Biological Anthropology The Early Hominids Hominid Species Ardipithecus

Biological Anthropology The Early Hominids

Hominid Species Ardipithecus ramidus Australopithecus afarensis Australopithecus africanus Australopithecus boisei Australopithecus robustus Homo habilis Homo erectus Homo sapiens

Ardipithecus ramidus A revolutionary find Why “revolutionary”? Let’s see what we know before her…

Australopithecus afarensis • 1973 – “Johanson’s knee” • First suggestion of bipedalism

Figure 11. 13

Australopithecus afarensis • 1974 – “Lucy” • 47 out of 207 bones

Australopithecus afarensis • 1975 – “First Family” • Over 200 fragments from at least 13 individuals

Australopithecus afarensis • 1978 – Laetoli footprints • 3. 6 my BP (K/Ar) • Clear bipedalism

Australopithecus afarensis • Fully bipedal, but… • Arms longer than legs • 3. 5 – 4. 0 ft tall

Figure 11. 08

Figure 06. 06

Australopithecus afarensis Cranial capacity: 375 -425 cc

Australopithecus afarensis • Rounded dental arcade (not parabolic) • app. 33% have large canine with diastema • Simian shelf present

Figure 11. 10 a

Australopithecus afarensis • Ca. (circa) 4 -3 my BP • Found only in East Africa • No known culture

Australopithecus africanus • First find made in 1924 by quarryman M. de Bruyn • Cleaned and identified by Raymond Dart

Australopithecus africanus • Dental evidence indicated a juvenile age • “Taung child”

Australopithecus africanus • Finds in Southern and Eastern Africa • Dates between app. 3. 0 -2. 0 my BP

A. africanus: bipedalism • Full biped • Pelvis smaller & upright • Parallel toes • Developed arch in foot

A. africanus: dentition • No large canines • No diastema • Simian shelf • V-shape jaw

A. africanus: cranial capacity • 400 – 600 cc

Osteodontokeratic culture • osteo = bone • donto = teeth • keratic = hair, horn • Postulated by Raymond Dart as early culture of Australopithecus africanus • May be the culture of all Australopithecus species

Australopithecus boisei Australopithecus robustus • Two very different types of hominids

Where were they found? A. boisei A. robustus East Africa (Olduvai!) South Africa

What are their dates? A. boisei A. robustus ca. 2. 5 – 1. 0 my BP

Cranial capacity A. boisei A. robustus mean ca. 510 cc

Bipedalism • Human-like bipedalism • Smaller in stature

dentition • • • Huge jaw Small incisors & canines Large premolars & molars Parabolic dental arcade Simian shelf

Chewing apparatus • Sagittal crest • No diastema

“Dietary Hypothesis” suggests two groups Gracile Robust A. afarensis A. boisei A. africanus A. robustus

Dietary Hypothesis Graciles Robusts Omnivorous diet High fiber diet

Figure 05. 34 a

“Ardi” Ardipithecus ramidus a 4. 4 million year old relative?

Found in Eastern Africa • First fossils discovered in 1992 • Includes a partial skeleton • And remains of at least 35 other individuals

An unexpected mix of traits…

Ardipithecus locomotion hands and arms indicate she could climb like a chimp, but walked on her palms (not knuckles) Chimp skeleton rigid feet are more like an Old World monkey’s than an apes A. afarensis skeleton Ardi legs and pelvis indicate that she could move on two legs like a biped

Ardipithecus cranial capacity • 300 – 350 cc • reconstruction based on CT scans of fossil fragments

Ardipithecus dentition Modern human Modern chimp Ardi’s canines are blunt – like a humans A move away from multi-male, multi-female mating patterns?

Why is Ardi so “revolutionary”? • Our earliest ancestor may not have looked like a modern chimp • Ardi undermines the “savanna hypothesis”

Ardipithecus dentition Modern human Modern chimp The wear patterns and isotope analysis of teeth suggest a varied vegetarian diet