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LAB 7 – LATE AUSTRALOPITHECUS TO EARLY HOMO

Today’s class: Quiz Lecture Lab. LAB 7 – LATE AUSTRALOPITHECUS TO EARLY HOMO. AN 102, Spring 2013. A. robustus (SOUTH) A. aethiopicus (EAST) A. boisei (EAST). * Sometimes placed in genus Paranthropus. The genus Australopithecus. For each species, we will learn:

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LAB 7 – LATE AUSTRALOPITHECUS TO EARLY HOMO

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  1. Today’s class: Quiz Lecture Lab LAB 7 – LATE AUSTRALOPITHECUS TO EARLY HOMO AN 102, Spring 2013

  2. A. robustus(SOUTH) A. aethiopicus(EAST) A. boisei(EAST) * Sometimes placed in genus Paranthropus The genus Australopithecus • For each species, we will learn: • The taxonomic name • Its chronological age • The site where it was found • The traits it manifests Gracile Forms A. anamensis(EAST) A. afarensis(EAST) A. africanus(SOUTH) garhi(EAST) A. sediba(SOUTH) Robust Forms*

  3. Australopithecus africanus The first Australopithecus specimen was discovered by Raymond Dart in South Africa in 1924. It was a 4-year-old child. • Dates from 3-2.0 mya • Foramen magnum anterior • Flatter face, bigger brain, smaller canines, non-sectorial P3 • 400-500cc cranial capacity “Taung Child”

  4. Australopithecus garhi • Discovered in Ethiopia in 1999 • Dates to 2.5mya • 450cc brain and very prognathic face • Bigger teeth than A. afarensis and A. africanus • Proportionally longer lower limb bones • At nearby localities, antelope bones exhibited cut marks and damage from hammerstones • Important because it was previously thought that no Australopithecine made tools

  5. Australopithecus sediba • Discovered in South Africa in 2008 • Dates to 1.977 mya • 420cc brain • Small cheek teeth (Homo-like!) • Human-like hand and pelvis • More ape-like foot. • Otherwise like A. africanus • Demonstrates that there were different ways to be bipedal

  6. RobustAustralopithecines • A. anamensis, A. afarensis, A. africanus, A. garhi, and A. sediba are all gracile Australopithecine forms. • Around 2.5 mya, a new group of Australopithecines evolves: the robusts. • They are found in East and South Africa • Dental and jaw morphology differ from those of gracile forms • Specialized diet Gracile Robust

  7. Robust Australopithecines • Robust Australopithecus species have: • Larger cheek teeth/ very reduced anterior teeth • Larger attachment sites for muscles involved in chewing • Sagittal crest in males • Broad, flaring cheek bones • Large temporal fossa • Post-orbital constriction Temporal fossa Face Postorbital constriction View looking down on the skull In other words, robust species are highly adapted “chewing machines”

  8. Robust Australopithecines The attachment area of the temporalis muscle was larger in robust Australopithecine forms than in modern humans

  9. Australopithecus aethiopicus • Found in Ethiopia • Dates to approx. 2.5mya • No postcranial bones identified for sure in this and other E. African robusts “the black skull” • A. aethiopicus exhibits a mix of traits: • Small brain and prognathic face (like A. afarensis) • Sagittal crest and large molar teeth (like other robust forms)

  10. Sagittal crest Temporal Fossa Large molar teeth Australopithecus robustus • South African form • Dates from 2.0-1.5 mya • 500-530cc brain size • Sagittal crest and other heavy chewing adaptations Flaring cheek bones

  11. Australopithecus boisei • East African form: First found by Mary Leakey at Olduvai Gorge in 1959 • Dates from 2.2-1.4 mya • “Hyper-robust” • Sagittal crest and other heavy chewing adaptations • Very sexually dimorphic in body size • 475-545cc brain size Very reduced anterior teeth Very large molars with thick enamel

  12. Kenyanthropusplatyops • The genus Kenyanthropus has only one species and was named by Meave Leakey, who discovered it in northern Kenya in 1999. • Dates to approx. 3.5mya • Less prognathic face (like later humans) • Small brain (400-500cc), like Australopithecines • No definitive post-cranial fossils • Relationship to Australopithecines not entirely clear (could be a regional variant)

  13. Australopithecine behavioral patterns • Locomotion • All have bipedal adaptations, but some also retain adaptations for climbing • Sexual Dimorphism • Moderate canine dimorphism • Moderate to high body size dimorphism • Development • Faster to reach sexual maturity, less infant dependency than humans; more than apes • Tool Use • Some Australopithecines may have used stone tools (e.g., A. garhi) Suggests polygynous or multi-male/multi-female social system

  14. Australopithecine behavioral patterns • Brain Size • On average, 20% larger brain than chimpanzees. But, still considerably smaller than humans. • Diet • Herbivory and hard seeds in robust forms • A bit more omnivory in gracile forms A. africanus A. robustus Scratches = grainy food items (leaves) Pitted = hard food items (seeds, tubers) Magnified tooth-enamel surface of two australopithecines

  15. Status and Body Size in Australopithecines Estimates show large differences in body mass and height between male and female Australopithecines.

  16. What are the phylogenetic relationships of all these species? Modern humans Present Modern chimps Later Homo (extinct) Early Homo (extinct) Robust Australopithecines (extinct) Gracile Australopithecines (extinct) Ardipithecines (Sahelanthropus, etc.) Past Miocene Hominoids Can we be more specific?

  17. One possible scenario…. time early Homo A. boisei A. robustus A. aethiopicus A. africanus Kenyanthropus A. ghari A. afarensis Why do we have such difficulty determining this kind of phylogeny? A. anamensis Pre-Australopithecine

  18. ? ? ? Recovered fossils (if we’re lucky) The Recovery Problem time Actual history of species relationships

  19. **A. sediba - G A recap of pre-Homo hominid evolution R R R G G G G

  20. Moving to the genus Homo time early Homo A. boisei A. robustus A. aethiopicus A. africanus Kenyanthropus A. garhi A. afarensis A. anamensis Pre-Australopithecine

  21. Homo habilis • The oldest known species of the genus Homo • Louis Leakey discovered the first specimen at Olduvai Gorge in Tanzania (where A. boisei was also found) in 1960. OH 7 mandible OH 7 hand

  22. Homo habilis • Leakey was convinced this fossil was not A. boisei because: • It had no sagittal crest • It had smaller teeth • It was found in close association with tools • Leakey named the new fossil Homo habilis, meaning “handy man,” in reference to its presumed tool-making abilities. • -Leakey also emphasized the fact that his specimen had a had a larger brain than any Australopithecine.

  23. Homo habilis Many paleoanthropologists rejected Leakey’s new classification. -They said the new fossil material was too fragmentary to accurately conclude it belonged in a new genus. -They did not like the idea of “tool use” being a criterion for naming a new genus. Richard and Louis Leakey Subsequently, Louis’s son Richard set up a new site at KoobiFora in Kenya, where he also found A. boisei and H. habilis. -At the time, his finding solidified the taxonomy of H. habilis -Today, some people argue that the name should be changed to A. habilis due to post-cranial and developmental features.

  24. Homo habilis • H. habilis is found at sites in East Africa • Dates from 2.4-1.5mya • Post-cranial features: • Long, strong thumb • Short, straight fingers • Broader fingertips Features associated with increased manual dexterity Post-cranial materials Found at Olduvai Gorge in 1986

  25. Homo habilis A. africanus Homo habilis Skull less rounded Skull more rounded Smaller brain (<500cc) Larger brain (600-700cc) Prognathic face Less prognathic Larger molars Smaller molars More postorbital constriction Less postorbital constriction

  26. Homo habilistaxonomy • Recently, some people have argued that based on the variation seen in the cranial fossils, Homo habilis should be divided into 2 species: • -Homo habilis (smaller brains, less robust) • -Homo rudolfensis (more robust with larger brains) • Not yet agreed upon whether variation is more likely within a single species or between 2, but we will refer only to Homo habilisin this lab.

  27. Homo erectus • Eugene DuBois discovered the first H. erectus fossils in Java in 1891. • 2 key specimens were recovered: a skullcap and a femur DuBois

  28. Homo erectus • In the 1930s, Davidson Black, Franz Weidenreich, and Pei Wenshong began to excavate at Zhoukoudian(China) • They uncovered over 100 fossils attributed to H. erectus • Over time this has been a very well-studied site

  29. Homo erectus • H. erectus shows up in the fossil record about 1.8mya • It is unequivocally different from any prior hominid: • It is bigger, and has a bigger brain • It is found in sites outside of Africa • It has more advanced tools • Many of its features approximate modern human traits

  30. Homo erectus: Cranial Traits • Significant increase in brain size • -Range of 750-1250cc • -Average of 900cc • More encephalized than H. habilis, less encephalized than H. sapiens

  31. Homo erectus: Cranial Traits • Cranium • Large browridges • Low forehead • Broad at skull base • Nuchal or Occipital torus • Thick cranial bones • Shovel shaped incisors (also found in some modern populations)

  32. A. africanus A. robustus H. erectus H. sapiens

  33. Homo erectus: Post Cranial Traits • As tall as modern humans • More sexually dimorphic than modern humans • Thicker long bones H. erectus A. afarensis H. sapiens

  34. H. sapiens H. neanderthalensis H. heidelbergensis H. ergaster H. erectus H. habilis Homo erectus and Homo ergaster • Researchers often distinguish between H. erectus (Asian form) and H. ergaster (African form.) For simplicity, I will refer to both as H. erectus, although they do exhibit a few differences.

  35. Time (millions of years ago) % of resting energy allocated to brain Increase in brain size and EQ in H. erectus

  36. Homo erectus at Zhoukoudian • Site occupied intermittently for over 250,000 years • Over 100,000 artifacts have been collected • Debates continue over how to interpret some of these artifacts

  37. Homo erectus in Africa (H. ergaster) • Paleoanthropologists have found several nearly complete H. erectus crania in East Africa. • KNM-ER 3733: Dates to 1.8mya. • KNM-ER 3883: Dates to 1.6mya KNM-ER 3733 KNM-ER 3883

  38. Homo erectus in Africa A particularly famous H. erectus fossil was discovered by Lake Turkana in 1984. It is commonly known as Turkana Boy or Nariokotome Boy • Is over 90% complete • Dates to 1.6mya • Was 8-12 years old when he died (younger if he grew in a more chimp-like way) • Was 1.6m tall (5’ 3”), and likely to have reached 1.85m (6’1”) • Had a long, linear body shape like modern humans • Had a cranial capacity of ≈ 900cc

  39. Homo erectus: World Traveler • Since 1999, several H. erectus* crania were unearthed at Dmanisi in the Republic of Georgia • These crania date to 1.77 mya, making them the oldest known hominins outside of Africa • They are associated with Oldowan tools, showing that H. erectus migrated out of Africa with their toolmaking skills. *Some have suggested a new species, H. georgicus, for these specimens

  40. Early and Later migrations Homo erectus

  41. H. sapiens H. neanderthalensis H. heidelbergensis H. ergaster H. erectus H. habilis Next time… Later Homo Evolution & Tools • Homo erectus is found in the fossil record from 1.8mya to 200,000 years ago (possibly hung around longer in East Asia) • Toward the end of this time period, another species of hominid appears in the fossil record, at 800 kya • This species takes on an even more modern appearance

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