Australopithecines and Ardipithecus Ramidus

Ardipithecus Ramidus

• Ardipithecus Ramidus resided in Ethiopia around 4.4 mya
• There is a speculation that it may be a hominin ancestor or a sister species, potentially having evolutionary links to Miocene apes and australopithecines
• Fossil remains are fragmentary, with bipedalism suggested by the forward position of the foramen magnum
• This species lived in a forest rather than a savannah environment
• Ardipithecus exhibits a more primitive dental pattern characterized by large canines

Australopithecines

• A. anamensis existed around 4.2 mya
• A. afarensis existed around 4 to 3 mya
• A. bahrelghazalia existed around 3.5 to 3 mya
• A. africanus existed around 3 to 2 mya
• A. garhi existed around 2.5 mya
• A. aethiopicus existed around 2.5 mya
• Robust australopithecines included A. robustus (1.8 to 1 mya) and A. boisei (2.2 to 1.3 mya)

A. anamensis

• The A. anamensis was discovered at two East Turkana sites in 1995
• Although A. anamensis featured large canines, they were more hominin-like due to thicker enamel
• The cranium of A. anamensis was primitive, but its postcranial skeleton suggests bipedalism
• This species inhabited open savannah and woodland environments
• It is believed to be an ancestor to all later hominins

A. afarensis Locomotion and Features

• "Lucy" of the A. afarensis species was discovered in Hadar, NE Ethiopia, in 1974
• Almost 40% of Lucy's skeleton was recovered
• Locomotion involved efficient climbing and time spent in trees, along with habitual bipedalism
• A. afarensis had a forward-projecting face and large canines, diastema, and a hint of a sagittal crest, smaller relative to apes

Anatomical features: Gorilla vs Hominin

• Gorillas possess a sagittal crest and large canines
• Relative to other tooth forms, there is a reduction and eventual disappearance of the diastema in hominins

A. bahrelghazalia

• A. bahrelghazalia existed in Chad, north-central Africa, in 1995
• It was contemporary with A. afarensis
• Its existence indicates that A. afarensis was not the only hominin species present at that time

A. africanus

• Raymond Dart (1893-1988) found A. africanus during quarrying in South Africa in 1924
• It took 4 years to analyze its dentition, separating the upper and lower jaws
• The formation and eruption of teeth indicated that it came from a child, named the "Taung Child"
• A. africanus has a less forward-projecting face, larger molars, smaller canines, and no sagittal crest
• Limb proportions are less ape-like compared to those of A. afarensis

A. Garhi Features

• In 1999 A. Garhi was found in the Afar region of Ethiopia
• There is evidence that it was a tool-using hominin
• There is debate that A. africanus is in the evolutionary line toward Homo

A. aethiopicus

• A. aethiopicus, also known as "The Black Skull," was found in Koobi Fora, Kenya
• It featured the smallest adult hominin cranial capacity
• Body size was comparable to other australopithecines
• It is believed to be an early species of robust australopithecine
• Some believe it should be Paranthropus

Robust Australopithecines

• Robust australopithecines had robust teeth and jaws, suited for chewing specializations
• A. robustus was from South Africa
• A. boisei lived in East Africa

Hominin Emergence

• Evidence for the genus Homo appears during the Plio-Pleistocene period dating back 5.3-1.8 million ya

Plio-Pleistocene Homo

• From 2.5 to 2 mya, the Miocene drying trend intensified
• In Africa, extinctions occurred, and new species emerged
• Evidence of gracile australopithecines disappears
• Hominins evolved into or were replaced by a new type with a major difference in brain size
• Australopithecines ranged from 400-550 cc, while new hominins were over 600 cc
• They coexisted with Australopithecus boisei

Early Examples of the Genus Homo

• Homo habilis, also known as "handy man", was discovered at Olduvai in 1963 by Louis Leakey
• Homo habilis had a cranial capacity of 680 cc
• Leakey believed this increase was significant enough to classify it as Homo
• The 1940s idea that the cut off should be midway between the largest gorilla and smallest human cranial capacity equalled 750 cc
• Leakey’s decision was challenged

Homo habilis

• Homo habilis existed 2.5 to 1.5 mya
• They were the first toolmakers
• Homo habilis had a relatively prognathic face
• They had some arboreality
• It is questioned whether they had any speech abilities because there is no physical evidence

Australopithecines versus Homo habilis

• The cranial differences, and not postcranial characteristics, such as body size and shape, are what set the two apart
• Homo habilis shows a reduction in postorbital constriction for an expanded brain

Early Homo Species

• Paleoanthropologists suspect that there is more than one species classified as Homo habilis
• Chris Stringer compared H. habilis cranial specimens from Olduvai and Koobi Fora
• Stringer found similar dental characteristics, but different cranial volumes, shapes, and face shapes
• This leads to to question whether there be new species designations

Homo rudolphensis

• Homo rudolphensis had a cranial capacity of 781 cc
• It was discovered in 1972 at Koobi Fora
• Homo rudolphensis was contemporary with H. habilis, living from 2.4 to 1.6 mya
• The feet are more like modern humans compared to H. habilis
• They had relatively larger teeth, relying on tougher foods
• The placement of in the Homo genus has been difficult, but it was given a new species name in 1986

Early Homo Tool Traditions

• The earliest stone tools were dated 2.5 mya in East African sites like Hadar
• Louis and Mary Leakey discovered the first specimens from the Olduvai site, naming it the 'Oldowan tool tradition'
• Oldowan tools are simple which makes it hard to to tell whether they were intentionally chipped or naturally chipped
• Taphonomy helps discern these tools by stylistic pattern, many examples at a single site, and Wear patterns (scanning electron microscope)
• They are made by percussion flaking using one stone struck with another stone
• Both flakes and cores, such as choppers, could be used as tools

Homo erectus

• Homo erectus is taller and larger-brained than H. habilis (895-1040 cc, about 70% of modern humans)
• They experienced rapid biological change which is called punctuated equilibrium instead of phyletic gradualism
• The oldest homo erectus is dated to 1.78 mya
• They were the first hominin species to venture out of Africa

Homo Erectus and Variation

• Homo erectus had significant variation in specimens, causing scientists to split the species
• Eastern Asian Homo Erectus include Homo Erectus
• African variations included Homo Ergaster
• Europeans included Homo Heidelbergensis

Homo erectus Characteristics

• Homo erectus shows more robust post-cranial body morphology
• H. erectus has sagittal keeling, a distinctive pentagonal form
• It also presents an occipital bun, a bony protruberance at rear of skull, and heavy brow ridges

Nariokotome Analysis

• The Nariokotome was found at Lake Turkana, Kenya by the Leakey team in 1984; It dated to 1.6 mya
• The adolescent (11-12 yrs) specimen was not fully grown, demonstrating prolonged development
• The Postcrania are virtually indistinguishable from modern Homo sapiens, except for a heavier body build (5’6”, over 100 lbs)

Homo Erectus Culture

• They may have continued the Oldowan tradition
• The Acheulian tool tradition included bigger "biface" or pear-shaped "hand-ax"
• Homo Erectus dissapeared 200,000 ya

Homo erectus Evidence for Spoken Language

• Evidence suggests that Homo erectus had linguistic skills at the level of a modern 6-year-old
• This is correlated with increased cranial capacity and brain remodelling (endocasts)
• Thoracic vertebrae of the Nariokotome adolescent suggest evidence for spoken language
• A small neural canal is not adequate for a smaller spinal cord, that requires less control over rub muscles
• Muscles are needed for precise breathing during speech

Homo erectus Culture

• They used fire as early as 1.4 mya, with definite use of fire for cooking by 500,000 ya
• They consumed big game and meat which made them 'accomplished scavengers or Hunters
• Hunting is a separation from apes

"Man the Hunted" Theory

• Historical data indicates that hominins were the prey
• A. afarensis lived with 10 times more predators, such as bears, cats, and reptiles
• Lacking tools, big teeth, and standing 3 ft tall, A. afarensis potentially used their brain, agility, and social skills to escape predators

Archaic Homo sapiens

• From 500,000 to 200,000 ya fossils presented a mix of H. erectus traits with larger cranial capacities
• Archaic H. sapiens living spanned from 300,000 to 40,000 ya
• "Archaic H. sapiens” is a cluster of subspecies
• Fossils have been recovered in Africa, Europe, and Asia
• The cultural context is considered to be "the Middle Palaeolithic.”

Cultural Timeline

• The Paleolithic era equates to the Stone Age
• It includes a a Lower, Middle, and Upper Palaeolithic Era
• This is followed by the Mesolithic, Neolithic, Bronze Age, and Iron Age

Homo naledi

• Emerging Archaic Homo sapiens co-existed with Homo Naledi in South Africa
• Flores, Indonesia shows evidence of Homo floresiensis, an island, during 100,000 – 60,000 years ago
• These species are often called "hobbits" due to their small body size which reflects biological diversity

Archaic Homo sapiens Species

• Stone tools link these species to Homo erectus
• These species likely co-existed temporally and in the area of early modern humans
• Neandertals fit within this group which began 130,000 – 35,000 ya
• Neandertal were first discovered in 1856, Neander Valley, near Dusseldorf, Germany

Neandertal Features

• In the 1950s, Neandertals were considered too "brutish” and "primitive” to be ancestors to modern humans
• Marcellin Boule (French anatomist, 1908-1913) believed they were not fully capable of bipedalism
• Boule focussed on differences rather than similarities between Neandertals and H. sapiens
• He also analyzed La-Chapelle-aux-Saints neandertal

La Chapelle-aux-Saints

• La Chapelle-aux-Saints was discovered in France in 1908
• The species has an older male with no teeth; Suffered osteoarthritis and possibly rickets, bowing their legs
• Altruism is believed to exist in these species

Neandertal Misconceptions

• Marcellin Boule's work caused a misconception that Neandertals were dim-witted, brutish and dull

Neandertal Characteristics

• Neandertals present massive skulls, continuous browridges, projecting midface, with no chins on mandible
• Neandertal teeth are larger with Taurodontism and a Retromolar Space
• They also present an enlarged pulp cavity and fused roots
• The species presented a receding forehead, occipital bun, projecting midface, with no chin and a heavy brow ridge
• They had a shorter, more robust skeletal frame than modern H. sapiens and were likely heavily muscled, and were adapted to cold
• Modern hyoid bones suggest those species could perform spoken language
• Scientifics ask whether they are Homo sapiens neandertalensis or simply Homo neandertalensis