Human evolution

^{Systemic position of Human}

^{Kingdom:                   Animalia}

^{Phylum:                      Chordata}

^{Sub-phylum:               Vertebrata}

^{Group:                         Craniata}

^{Division:                     Gnathostomata}

^{Superclass:                  Tetrapoda}

^{Class:                           Mammalia}

^{Order:                           Primate}

^{Sub-order:                   Anthropoidea}

^{Super-family:-             Catarrhini}

^{Family:                        Hominidae}

^{Genus:                         Homo}

^{Species:                       sapiens}

^{The wonder about the origin of human, from where human came to this earth remain unsolved for thousands of years. Huxley (1863) in his book “Man’s place in nature” established a close relation among monkeys, apes and man.}

 He proposed that human evolved from apes like ancestors. This view was supported by Charles Darwin (1871) in his book “Descent of man”. However, fossil evidences of humans and apes were almost unknown at that time. Carolus Linnaeus gave the name Homo sapiens to man. The studies on the fossils of prehuman and human showed that both apes and human have common ancestry. Scientists studying human evolution (Anthropology) are called as Anthropologists and some of them are Eugene Dubois, Raymond Dart, W.C. pie, Mary clark, L. leakey,simon, Mac Gregor etc. Anthropologists agree that the place of human origin is central Asia and cardle of human evolution is central Africa (Savannah). The time of human origin is about 24-36 million years ago. The history of human evolution is based on palaentological and comparative molecular biology.

^{Evolutionary history of man}

^{Origin of Mammals:}

^{Mammals are supposed to be evolved from cynodont reptiles (a branch reptiles called as cotylosaures) in early Jurassic period about 210 million years ago (MYA). They were insectivorous, quadripedal, nocturnal, arboreal and highly sensitive to change in environment. They were like Tree shrews of present time. They were more diversified after extinction of Dinosaurs in the cretaceous period of Mesozoic era.}

^{Origin of early primates:} 

^{The early primates were originated about 65 MYA. They were prosomians and arboreal in habit. The prosomians are Lemurs, Tarsiers and Lorises. Lemurs were the first primate to evolve with less specialized grasping feet.}

^{Origin of Anthropoids:}

^{Anthropoids include old world monkeys, new world monkeys, apes and man. They were supposed to be evolved about 36 MYA. The monkey stock remained arboreal and became became specialized for their arboreal life. In about 20-24 MYA, the hominids, the ancestors of apes and man; evolved while the monkeys diverged along a separate line. The apes evolved on two families Hyalobatidae (Gibbon) and Pongidae (Orangutan, Chimpanzee and Gorilla). The ancestors of apes mainly remained on trees and walked on all four limbs while ancestors of man came down to ground and walked on two feet.}

 ^{Parapithecus: “Monkey-ape” was the common}

 ^{ancestor of old world monkey, apes and man. It was in existence about 40 MYA (Oligocene epoch). Its fossils was identified and studied by Gregory (1951) and Colbert (1955).}

^{Dryopithecus:  “Ape-man” was the common ancestor}

 ^{of man and apes. It was in existence about 15-26 MYA (Miocene epoch). Its fossils were discovered from rocks of Africa and Europe. It was more ape like but arms and legs of small length, semi-erect posture and with large brain. They were arboreal. D. africanus was followed by Proconsul africanus.}

Dryopithecus

^{The apes were diverged from main line of hominids at different periods;}

^{-   Gibbons were diverged from the main line about 10 MYA.}

^{- Orangutans were diverged from the main line about 8 MYA.}

^{-Chimpanzee & Gorilla were from the main line about 4 MYA.}

^{-Chimpanzee and Gorilla were separated with each other about 2.3 MYA.}

^{Ancient human fossils:} 

^{The fossils of Ramapithecus and Australopithecus are regarded as ancient fossils of human.}

^{Ramapithecus:} 

^{The oldest known direct ancestor of man is Ramapithecus which was evolved from Dryopithecus in late Miocene epoch. It was supposed to be the earliest man like primate and oldest of human ancestors. It was in existence about 14-15 MYA.}

^{Shivapithecus and Kenyapithecus were other forms} 

^{and similar to Ramapithecus.}

Fossils of Shivapithecus were discovered from Shivalik hills of India by E. Lewis.

Fossils of Kenyapithecus wicker was discovered by L. Leaky from Kenya.

Its fossil was also identified from Dang valley of Nepal.

They showed erect posture, more man like, arboreal and also walked on ground. The jaws and teeth were like humans. They ate nuts and seeds. They became extinct about 7 MYA.

Shivapithecus

^{Australopithecus:}

“African ape man” its fossils was discovered by Raymond Dart (1924). Fossils of A.africanus was discovered in Pliocene rocks near Tuang in Africa and was in existenceabout 4-5 MYA. It was with erect or semi-erect posture, walked on legs (bipedal), teeth like human and cranial capacity about 350-450 cc. It was omnivorous and diet included fruits. It gave rise to A. robustus and A. boisei but they blindly ended.

Australopithecus

^{Modern ancestors of human:}

The ancestors of human with genus Homo are considered as modern human ancestors. They are as listed below;

^{Homo habilis/ Skill full man/ Tool maker:}

^{A. africanus gave rise to Homo habilis about 3.5 MYA. Its fossils was discovered by} Mary and L. Leaky (1960) in Pleistocene rocks of Olduvai Gorge East Africa.They were about 1.2-1.5 meter tall, bipedal with erect posture, cranial capacity about 650-800cc. and teeth like that of modern man. They made stone tools hence known as tool maker. It led community life and lived in caves. 

Homo habilis

^{Homo erectus/ Erect man:}

It evolved from H. habilis about 1.7 MYA and spread to Asia and Europe. It was 1.5-1.8 meter tall, cranial capacity was 900cc and erects posture. The skull was flat, smaller chin and large teeth. They used stone tools for hunting. They were omnivorous but meat was main diet. They lived in caves and used fire for hunting, defense and cooking. The habit of cannibalism was present.

The fossils were discovered from Java, Peking and Germany.

^{*Java man: It was discovered by Eugene Dubois (1891) on the bank solo river, near Trinil, Java, Indonesia. It is called as Homo erectus erectus.}

java man

^{*Peking man: It was discovered from Peking China by W. C. Pie and Mayer (1924) and named Homo erectus pekinensis. Its cranial capacity was more than that of Java man about (850-1300)cc.}

peking man

*Heidelberg man: It was discovered from Heidelberg, Germany by Otto Schoensack. It is regarded as ancestor of Neanderthal man. It was named Homo erectus heidelbergensis.

Heidelberg man

^{*Neanderthal man/ Homo sapiens neanderthalensis:}

^{Its fossil were discovered from Neander valley of Germany by Fullhort (1856). It lived about (100,000 to 40,000) years ago in Europe, Asia and North Africa. It became extinct about 25000 years ago.}

^{They were about 1.5-1.6 meter tall, cranial capacity was about 1400cc, forehead was sloopy, the skull protruded behind, cave dwellers, good hunters, used animal skin as clothing, used tools for hunting, used fire for defense & cooking. They maintained burial customs. It is supposed to be the primitive form of man. They built hut like structures for dwellings and also lived in small groups for protection.}

^{They were considered as directive ancestors of modern man. Probably they were wiped out by Cro-magnon man or absorbed in the gene pool of modern man by interbreeding.}

Neanderthal man

^{Cro-magnon man/ Homo sapiens fossilis:}

^{Its fossils were discovered from cro-magnon rocks of France by Mac Gregor. They lived about 34000 (20,000-50,000) years ago. It is regarded as direct ancestor of modern man. Its cranial capacity was about 1650 cc and 5-6 feet tall( 1.8 meter), narrow skull with broad face, strong and thick jaw with distinct chin, raised forehead with distinct nose, lived with family in caves, developed paintings in caves, prepared sophisticated weapons, great hunters, carnivorous in diet, made ornaments of stones & bones but no idea of agriculture and domestication of animals.}

^{They become extinct about 10,000-11,000 years ago.}

Cromagnon man

^{Modern man/ Homo sapiens sapiens:}

^{It probably evolved from Cro-magnon man about 25,000 years ago and spread all over world. The changes include more cultural rather than anatomical. The thining of skull bones, slight reduction in cranial capacity about 1450 cc and perfection in vertebral column are the major changes.}

^{The superior power of brain helped to adapt and control his environment. He started cultivating plants and domesticating animals, developed civilization, social and cultural awareness. They become a dominant species.}

^{The modern man migrated in 3 main directions; the first group migrated to west are called White race (in Europe, America, southwest Asia); second group migrated to north east are called Mongoloid race (in china, Japan, Siberia) and third group migrated to south called Negroid race (in India, South Africa, Malaysia).}

^{Homology in chromosomes of man and apes}

^{The similarities in chromosome number, banding pattern of chromosomes and DNA content of apes and man support the idea of common ancestry. The similarities are:}

^{-  The number of chromosomes in man is 46 while in apes (chimpanzee, Orangutan and Gorilla) is 48.}

^{-The banding pattern of chromosomes (number 3 and number 6) is similar in man and apes.}

^{- Total amount of DNA in human diploid cell and that of apes is not much different.}

 Some other evidences supporting common ancestry are:  ^{- Presence of similar type of blood protein in man and apes.}

 ^{-  99% homology in haemoglobin of man and apes.}

 ^{- Presence of two type of blood group-A, group-B and Rh-  factor in apes.}

^{- Morphological similarities: man resembles apes in having tail less body, erect posture, bipedal locomotion and dental formula.}

^{-Vestigial organs in man are also found in apes either as vestigial or functional organ.}

^{- Menstrual cycle of human female is of 28-32 days while of 28-32 days in Chimpanzee and 30-35 days in Gorilla.}

^{- Gestation period in human is of 270-290 days while of 265-280 days in Gorilla and 210-252 days in Chimpanzee.}

^{-Sperms and eggs of human beings are indistinguishable from those of apes.}

^{-Embryo of human is covered with hairs.}

^{Think further}

^{If man evolved from apes then why are here still apes?}

^{-  Man did not evolve from modern apes. Man and modern apes had a common ancestor which is extinct.}

^{Evolution is not a straight line where entire population changes into new species all at the same time. Often times, a small group of population breaks away from a population and begins to evolve independently of the source group. The source group does not need to go extinct and is generally unaffected by the development of smaller group. This is called “Allopatric speciation”. There is nothing in evolutionary theory which states a source population must go extinct in order for new species to evolve.}

^{*Cardle of human evolution- Central Africa, Savannah.}

^{*Place of human evolution- Central Asia.}

^{*Java man and Peking man were cannibal.}

^{*Most primitive ape-Gibbon while most advanced ape-Gorilla.}

^{*Australopithecus was first to show bipedal locomotion.}

^{*Man of future- Homo sapiens futuralis, proposed by American Anthropologist Dr. Sapiro.}

^{*Remember like this:} 

                           ^DRAHENS

                                                  ^{D: Dryopithecus}

                                                  ^{R: Ramapithecus}

                                                  ^{A: Australopithecus}

                                                  ^{H: Homo habilis}

                                                  ^{E: Erect man}

                                                  ^{N: Neanderthals}

                                                  ^{S: sapiens ( Homo sapiens fossilis & Homo sapiens sapiens)}

                                                    

^{*Differences between new world monkeys and old world monkeys:}

characters	New world monkey	old world monkey
Included in	super family Platyrrhini	super family Catarrhini
Distribution	south America and central America	Asia and Africa
Nose/Nostrils	Flat nose with widely separated outwardly directed nostrils	Narrow nose with closely placed and downwardly directed nostrils
Tail	elongated prehensile	short non-prehensile
Brain	unspecialized and poorly developed	specialized and well developed
Limbs	Not used for grasping	Used for grasping
Teeth	3 molars and 3 premolars	3 molars and 2 pre molars
Cusps in molar teeth	3	4 to 5
Examples	Spider monkey, Marmosets etc.	Baboons, Proboscis monkey

^{*Differences between apes and man:}

Characters	Apes	Man
Habitat	semi-arboreal	Terrestrial
Body Posture	semi-erect and take help from forelimbs during locomotion	Erect and forelimbs are free during locomotion
Limbs	Fore limbs longer than hind limbs	Hind limbs are longer and more powerful
Forehead & skull	Both are flat	Forehead flat and protruded with dome shaped skull
Teeth	Large	Small
Lumbar curve	Lumbar curve is not found in vertebral column	Lumbar curve is found in vertebral column
Hallux/ Pollex	Hallux (Great toe) / Pollex( Thumb) both are opposable	Only Pollex is opposable
Face	Prognathus (protruding)	Orthognathus ( flat)
Simian gap	(Gap between incisors and canine) present	Absent
Cranial capacity	Gibbon=100cc, Orangutan=395cc, Chimpanzee=400cc & Gorilla= 510cc.	About 1450-1550cc