Zoology For HSEB: Origin and evolution of life.

Origin and evolution of life

Origin of earth and primitive atmosphere

Scientist believed that the earth was formed about 4.6 billion year ago. The entire solar system was formed by condensation of cloud, dust and gas. At the time of origin earth was found in gaseous form. So that there was no environment for origin of life. Elements like iron, nickel, zinc were collected at inner core of earth. Lighter element like Al, Si, P, S etc were collected at middle part of the earth. Lightest element like He, H, O, C, N were collected on the surface of atmosphere of the earth. The primitive atmosphere of earth had water, methane, ammonia and cynamide but there is no free oxygen. ………DIAGRAM

Formation of primitive sea:

The earth cooled slowly. Water vapor clouds condense forming rain and the surface of the earth was filled with water in different sources like sea, lake, river, and ocean. Some of the organic substances were present dissolved in the water. These are sugar, alcohol, aldehydes, ketones and organic acid. These organic substances were formed due to presence of UV rays, electric discharge, heat etc.

Actually these organic substances were basic compound of life. It takes 3.7 billion years to origin the life on the earth after the origin of earth.

Later on evolution started and the organisms are formed in this present state. The term evolution is gradual and progressive change of simple organism to complex one.

Origin of life (3.7 billion years ago)

There are different theories of origin of life.

Theory special creation.

This theory was proposed by spiritual people. According to this view plants and animals were created by some super natural power or god. According to Christianity god created the universe and man in about 6000 years ago years ago while first woman was Eve was formed from one of his rib.

According to the Hindu mythology Brahma was the creator who created various forms of life from different parts of his body. God, devil and human from head goat from mouth birds from chest and other animals and plant from hair. Manu and shradha were the first man and woman on the earth created by god.

Cosmogenic theory

This theory state that life came on the earth from other planet in the form of spore called pranspermia. The theory was explain by Richer (1865) and Arrhenius (1908)

Empedocles was the father of evolution idea. He gave four ideas in his philosophy

a. The life evolved gradually in Abiogenesis.

b. Plant life came first and animal life developed later on,

c. Incomplete or imperfect forms were developed later on

d. Perfect forms were produce naturally due to the extinction of imperfect forms.

Aristotle who was the Greek scientist gave some ideas about the origin of life.

a. All evolutionary changes cause due to the natural activities.

b. He had given the best idea of intelligence designs in nature.

c. He believed in gradual transition from imperfect from perfect forms.

d. According to him acquired character are inheritated in embryonic development.

Abiogenesis theory (Theory of spontaneous generation) -Before the end of seventeenth century both scientists and philosophers believed that living things could arise spontaneously or automatically from nonliving substances. For example, insect were believed to arise from dew, frogs and toad from muddy bottom of ponds, butterflies from cheese and fly maggots from flesh. The idea was appreciated by Aristotle (384-322 BC). Van Halmont (1652) stated that young mice could arise from wheat grain when these were put in a dark room along with a moist dirty shirt.

Theory of biogenesis According to many scientists life arises from pre-existing life. Following experiments were conducted to discredit theory of abiogenesis.

Redi experiment- Italian biologist Francesco Redi (1688) demonstrated that maggots could not be created from meat but the smell of meat attracted flies which laid eggs on the flesh ( biotic substance ). The maggots appeared when eggs hatched. Redi placed boiled meat in different material so that smell of meat could spread outside but flies could not enter inside the jars. Only one jar was not covered in which flies laid eggs and maggots were appeared on the meat but not in covered jars. …………….DIAGRAM

Spallanzani experiment-In 18^th century the lazzaro spallanzani conducted following experiment. He poured hay infusion in eight bottles and boiled all of them. Four of them were not air tight with cork and four were made air tight. After few days he found there was thick growth of micro organisms in all the corked bottles but not the airtight bottles. He argued that air contains micro-organism and was the source of contamination.

…………….DIAGRAM

Pasture’s experiment-Louis pasture (1864) prepared hay infusion in swan-necked flask as shown in fig. The infusion was boiled to kill the microbes in the infusion and make it sterile. The flask was remained free of life for over 18 months. But when swan-neck was broken and infusion came in contact with air microbes appeared. Thus pasture proved that life comes from pre-existing life only.

…………….DIAGRAM

Biochemical origin of life

Russian scientist AI Oparin (in 1938) Stated that life originated from some non-living organic compound in the ocean of primitive earth about 3.7 billions year ago.

He explained about primitive atmosphere on earth and origin of life. Primitive atmosphere means reducing type of atmosphere with no free oxygen.

He explained his theory on three steps.

Chemogeny
Biogeny
Cognogeny

A. Chemogeny can also called chemical evolution. Actually it was synthesis of simple organic molecules from C, H, N, and O. As the earth surface gradually cooled these element combined each other to form H₂O, NH₃, CH₄, CN etc. As the temperature of earth cooled up to 100⁰c the highly reactive free radicals –CH and –CH₂ condensed to form different hydrocarbon.

CH+CHàC₂H₂( acetylene)

CH₂+CH₂àC₂H₄(ethylene)

CH₂+CH₂àCH₄+C (methane)

When hydrocarbon reacted with steam aldehydes and ketones were formed.

CH₂+ H₂OàCH₃CHO (acetaldehyde)

Similarly sugar amino acids and fatty acids formed.

CH₄+ H₂OàC₆H₁₂O₆ sugar

CH₄+H₂O+NH₃àAmino acids

These molecules were formed due to condensation, polymerization, oxidation and reduction.

These molecules reacted each other again in hot water and form new molecules purines pyrimidines and nucleotides.

Energy for such reaction was available form UV-radiation, electric energy form lightning heat energy form volcanoes and temperature of each itself.

The hot sea water with primary organic compounds (Purines, Pyrimidines, and nucleotide) was known as “hot dilute soup” or pre-biotic soup by Haldane. There was no free O₂ on the primitive earth.

B. Biogeny is also called biological evolution. Actually it was synthesis of complex and self reproducing biological molecules. This can be described under the following steps.

Formation of nucleic acid- Sugar, phosphate purines and pyrimidine combined to form basic unit of DNA and RNA. Then the nucleic were formed.
Formation of co-acervates- The nucleic acids, other macromolecules and primordial soup combine to form an intermediate form of life called co-acervates. Oparin said co-acervates gave rise to life.
Formation of primary organism- These coacervates absorbed organic soup and multiplied. These grew in size and formed first cells. Oparin called them protobionts. These formed monera and later protista.

C. Cognogeny is diversification in protozoa, metazoa and metaphyta. Due to the shortage of food material in sea organism changed their feeding habitat and become parasitic, saprophytic, and chemosynthetic and so on. Some became autotrophic and some become heterotrophic types of organisms.

Origin of Autotrophs

The anaerobic heterotrophs increased gradually and consumed organic nutrients that caused shortage of natural food. Some prokaryotes acquired enzymes to synthesize the simple carbohydrates from inorganic substance of ocean. This was supposed to be the beginning of autotropism. There were no chlorophylls so energy required for autotrophism was given form anaerobic break down. The process is called chemoautotropism.

Certain sulphur bacteria could absorb solar energy form sunlight and synthesized carbohydrates.

6CO₂+12H₂S -^{solar energy}à C₆H₁₂O₆+6H₂O+12S

Some bacteria changes to form the development of chlorophyll. The presence of chlorophyll made possible the process of photosynthesis.

6CO₂+6H₂O ^{solar energy}à C₆H₁₂O₆+6O₂

Oxygen evolution

Due to process of photosynthesis by blue green algae O₂ liberate into the atmosphere. This O₂brought about a number of changes in the primitive atmosphere. So reducing atmosphere changed to oxidizing atmosphere. The anaerobic organism changed into aerobic organism.

…………….DIAGRAM

Millers and Urey experiment( name of scientist, purpose, procedure and conclusion)

Professor Urey and miller have tried to create the in the laboratory the condition which might have existed in the early primitive atmosphere, when synthesis of molecules must have started. When mixture of water vapors, methane, ammonia and hydrogen gases are exposed to electrical discharge in closed chamber and the fluid thus formed is allowed to stand foe several weeks number of amino acid glycerin and aniline like organic compounds are formed from the fluid. The basic molecules of life are formed in this way, this experiment suggest that electric discharges produce during lightening in primitive atmosphere of earth might have resulted in the formation of acids and other complex organic compounds in presence of above gases. It support the oparin-haldene theory which presumes that the first living forms had arisen from simple inorganic compounds (methane, ammonia and water) under the influence of electric discharges, ultraviolet rays and heat radiation.

DIAGRAM…………………..

Concept of Organic Evolution

Formation of complex organism from simpler forms of organic substances is called organic evolution.

Evolution is the gradual change. Evolution is defined as “descent with modification.” Charles Darwin (1859).Organic evolution is defined as slow, continuous process in which the simple and primitive organisms changes into complex and advanced organisms.

Evidences of organic evolution

1. Evidences from morphology and comparative anatomy and vestigial organs.

2. ,, ,, ,, paleontology.

3. ,, ,, ,, embryology.

4. ,, ,, ,, biochemistry and serology.

1. Evidences from morphology and comparative anatomy and vestigial organs.

Morphology is study of external structure (visible from outside) and anatomy is study of internal structures. Different vertebrates show a basic plan in their body organization. This indicates animals have arisen from common ancestor.

Homologous organs, analogous organs and vestigial organs of different animals provides evidences in favour of evolution.

a. Homologous organs –these organs are similar in origin but different in functions. Richard Owen first introduced the term. For example, forelimbs of whale (flippers), bat (wings), horse and man. Functions of forelimbs in these animals are different but these are constructed on the same pattern. The forelimbs are made up of same bones (humerus, radio-ulna, carpals, metacarpals and phalanges). It is concluded that Homologous organs of organisms might be evolved from common ancestors.

DIAGRAM………………

b. Analogous organs –these organs are the organs which are similar in function but different in origin. These organs are similar in appearance and perform the same function but group of animal are different. For examples, the wings of butterfly, bird and bat. It is concluded that Analogous organs of organisms might be evolved from dissimilar ancestors.

DIAGRAM………………

c. Vestigial organs-these organs are non functional but might have been functional in ancestors. About 90 such organs are present in our body. Examples are appendix, canines teeth, vertebrae –coccyx, nictitating membrane, ear muscle etc. It is concluded that the vestigial organs like vermiform appendix suggest that the human being might be evolved form herbivorous like ancestors.

DIAGRAM………………

Atavism (Reversion)-Atavism is a suddenly appear of certain character which were present in their earlier ancestors. For example, Human baby with tail, cervical fistula, extra nipples, large and thick body hair etc. DIAGRAM………………

Evidences from paleontology. Paleontology deals with the study of fossils. A fossil is defined as impressions of plants or animals inside the land before millions of years ago. Father of paleontology is Leonardo de Vinci.

Fossilization is the process of fossil formation. These are following types;

1. Intact or entire organism-In this type, entire or parts of organism is preserved in cold or dry regions. For example, ancient elephant preserved in frozen ice of Siberia. Insects are preserved in amber (resin of pine trees).

2. Petrifaction-In this type, hard parts like bones, teeth and exoskeleton of organisms are preserved.

3. Mould or Casts-In this type, skeleton decays leaving the impressions only but the buried harden organism is an exact replica.

4. Compression-In this type, internal structure is lost and thin carbon film of organism is left.

5. Imprints or impressions-These are the foot prints of crawling worm or snake become safe due to deposition of mineral.

What are pseudofossil? These are not fossils but such structures present in the rocks like the remains of plant. These are the product of minerals. (Students should consult book for diagrams)

Evidences from paleontology or importance of paleontology

1. It explains the evolutionary history (simple to complex) or phylogeny of different organisms. Example phylogeny of horse – complete fossil record has found in North America sedimentary rocks. Phylogeny of elephant and m an also.

2. Fossils found in older rocks and newer rocks similarly fossils found in lower strata and upper strata of sedimentary rock shows the evolution to complex form.

3. Archaeopteryx like fossil bird link two groups of animal- reptiles and birds which is suggested that birds have evolved from reptiles.

Write short note on archeopteryx:-

It is a fossil – bird which full name is archeopteryx lithographica. It was found in rock of Jurassic period by Andrea Wagner from Germany. It was about the size of crow and showed features of both birds and reptiles as follows.

i) Beak like birds but teeth and jaws like reptiles.

ii) Wings like birds but claws on its wings like fore limbs of reptiles.

iii) Feathers like birds but scales like reptiles.

iv) Tail like birds but with vertebral like reptiles.

Geological time scale and eras

It was determined by studying the age of fossils in rocks. Age was determined by radioactive dating dating method of fossils found in different strata. So it is also called stereological scale.

Geologists have classified geological history into following eras.

AZOIC ----------------No life

i. Archeozic era------------- era of primitive life ------2000 million years ago.

ii.Proterozoic era-----------era of early life ---------370 millions years ago.

iii. Paleozoic era -----------era of ancient life ----------------270 years ago.

iv. Mesozoic era ----------- era of middle age --------------135 years ago.

v. Enozoic era --------- era of modern life------------75 years ago to present.

Eras are divided into periods and periods are divided into epochs.

Evolution of horse

Evolution of horse id estimated before 60 million years ago in the Eocene period. Ancestor of horse called eohippus. This animal was a size of fox (less than one footy). Teeth were 44. The front foot has four toes and a splint and hind foot with

Three toes and two splints. Equus is modern horse.

Major modification from Eohippus to Equus is:-

i. Increase in body size.

ii.Increase in length and mobility of neck.

iii. Reduction in the number of toes from four to one.

iv. Elongation in skull.

v. Elongation of limb which increase height.

vi. Molar and pre-molar teeth are formed for grinding.

vii. Fusion of metatarsals and metaearpals.

Evidences from biochemistry and serology.

1. Protoplasm chemistry: - protoplasm of cell of plant and animal found to be made up of elements C, O, H and N as well as major component of bio- molecules also.

2. Chromosome chemistry: - chromosome of all organisms basically consists of nucleic acids (DNA and RNA) and proteins. (Histones and protamines)

3. Enzymes and hormones: - a large number of enzymes (bio-catalysts) are same protein splitting enzyme is present from protozoan to mammals and hence called ancient enzyme. Similarly amylase is found from sponges (porifera) to mammals.

4. Thyroid – hormone is common in all vertebrate melanophore stimulating hormone (MSH) is found in amphibians and mammals which proofs show the common ancestor y.

5. Comparative serology (precipitation test) serum is prepared by removing the clot part of blood which is yellowish fluid of plasma. When the human serum is injected into a rabbit antibodies are produced against the serum (antigen) to destroy the antigen (human – serum). Now it is called anti human serum. If the serum of the man is mixed with this antiserum, a white precipitate is formed. When it is mixed with serum of dogs and cats precipitation does not take place but precipitation occur readily with monkey, apes etc. this test shows the relationship with man and the other primates but not with dogs and cats.

Recapitulation theory (biogenetic law)

Ernst Haeckel theory explained ‘ontogeny recapitulates phylogeny.’ It explained the different stages of embryo of higher animals close similarities with the adult stages of ancestors. For example fertilized egg of human similar to single called protozoa. Blastulla stages of embryo correspond to two layers coelenterate like hydra. Three germ layers embryo of human close to embryo of flat worm. Gill-slits like fish also seen in development of embryo of human.

In another example: - tadpole (larva) of frog has gills, fins and stream lined body like fish. It indicates that the frog has been evolved from fish like ancestor. In other word an organisms repeats its ancestral history during its development.

Theories of organic evolution

Following theories are important to explain process of organic evolution.

1. Lamarckism (theory of inheritance of acquired characters).

2. Darwinism (theory of natural selection).

3. Modern synthetic theory (Neo-Darwinism).

Lamarckism:-

Lamarckism is the theory of biologist jean baptiste de Lamarck. He is a French biologist postulated the first theory of organic evolution in 1809 entitled ‘Inheritance of acquired character.’

Fact of Lamarckism

1. Tendency to grow: -The interval of life tends to increase the size of an organism. Size increase up to certain limit.

2. Formation of new organs: - need and want of organisms cause formation of organs.

3. Use and disuse of organ: - the degree of development of organs is directly proportional to their use. Continues use of organ become strong.

4. Inheritance of acquired characters: - characters acquired by organisms due to different modification caused by environment are transmitted to offspring. After many generations new species is originated by continuous modifications.

Examples:-

1. Giraffe: - lamarcked explained the long necked and long limbed giraffe id evolved from short necked and short limbed giraffe like goat. It is due to shortage of grass and leaves of tree giraffe started feeding on leaves of long trees so limb and neck also stretched.

2. Horse: - the ancestors of modern horse left the soft ground of jungles and took to live on dry and hard land which cause changed in length and structures of legs.

3. Snakes: - the absences of feet in snakes are an example of disuse of limbs.

Objections of Lamarckism

i. If the limb finger or tail is multiplied or cut it does no disappear in offspring.

ii.Eyes develop defect instead of being improved as continuously being used.

iii. Lamarckism explains the improvement of character or change but not its initiation.

Neo- Lamarckism

In the light of researches Lamarckism has been reviewed again. It is realized that heritable factors and environmental condition may have the role of evolution. Weismann proposed germ plasma theory which gave vision of neo-Lamarckism. It explained the changes in somatic cells are not inherited whereas the changes in the germinal cells are only inherited.

Darwinism or theory of natural selection

Darwinism is theory of naturalist and philosopher Charles Robert Darwin. He is an English naturalist. Darwin spent five years for voyage of exploration on H.M.S ship from 1831. He visited many island and coasts. Galapagos Island is most important. During these periods he collected a lot of data of variation.

He published a book ‘origin of species’ in 1859. On the base of his works.

Darwinism can be explained on the five fundamental facts. These are:-

1. Enormous fertility or over- production

2. Struggle for existence

3. Natural selection

4. Variation and heredity

5. Origin of species

1. Enormous fertility or overproduction:-Housefly lay about 6 batches of eggs. Each batch has 120 to 140 eggs. If all hatched housefly survived there will be 19*10^18 progenies in a year.

Paramecium divides three times in 48 hrs. If the rate remains same paramecium occupy 10000 times more volume occupy by earth at the end of 9000^th generation.

Elephant is slowest breeding animal. They have life span of 100 years. A matured female elephant may give birth to six young’s. If all young’s survived and continued to reproduce there will be 19*10^6 number of elephants from single pair.

In this way organism has got a tremendous power to reproduce or reproductive potential. All these progenies do not survive on the earth.

2. Struggle for existence:-There is always an active struggle or competition between organisms for food and space.

The competition between same species is called intra specific and the completion between different species is called inter specific competition.

These organisms also struggle against the natural calamities (flood, cold, heat, earthquake, volcanoes etc).

3. Survival for fittest:-As a result of struggle among the organisms they become stronger. Strongest win and survive weaker rooted out. They develop some beneficial variations or modifications in their body. Which able to fit or adopt themselves to survive in nature. Which is also called survival for fittest or natural selection.

4. Variation and heredity: - the everlasting struggle among organisms has completed them to change to survive in nature. The change is called variation.

Darwin explained about harmful and useful variations. Useful variations make the organisms fit in the nature. Useful variations are transmitted to the next generations so that progenies are more suited. Progeny of same parents differs from each other and with parents also.

5. Origin of species: - due to the continuous variation organisms become better adopted to their environment. After many generations the organisms become different is established.

Objections of Darwinism

Darwin’s theory was well supported and reasonable hence most of biologists soon accepted it. Some objections are: =

1. It explained slow and small variations but did not explain about underdeveloped organ.

2. It did not explain about vestigial organs.

3. He did not differentiate between somatic and germinal variations.

4. It did not explain arrival of fittest.

5. Natural selection did not explain the over specialization of particular structure.

Neo- Darwinism

In light of modern theory of evolution Darwinism explained as heading of ‘neo-Darwinism’ or modern synthetic theory of evolution.

It includes followings concepts

1. Mutation

2. Genetic recombination

3. Natural selection

4. Reproductive isolation

5. Genetic drift

1. Mutation: - it is sudden heritable changes in the organisms. It was first proposed by Dutch botanist Hugo de varies.

Mutations are two types:-

I. Chromosomal mutation – it is changes in chromosome by changing number and structure of chromosomes.

II. Gene mutation: - it is the mutation which occurs in gene. It affects the genetic makeup and genetic constitution.

By that type mutation cause variations in population and brings evolution.

2. Genetic recombination: - it reshuffling mixing of gens between different organisms. As result new combatants (organisms) are produced genetic recombination occurs during:-

I. crossing over in pachytene stage( prophase-I)

II. Free selection of genes at the time of gamete formation.

III. Random union of gametes the time of fertilization.

It is major source of genetic of Darwin’s theory is fully accepted as it was more reasonable.

Nature is the super power that selects best fitted individuals and reject poorly developed and thus usually die.

For example stronger physically fit wild male animal (lion, tiger, horse, jackal, bull, deer) always involves in sexual activity and copulation. Only active and fast swimmer spermatozoa fertilize the healthy ovum others die.

4. Isolation: - it is separation of organisms from their original population. It results in the prevention of mating amongst inter breeding groups. So that always active breeding groups. So that always active fertile population is produced.

Types of isolation

ØGeographical isolation: - the original or previous population is divided into many groups due to mountains, rivers, oceans, forests , desert etc. example Darwin’s finches

ØReproductive isolation: - it is prevention of interbreeding between the populations of two different species. It maintains the characters and prevents the formation of sterile hybrid.

5. Genetic drift: - some genes are responsible for specific characters of organisms which are not selected by nature are called genetic drift. It was described by Sewell Wright (the American geneticist). It is also a cause of variation of organisms and origin of new species.

Genetic basis of adaptation

1. Resistance of mosquito to pesticides: - when DDT was first used to control mosquitoes. It became effective but now a day’s DDT has ineffective against mosquito. It is due to resistant genotypes. In the beginning some mosquitoes were resistant to DDT but latter the resistant mosquito reproduces and multiplies. Hence the DDT became ineffective.

2. Industrial melanism: - peppered moth (biston betularia) existed into two forms-light colored (non-melanic) and melanic (black) in Britain. Due to industrial pollution tree-trunks became more and more blackened near the industries. As a result light coloured moths were clearly seen on the trunk and easily found and eaten by predator (birds) so that the moth developed melanin pigment to match their body to surroundings. It is protective type of natural selection.

3. Variation in finches: - Darwin explained the finches on the Galapagos Island were migrated from South America continent. Darwin observed that there were many kinds of finches which were varied with respect to their beaks but closely related with each other. Different environment evnditions exits, undergo adaptive changes and new species of finches originated to fit or adopt in new habitat. It is called the adaptive radiation.

4. Extinction of Dinosaurs- Word meaning of dinosaurs is terrible lizard. These were huge and heaviest reptiles which dominated all over the world in Mesozoic era. So the era was golden age of reptiles. Darwin mentioned following reasons to extant the dinosaurs

I. climate was growing cooler and drier.

II. As they were hung, heaviest so they could not travel long distance to gain favorable climate.

iii. Sear city of food for these large reptiles.

iv. Due to large body size of dinosaurs it was not possible to have better protection from enemies.

Origin and Evolution of man

Study of origin and evolution of man is called anthropology. Scientific name of modern man is Homo sapiens. Paleontology should men have arisen in the plains of Asia, Africa and Europe. The ancestor of man was non-human, sub-human or ape like forms. These forms lived 20-24 million years age.

Modern man might have been evolved by passing following forms.

Primitive ethereal (placental mammal) insect various in cretaceous periods (65-144 million years).

ØPros moan primates (order of mammal includes monkey, apes and human) like tarsier and

Lamer Tarsioids (monkey like)

Aanthropoids

Man2.3

Modern monkey modern old-world monkey apes (gorilla, chimpanzee) 4

Differentiate between new world monkey and old monkey

New world monkey (platyrrhini)	Old world monkey(catarrhini)
1. It is a flat nose monkey.	1. It is a narrow nose monkey.
2. Tail is long and prehensile.	2. Tail is short and non-prehensile.
3. Nose is flat and nostrils are opened.	3. Nose narrow and nostrils are downwardly directed.
4.Number of teeth are 36	4.Number of teeth are 32

The modern apes and man had common ancestors which diverged in different directions. Man developed many specialized feathers but not by apes.

Evolutionary trend

It is changes or modification of ancestors of man to form modern man. These are: -

i. Bipedal locomotion and fore limbs became free

ii. Toes became non-opposable

iii. Erect posture

iv. Increase in size of brain low blood circulation

v. Reduction in size of a. eye brow b. canine and incisor teeth VI. Development of chin.

Position of modern an

Kingdom-animalia

Phylum-chrodata

Sub-phylum-vertibrata

Class – mammlia

Order-primates

Family-hominidae

Genus-Homo

Species-sepiens

Sub-species-sapiens

Fossils of pre-man ancestor

1. Ape like fossils

a. Proconsul- found in Lake of Victoria reported by Leakey in 1930. Proconsul was more near to ape than man.

b. Dryopithecus- similar to proconsul found in Africa. It is assumed that dryopithecus might the ancestor of ancient human fossils like Rramapithecus, Sivapithecus and Austrapithecus.

2. Human like fossils

a. Ramapithecus – it existed about 14 million year ago. Its fossils were recived from shivalik hills in India and form Lake of Victoria in Africa and teeth of Ramapithecus from Dang valley of Nepal.

b. Sivapithecus – it is similar to Rramapithecus. It existed about 10 million years ago. Its fossils recovered from Shivalik Hills in India.

c. Australopithecus

Time- 5 million years ago

Location- dry land of Africa

Brain capacity – 600c.c. (cubic centimeter)

Walk- upright

Height-3.5 -5ft tall

There were two types

Modern human ancestors

i. Homo habilis

ii. homo erectus

iii. Neanderthal man

v. Cro-magnon man

i. Homo habilis

Existed time – 2 million years ago

Location – east Africa

Brain capacity – 700 c.c.

Weight – 40- 50 kg

Height-4.5 feet

Feed- omnivorous

Ability- hunting and defense

ii. Homo erectus- it existed about 1.7 million years ago. These are java man peking man.

a. Java man

Existed time –50000 years ago

Location – Java

Brain capacity –9700 c.c.

Weight – 70kg

Height-5 feet

Feed- omnivorous

Ability- use tool and light fire

b. Pecking man

Existed time – 50000years ago

Location – caves near pecking in china

Brain capacity – 1075 c.c.

Weight – 70kg

Height-5 feet

Feed- omnivorous Ability-like java

Special feature- under developed chin but developed eye

iii. Neanderthal man

Existed time – 40000years ago

Location – Neanderthal valley of Germany

Brain capacity – 1450 c.c.

Weight –

Height-5 feet

Feed- omnivorous

Ability-used fire, made tools, used animal

Special feature- had primitive type of social life, religion and culture

iv.Cromagnon man

Existed time – 34000years ago

Location – cro-magnon rocks of france

Brain capacity –1600 c.c.

Weight –

Height-5 feet

Ability-expert making weapons and tools left some beautiful picture of animals.

Special feature-fore head was broad, narrow nose and clear chin.

Modern man

Existed time – 10000years ago after geological period

Location – modern man migrated in three directions

West wards- Europe, south west asia and north Africa (white race)

East wards – china, Siberia (mongoloid race)

South wards- india south Africa and malasia (negroid race)

Cranial capacity – 1400-1450 c.c.

Ability-creative, intlectual, scientific mind

Homology (similarity) of chromosome of man and ape.

a. Chrom number in man is 46 and in apes are 48.

b. DNA amount in diploid cell is similar in man and apes.

c. 3 number chromosomes and 6 number chromosomes have similar banding patterns.

Difference between modern man and apes

Apes	Modern man
Apes hve small brain box i.e. brain cavity. Gibbon -10cc oragunats-395cc,chimpanzee -400cc gorilla-52	Man has large brain box (1400-1450)cc
Apes have semi erect posture	Man has fully erect posture
Bipedal locomotion but take support of fore Limbs.	Bipedal locomotion and freeing of fore limbs From the ground
Head is buried in heavy soldures	Head is well placed on slender neck.
Incisors and canine ale large.	Incisors and canine are smaller
Arms are longer than legs	Arms are shorter than legs
Have flow flat skull and a flat nose	Have large skull and raising nose.

Evidences from paleontology or importance of paleontology

2. Fossils found in older rocks and newer rocks similarly fossils found in lower strata and upper strata of sedimentary rock shows the evolution to complex form.

3. Archaeopteryx like fossil bird link two groups of animal- reptiles and birds which is suggested that birds have evolved from reptiles.

Write short note on archaeopteryx:-

It is a fossil – bird which full name is archaeopteryx lithographical. It was found in rock of Jurassic period by Andrea Wagner from Germany. It was about the size of crow and showed features of both birds and reptiles as follows.

i) Beak like birds but teeth and jaws like reptiles.

ii) Wings like birds but claws on its wings like fore limbs of reptiles.

iii) Feathers like birds but scales like reptiles.

iv) Tail like birds but with vertebral like reptiles.

Diagram of archaeopteryx

Geological time scale and eras

It was determined by studying the age of fossils in rocks. Age was determined by radioactive dating dating method of fossils found in different strata. So it is also called stereological scale.

Geologists have classified geological history into following eras.

AZOIC ----------------No life

i. Archeozic era------------- era of modern life ------2000 million years ago.

ii.Proterozoic era-----------era of early life ---------370 millions years ago.

iii. Paleozoic era -----------era of ancient life -------270 millions years ago.

iv. Mesozoic era ----------- era of middle age ------135 millions years ago.

v. Enozoic era --------- era of modern life----------75 millions years ago to present.