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MHT-CET : Biology Entrance Exam

MHT - CET : Biology - Human Evolution Page 1

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  1. Human beings have a long evolutionary history. The present day man is a product of evolutionary changes in pre-human ancestors who were arboreal in habit.
  2. Family Hominidae: Humans belong to the only living species of this family, namely, Homo sapiens.
  3. Linnaeus gave the name Homo sapiens to man.
  4. The ancestors of man and other related organisms are said to have evolved around 24 million years ago.
  5. The common ancestry between great apes and man is based on similarities in their DNA content, chromosome number and banding patterns of chromosomes.
  6. The study of fossils to determine the structure and evolution of distinct animals and plants is called palaeontology.
  7. Parapithecus: 36-million-year-old fossil. It was unearthed from a place called Fayum in Egypt.
  8. Ramapithecus: It was named so because it was found in the Siwalik Hills of India in the year 1910. It is a 12-14-million-year-old fossil.
  9. Palaeontological evidence shows that major changes in human evolution were with reference to the skull, dentition, vertebral column, girdles and limbs.
  10. The different stages in the evolution of man are:
    1. Dryopithecus
      Important characteristics of Dryopithecus:

 

      • It was the size of a rhesus monkey.
      • The body was slender.
      • The tail was absent.
      • It had a relatively smaller head.
      • The face showed projecting snout; prognathism (projecting jaws) was not very prominent as in modern apes.
      • It had 32 teeth like modern apes.
      • The canines were smaller than in apes.
      • Incisors were straight like that in Hominidae and not slanting as in apes.
      • The teeth were arranged in a U-shaped pattern, as in apes.
      • They lacked brow-ridge, which is one of the important characteristics of apes.
      • They had a comparatively well-developed brain.
      • The thumb of Dryopithecus was comparatively longer than in apes.
      • The pelvic girdle and vertebral column suggest that Dryopithecus was not capable of walking erect. It probably was quadrupedal.
    1. Australopithecus
      Australopithecus is the earliest known Hominid.
      Australopithecus is considered a connecting link between ape and man.
      Early Australopithecus were of two types, namely A. ramidus and A. afarensis.

      Australopithecus Afarensis
      Main Characteristics:
      • They were 1 to 1.5 metre in height.
      • They were fully bipedal.
      • Their snout was prognathous.
      • The average size of the brain was 400 ml.
      • They had parallel rows of teeth like those in apes.
      • They had fairly large and sharp canines.
      • The knee joint and femurs showed modifications for walking erect.

        There are three kinds of later Australopithecus namely:
      • Australopithecus africanus, also called gracile.
      • Australopithecus robustus, also called robust Australopithecus.
      • Australopithecus boisei, also called superrobust Australopithecus.


Australopithecus Africanus

      • They were comparatively small, i.e. 4.5 feet in height.
      • The face was only slightly prognathous.
      • They had less massive jaws.
      • They were without sagittal crest (sagittal crest is a bony ridge along the top of the skull running from front to back. It is used for attachment of muscles).
      • They are slender and hence called gracile.

Australopithecus Robustus

      • They were comparatively larger, i.e. 5 feet.
      • The face was even less prognathous compared to the A. africanus.
      • They had heavy jaws.
      • They had a sagittal crest.
      • They had reduced incisor and canine teeth.
      • They were robust or tough and hence called A. robustus.


Australopithecus Boisei

      • They were very robust, and hence the name.
      • Rest of the features were the same as A. robustus.
    1. Homo Habilis
      Main Characteristics:
      • Cheek teeth were not as large. Proportionate size of cheek teeth and front teeth were similar to human beings.
      • Like humans, premolar and molar teeth had different structures.
      • Cranial capacity was estimated to be 650 ml.
      • Feet bones were human-like.
    2. Homo Erectus
      Homo erectus is called the first true man. It is also called the African ape-man or Java man. Homo erectus is the descendent of Australopithecus.

      Main Characteristics:
      • The height of Homo erectus was between 1.5 to 1.8 metre (5-6 feet).
      • Homo erectus had flat sloping forehead, which ended in prominent brow ridges.
      • They had a flat face with modern dentition.
      • Homo erectus had protruding jaws.
      • The jaws and teeth were more massive compared to humans and there was no chin.
      • The brain of Homo erectus was larger than Australopithecus.
      • The cranium was much flattened on top.
      • The cranial volume ranged between 800 and 1,200 ml. (i.e. about 900 ml).
      • Homo erectus had thick muscular body.
      • Homo erectus had thin skin and lesser hair.
      • Homo erectus was bipedal.
      • The vocal organs had the ability to produce complex sounds.
      • Homo erectus possessed the power to speak (like a modern child) and communicate.
      • In Homo erectus, the males used to hunt animals, while females gathered food and looked after their young ones.
      • Homo erectus used fire for cooking and warmth.
      • Homo erectus used stone tools for hunting. They were expert hunters.
      • Homo erectus was a fairly intelligent and socially interacting animal.
      • In addition to caves, crudely made huts were used for habitation.
    3. Homo Sapiens
      Neanderthalensis

      Homo Sapiens neanderthalensis is also called the Neanderthal man.
      Main Characteristics:

1.      The maximum height of Neanderthal man was about 170 cm (5.5 feet). The female was shorter than the male.

2.      Body and limbs of Neanderthal man were heavy and bulky.

3.      The typical features of Neanderthal man were low and long skull, sloping forehead and prominent brow ridge.

4.      The Neanderthal man had protruding jaws.

5.      The mandible was absent in Neanderthal man and he either had a small chin or no chin at all.

6.      Feet of Neanderthal man were broader than modern humans.

7.      The knee of Neanderthal man was slightly bent and hence he walked with a stooping gait.

8.      The Neanderthal man was bipedal. He had long arms and short legs.

9.      Homo with a cranial capacity of over 1,200 ml is considered to belong to Sapiens species. The average brain size of Neanderthal man was 1,300 ml.

10.  The Neanderthal man used more refined stone tools. They obtained flakes by splitting stones into thin layers.

11.  They were good hunters and mainly killed animals by spearing with their favourite spear made of wood.

12.  Since the Neanderthal man lived in ice age, they covered themselves with crudely stitched animal hides clothing.

13.  They had better language compared to Homo erectus. However, the vocal apparatus was not as well-developed as that in modern man.

14.  The Neanderthal man could be performing religious ceremonies during the burial of their dead ones in caves. This was interpreted from the discovery of fossilised pollen grains, suggesting that they offered flowers to the dead bodies.

    1. Homo Sapiens Sapiens
      Homo sapiens sapiens is the modern man.
      Main Characteristics of Homo Sapiens Sapiens:
      • The Homo sapiens sapiens are 5-6 feet tall (average 5.5 feet or 170 cm).
      • The Homo sapiens sapiens have round head, vertical forehead and a distinct chin.
      • The Homo sapiens sapiens have a well-developed brain and enlarged cranium. The cranial capacity is 1,350 ml. The cranium became rounded partly because the brain was pushed up from below due to the increase in the size of pharynx and nasal sinuses.
      • The larynx or the voice box of the Homo sapiens sapiens is larger.
      • The Homo sapiens sapiens have proportionate eyes and prominent nose and chin.
      • They have better speaking ability, which has helped them displace Neanderthals.
      • The lower limbs of the Homo sapiens sapiens are well adapted for upright posture and bipedal walking.
      • The Homo sapiens sapiens are very good at communication.
      • The Homo sapiens sapiens have domesticated animals and have number of cultural practices.
      • The Homo sapiens sapiens have made progress in the fields of science and technology, which has helped them have a better lifestyle.

 

 

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