Question

1) What are some of the evolutionary changes that made us humans? Provide THREE examples based on the lecture (origins of bipedalism, changes in the skeleton, etc.) or any other source.

Answer 1

Ans.

• The lengthy process of change which resulted in the origins of people from ape like ancestor is termed as human evolution.
• It is believed and proved by many scietific evidences that all people sharing physical and behavioral traits origaned from apelike ancestor following over 6 million years of evolution period.
• Several scientific disciplines such as physical anthropology, paleontology, evolutionary psychology, ethology, neurobiology... etc are studied to understand human evolution.
• Many morphological, developmental, behavioral and physiological changes charaecterize human evolution.
• The most significant evolutionary changes responsible for the origin of human are;

1). Bipedalism -

• It is hominid's most basic adaptation causing the skeletal change which all bipedal hominids share.
• Sahelanthropus or Orrorin primates of 6 to 7 million years ago are considered to be the first bipedal primatives.
• The early bipeds get evolved into the australopithecines giving rise to genus Homo in following time period.
• Several possible reasons for the origin of bipedalism have been put forward such as;

1. Freeing the hand for reaching and carrying food
2. To save energy during movement
3. Beneficial for running and hunting
4. Prevention from hyperthermia bhy reducing the direct exposure of large surface area of body.

• A large number of skeletal changes also occured with bipedalism.
• These structural changes covered most of the body parts such as legs, pelvis, vertebral column, feet, ankles and skull.
• These all features proved to be advantageous for survival in the changing environmental conditions.

2). Encephalization -

• Brain of human species became larger then the other primates - 1330 cm3 .
• This change allowed for an increases time period of social learning and language acquisition in juvenile humans approx. 2 million years ago.
• There were also some changes in brain structure.
• The temperal lobe and prefrontal cortex increased disproportionaly in size.
• Encephalization increased the amount of meat and starch in diet and cooking practice was developed.
• As a response to solve social problems, human intelligance was increased by encephalization.
• Changes in morphology of skull, like a decrease in mandibles size and attachment of mandible muscle created more space for the growth of brain.
• It is believed that major brain changes were associated with changes in many social and behavioral changes and represent the survival advantages of encephalization.

3). Ulnar opposition -

• It is a unique feature of genus Homo which provided a survival advantage.
• It is the contact between the first digit (thumb) and fifth digit's (little finger) tip of the same hand.
• In primates other then human, because of it's short size, thumb is unable to touch the little finger.
• This feature allowed the precision grip and power grip of human hand, responsible for all the skilled works.