LECTURE 24 - Hominoidea

Question 1

What are some of the first human traits?

Answer 1

• Sahelathropus tchadensis skull
• One of the oldest species in the hominins
• One of nine cranial specimens found in Toros-Menalla, Chad (2001)
• Has a sloping face and prominent brow ridge
• Two unique human traits seen for the first time:
  
  • small canine teeth
    
    • Canine/premolar (C/P3) honing complex
  • spinal cord opening underneath skull (foramen magnum) - bipedalism

Question 2

What is ‘Ardi’?

Answer 2

• Aridipithecus ramidus
• One of over 100 fossil specimens
• First found between 1992-1994, Middle Awash, Ethiopia
• May have descended from an earlier species of Ardipithecus from the same region of Ethiopia, Ardipithecus kadabba
• Smaller diamond-shaped canines, enamel medium thickness
• Some evidence of bipedalism
  
  • pelvis indicates upright walking
  • large toe however is fully opposable (palmigrade quadrupedalism)

Question 3

Who is AL 288-1: Lucy?

Answer 3

• Australopithecus afarensis
• 40% of a female
• Found in Hadar, Ethiopia (1974)
• date3d to ~3.2 million years ago
• Mixture of ancestral and derived traits, a transition point?
  
  • Pelvis and leg bones suggesting she stood upright and walked erected
  • long arm bones and crest, indicative of tree climbing

Question 4

Who is the ancestor genus Homo?

Answer 4

• Australopithecus africanus
• First individual found in 1924, named “Taung child)
• One of the first early human fossils found in Africa, first time seen evidence of bipedalism (foramen magnum)
• Rising forehead and round eye-sockets
• Cranial capacity (400-500 cc) more similar to a modern adult chimpanzee
• Much dissent and criticism upon publishing by Raymond Dart

Question 5

What are some new tools and new insights that help with studying phylogenetic trees?

Answer 5

• Mitochondrial DNA (mtDNA)
  
  • DNA we inherit exclusively from our maternal lineage, able to track ancestry directly
• Ancient DNA (aDNA)
  
  • DNA isolated from ancient specimens, as old as two million years old (as of 7 December 2022)

Question 6

What is the “Out of Africa” origin theory?

Answer 6

• an evolutionary theory of modern human origin that posits that modern humans arose in the late Pleistocene, about 100,000–200,000 years ago, in Africa

Question 7

What is mitochondrial Eva?

Answer 7

• the matrilineal most recent common ancestor (MRCA) of all Homo sapiens
  
  • NOT the most recent common ancestor/NOT the only woman/NOT a fixed individual
• All living humans descend in an unbroken line –> all lines converge on one woman
• Thought to have lived ~150,000 years ago, in Botswana
• Provides some of the strongest evidence for “Out of Africa” origin theory

Question 8

How do we know there was inter-breeding amongst species?

Answer 8

• The proof is in the teeth