ANT101 Lecture 15 - Early Hominins II

Some Uniquely Human Features

• Brain Size: Extremely large brain compared to other hominins.
• Bipedalism: Anatomical features support walking on two limbs.
• Dental Characteristics: Very small canines and relatively flat faces (orthognathic).
• Tool Use: The ability to modify raw materials into recognizable tool types.
• Chin: Presence of a chin, a distinct feature of modern humans.
• Language: Capability to both learn and invent language.

Early Stone Tools

• Oldest Tools: Found in Lomekwi, Kenya, dating back to ~3.3 million years ago.
  • Potential Makers: Possible association with Australopithecus afarensis or Paranthropus aethiopicus.
  • Lomekwian Tool Culture: Early tools made using hammer and anvil technique; simple tool-making technique resembles monkey behavior (e.g., nut cracking).

Rise of the Genus Homo

• Timeline: From 2.5 million years ago; several hominin species existed in Africa.
• Transition: Body form transition occurred between 2.3 and 1.7 million years ago.
• Evolutionary Milestones: The genus Homo evolved roughly around 2.3 million years ago.

Emergence of Homo

• Characteristics:
  • Larger brain case, more rounded shape.
  • Less projecting facial structure.
  • Smaller teeth.
  • Improved bipedal efficiency.

Context: The Pleistocene Ice Ages

• Genus Homo emerged during the Pliocene-Pleistocene transition, a period characterized by global temperature fluctuations.

Homo habilis - "Handy Man"

• Discovery: First discovered in 1964 by Louis Leakey in Olduvai Gorge, Tanzania.
• Age: Lived approximately from 2 to 1.6 million years ago.
• Habitat: Found in both eastern and southern Africa.
• Brain Size: 661-503 cubic centimeters (cc).
• Tool Association: Linked to simple stone tools known as “Oldowan.”
• Anatomical Features: Prognathic face, no sagittal ridge, large incisors, small postcanine teeth; adapted for climbing with curved phalanges but with bipedal features visible in legs and hips.

Olduvai Gorge

• Significance: One of the most important fossil hominin sites, providing extensive information on early humans.
• Geological Importance:
  • Faults expose geological beds.
  • Rapid sedimentation preserves bones and artifacts well.
  • Volcanic activity aids in radiometric dating of finds.

Archaeological Evidence

• Documentation: Olduvai offers a well-documented archaeological sequence covering geological, paleontological, and archaeological data.
• Stone Tool Industry: Oldowan tools characterized by percussion manufacture technique; associated with early Homo.

The Discovery of Hominins

• Zinjanthropus: First hominin found at Olduvai, now reclassified as Paranthropus boisei; discovered by Mary Leakey in 1959.
• Major Hominins at Olduvai:
  • Australopithecus
  • Paranthropus boisei
  • Homo habilis

H. habilis and Tool Use

• Oldowan Tool Usage: Once believed to be the only hominin to make and use stone tools until the discovery of Lomekwian tools.

H. habilis Classification Debate

• Classification Dispute: Debate regarding whether H. habilis should be classified as a member of genus Homo or remain within Australopithecus due to certain anatomical features.
  • Insufficient evidence shows H. habilis has larger brain sizes, advanced language, or tool-making capabilities compared to Australopithecus.

H. habilis Co-existence with Robust Australopithecines

• Timeline: Existed alongside robust australopithecines for approximately 1 million years.

Homo habilis or Homo rudolfensis?

• Discovered: The latter discovered in 1972 by Richard Leakey in Lake Turkana, Kenya.
  • Existed around 2.4 to 1.6 million years ago; few fossils available.
  • Brain size around 736 cc; distinctive facial features.

Differences and Speculation

• H. habilis vs H. rudolfensis: Differences in body size and diet; potential debate on classification as the same or separate species.

Introduction of Homo erectus

• Timeline: First discovered in 1891 in Indonesia, dating back to 1.8 million years. The skull cap and femur found labeled as “Java Man.”
• Sites Globally: Significant finds in various locations including Africa, Europe, and Asia, suggesting early hominin dispersal out of Africa.