Sometime around 7 mybp east African primates began on an evolutionary path distinct from central and west African primates.
Sometime around 7 mybp east African primates began on an evolutionary path distinct from central and west African primates.
West was more densely wooded. East less so, more open. East African primates went bipedal. Why? We don’t know
Carrying babies?
Making tools?
Thermodymics?
Wading along shorelines?
Looking for predators?
More efficient movement?
Sahelanthropus tchadensis. (Toumai, “hope of life” in Goran). A single skull, jaw fragments, several teeth, unearthed in 2002 by Michael Brunet, dated to about 6.5 mybp Found in Chad, central Africa?
Sahelanthropus tchadensis. (Toumai, “hope of life” in Goran). A single skull, jaw fragments, several teeth, unearthed in 2002 by Michael Brunet, dated to about 6.5 mybp Found in Chad, central Africa?
Forward position of foramen magnum suggest bipedalism
Orrorin tugenenis “original man” in the local Tugen language. February 2001, French researcher Brigitte Senut, a few teeth and limb bone fragments in the Tugen hills of Kenya, dated to about 6mybp
Orrorin tugenenis “original man” in the local Tugen language. February 2001, French researcher Brigitte Senut, a few teeth and limb bone fragments in the Tugen hills of Kenya, dated to about 6mybp
Femur (valgus) angle suggests bipedalism
Ardipithecus kadabba found in the Middle Awash region of Ethiopia, dated to around 5.5 mybp
Ardipithecus kadabba found in the Middle Awash region of Ethiopia, dated to around 5.5 mybp
Ardipithecus ramidus (Ardi) remains are dated to between 5-4.4 mybp; forest-dwelling, bipedal, but at home in trees as well. No evidence of knuckle-walking; is this derived feature in great apes?
Contros:
Are kadabba and ramidus related?
Are kadabba, orrorin, and sahelanthropus related?
Ardi appears to have low sexual size dimorphism, but australopiths have traditionally been thought of as highly dimorphic species?
Is Ardi the only one likely to be ancestral to Homo?
Australopithecus anamensis, first uncovered in 1995 in northern Kenya and dated to between 4.2 and 3.9 mybp. Descended from knuckle-walker (terrestrial before bipedal?; contrast with Ardi.
Australopithecus anamensis, first uncovered in 1995 in northern Kenya and dated to between 4.2 and 3.9 mybp. Descended from knuckle-walker (terrestrial before bipedal?; contrast with Ardi.
Australopithecus afarensis (Lucy) found in the mid-1970’s by Donald Johanson and dated to around 3.3 mybp, similar date for “Lucy’s child” found at Dikika, Ethiopia, est. 3yrs of age.
Australopithecus africanus, Tung child found by Raymond Dart of the University of Witwatersrand in South Africa, 1922. Dated as somewhat more recent than Lucy
Australopithecus sediba:
Australopithecus sediba:
Discovered in 2008 by Matthew Berger (9 year old son of Lee Berger). Not described until 2010. South Africa
Later australopith showing a mosaic of australopith (teeth, limbs, upper chest) and homo features (lower chest, skull, face, pre-molars)
A species at the transition point between Australopiths and Homo?
Dated to 2-1.5 mybp
Lucy bones – unquestionably bipedal. Some adaptations for tree-dwelling present. Small 3-4 feet in stature. High sexual dimorphism. Probably didn’t run very well. Ate fruits, nuts, insects, small USOs, amounts of meat. Was prey as much as predator.
Lucy bones – unquestionably bipedal. Some adaptations for tree-dwelling present. Small 3-4 feet in stature. High sexual dimorphism. Probably didn’t run very well. Ate fruits, nuts, insects, small USOs, amounts of meat. Was prey as much as predator.
Dart’s Taung child, killed by predator? Dated at about 2.5mybp, est. 4yrs.
Dart’s Taung child, killed by predator? Dated at about 2.5mybp, est. 4yrs.
Period of nutritional stress at 2.5yrs, possible early weaning age compared to apes; evidence of cooperative breeding, care of young?
The pitted pattern of Laetoli feet, about 3.5 mybp.
The pitted pattern of Laetoli feet, about 3.5 mybp.
Two general types:
Two general types:
Gracile: Thinner boned, less powerful jaws, probably ate more fruits, insects, etc. (ex. Africanus, afarensis)
Robust: thicker boned, more powerful jaws, ridge crest on cranium, flatter teeth, seed-crusher?, fibrous vegetable material (probably not human ancestor; ex: Australopithicus or Paranthropus boisei and A. or P. aethiopicus)
Summary: Time period 5-1mybp, robust later than gracile. Robusts may have made stone tools, but little evidence. High sexual dimorphism, male – male competition. Small family – female bonded groups, single male. Bipedal but well adapted to trees. Forest, waterside dweller. Chimp-size brain, robust a little larger. Probably restricted to Africa. Bipedal apes.
Summary: Time period 5-1mybp, robust later than gracile. Robusts may have made stone tools, but little evidence. High sexual dimorphism, male – male competition. Small family – female bonded groups, single male. Bipedal but well adapted to trees. Forest, waterside dweller. Chimp-size brain, robust a little larger. Probably restricted to Africa. Bipedal apes.
Homo habilis: Unearthed 1960’s Louis Leakey. Olduvai Gorge in northern Tanzania. Larger brain size (640cc; note chimps are about 400cc). Evidence of simple stone tools found also (Oldowan tools).
Homo habilis: Unearthed 1960’s Louis Leakey. Olduvai Gorge in northern Tanzania. Larger brain size (640cc; note chimps are about 400cc). Evidence of simple stone tools found also (Oldowan tools).
Homo rudolfensis: 1970’s Richard Leakey. Brain size 750cc, but with more primitive looking face. Both dated to around 2.3-2.0 mybp
Simple stone tools made by striking a hammer stone against a core to make a shape flake (cores may also have been used occasionally as tools). 2.6mybp
Simple stone tools made by striking a hammer stone against a core to make a shape flake (cores may also have been used occasionally as tools). 2.6mybp
Pad to side grip: thumb to side of index finger
Pad to side grip: thumb to side of index finger
Three jawed chuck grip: thumb, index, middle finger (baseball grip)
Five jawed cradle: thumb against four fingers
Lucy could use these grips, apes generally cannot. Pounding, digging (USOs), throwing. Oldowan tools probably not, but maybe robusts later.
What Lucy could not do:
Oblique power grip: fourth and fifth fingers in ulnar opposition to thumb, used for holding and swinging clubs and hammers
Pet scans of Oldowan knapping: visual-motor coordination
Pet scans of Oldowan knapping: visual-motor coordination
Produces “oldowan-like” tools, but not using percussion technique
Less power; less precision and selectivity
Percussion technique requires motor control beyond that of nonhuman apes. Some advance in planning perceptual motor skills.
Percussion technique requires motor control beyond that of nonhuman apes. Some advance in planning perceptual motor skills.
Some evidence of adjustment in ongoing flaking process (Lokalalei site, northern Keyna)
Probably not a big cognitive advance.
“Nariokotome boy”: 1984 Richard Leakey. Near complete skeleton of 12 year old boy, west of Lake Turkana in northern Kenya, dated to around 1.4mybp.
“Nariokotome boy”: 1984 Richard Leakey. Near complete skeleton of 12 year old boy, west of Lake Turkana in northern Kenya, dated to around 1.4mybp.
1984 the bones of an 11 ½ year old boy were found under a tree along a dry stream channel west of Lake Turkana
1984 the bones of an 11 ½ year old boy were found under a tree along a dry stream channel west of Lake Turkana
Erectus/ergaster probably emerged around 1.8mybp in Africa.
Erectus/ergaster probably emerged around 1.8mybp in Africa.
Evidence of a quick expansion out of Africa into East Asia (1.7mybp) and Southeast Asia (1.5mybp).
Some argue that Asia derivative should be ‘erectus’ and African should be ‘ergaster.’
Fully committed biped.
Much larger brain: NB = 900cc
Much lower sexual size dimorphism (in human range)
Larger, more cooperative social groups
More meat in diet
Use, maybe control of fire
Around 1.4mybp – emergence of new tool technology: Acheulen tools.
African ergaster:
African ergaster:
Ergaster migrated out of African almost as soon as it emerged.
The ergaster that remained in Africa either (a) slowly evolved into modern Homo sapiens or (b) went extinct, leaving Africa to be re-colonized by descendants of Asian erectus who eventually evolved into modern Homo sapiens
Asian erectus
Asian erectus
remained in extreme southeast Asia until as recently as 20,000 ybp (Homo florensiensis – ‘the hobbit’)
Evolved into Homo heidelbergensis in Eurasia (500,000ybp) who eventually gave rise to Neanderthals and quite possibly Homo sapiens
H. heidelbergensis very likely migrated extensively throughout Europe, east Asia, and possibly Africa. Probably the first true big-game hunter.
350,000 to 500,000 YA. The Homo heidelbergensis Skull Atapuerca 5 was discovered in Spain in 1992 by Juan-Luis Arsuaga, in the fossil-rich caves of Sima de los Huesos (Bone Pit), Sierra de Atapuerca, This site has thus far yielded over 5000 fossil hominid remains. Although somewhat smaller than other H. heidelbergensis, this individual is considered among the most complete premodern skulls ever found. The cranial capacity is 1125 cc.
350,000 to 500,000 YA. The Homo heidelbergensis Skull Atapuerca 5 was discovered in Spain in 1992 by Juan-Luis Arsuaga, in the fossil-rich caves of Sima de los Huesos (Bone Pit), Sierra de Atapuerca, This site has thus far yielded over 5000 fossil hominid remains. Although somewhat smaller than other H. heidelbergensis, this individual is considered among the most complete premodern skulls ever found. The cranial capacity is 1125 cc.
Larger tools, more specialized, exemplified by the hand axe
Larger tools, more specialized, exemplified by the hand axe
Later versions of hand axe (.5mybp) suggest an image to guide tool creation, attention to symmetry and shape. Some may not have been strictly utilitarian.
Boxgrove debitage (400kybp)
Boxgrove debitage (400kybp)
Berekhat Ram (230kybp)
Levallois “prepared core” technique (300kybp
Pigment use (300kybp)
Control of fire (300kybp)
Tools with multiple components: (1) point, affixed to a (2) shaft, using a (3) binder. Extended construction processing possibly requiring the same type of sequential motor planning necessary for language.
Tools with multiple components: (1) point, affixed to a (2) shaft, using a (3) binder. Extended construction processing possibly requiring the same type of sequential motor planning necessary for language.
