Human evolution
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Human Evolution. Characteristics: Eyes in front of the face Opposable thumb Well developed brain Omnivorous. D: Eukarya K: Animalia P: Chordata C: Mammalia O: Primate. Primate Classification. The Geological Time Scale. Humans. Chimpanzees.

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Human Evolution

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Human evolution

Human Evolution


Primate classification

Characteristics:

Eyes in front of the face

Opposable thumb

Well developed brain

Omnivorous

D: Eukarya

K: Animalia

P: Chordata

C: Mammalia

O: Primate

Primate Classification


The geological time scale

The Geological Time Scale

Humans

Chimpanzees

  • Fossil Patterns were used to create 5 Major Categories of Time (Eras):

    • Archaean

    • Proterozoic

    • Paleozoic

    • Mezozoic

    • Cenozoic


Types of evolution

Types of Evolution

New species from heritable changes through time (linear)

New species from speciation events (branching)

Anagenesis

Cladogenesis


Human evolution

Anagenesis?

Cladogenesis?

Which pattern did human evolution follow?


Aside hypothesis driven science

Aside: Hypothesis Driven Science

  • How do you test hypotheses on the past?

    • Experimentation is not possible

  • Need to come up with hypotheses that can be tested by observations


Evolution

Evolution

  • Fossils

  • Biogeography

  • Comparative Morphology

  • Comparative Development

  • Comparative Biochemistry


Fossils

The preserved remains or traces of organisms from the past

Found in sedimentary rock layers created by water deposition

Dated and used to determine Earth’s biological past

Over time, fossils found in stratified soil layers show consistent patterns in the diversity of living organisms

FOSSILS


Human evolution

On November 30, 1974 Donald Johanson and Tom Gray discovered a remarkablycomplete hominid fossil in Hadar, Ethiopia. This fossil became known as ‘Lucy’ and was later determined (by radiometric dating) to be 3.2 million years old. This isone of the most compelling missing link fossils ever found.

Lucy was not human—clearly a different species,which was named Australopithecus afarensis—but shewas clearly hominid and very different from chimps.

Outstanding and mysterious question: what has happened to our speciessince the divergence from the lineage leading to chimpanzees?


Human evolution

What Makes A Hominid? - Bipedalism

  • Primary feature distinguishing hominids from other hominoids is walking erect on two legs – erect bipedalism


Why did bipedalism become the primary adaptation of hominids

Why did bipedalism become the primary adaptation of hominids?

1.Carrying behavior

2. Heat stress - facilitates heat loss through convection by exposing body to air currents, only humans have sweat glands that produce moisture to cool body

3. Most energy efficient way to travel long distances

4. Allows for better vision in open environments & defensive action against predators by freeing hands to throw objects


Human evolution

The impressionsin the ash suggestthat weight was shifted during walkinglike a modern bipedalhuman rather than like a modernchimpanzee.

Footprints in volcanic ashat Laetoli (3.7 million years old)

Human

Chimp

Was Lucy bipedal?


Human evolution

Other evidence for bipedalism.

Chimp pelvis

Lucy pelvis

Angle that the femurmakes with kneealso is important, and different in bipeds thanin chimps.

This arrangement moreefficient for bipedalism.


Variation within and between species

Variation within and between species

Homo sapiens

Australopithecus afarensis

How much “normal” variation can there be within a species?


Normal variation

Normal % Variation

Standard Curve (Bell-shaped)

Mean

1 sd=66%

2 sd=95%

N%V=((4*sd)/mean)*100


Lab hints

Lab Hints

“R” program for statistics is on CU Learn website

After completing one set of skull measurements, I will give you a handout with the rest

Measure facial projection with zygomatic arches parallel to the floor (skull tilt affects the measurement)

Lab report due next week

There will also be a quiz next week.


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