Lecture 8: The Early Hominins

Question 1

strepsirrhines

Answer 1

• were flourishing by 54 mil yrs ago

Question 2

haplorrhines

Answer 2

• since 54 mya have further branched into monkeys and apes

Question 3

hominids

Answer 3

•evolved into chimps gorillas and humans
•appeared 8 mya
•broader than hominins
Refers to the taxonomic family that includes humans and the African apes and their immediate ancestors

Question 4

hominins

Answer 4

• ancestors of only humans
• after the split of the African ape line
• hominins are hominids

Question 5

missing link

Answer 5

• b/w humans and chimps

* based on false assumption that we evolved from chimps

Question 6

hogopan

Answer 6

• last common ancestor between humans chimps gorillas

* split into different evolutionary lines and their diets became specialized

Question 7

bipedalism

Answer 7

Ability to see over tall grass
Ability to carry items
Reduces body’s exposure to solar radiation
Position of spinal chord in back of skull
Pelvis forms a basket that balances the weight of trunk

Question 8

hominin evolutionary trends (7)

Answer 8

• body size
• locomotion (bipedalism)
• cranial capacity
• tool use
• dentition (tooth size/type)
• cranial morphology (brow ridge, sagittal crest, zygomatic arches)
• diet

Question 9

sahelanthropus tchadensis

Answer 9

• 6-7 mya
• “Toumat”
• discovered in Chad in 2001
• blends apelike and human characteristics
• lived in mixed environment
• somewhat bipedal
• hominin? inconclusive
• no post cranial remains, everything has been reconstructed

Question 10

rift valley

Answer 10

• east Africa
• where most of early hominin evolution occurred
• open grassland savannah ecologies
• geography indicates the separation of chimp and gorilla ancestors from humans’

Question 11

genus ardipithecus

Answer 11

• 2 species ~5mya
• kadabba
• ramidus
• bipedal, but ape-like in size, anatomy, and habitat
• often considered earliest hominin
• arboreal surprisingly

Question 12

ARDI

Answer 12

*earliest potential hominin
4.4 mya
•most complete early hominid specimen
•110 different pieces of fossilized bone found
•120lbs 4ft tall female
•opposable big toe (arboreal)

Question 13

Australopiths

Answer 13

•more ape-like from the top-down
   •dentition: large molars due to chewing intensive diet
    brain size, diet
•more human-like from the ground up
   •bipedalism (less exposure to sun)

Question 14

gracile & robust Australopiths

Answer 14

Robust - large post canine teeth, large molars, incisors canines reduced, flatter faces, large chewing muscles = heavy brow ridge, large zygomatic arches
Gracile - reduced zygomatic arch, less robust features in general

Question 15

competition

Answer 15

• genus homo came on the scene 2mya
• many species coexisted for extended periods of time and competed for resources
• homo sapiens are chosen ones

Question 16

oldowan pebble tools

Answer 16

• used for animal butchering
  enabled some species to become omnivorous
• Cores and flakes - flakers were good for cutting and animal butchering
• Choppers for pounding, breaking, or bashing

Question 17

homo habilis

Answer 17

• “handy man”
• first stone tools were associated with this first member of our genus
• Australopithecus garhi in Ethiopia was a “surprise” bc
they were using tools
• also in 2015 researchers discovered stone tools
3.3mya in Kenya

Question 18

hominin taxonomy

Answer 18

A. anamensis (4.2-3.9mya) Kenya
A. afarensis (3.8-3.0) East Africa
A. africanus (3.0-2.0) South Africa
A. garhi (2.5) Ethiopia
A. robustus (2.0-1.0) East/South Africa
A. boisei (2.6-1.2) East Africa
*Homo habilis lived alongside A. boisei for about a million years.

Question 19

dentition and diet

Answer 19

large molar size in correlation to diet; coarse gritty vegetation for heavy chewing on fibrous foods

Question 20

competition and Australopith extinction

Answer 20

• Tool users displaced other hominins, pushing them into drier, less diverse zones, and some ultimately to extinction
• Ppl thought Homo habilis was first tool user but A. garhi also used tools