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Hominid Evolution:
Primates are one branch of the archontan group of placental mammals. Archontans are primarily tree dwellers: bats, tree shrews, and dermopterans (flying "lemurs"). Archontans are present by the end of the Cretaceous. Primates appear during Paleocene.

Primates possess:

• Nails instead of claws
• Forward-directed eyes
• Larger brains than many mammals

Widespread throughout North America, Eurasia, and Africa during early Paleogene; die out in North America but survive elsewhere.

Anthropoids: "higher primates" ("monkeys", "apes", and humans); proportionately larger brains. "Monkeys" are a paraphyletic grade (or more accurately, a paraphyletic grouping of two monophyletic clades, one South American, the other Eurasian-African). Monkeys move along the tops of branches.

Hominoids: "apes" and humans. Strictly Old World ("Eurasian-African") until Pleistocene. Move by swinging underneath branches: developed wide shoulders and wide-ranging arm motions. During Miocene many groups of "apes" throughout Eurasia and Africa. One Asian branch (pongids) contained Gigantopithecus (largest primate known) and the modern orangutan (Pongo).

In Africa: the hominids. Derived condition of knuckle-walking. Ancestrally were forest dwellers living in small communities, primarily herbivores with some meat, use wooden tools; gorillas (Gorilla) and chimps and bonobos (Pan) retain these habits.

At around 7 Ma, one lineage of hominids split from the ancestors of Pan. The first hominines ("hominids" in the old sense) primarily lived on edges of forest and grassland. New evidence showed that they could knuckle-walk. Omnivores with shorter faces and smaller canines. Evidence of stone tool use.

May have spread out of forests in response to general drying climate (rise of Himalayas?)

Basal hominine taxonomy is confused: traditionally grouped into a paraphyletic "Australopithecus"; probably better placed into a series of basal taxa (Sahelanthropus, Orrorin, Ardipithecus, Praeanthropus, etc.) and three clades of advanced genera with fully upright posture and fully opposable thumbs:

• Australopithecus proper:
  • Gracile australopithecines
  • Generally retained the primitive condition
  • Survived until almost 2 Ma
• Paranthropus:
  • Robust australopithecines
  • Bigger than Australopithecus
  • Had massive jaws and huge molars (presumably a diet with a LOT of tough vegetation)
  • Survived to 1 Ma
• Kenyanthropus and Homo:
  • Humans (broadly defined)
  • Bigger brains than other hominines
  • Shorter faces, smaller teeth

Taxonomy of species of Homo being revised. Some general patterns:

• Basal Homo (H. habilis):
  • African only
  • Not much larger than Australopithecus
• "Pithecanthropine"-grade Homo ( H. erectus, H. ergaster, H. georgicus, H. floresiensis):
  • African in origin, but spreads to Europe and Asia as far as China and Indonesia
  • Larger over all
  • Considerably larger brain
  • Much more diverse "toolbox" than earlier hominids
  • Used fire
  • Survived in eastern and southeastern Asia until 100 ka (but see below!); died out elsewhere earlier
  • H. floresiensis, the "hobbits", a surprising discovery: island-dwarf pithecanthropines in Indonesia, suriving to at least 13 ka. This makes them the last species of Homo to die out.
• "Archaic moderns", including Neanderthals (H. antecessor, H. heidelbergensis, H. neanderthalensis):
  • Around from c. 500 ka to c. 30 ka
  • Primarily European, but also in Near and Middle East
  • May have been the most glacially-adapted of hominids
  • Neanderthals in generally were short but powerfully built (estimates on bone size suggests average comparable strength to late 19th/early 20th century circus strongmen or Olympic wrestlers and weight lifters)
  • Had brain sizes comparable to H. sapiens (and thus a half again or more larger than H. erectus size)
  • More complex toolbox than pithecanthropine-grade Homo, but (like H. erectus) it remains relatively constant throughout the lifespan of the species
  • At least some evidence that H. neanderthalensis may have had a religion:
    • Burial of the dead, with possible grave goods
    • Stacked cave bear skulls in caves
• Modern humans (H. sapiens): us.
  • Oldest specimens around 195 ka (some possibly from 400 ka), from Africa and Near East
  • Most evidence suggests H. sapiens spread out of Africa and colonized other parts of the world, perhaps absorbing local populations (Neanderthals in Europe, late H. erectus in Asia), perhaps wiping them out (H. floriensis in Indonesia).
  • Shorter-faced than all other hominids
  • Longer legged
  • Undergoes a Great Leap Forward from primitive technologies to advanced, diverse technology and art sometime around 100-70 ka (once thought to be as recent as 50-40 ka)
    • Toolbox does NOT remain stable over time, but becomes radically more complex
    • Human cultures very different from place to place
    • Art: both representational (pictures of animals) and abstract
    • Boats: some evidence many early H. sapiens populations may have traveled along coasts by boat
  • Genetic evidence suggests a population bottleneck (down to 10,000 individuals or so) at around 80 ka, prior to spread out of Africa.

Some accomplishments of humans pre-Holocene:

• Migrations: migrations to Australia (c. 60 ka), Boreal Asia (c. 30 ka), and the Americas (definitely before 13 ka, possibly by 30 ka)
• Domestication of plants and animals, and transport of such domesticates
• Extinctions: extinctions of large-bodied mammals and flightless birds in almost every region humans arrive coming out of Africa. The Pleistocene "mass extinction" is very different from all others, since small organisms and marine invertebrates are not affected: suggests overhunting was a factor (although not only factor)

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Last modified: 2 January 2008