Lecture 14 - Emergence of Homo: Homo habilis

Question 1

introducing Homo

introduction of Homo

Answer 1

• 18th century - Carolus Linnaeus
• Homo habilis is the earliest Homo - “first human”
• Linnaeus did not assign a type specimen
• late 18th C: Blumenbach - provided a description of Homo –> small canines, chin, round skull, erect posture

Question 2

type of specimen

Answer 2

specimen that has all the characteristics of the genus/species

Question 3

not the first Homo fossil found

Answer 3

• H. erectus (1894) & H. neanderthals (1894) had been known for a while

Question 4

discovery of Homo habilis

Olduvai findings

Answer 4

• partial foot with arch = bipedal locomotion
• mandibles
• partial cranial remains
• complete crania (of OH24, 8 years after the original discovery)

Question 5

discovery of Homo habilis

discovery of Homo habilis

Answer 5

• excavated by Mary Leakey with the help of her son Jonathon
• several fossil in 1959/1960

Question 6

Homo vs Aus

Homo vs Aus tech

Answer 6

• ‘Oldowan’ tools ~2.5 Ma, TOO SIMPLE (for Homo?)
• Aus. thought to be pre-technology
• have found more evidence for tools older than those at Olduvai = Lomekwian tools

Question 7

Homo vs Aus

Homo vs Aus diet

Answer 7

• meat eating?
• small teeth and mandible
• larger brain

Question 8

H. habilis genus?

genus definition

Answer 8

clade, or monophyletic group, whose members occupy a single adaptive zone

Question 9

H. habilis genus?

main question

Answer 9

are they in the same clade as other Homo?
are they in the same grade as other Homo?

Question 10

H. habilis genus?

brain comparison

same clade?

Answer 10

early H. habilis have a smaller brain than expected, more in the range of Aus than later Homo

sharp increase in Homo brain size after H. erectus

Question 11

H. habilis genus?

mandible comparison

same clade?

Answer 11

Olduvai OH7 mandible recently reconstructed as Aus-like

Question 12

H. habilis genus?

general comparison

same clade?

Answer 12

diet, brain size, manual dexterity = more like Aus than Homo

Question 13

H. habilis genus?

same clade - implications

Answer 13

if they are in the Homo clade and grade, that makes Homo genus tricky to define
- could be potential stem members?

Question 14

Koobi Fora discoveries

KNM-ER 1470 + 1813

Answer 14

• discovered by Richard Leakey
• two nearly complete skulls
• most H. habilis fossils found to this day come from Koobi Fora

Question 15

Koobi Fora discoveries

KNM-ER 1470 general info & characteristics

Answer 15

• c. 1.9 Ma
• Homo habilis like-traits
• greatest weight across midface (different from 1813)
• little prognathism
• relatively large size
• relatively large brain (>600cc)
• larger molars

Question 16

Koobi Fora discoveries

KNM-ER 1813

Answer 16

• c. 1.9 Ma
  traits
• greatest width across upper face
• relatively prognathic
• relatively small size (not much large than aus.)
• relatively small brain at 510 cc
• smaller molars

Question 17

Koobi Fora discoveries

should we argue one or two species?

Answer 17

• same time, same place BUT different traits
• so sexual dimorphic species or just 2 species
• splitters argue that 1470 and sever other fossils should be included ina. distinct species (s.s.)
• lumpers disagree, and want to include these fossils within H. habilis (s.l.)

Question 18

early Homo species

H. rudolfensis geeral traits

Answer 18

• bigger brain than H. habilis s.s - 600-800cc (derived)
• Eastern Africa only
• larger and flatter face
• robust jaw and large molars

Question 19

Ledi-Geraru discoveries

Discovery from Ledi-Geraru, Ethiopia

Answer 19

• very close to Hadar
• partial mandible found in 2013 from c. 2.8 Ma
• may be H. habilis or a new species
• derived with respect to Aus.
• pushes the probable date of appearance of Homo back from 2.3Ma to 2.8 Ma
• too little information ot confidently attribute it to a species

Question 20

H. habilis traits broad sense

brain

Answer 20

trends toward larger - 30% increase than Aus
but still smaller than later Homo

Question 21

H. habilis traits broad sense

teeth / dental arcade

Answer 21

• smaller and thinner enamel than megadont species
• some people use the argument that tool use = outsourcing anatomical work of processing food
• more parabolic dental arcade

Question 22

H. habilis traits broad sense

prognathism

Answer 22

• less prog than in Aus
• Para not very prog

Question 23

H. habilis traits broad sense

muscles

Answer 23

reduction of muscles related to mastication than in megadont species

Question 24

H. habilis traits broad sense

postcrania

Answer 24

• relatively small-bodied @ ~3-4ft and ~70lbs
• relatively long arms
• few postcranial remains are known