Lecture 2A

Lecture 2A

1. 1. Reasoning by homology

   • Homologous Traits
     • Closely related species
       • due to descent from common ancestor
     • Non human primates & humans

2. 2. Reasoning by analogy

   • Analogous Traits
     • Similar environments = similar selection pressures
       • =similar adaptations
         • ie: sexual dimorphism
           • canine size, body size
             • social organization
               • monogamous
               • 1 male, multi-female
               • multimale, multifemale
         • ie: group types
   • Comparative method (w/ fossil record)

3. ORDER: PRIMATES (Placental Subgroup)

   • Mammalian Synapomorphies
     • shared derived characteristics from common ancestor
     • Primitive for primates (shared with last common ancestor with all other mammals)
       • Warm blooded
       • Viviparity (tummy mommys)
       • Lactation & Mammary Glands
       • Body Hair
       • PRIMITIVE means it came first (not inferior)

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