Primate Evolution and Early Hominins

• Primates share traits like grasping hands and feet, opposable thumbs, forward-facing eyes for depth perception, large brains relative to body size, flexible limbs, and social behavior.
• Humans are most closely related to chimpanzees and bonobos, sharing approximately 98-99% of their DNA.
• What distinguishes humans from other primates includes bipedalism, larger brain size, complex language, advanced tool use, prolonged childhood development, and symbolic thought.

Early Hominins

• Australopithecines are identified as more human-like than ape-like due to bipedal locomotion, smaller canines, and larger brains than apes.
• Traits of the human skeleton that are adaptations to bipedalism include an S-shaped spine, arched feet, a short and broad pelvis, an inward-angled femur, and a forward-placed foramen magnum.
• Larger molars in australopithecines suggest a plant-based diet, while smaller teeth in later Homo species indicate more meat consumption.
• A. boisei and H. habilis coexisted; H. habilis likely survived due to a more adaptable diet and tool use.
• Cooler, drier climates led to open savannas, favoring bipedalism and dietary adaptability, influencing human evolution.

Homo erectus

• H. erectus differs biologically from H. habilis with a larger brain (~900-1100 cc), more robust skeleton, longer legs, smaller teeth, and better endurance.
• H. erectus was the first hominin to leave Africa, control fire, create more advanced tools (Acheulean hand axes), possibly use rudimentary language, and engage in cooperative hunting.

Neanderthals

• Neanderthals had a stocky build, large nose, heavy brow ridges, and a brain size slightly larger than modern humans (~1500 cc).
• Neanderthals buried their dead, cared for the sick, used complex tools (Mousterian), and possibly had symbolic thought and language.
• Neanderthals may have become extinct due to competition with modern humans, climate change, possible interbreeding, and lower population numbers.

Modern Humans

• The Out of Africa Model suggests modern humans evolved in Africa and spread, replacing other hominins.
• The Multiregional Model proposes modern humans evolved simultaneously in different regions with gene flow between populations.
• Modern humans differ biologically from Neanderthals with a more gracile skeleton, smaller brow ridges and faces, and advanced brain function.
• Modern humans differ culturally from Neanderthals with more advanced tools, art, larger social networks, and more complex language.

Tool Technology

• Oldowan tools (H. habilis) are simple stone flakes used for cutting.
• Acheulean tools (H. erectus) are hand axes for more advanced cutting.
• Mousterian tools (Neanderthals) are more specialized flake tools used for hunting and processing animals.
• A chopper is a basic stone tool with a sharp edge for cutting.
• Acheuleian refers to the tool industry associated with H. erectus, featuring hand axes and bifacial tools.