Human Evolution

I. What are humans related to?

Human Evolution I. What are humans related to? - Morphologically similar to apes

Human Evolution I. What are humans related to? - Morphologically similar to apes - hands, binocular vision (Primates) No tail

Human Evolution I. What are humans related to? Apes

Human Evolution I. What are humans related to? Apes II. How do we differ?

Human Evolution I. What are humans related to? Apes II. How do we differ? - Behaviorally (walk erect)

Human Evolution I. What are humans related to? Apes II. How do we differ? - Behaviorally (walk erect) - Behaviorally (intelligence and learning)

Human Evolution I. What are humans related to? Apes II. How do we differ? - Behaviorally (walk erect) - Behaviorally (intelligence and learning) - Morphologically, humans have: - larger head/body ratio

Human Evolution I. What are humans related to? Apes II. How do we differ? - Behaviorally (walk erect) - Behaviorally (intelligence and learning) - Morphologically, humans have: - larger head/body ratio - smaller jaw/head ratio

Human Evolution I. What are humans related to? Apes II. How do we differ? - Behaviorally (walk erect) - Behaviorally (intelligence and learning) - Morphologically, humans have: - larger head/body ratio - smaller jaw/head ratio - shorter arms/body ratio

Human Evolution I. What are humans related to? Apes II. How do we differ? - Behaviorally (walk erect) - Behaviorally (intelligence and learning) - Morphologically, humans have: - larger head/body ratio - smaller jaw/head ratio - shorter arms/body ratio - less hair

Human Evolution I. What are humans related to? Apes II. How do we differ? - Superficial Morphology Human Chimp Gorilla Orangutan Gibbon

Human Evolution I. What are humans related to? Apes II. How do we differ? - Genetically: Big Surprize! Human Chimp Gorilla Orangutan Gibbon

Human Evolution I. What are humans related to? Apes II. How do we differ? - Genetically: Big Surprize! Human Chimp Gorilla Orangutan Gibbon < 1% difference in gene sequence

Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? Can this 1% difference account for the dramatic behavioral and morphological differences we see? Yes, some genes have big effects. These are regulatory genes, acting during development. They influence the expression of lots of other genes…

Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? Can this 1% difference account for the dramatic behavioral and morphological differences we see? Yes, some genes have big effects. These are regulatory genes, acting during development. They influence the expression of lots of other genes… - Can we test this hypothesis? Do the differences correlate with developmental effects?

- Yes. All differences correlate with developmental differences between juvenile primates and adults… Juveniles Adults Larger Head/body ratiosmaller Smaller jaw/head ratiolarger Shorter limb/body ratiolonger

- Yes. All differences correlate with developmental differences between juvenile primates and adults… Juveniles Adults Larger Head/body ratiosmaller Smaller jaw/head ratiolarger Shorter limb/body ratiolonger Less hairmore hair Better learningpoorer learning

- Yes. All differences correlate with developmental differences between juvenile primates and adults… Juveniles Adults Larger Head/body ratiosmaller Smaller jaw/head ratiolarger Shorter limb/body ratiolonger Less hairmore hair Better learningpoorer learning Human-likeApe-like

Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? Can this 1% difference account for the dramatic behavioral and morphological differences we see? Yes, if the small change is in developmental genes, they can have BIG effects…humans might be a type of ape that didn’t grow up… The ways we differ supports this hypothesis…

Yes, if the small change is in developmental genes, they can have BIG effects…humans might be a type of ape that didn’t grow up… Primate developmental trajectory Chimp Small changes in development, especially if they occur early in development, can result in big effects. Human

Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? IV. Are there common ancestors?

Molecular clock analyses predicts oldest ape should be about 15 my old

Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? IV. Are there common ancestors? Yes. Just where evolution predicts they should be (After other monkeys and apes, before humans and existing apes).

Science, Nov 19, 2004 Pierolapithecus catalaunicus mya – oldest ape

V. Are there common ancestors? - Fossil and genetic analysis independently predicted a common ancestor between humans and chimps lived 5-8 million years ago. Chimpanzee Human Homo sapiens

V. Are there common ancestors? - Fossil and genetic analysis independently predicted a common ancestor between humans and chimps lived 5-8 million years ago. Chimpanzee Human Homo sapiens Sahelanthropus tchadensis – discovered in Chad in Dates to 6-7 mya. Only a skull. Is it on the human line? Is it bipedal? Probably not (foramen magnum). Primitive traits, as a common ancestor might have.

Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? IV. Are there common ancestors? V. Are there intermediate links to modern humans?

- yes, and in a nicely graded sequence…. Chimpanzee Human Homo sapiens Australopithecus afarensis Australopithecus africanus Homo habilis Homo erectus