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.
New species from heritable changes through time (linear)
New species from speciation events (branching)
Which pattern did human evolution follow?
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 organismsFOSSILS
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?
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
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)
Was Lucy bipedal?
Angle that the femurmakes with kneealso is important, and different in bipeds thanin chimps.
This arrangement moreefficient for bipedalism.
How much “normal” variation can there be within a species?
Standard Curve (Bell-shaped)
“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.