of about
40,000 to 50,000 years age can be calculated.

18. AGE OF FOSSILS
Uranium – Lead dating :- Gradually U238 is
converted into Pb207, K47 into Ar40, Rb87 into St87.
By knowing their half lives fossil age can be
calculated.
Electron Spin Resonance (ESR) and Fossil DNA
Method :- It was discovered by RINK (1997 – 98).
It is done by measuring trapped electric charges
accumulated in crystalline materials due to low
level of radioactivities at sites of fossils.

19. EVIDENCES FROM FOSSILS
 Archaeopteryx – is the missing link between reptiles
and birds.
 Reptilian characters – long tail, scales, clawed
digits in wings, teeth in beak.
 Birds characters – Wings, feathers, beak.
 Latimarea – Connecting link between cartilaginous
and boney fish.
 Paripatus – Connecting link between annelid and
arthropoda.
 Prototheria – Connecting link between reptiles and
mammals.
 Euglena – Connecting link between plant and animal.
 Evolution of horse – eohippus, orohippus, mesohippus,
miohippus, merychippus, pliohippus, equus.
 Evolution of Man – various stages described later.

20. ARCHAEOPTERYX

21. FACTS FROM FOSSILS EVIDENCES
Fossils at different rock strata – Fossils at lower
or older rocks were of simple organisms and that
on upper or newer rocks are of complex
organisms. So complex organisms evolved from
simple ones.
Earlier unicellular protozoans were formed and
later multicellular organisms evolved.
Some connecting links, some missing links and
some transitional stages represents probable
evolution of one species from other.
From fossils, various stages of evolution of an
animal or plant species can be known as in case of
horse, man, elephant etc..

22. EVIDENCES FROM TAXONOMY
Taxonomy is the study of
identification, naming and
classification of animals and plants.
Animals are classified on the basis of
structural similarities and phylogeny
(evolutionary hostory).
Grouping of animals into various taxa
on some similarities reveals their
common ancestry.

23. EVIDENCES FROM PHYSIOLOGY,
BIOCHEMISTRY AND BIO MOLECULES
 Composition and nature of protoplasm is same
from protozoa to mammals.
 Enzymes are same in all animals.
 Adenosine tri phosphate (ATP) is energy
currency in almost all animals.
 Genetic material is nucleic acid (DNA / RNA) in
all animals and it has same basic structures.
 Serum precipitation test (M. F. Nattle) reveals,
antiserum of blood of human precipitate more
with serum of apes, lesser with monkeys and
much lesser with rabbit, dogs etc. It shows
closeness of more precipitation groups.

24. FROM BIO-GEOGRAPHICAL DISTRIBUTION
Some species have worldwide distributed while
some have restricted. The discontinuous
distribution of animals is due to evolution.
Lung fish – found in South America, Australia,
Africa but not in intermediate regions. (it may
had worldwide distribution in past but extinct
in intermediate regions in course of time).
Madagascar is only 260 miles from Africa but
have markedly different flora & fauna (Once
Madagascar may be a part of Africa having
uniform distribution but later cut off by
extension of sea, long isolation may developed
into different forms).

25. CONNECTING LINKS
Virus :- Between living and non-living. Virus
are obligate parasites, non-living outside a host.
Bacteriophages :- These are viruses infecting
bacteria. They link virus and bacteria.
Euglena :- Between plants and animals. It is
autotrophic in light and heterotrophic in dark.
Proterospongia :- Between protozoa and
porifera. These are colonial protozoa with collar
cells.
Neopilina :- Between annelida and mollusca.
Peripatus :- Between annelida and arthropoda.
Balanoglossus :- Between non-chordates and
chordates.

26. CONNECTING LINKS
Lung fish :- Between fish and amphibia. They
have functional swim bladder.
Prototheria :- Between reptiles and mammals.
MISSING LINKS
Archaeopteryx :- Between reptiles & birds.
Seymouria :- Between amphibia and reptiles.
Connecting link :- It is a past animal still living.
Missing link :- It is a past animal not existing
today, only its fossil records are present.

27. EVIDENCES FROM GENETICS
Sexual reproduction is possible between
opposite mates of same species.
Now genetics and bio-technology made it
possible to produce hybrids between variously
related species.
Example :-
Mule – Hybrid of a male donkey
( called Jack ) & a female horse
( called mare ), they are sterile.
Hinny – Hybrid of a male horse and
a female donkey.

28. EVIDENCES FROM CAMOUFLAGE
Camouflage is the adaptive resemblance of an
animal to its environment to escape or perform
predation or maintain food chain. It may be due
to gene mutation gradually led to evolution.
Butterflies, Moths and Caterpillars – Closely
resembles the leaves, branches and plants in
which they live.
Preying Mantis – Resembles branch of plant.
Scale insect – Look like leaf.
Octopus, Salamander, Chamelion - Can
change appearance as per need.