Introduction to stages of evolution of man

Man like other animals, is a product of organic evolution. He is the most intelligent vertebrate on this planet. The supremacy of man is mainly due to the evolution of his hand and his brain. Recent discoveries support origin of man from apes. The early stages of human evolution are studied by means of comparative study of fossils. Later stages are studied using the archaeological investigations. Human beings belong to a group of mammals called primates which also includes tarsiers, lemurs, monkeys and apes. Charles Darwin in his book ‘The descent of man’, suggested that man and apes had a common ancestor. About 25-30 million years age ape and man stalk1 diverged from that of monkeys and subsequent separation of apes2 and human ancestors occurred 5-10 million years ago.

The Significant Changes in the Evolution of ManParticular significance in the evolution of man was the development of an upright posture (bipedism), increase in brain size and  change in skull shape. The other observable changes are the development of the opposable thumb which allowed advanced tool use, change in pelvis and spine shape .There was also marked difference in jaw size which reduced reflecting changes in the species diet.

Ramapithecus and  Proconsul:

Ramapithecus and Proconsul  were the earliest ape-like ancestor. They did not walk upright and were similar in size to the chimpanzee, but stockier3. They were present about 15 million years ago. These species possessed a deeper jaw, had teeth with small canines, flattened4 molars and thick enamel5. They used to eat seeds and nuts6. The posture was partially upright. These are the earliest fossil ape, persisted until 10 million years ago.

1 stalk /stɔ:k/ sustantivo (of plant) tallo.2 Ape /eɪp/ sustantivo (Zool) simio , mono.3 stocky /'stɑ:ki/ adjetivo stockier, stockiest bajo y fornido.4 Flattened allanado.5 enamel /ɪ'næməl/ n uncountable esmalte.6 nut /nʌt/ fruto seco (nuez, almendra, avellana etc).

Australopithecus africanus:

Australopithecus africanus   lived around three and two million years ago.  They were bipedal, but had a slightly larger body size.  The posture was fully erect. The brain size was slightly larger ranging around 500 cc. The brain was however not very advanced enough for speech. The molars were much larger than that of the modern human.  They had small canines and small incisors. These hominids were herbivorous and ate tough7 plants which were hard to chew. The shape of the jaw was similar to the present day human.

Homo habilis:

Homo habilis was known as the handy man. The tools made by them were found with his fossil remains. This species was discovered to have existed between the years 2.4 and 1.5 million.  The earlier fossil remains of the Homo habilis had a smaller brain size of about 500cc but it is seen that there was an increase to 800cc toward the later part of the time period.  The brain shape indicates the development of speech.  Habilis   was 5 feet tall and weighed around 100 pounds. They were carnivores and are seen to possess small carnivorous teeth.  They were fully erect.

Later Stages in Evolution of Man Homo erectus:

Homo erectus lived nearly 1.8 million and 300,000 years ago.  The brain size grew to 900cc. By the end of its era the brain size grew to 1200cc similar to the modern day man. They developed speech. They are known to have developed tools, weapons, and fire. He learned to cook food using fire.  The Homo erectus is seen to have travelled out of Africa into China and Southeast Asia. They developed clothing to cope up with8 the northern climates. The face had massive jaws .no chin, huge molars thick brow ridges9 and a long, low skull. He was much stronger than the modern day man.

Homo sapiens neandertalensis:

7 tough /tʌf/ fuerte(not tender) ‹meat› duro.8 cope [kəʊp] verbo intransitivo arreglárselas, poder [with, con].9 ridge /rɪdʒ/ sustantivo (hilltop) cresta.

Homo sapiens neandertalensis lived 150,000 and 35,000 years ago in Europe and the Mideast.  It is seen in recent DNA studies that the neandertal man cannot be merged with H. sapiens gene pool10. The brain sizes was bigger than the present day man and ranged around 1450cc The head was  longer  with a massive jaw and a receding11

forehead . They were generally gigantic in structure and had a heavy skeleton with massive muscles.

Homo sapiens:

The homo sapiens appear to have originated from H. erectus in Africa and  then migrated outwards to Europe & Asia. They replaced existing species H. erectus & H. neanderthalis. Cro-Magnon man is the earliest y Homo sapiens (the species to which modern humans belong) that lived about 40,000 years ago.  They possessed vaulted12 cranium shorter skull and reduced jaws. The brain capacity was around 1400cc. They were omnivorous.

- Introduction to stages: http://www.tutorvista.com/science/stages-of-evolution-of-man

- Human evolution: http://www.tutorvista.com/biology/human-evolution

10 gene pool: banco de genes y en este contexto herencia genética.11 receding adj el mentón hundido.12 vaulted /'vɔ:ltəd / || /'vɔ:ltɪd/ adjetivo ‹ceiling/roof› abovedado.