Origin and Evolution of Man - Practice Questions & MCQ

• About 2000 million years ago (mya) the first cellular forms of life appeared on earth. 
• The mechanism of how non-cellular aggregates of giant macromolecules could evolve into cells with membranous envelopes is not known. 
• Some of these cells had the ability to release O2. 
• The reaction could have been similar to the light reaction in photosynthesis where water is split with the help of solar energy captured and channelized by appropriate light-harvesting pigments. 
• Slowly single-celled organisms became multicellular life forms. 
• By the time of 500 mya, invertebrates were formed and active. 
• Jawless fish probably evolved around 350 mya. 
• Sea weeds and few plants existed probably around 320 mya. 
• We are told that the first organisms that invaded land were plants. 
• They were widespread on land when animals invaded land. 
• Fish with stout and strong fins could move on land and go back to the water. This was about 350 mya.
• In 1938, a fish caught in South Africa happened to be a Coelacanth which was thought to be extinct. 
• These animals called lobe fins evolved into the first amphibians that lived on both land and water. 
• The amphibians evolved into reptiles. They lay thick-shelled eggs that do not dry up in sun unlike those of amphibians.
• Again we only see their modern-day descendants, the turtles, tortoises and crocodiles.
• In the next 200 millions years or so, reptiles of different shapes and sizes dominated on earth. 
• Giant ferns (pteridophytes) were present but they all fell to form coal deposits slowly. 
• Some of these land reptiles went back into water to evolve into fish-like reptiles probably 200 mya (e.g. Ichthyosaurs). 
• The land reptiles were, of course, the dinosaurs. The biggest of them, i.e.Tyrannosaurus rex was about 20 feet in height and had huge fearsome dagger-like teeth. 
• About 65 mya, the dinosaurs suddenly disappeared from the earth. We do not know the true reason.
• Some say climatic changes killed them. Some say most of them evolved into birds. The truth may live in between. 
• Small-sized reptiles of that era still exist today.
• The first mammals were like shrews. Their fossils are small-sized.
• Mammals were viviparous and protected their unborn young inside the mother’s body.
• Mammals were more intelligent in sensing and avoiding danger at least.
• When reptiles came down mammals took over this earth.
• There were in South America mammals resembling horse, hippopotamus, bear, rabbit, etc. 
• Due to continental drift, when South America joined North America, these animals were overridden by North American fauna.
• Due to the same continental drift pouched mammals of Australia survived because of lack of competition from any other mammal.
• Lets we forget, some mammals live wholly in water. Whales, dolphins, seals and sea cows are some examples.
   

• Man is placed under the family Hominidae of the order Primate and differs from other anthropoid apes by having: 
  • Large size of the brain with greater functional ability
  • The brain case is larger than face region
• Available fossils give the evidence that most of the fossils of pre-human ancestors including monkeys and apes have been recovered from Africa, Asia and Europe.
• The modern man possesses the following special features, which have been acquired during the course of evolution:-
  • Bipedal locomotion
  • Large brain and cranial cavity
  • Grasping hands and feet
  • Erect posture
  • Stereoscopic (binocular) vision
  • Sensitivity
  • Social organization
  • Expression by speech
• Morphological changes that have occurred in man during the process of evolution are
  • Increase in brain size and intelligence
  • Attainment of erect posture
  • Flattening of face
  • Shortening of body hair and reduction in their number
  • Elevation and narrowing of the nose
  •  Formation of chin

Early human ancestors:

• Dryopithecus and Ramapithecus:
  • About 15 mya, primates called Dryopithecus and Ramapithecus were existing
  • They were hairy and walked like gorillas and chimpanzees
  • Ramapithecus was more man-like while Dryopithecus was more ape-like
  • Few fossils of man-like bones have been discovered in Ethiopia and Tanzania
  • These revealed hominid features leading to the belief that about 3-4 mya, man-like primates walked in eastern Africa
• Australopithecus (the first man-ape):
  • About two mya, Australopithecines probably lived in East African grasslands.
  • Australopithecines are considered to be ancestral to all hominids of genus Homo.
  • They walked nearly or completely straight.
  • Australopithecus have 500 c.c. cranial capacity.
• Homo habilis:
  • The brain capacities were between 650-800cc.
  • They probably did not eat meat.
  • The brain capacities were between 650-800cc. 
  • They were the makers of stone tools.
• Homo erectus:
  • About 1.5 mya, Homo erectus arose.
  • Homo erectus had a large brain around 900cc.
  • Homo erectus probably ate meat.
• Neanderthal man:
  • Their fossils were found in the Neanderthal Valley in Germany.
  • They arose some 1,00,000-40,000 years back near east and central Asia.
  • The skull bones were thick, forehead was low and slanting and the eyebrow ridges were heavy. 
  • The jaw was deep with no chin. 
  • The cranial capacity was about 1450 c.c. (almost equal to the modern man).
  • It was quite intelligent to use and construct tools. 
  • It buried its dead and could perform ceremonies as well as constructed hut-like dwelling structures.
• Cro–Magnon Man: 
  • These lived during the last 30,000 years or more in Europe. 
  • These succeeded Neanderthals and became extinct about 10,000 years ago in the last glacial period.
  • The cranial cavity was about 1660 cc. 
  • These were cave-dwelling and hunters. 
  • They made tools from stones and ornaments from ivory.
• Modern Man (Homo sapiens–sapiens):
  • During the ice age between 75,000-10,000 years ago, modern Homo sapiens arose. 
  • Prehistoric cave art developed about 18,000 years ago. 
  • Agriculture came around 10,000 years back and human settlements started.