Ardipithecus ramidus

• Hominid who walked bipedally 4.4 mya • Discovered in 1992 by Tim White in Aramis, Ethiopia (as yet largely unpublished) • Distinct enough to be a new species?

– ape-like dentition – bipedal locomotion – overall hominid-like skeleton – small cheek teeth with thin enamel and large canines – arm bones are hominid-like – foramen magnum indicates bipedalism

The Varied Australopithecines

• • •

There are two major hominid genera: Australopithecus and Homo.

However, in 1992 Berhane Asfaw and Tim D. White discovered substantial remains considered to be from hominids ancestral to the australopithecines; these remains have been called Ardipithecus ramidus (thus establishing a third hominid genus) and dated a 4.4 m.y.a.

A more recent (1995, by Maeve Leakey and Alan Walker) discovery has been named Australopithecus anamensis and been dated at 4.2 m.y.a.

Pelves

A comparison of human and chimpanzee pelves.

Skeletons

Comparison of human and chimpanzee skeletons.

Crania Comparison

Dentition

Comparison of dentition in ape, human, and

A. afarensis

palates.

Australopithecines

Skulls of Robust (left) and Gracile (right) Australopithecines.

Early Hominids

Australopithecus afarensis

• • • • •

apelike features (long arms, prognathic face, toothrow, brain capacity) pelvis, leg, feet, and foramen magnum all indicate bipedalism 4.2 mya, with oldest definite specimen placed at 3.8 mya first discovered by Don Johanson in 1974 and called “Lucy” thought to be the “missing link” until A. anamensis was discovered 20 years later

Australopithecus afarensis

Left: Trail of footprints of

A. afarensis

made in volcanic ash, discovered by Mary Leakey at Laetoli.

Right: Close up of footprint at Laetoli

A. africanus

• 3.5 - 2.5 mya • 3.8 - 4.5 feet tall, 55-130 lbs • ape-like tibia, grasping big toes • wide pelvis, parabolic tooth row • primitive bipedalism • first found by Raymond Dart in Taung, South Africa in 1925

Map of Australopithecine Finds

Map of Australopithecus sites in Africa, with a focus on the East African rift valley and limestone caves of South Africa.

Hominid Evolution

• Major

Homo

advances: – Brain size – Better bipedalism – Hunting – Fire (

H. erectus

) – Tools • Oldowon (

H. habilis

) • Acheulean (

H. erectus

) • Mousterian (

H. heidelbergensis

) • Solutrean (

H. sapiens

) – Built shelters (

H. heidelbergensis

) – Clothing (

H. neandertalensis

) – Language (Neandertals?)

Homo habilis

Artist’s representation of a habilis Homo band as it might have existed two million years ago.

• 612 cc brain • 2.3 - 1.6 mya • first toolmaker • prognathic face, brow ridge • probable meat-eater • possibly arboreal • discovered in 1960 by Leakeys • no speech

H. habilis

v.

H. erectus

• Finds in east Africa indicate that

Homo habilis

was not very different from the australopithecines in terms of body size and shape.

• The earliest

Homo erectus

remains indicate rapid biological change.

– The fossil record for the transition from

H. habilis

to

H. erectus

supports the punctuated equilibrium model of evolution.

–

H. erectus

was considerably taller and had a larger brain than

H. habilis

.

Homo erectus

• 1891 - Eugene Dubois discovers

H. erectus

in Java • Dubois calls it

Pithecanthropus erectus

initially, also dubbed “Java Man” • finds in China called

Sinanthropus

• dates from 1.9 mya to 27,000 years B.P.

• 994 cc brain size (compare to 612 for

H. habilis

) • Acheulean tool industry Photograph of Nariokotome boy, an early Homo erectus Turkana, Kenya.

found near Lake

Homo neanderthalensis

• discovered in the Neander Valley (Tal) near Dusseldorf, 1856 • massive brain--about 1,400cc on average • large torso, short limbs, broad nasal passages • later remains show decrease in robustness of the front teeth and face, suggesting use of tools replaced teeth • retained occipital torus, some mid-facial prognathism The skull of the classic Neandertal found in 1908 at La Chapelle-aux Saints.

What happened to Neandertals?

•

H. neanderthalensis

coexisted with

H. sapiens

for at least 20,000 years, perhaps as long as 60,000 years • What happened?

– Neandertals interbred with

H. sapiens

– Neandertals were killed off by

H. sapiens

–

H. sapiens

drove Neandertals into extinction by competition

Cro-Magnon Man

• Cro-Magnon humans – 35,000 years B.P. in western Europe to 17,000 years B.P.

– 1,600 cc cranial capacity – Name comes from a hotel in France –

Not

a different species, just old

Homo sapiens

from Europe Artist’s reconstruction of a Cro-Magnon man

Homo sapiens

• Archaic – 100,000 to 35,000 years BP – Sometimes called

Homo sapiens

and

Homo sapiens neanderthalensis

• Modern – 35,000 years BP to present – Anatomically modern – Sometimes called

Homo sapiens sapiens