Mockoul Ma’am Name : -Priyam Mukherjee

Class / Sec : - X – D Roll No. : - 33

Subject : - Biology Topic : - Evolutionary

Evidences Teacher : - Bindu Mockoul Ma

‘am

DELHI PUBLIC SCHOOL, RISALI, BHILAI, (C.G.)

(2014 – 2015)

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SR NO. CONTENTS PAGE NO.

1. Face Page 01.

2. Index 02.

3. Evolution 04. 4. Pre-Darwinian Theories 05.

5. Inheritance of Acquired Characteristics 06.

6. Darwin’s Theories 07.

7. Evidence of Natural Selection 08 - 10.

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SR NO. CONTENTS PAGE NO.

8. Artificial Selection 11– 13.

9. Fossil Record 14– 17.

10. Bone Comparison 18.

11. Anatomical Evidence for Evolution 19 – 24. - Homologous structures - Analogous structures - Vestigial structures

12. The Physical Evolutions of Humans 25 –30.

13. Bibliography 31.

EVOLUTIONEvolution or organic evolution (Spenser, 1852) is the development of newer types of organisms from the pre-existing ones through modification. Darwin (1859) has called evolution to be descent with modifications. Modification occur due to variations. Variations develop during reproduction due to errors in DNA copying and mutations, chance separation of chromosomes during gametogenesis, crossing over and chance pairing of chromosomes. Variations taking part in evolution are genetic variations. Certain variations develop during life time of an organism. They are called acquired variations. Acquired variations have no role in evolution.

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Pre-Darwinian Theories

• Idea of evolution did not originate Charles Darwin• Earliest references are from the Greeks; even Darwin’s grandfather believed in the common ancestry of all organisms• Jean Baptiste Lamarck (French zoologist) believed species were derived from preexisting species

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Inheritance of Acquired Characteristics

•Widely accepted in early 1800s – believed organisms develop new organs or modify existing organs as environmental problems present themselves•Organs change as the need arises•Used giraffes as his explanation

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Darwin’s Theories• Summed up in 2 theories

• Descent with Modification: new forms

appearing in the fossil record are actually

the modified descendents of older species

• Inferred that All species had descended

from one or a few original types of life

• Accounted for biogeography: similar

organisms arise in the same geographic

location

• Modern kangaroos evolved from now-

extinct ancestor

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Evidence of Natural Selection

Darwin collected a closely related group of 14 finch species in the Galápagos Islands•All were similar except for beak characteristics•Darwin hypothesized that different beak shapes were related to food gathering•Darwin wrote “…one might really fancy that…one species has been taken and modified for different ends.”

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Evidence of Natural Selection

Darwin’s finches 9

Evidence of Natural Selection•Modern research has verified Darwin’s selection hypothesis

•3 conditions of natural selection

Variation must exist in the population

This variation must lead to differences among individuals in reproductive success

Variation among individuals must be genetically transmitted to the next generation

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Artificial Selection

Laboratory Experiments•Drosophila melanogaster (fruit fly)

i. Selected fruit flies with many bristles on abdomen

ii. Chose only those with most bristles to reproduce

iii. 86 generations later: average number of bristles had quadrupled

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Artificial Selection

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Artificial Selection

Agriculture

Corn looks very different from its ancestor

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Fossil RecordLayers of rock contain fossils new layers cover older ones

creates a record over time

fossils show a series of organisms have lived on Earth over a long period of time

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Fossil Evidence of Evolution

•Fossils document evolutionary transition•The oldest known bird fossil is the Archaeopteryx•It is intermediate between bird and dinosaur•Possesses some ancestral traits and some traits of present day birds•Archaeopteryx was first found in 1859

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Fossil Evidence of Evolution

Fossil of Archaeopteryx 16

Fossil Evidence of Evolution

Recent discoveries•Four-legged aquatic mammal

Important link in the evolution of whales and dolphins from land-dwelling, hoofed ancestors

•Fossil snake with legs•Tiktaalik: a species that bridged the gap between fish and the first amphibian•Oysters: small curved shells to large flat shells

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Compare the bones

How could thesevery different animalshave the same bones?

•The same bones under the skinlimbs that perform different functions are built from the same bones

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Anatomical Evidence for Evolution

•Homologous structures: structures with different appearances and functions that all derived from the same body part in a common ancestor•The bones in the forelimb of mammals are homologous structures•Different functions, same ancestor structure

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Homology of the bones of the forelimb of mammals

Anatomical Evidence for Evolution

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Anatomical Evidence for Evolution

•Analogous structures : wing of an insect, bird bat and pterosaur

•Strongest anatomical evidence supporting evolution comes from comparisons of how organisms develop.

•Early vertebrate embryos possess pharyngeal pouches that develop into:

In humans: glands and ducts

In fish: gill slits 21

Anatomical Evidence for Evolution

Analogous structures :

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Anatomical Evidence for Evolution

•Vestigial structures: have no apparent function, but resemble structures their ancestors possessed.

Vestigial structures of a whale

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Anatomical Evidence for Evolution

HumansMuscles for wiggling ears

Boa constrictorsHip bones and rudimentary hind legs

ManateesFingernails on their fins

Blind cave fishNonfunctional eyes

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THE PHYSICAL EVOLUTION OF HUMANS

Evolution traces human development through several stages or species from the first humanlike beings to modern humans. Although we still do not know exactly when the evolution of humans and apes diverged or who our common ancestor is, we do know that hominids (humanlike creatures) began to appear over four million years ago.

Hominids are distinguished from apes most notably by their bipedalism (their ability to walk on two feet) and by their larger brain size. All hominids are members of the human family tree.

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THE AUSTRALOPITHECINES

•Australopithecus Anamensis •Australopithecus Afarensis

•Australopithecus Africanus

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IN SEARCH OF HOMO SAPIENS

•Homo Habilis :- 2.5 million years ago

•Homo Erectus :- 2 million years ago

•Homo Heidelbergensis :- 500 000 years ago

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Homo Sapiens

The species name, Homo Sapiens, means “man who thinks”-an appropriate title for the species that formulated the spoken language and developed more sophisticated tools. The most ancient find was discovered in Hungary in 1965, dating from about 450 000 to 400 000 years ago.

Other remains of Homo Sapiens have been found in England, Germany, and France. These bones date from approximately 250 000 years ago, the period between the third and fourth ice ages.

There are two types of Homo Sapiens; the Neanderthals, or Homo Neanderthalis, and Modern Human, or Homo Sapiens Sapiens.

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THE MODERN HUMAN

About 40 000 years ago, modern humans moved into Europe armed with the skills to make clothing, better shelters, and more efficient hearths. Nineteenth-century scientists named these newcomers Cro-Magnon people after the French rock-shelter where three anatomically modern skeletons were discovered in 1868.

Cro-Magnons were Homo Sapiens who evolved in Africa and slowly pushed their way into Europe. They developed the ability to endure colder climates, even climates as cold as those found in Iceland or Greenland.

Cro-Magnon people were about as tall as modern northwestern Europeans. They also had many of the same facial and cranial features as modern northwestern Europeans.

Eventually, their successors moved into Asia. About 30 000 years ago, they crossed the Bering Strait after the retreat of the ice and entered the Americas. Others reached Australia.

With this migration, our modern human ancestors spread throughout the world.

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•http://www.techapps.net/interactives/peppermoths.htm

•http://www.pbs.org/wgbh/nova/beta/evolution/arms-race-superbug.html

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