Pre-History

Question 1

The Divergence of Hominins from the Common Ancestor with Chimpanzees

during the late Miocene epoch, a pivotal event occurred that set the stage for human evolution: the divergence of the hominin lineage from the common ancestor shared with chimpanzees and bonobos. This separation marks the beginning of the hominin branch, eventually leading to Homo sapiens.

One of the earliest known species that may represent this divergence is Sahelanthropus tchadensis, discovered in 2001 in Chad. This species exhibits a blend of primitive and advanced features:

• Cranial Features: The skull has a mix of ape-like and human-like characteristics. The foramen magnum (the hole through which the spinal cord passes) is positioned in a way that suggests bipedalism.
• Bipedalism: The adaptation towards walking on two legs is a significant hallmark of hominins. Bipedalism would have been advantageous in open environments, allowing for efficient long-distance travel and the ability to spot predators over tall grasses.

Answer 1

7 million bce

Question 2

Australopithecus afarensis and the Rise of Bipedalism

Introduction to Australopithecus afarensis
- A hominin species known as Australopithecus afarensis thrived in the landscapes of East Africa.
- This species is one of the most significant in our understanding of human evolution due to its mix of ape-like and human-like features.
- The most famous specimen of A. afarensis is “Lucy,” discovered in 1974, whose fossilized remains have provided invaluable insights into early hominin anatomy and locomotion.

Consequences and Evolutionary Significance
- Energy Efficiency: Bipedal walking is more energy-efficient over long distances compared to quadrupedalism, advantageous for foraging across the expanding savannas.
- Predator Avoidance: Standing upright allows for better visibility over tall grasses to spot predators.
- Thermoregulation: Reduced surface area exposed to the intense midday sun could help with temperature regulation.
Anatomical Evolution:
- Freed Hands: Bipedalism freed the hands for carrying food, tools, and offspring, which could have led to increased survival rates.
- Brain Development: While brain size remained relatively small, the foundation was set for future increases in brain capacity in later hominins.

Answer 2

Between 3.9 and 2.9 million BCE