Question

Given Below is the diagram depicting the stages of human evolution. Study the same and then answer the question that follows:

1. Name the different stages shown in the diagram.
2. Write about the changes in
   (a) Bipedalism
   (b) Forehead and brow ridges
   (c) Chin
   (d) Cranial capacity.

Answer 1

1. Identification of the diagram

1. The given image shows human ancestry. The following ancestors are illustrated in the image.

Australopithecus:

1. Human Ancestry started with Australopithecus.
2. Australopithecus is also called the first man-ape.
3. They were human-like below the neck and ape-like above the neck.
4. Locomotion was bipedal but they have bent knees.

Homo habilis:

1. Homo habilis is also called the early true man.
2. They existed 2 to 2.5 million years ago.
3. Homo habilis used chipped stone tools and sheltered themselves from wind, rain, and animals.

Homo erectus:

1. Homo erectus existed about 0.25 to 1.7 million years ago.
2. The foot was arched to support body weight and their posture was erect.
3. They learned to use fire and developed a primitive form of speech.

Neanderthal Man:

1. Neanderthal Man existed about 40,000 and 3,00,000 years ago.
2. They were similar to us below the neck and were heavily built with the outwardly curved thigh bone.
3. They started using animal hides, buried the dead, and lived both in caves and hut-like structures.

CroMagnon Man:

1. CroMagnon Man is closely related to the Modern man.
2. CroMagnon Man were cave dwellers and made cave paintings.
3. They domesticated dogs and used them for hunting and protection. They used arrowheads and spears made of stone, garments made of animal skin, and ornaments made of ivory.

Modern man:

1. The modern man is associated with neolithic culture.
2. They have perfect bipedal locomotion.
3. Modern man learned to cultivate plants and domesticate animals of economic importance.

2. Changes in characteristics-

(a) Bipedalism:

1. Bipedalism refers to locomotion in a living organism using two feet.
2. Due to changes in the shape of the vertebral column, pelvic girdle, spinal cord, bones of limbs, knee, and ankle joints bipedalism has occurred throughout evolution gradually.
3. Other external factors that: at having influenced this character changes in habitat and climate, usage of tools, the gathering of food, etc.

(b) Forehead and brow ridges:

1. Australopithecus, Homo habilis, Homo erectus: They all had prominent brow ridges.
2. Neanderthal Man: Their forehead was broad and sloping. They also had broad brow ridges.
3. CroMagnon Man: They had a broad, arched forehead. Their brow ridges were moderate.
4. Modern Man: Modern man developed a vertical forehead and their brow ridges got reduced.

(c) Chin:

1. Australopithecus, Homo habilis, Homo erectus: They did not have a chin.
2. Neanderthal Man: They developed a small chin.
3. CroMagnon Man: They had a defined chin.
4. Modern Man: Modern man developed a prominent chin.

(d) Cranial capacity:

1. Australopithecus: Their cranial capacity was 400-600 cm³.
2. Homo habilis: They had a cranial capacity of 650-800 cm³.
3. Homo erectus: Their cranial capacity ranged from 775-1255 cm³.
4. Neanderthal Man: Their cranial capacity ranged between 1200-1600 cm³.
5. CroMagnon Man: Their cranial capacity was 1650 cm³.
6. Modern Man: Their cranial capacity was about 1450 cm³.