Evolution of humankind

-Aastha Joshi

According to Darwin’s theory species have evolved due to minor variation in the individual members of species, which ways they are inherited by the offspring’s and so the variation end up on the emergence of a new specie. amongst the species that are extant, apes and monkeys are the closest resemblance to human beings.

1. PRIMATES-Monkeys, humans and apes belong to primates group. They have features which allow them to climb on trees with ease and use their forelimbs extensively. They are prehensile. Because of evolution they have got stereoscopic vision because of which they get a three dimensional picture of the surroundings.

Classifications of primates

a. Prosimii – They are more primitive. They include lemurs, lorises and tarsiers.Some zoologist also classify tree-shrews with prosimians. They are small squirrel like creatures who might represent transformation from insectivores to early primates. They are small in size but possess large eyes. Their eyes are located in ring like structure.

b. Anthropoidea – More advanced primates like money, apes and humans. They differ from the prosimii in the structure of bones in which their eyes are places. Their eyes are bowl like in shape, which allows them greater freedom of vision to see in various angles.

Hominoidea are furture classified into :1. PONGIDEA-Also classified as apes,gorillas, orangutans are a part of this group of species.

2. HOMINIDAE-Human beings and extant species of closest ancestors.

● APES-They are relatively larger in size than monkeys and have large cannon size teeth which are built strong.They are not adaptive to arboreal habitat and so exploit land resources equally as the resources from trees.

DRYOPITHECUS-Fossil evidences reveal that apes which lives in Africa were well adaptive to living in group such type of apes were referred as Dryopithecus

RAMAPITHECUS-15 million years ago the African-Arabian landmass collided with Asia bringing two continents together. This created conditions of expansion from Africa to Asia. A branch of dryopithecus separated and evolved into what we call ramapithecus. Their fossils

have been found in Siwalik hills and Rawalpindi areas.

The molecular biology has reveled that humans are decedents of African apes. Who first developed bipedalism and then in the second phase rapid expension of brain size was seen. On the basis of fossils hominids have been divided into two parts:

1. AUSTRALOPITHECUS-They were first evolved, what separated them from apes was their upright posture. Their fossils were originally discovered in south Africa by Raymond Dart. They are further classified into

AUSTRALOPITHECUS AFRICANUS-Their forehead is steeper and the skull was more round at the top. The were omnivorous

AUSTRALOPITHECUS ROBUSTON-They have flatter forehead and cheek teeth. In males they have a bony crest at the top of the skull. They were herbivorous.AUSTRALOPITHECUS BOISEI- Their fosssils were discovered in east Africa. Louis and Mary Leakey found its remains in Tanzania. These species were caked zinjanthropus now called Australopithecus boisei.

AUSTRALPITHECUS AFARENSIS- These were evolved much earlier then other forms of australpithecus and might be the ancestors of other species.

★ HOMO- The had an upright posture with changes in jaw and teeth leading to the increase in the size of brain. They are further subdivided into:

★ HOMO HABILIS- They are the oldest form of homo and were found near the lake Turkana in Kenya. Its brain size was 800 cc and they were tool makers.

★ HOMO ERUCTUS- Their fossils were found in east turkana Kenya, thy were almost like modern humans ,apart of upright posture they had larger brain size and well developed hands. They were much taller then Australopithecus and had abrain size of 1000 cc, while made tools with great skills

★ NEANDERTHALS- They were early homo sapiens and found in Germany first in 1856. In them brain size was further expanded wand stone tools became more efficient but their skull was thicker and less rounded unless modern humans

HOMO SAPIENS SAPIENS-Richard Leakey argued that they had African origin. They had a brain size of 1350 c.c. and they had mobility in speech except high level social interaction and complex stone tools. A larger brain size combined with well developed hands that were free to use was a revolutionary change, they also had better social interaction. They skull of modern humans is of globular shape while the changes in neck help with speech for resonation of sounds as they were able to produce vast amounts of sounds which were unique. Language and communication with the ability to arrange theideas is what made them efficient and adaptive the most and this feature of helped them to transmit knowledge and information to the successive generations also the more advanced brain help them to store information.