Australopithecines And Early Homo

Australopithecines (Australopiths)  Clearly bipedal  Relatively small brains  Large teeth, especially molars  Faces large relative to cranial vault (brain case)  Found in all major geographical locations in Africa  Lumper vs. Splitters  Gracile  Australopithecus  Robust  Paranthropus  Clearly bipedal  Relatively small brains  Large teeth, especially molars  Faces large relative to cranial vault (brain case)  Found in all major geographical locations in Africa  Lumper vs. Splitters  Gracile  Australopithecus  Robust  Paranthropus

Why the Rift Valley?  In East Africa, early hominid sites are located along the Great Rift Valley  Stretches over 2,000 miles  Formed by geological shifting  Same geological process as that leading to continental drift  Has led to faulting (w/ earthquakes) volcanoes, and sometimes rapid sedimentation  Key locales within the Rift Valley – more than 2,000 hominid fossils have been found  Especially in Middle Awash area in northeastern Ethiopia  In East Africa, early hominid sites are located along the Great Rift Valley  Stretches over 2,000 miles  Formed by geological shifting  Same geological process as that leading to continental drift  Has led to faulting (w/ earthquakes) volcanoes, and sometimes rapid sedimentation  Key locales within the Rift Valley – more than 2,000 hominid fossils have been found  Especially in Middle Awash area in northeastern Ethiopia

East Africa: Australopithecus anamensis  4.2 – 3.9 mya  Eastern and southern ends of Lake Turkana, Kenya and Ethiopia  Mixed woodland and grassland environment  4.2 – 3.9 mya  Eastern and southern ends of Lake Turkana, Kenya and Ethiopia  Mixed woodland and grassland environment

East Africa: Australopithecus anamensis  Broadly similar to Ardipithecus  Ape-like characteristics  Very large canines  Parallel tooth rows in upper jaw (maxillae)  Difference in size between two cusps on lower premolars  Efficient tree climber?  Broadly similar to Ardipithecus  Ape-like characteristics  Very large canines  Parallel tooth rows in upper jaw (maxillae)  Difference in size between two cusps on lower premolars  Efficient tree climber?

East Africa: Australopithecus afarensis  mya  Two Main Sites:  Laetoli in Tanzania, Kenya  Hadar in Ethiopia  Afar Region  Lived in various habitats  Recently-Dikiki, Ethiopia recovered 3 year old  mya  Two Main Sites:  Laetoli in Tanzania, Kenya  Hadar in Ethiopia  Afar Region  Lived in various habitats  Recently-Dikiki, Ethiopia recovered 3 year old

East Africa: Australopithecus afarensis  “Lucy”  40% of skeleton discovered  Both arms, much of the pelvis, L. femur, R. tibia, hand and foot bones  Bipedalism differs from modern humans  Legs short relative to lengths of trunk and arms  Shorter stride length  “Lucy”  40% of skeleton discovered  Both arms, much of the pelvis, L. femur, R. tibia, hand and foot bones  Bipedalism differs from modern humans  Legs short relative to lengths of trunk and arms  Shorter stride length

East Africa: Australopithecus afarensis  Cranial capacity- 430 cc  Large canines  Face below nose projects similar to apes  Tooth rows parallel with slight convergence  Males w/ small sagittal crest  Lived in various habitats  Tooth wear varied - indicates diverse diet  Cranial capacity- 430 cc  Large canines  Face below nose projects similar to apes  Tooth rows parallel with slight convergence  Males w/ small sagittal crest  Lived in various habitats  Tooth wear varied - indicates diverse diet

East Africa: Australopithecus afarensis  Laetoli  Preservation of footprints  20 different animal species, including two hominids  Eruption of nearby volcano  Thin layer of ash  Light rain  cement  Estimation of stature  4 feet 9 inches  4 feet 1 inch  Laetoli  Preservation of footprints  20 different animal species, including two hominids  Eruption of nearby volcano  Thin layer of ash  Light rain  cement  Estimation of stature  4 feet 9 inches  4 feet 1 inch

East Africa: Australopithecus (Kenyanthropus) platyops  mya  Western side of Lake Turkana  Mainly woodland  Face unusually flat  Contention whether separate species  mya  Western side of Lake Turkana  Mainly woodland  Face unusually flat  Contention whether separate species

Emergence of Two Evolutionary Lineages (Later Australopithecines)  Reflects two different adaptations  One pattern associated with origin and evolution of Homo  Second pattern represented by descendents of A. afarensis, leading to two later australopithecine lineages-  East Africa  South Africa  Reflects two different adaptations  One pattern associated with origin and evolution of Homo  Second pattern represented by descendents of A. afarensis, leading to two later australopithecine lineages-  East Africa  South Africa

East Africa: Australopithecus garhi  Ethiopia’s Middle Awash Region  Bouri  2.5 mya  Bones, teeth, partial skeleton, skull  Cranium approx. 450 cc  Teeth larger than earlier australopithecines  Lower third premolar with cusps about same size  Ethiopia’s Middle Awash Region  Bouri  2.5 mya  Bones, teeth, partial skeleton, skull  Cranium approx. 450 cc  Teeth larger than earlier australopithecines  Lower third premolar with cusps about same size

East Africa: Australopithecus garhi  Ratio of arm length to leg length more human like  Result from femur lengthening  Decreased commitment to arborealism of earlier Australoptihecines  Suggest ancestral to Homo?  Ratio of arm length to leg length more human like  Result from femur lengthening  Decreased commitment to arborealism of earlier Australoptihecines  Suggest ancestral to Homo? Fig. 3. The most complete palates of A. afarensis (A.L a; canine reset) (A) and A. boisei (OH-5) (B) compared with that of A. garhi (C and D). The photograph (©David L. Brill 1999Atlanta) was mirror-imaged on midline. Australopithecus garhi has relatively large canines like A. afarensis and absolutely large but morphologically nonrobust premolars and molars. Drawings ©L. Gudz.

Stone Tools  Stone tools found from a number of sites in E. Africa dating to mya  At Bouri, mammal bones with distinct cut marks and percussion marks by stone tools  Australopithecine hand bones have anatomical features associated with finer manipulation  Some evidence of bone-tool manufacture among early hominids  Stone tools found from a number of sites in E. Africa dating to mya  At Bouri, mammal bones with distinct cut marks and percussion marks by stone tools  Australopithecine hand bones have anatomical features associated with finer manipulation  Some evidence of bone-tool manufacture among early hominids

South Africa: Australopithecus africanus  mya  Taung, Sterkfontein, Makapansgat, Gladyvale  Less ape-like than earlier australopithecines  Dentition more human-like  Front teeth relatively large  Canine did not project  Wear pattern suggests “soft” diet  Ex. Taung child  mya  Taung, Sterkfontein, Makapansgat, Gladyvale  Less ape-like than earlier australopithecines  Dentition more human-like  Front teeth relatively large  Canine did not project  Wear pattern suggests “soft” diet  Ex. Taung child

South Africa: Australopithecus africanus

Late Australopithecines: Robust Species  Range of variation in physical appearance between earlier gracile austarlopithecines overlaps with later robust species  All robust australopithecines shared some characteristics in their heads  Larger jaws  Much larger back teeth (molars) and small front (anterior) teeth compared to early Homo  Males with pronounced sagittal crests  Robust species placed in new genus- Paranthropus  Range of variation in physical appearance between earlier gracile austarlopithecines overlaps with later robust species  All robust australopithecines shared some characteristics in their heads  Larger jaws  Much larger back teeth (molars) and small front (anterior) teeth compared to early Homo  Males with pronounced sagittal crests  Robust species placed in new genus- Paranthropus

Late Australopithecines: Robust Species  Morphology cont.  Postorbital constriction  Pronounced sagittal crest  Broad cheek bones (zygomatics)  Large, backwardly extending zygomatic arch  Large molars, small incisors and canines  Morphology cont.  Postorbital constriction  Pronounced sagittal crest  Broad cheek bones (zygomatics)  Large, backwardly extending zygomatic arch  Large molars, small incisors and canines

Paranthropus aethiopicus (“Black Skull”)  West side of Lake Turkana, Ethiopia  2.5 mya  Cranial capacity 410 cc  The very anterior zygomatic process of the maxilla whose size and orientation creates a flat, flaring face  Thought to be transitional form from one of the gracile species that came before due to small cranium  West side of Lake Turkana, Ethiopia  2.5 mya  Cranial capacity 410 cc  The very anterior zygomatic process of the maxilla whose size and orientation creates a flat, flaring face  Thought to be transitional form from one of the gracile species that came before due to small cranium

Paranthropus boisei  Oldovai Gorge, East Africa  mya  Cranial capacity 510 cc  Prominent sagittal crest  Very large grinding teeth with thick enamel  Oldovai Gorge, East Africa  mya  Cranial capacity 510 cc  Prominent sagittal crest  Very large grinding teeth with thick enamel

Paranthropus robustus  South Africa  mya  Teeth adapted to eating tough, fibrous vegetable foods  Wear pattern indicates regularly ate hard nuts and seeds  Large sagittal crest  Cranial capacity cc  The zygomatic arches - cheek bones - are large and positioned forward on face, creating a characteristic dish- shaped face.  South Africa  mya  Teeth adapted to eating tough, fibrous vegetable foods  Wear pattern indicates regularly ate hard nuts and seeds  Large sagittal crest  Cranial capacity cc  The zygomatic arches - cheek bones - are large and positioned forward on face, creating a characteristic dish- shaped face.

Early Homo  Genus Homo usually defined in terms of an increased brain size, reduction in the size of the face and teeth, and increased reliance on cultural adaptations  Cranial capacity generally between cc  Forehead rises more steeply  Skull more globular in shape with smaller torus  Moderate postorbital constriction  Genus Homo usually defined in terms of an increased brain size, reduction in the size of the face and teeth, and increased reliance on cultural adaptations  Cranial capacity generally between cc  Forehead rises more steeply  Skull more globular in shape with smaller torus  Moderate postorbital constriction

Homo habilis (“handy man”)  mya  First discovered at Oldavai Gorge in Tanzania  Found only in the Great Rift Valley system in East Africa  mya  First discovered at Oldavai Gorge in Tanzania  Found only in the Great Rift Valley system in East Africa

Homo habilis (“handy man”)  Avg. cranial capacity 610 cc  Teeth generally smaller than australopithecines, but larger than modern humans  Less than 4 feet tall  Relatively long arms and short legs  Somewhat curved fingers and toes  Argued should be reclassified into genus Australopithecus  Avg. cranial capacity 610 cc  Teeth generally smaller than australopithecines, but larger than modern humans  Less than 4 feet tall  Relatively long arms and short legs  Somewhat curved fingers and toes  Argued should be reclassified into genus Australopithecus

Homo rudolfensis  mya  Lake Rudolf (former name of Lake Turkana) in Kenya  Brain size larger than H. habilis  Back teeth also larger  Midface is broader  mya  Lake Rudolf (former name of Lake Turkana) in Kenya  Brain size larger than H. habilis  Back teeth also larger  Midface is broader

Oldowan Tradition  Associated with Homo habilis, but also perhaps robust australopithecines  Cores, hammers, and flakes  Made from flint, obsidian, or quartz  Cutting meat and plant material, scraping meat off bone, sawing bone or wood  Associated with Homo habilis, but also perhaps robust australopithecines  Cores, hammers, and flakes  Made from flint, obsidian, or quartz  Cutting meat and plant material, scraping meat off bone, sawing bone or wood OLDOWAN TOOLS (left to right): end chopper, heavy-duty scraper, spheroid hammer stone (Olduvai Gorge); flake chopper (Gadeb); bone point, horn core tool or digger (Swartkrans).

Oldowan Tradition  10 Olduvai sites  Initially considered to be some sort of home base  No considered “stone cache” sites  At these sites, find mostly lower leg bones of antelope  10 Olduvai sites  Initially considered to be some sort of home base  No considered “stone cache” sites  At these sites, find mostly lower leg bones of antelope

Big Ideas  All of these species had restricted ranges.  Most species (except Homo) at least partially tied to arboreal habitats  Early Homo shows both increased encephalization and numerous occurrences of likely association with stone tools.  All of early African hominids show accelerated developmental pattern  Approximately 2.5 to 1 mya three separate hominid lineages living in same area during same time (in some cases side by side)  The immediate ancestors of early humans were most likely late gracile australopithecines. At present, the leading contender for that ancestral species is Australopithecus garhi or possibly Australopithicus africanus.  All of these species had restricted ranges.  Most species (except Homo) at least partially tied to arboreal habitats  Early Homo shows both increased encephalization and numerous occurrences of likely association with stone tools.  All of early African hominids show accelerated developmental pattern  Approximately 2.5 to 1 mya three separate hominid lineages living in same area during same time (in some cases side by side)  The immediate ancestors of early humans were most likely late gracile australopithecines. At present, the leading contender for that ancestral species is Australopithecus garhi or possibly Australopithicus africanus.