This document provides an overview of the key concepts and evidence for the theory of evolution. It discusses how evolution occurs gradually over millions of years through natural selection, where organisms with favorable variations are more likely to survive and pass on their traits. As evidence, it outlines homologous and analogous organs, fossils, vestigial organs, and embryonic similarities found across species. Important figures in the development of evolutionary theory, like Charles Darwin, Alfred Wallace, and Jean-Baptiste Lamarck are also mentioned. The document also briefly discusses human evolution and provides an example of evolution through artificial selection of cabbage varieties.

1. History of
evolutionAJAY KUMAR
10 D
KENDRIYA VIDYALYA VIKAS
PURI

2. Evolution...?
Evolution is the sequence of gradual changes which take
place in the primitive organisms over millions of years in
which new species are produced…

3. Example of evoluton

4. EVIDENCES FOR EVOLUTION
HOMOLOGOUS ORGANS
ANALOGOUS ORGANS
FOSSILS
VESTIGIAL ORGANS(NOT IN SYLLABUS BUT MORE IMPORTANT EVIDENCE THAN IN OUR BOOKS )
EMBROYNIC EVIDENCE

5. Homologous Organs :- are organs which are similar in structure but
different in functions.
Eg :- The fore limbs of amphibians, reptiles, birds, and mammals have similar structures but
different functions. Frog (amphibian) uses its fore limb to raise the front of the body. Lizard
(reptile) uses its fore limb for walking and running. Birds fore limbs are modified as wings for
flying. Mammals use the fore limbs for grasping, walking, running, swimming, flying etc. This
shows evolutionary relationship.

6. Analogous Organs :- are organs whichare different in structures but similar in
functions.
Eg :- The wings of butterfly, bird and bat have different structures but similar functions. This
shows evolutionary relationship.

7. Fossils :- are the remains of organisms which lived long ago. From the study of fossils we
can know their structures and the time period in which they lived. The fossils of complex and
recent organisms are found closer to the surface of the earth and the fossils of simpler
organisms are found deeper inside the earth. The age of fossils can be determined by Radio
Carbon Dating. The study of fossils show evolution of simpler forms into complex forms and
their evolutionary relationship.
Tree trunk fossil Fish fossil (Knightia)
Ammonite – Invertebrate Trilobite – Invertebrate Dinosaur skull - Rajasaurus

8. SCIENTISTS WHO STUDY FOSSILS ARE KNOWN AS
PALAENOTOLOGISTS .

9. VESTIGIAL ORGANS
 ORAGANS WHICH ARE FUNCTIONAL IN OUR ANCESTORS BUT NON FUNCTIONAL
IN PRESENT ORGANISM IS CALLLED VESTIGAL ORGANS .
 EXAMPLE : WISDOM TEETH
 APPENDIX
 HAIRS ON THE BODY
 EARS MUSCLE
 NITITING MEMBERANE ( CORNER OF OUR EYES )
 THERE ARE 100 + VESTIGIL ORGANS IN OUR BODY .

11. EMBROYNIC EVIDENCE
 THERE IS A LINE GREEK LANGUAGE
 “ ONTOGENY REPEATS PHYLOGOMY “
 MEAN HUMAN REPEATS ALL HIS EVOLUTION IN HER LIFE
 AND THIS CAN BE SEEN IN HUMAN EMBRYO

13. Embryology

14. Darwin’s Theory of
Evolution

15. Charles Darwin
Born in England, February 12, 1809
Ships naturalist on a trip around the world aboard
the HMS Beagle
During his travels, Darwin made numerous
observations and collected evidence that lead him
to propose a revolutionary hypothesis about the way
life changes over time

16. How Evolution Works
 Explained by Charles Darwin and Alfred
Russell Wallace
 Darwin wrote On the Origin of Species

17. DARWIN’S THEORY OF EVOLUTION CAN BE
EXPLAIN AS FOLLOWS :
 WITHIN ANY POPULATION , TERE IS ANATUAL VARIATIONS . SOME INDIVIDUALS HAVE MORE FAVORABLE
VARIATIONS THAN OTHES.
 EVEN THOUGH ALL SPICIES PRODCE A LARGE NUMBER OF OFF SPRINGS, POPULATIONS REMANS FAIRLY
CONSTANT NATURALLY
 THIS IS DUE TO THE STUGGLE BETWEEN MEMBERS OF THE SAME SPICIES FOR FOOD SPAE AND MATE.
 THE STRUGGGLES FOR SURVIVALWITHIN POPULATION ELIMINATES THE UNFIT INDIVIDUALS POSSESING
FAVOURABLE VARIATIONS SURVIVE AND REPRODUCE .THIS IS CLLED NATURAL SELECTION .
 THE INDIVIDUALS HAVING AVOURABLE VARIATIONS PASS ON THESE VARIATIONS TO THEIR PROENY FROM
GENERATION TO GENERATION .
 THESE VARIATIONS WHEN ACCUMULATED OVER A LONG PERIOD OF TIME , LEAD TO THE ORIGIN OF A NEW
SPICIES .

18. ANEXAMPLETOILLUSTRATEDARWIN’S
THEORYOFEVOLUTION

19. Lamarck

20. Lamarck’s Theory of Evolution
 Tendency toward Perfection(Giraffe necks)
 Use and Disuse (bird’s using forearms)
 Inheritance of Acquired Traits
 Are you still paying Attention?

22. Evolution by stages
Complex organisms and its organs developed from simpler organisms gradually over generations.
i) Evolution of eyes :- The eyes of planaria are just eye spots to detect light. It developed gradually into
a complex organ in higher animals.
ii) Evolution of feathers :- Feathers were first developed in dinosaurs and used for protection from cold.
Later birds used them for flying.
iii) Evolution by artificial selection :- Humans cultivated wild cabbage for over 2000 years and produced
different vegetables from it by artificial selection.
Eg :- Cabbage – by selecting short distance between the leaves.
Cauliflower – by selecting sterile flowers.
Kale – by selecting large leaves
Kholrabi – by selecting the swollen stem
Broccoli – by arresting flower growth

23. Evolution should not be equated with progress
Evolution has not resulted in progress. Evolution has resulted in the
formation of several complex species from simpler species due to
variations, genetic drift and natural selection. This does not mean that one
species gets eliminated when new species are formed or that the new
species are better than the older species. Species get eliminated only if they
are not able to adapt to the changes in the environment. Several species
which could adapt to the changes in the environment still continue to
survive for example bacteria.
Human beings have not evolved from chimpanzees. They had a common
ancestor from which they evolved separately. Human beings are not the
pinnacle of evolution but they are only one species among the several
evolving species.
Human evolution (Homo sapiens)
There is a great diversity among human beings in their form and features
around the world. Human beings evolved in Africa. Some of them stayed
there and others migrated to different parts of the world.
Then due to genetic variations and the environmental changes in different
geographical regions they developed changes in their forms and features.

26. Evolutionary Tree

27. ORIGIN OF LIFE ON THE EARTH
A BRITISH SCIENTIST J.B.S HALDANE
SUGGESTED THAT IFE MUST HAVE
DEVELOPED FROM HE SIMPLER
MOLECULESWHICH WERE PRESENT ON
THE EARTH SOON AFTER IT WAS
FORMED .HE SAID THAT THE
CONDITIONS ON EARTH AT THAT TIME
COULD CONVERTED SIMPLES INGORNIC
MOLECULESINTO COMPLEXORGANIC
MOLECULES WHICH WERE NECESSARY
FOR LIFE . HALDNE ALSO SUGGESTED
THAT LIFE MUST ORIGINATED IN THE
SEA WATER .

28. THE THEORY OF LIFE ON EARTH PROPOSED BY
HALDANE WAS CONFIMEDBY EXPERIMENTS
CONDUCTS BY STANELY L.MILLER AND HAROLD
C.URY IN 1953 . THEY ASSEMBLED AN APPARATUS
TO CREATE AN EARLY EARTH ATMOSPHERE
WHICH WAS SUPPOSED TO CONSIST OF GASES
LIKE METHANE, AMMONIA AND HYDROGEN
SULPHIDE ,ETC BUT NOT OXYGEN , OVER WATER
.THIS WAS MAINTAINED AT ATEMPERATRE JUST
BELOW 100 C AND ELECTRIC SPARS WERE THEN
PASSED THROUGH THE MIXTURE OF GASES FOR
ABOUT ONE WEEK . AT THE END OF ONE WEEK ,
IT WAS FOUND THAT 15 PERCENT OF CARBON
INCLUDING AMINO ACIDS WHICH MAKE UP
PROTIEN MOECULES FOUND IN LIVING ORGANISM
. THIS EXPERIMENT PROVIDES THE EVIDENCE
THAT THE LIFE ORGINATED FROM INANIMATE
MATTER LIKE ORGANIC MOLECULES .

29. AJAY KUMAR
10 D
KENDRIYA VIDALAYA VIKAS PURI