chapter 6-3 rate of change. how do new species form? a new species can form when a group of...
TRANSCRIPT
Chapter 6-3
Rate of Change
How Do New Species Form?
A new species can form when a group of individuals remains isolated from the rest of its species long enough to evolve different traits that prevent reproduction.
Example-Fig 1 on p181 The squirrels are separated by the Grand Canyon. They are the species but overtime can become separate species.
What Patterns Describe the Rate of Evolution?
Two patterns describe the pace of evolution: gradualism & punctuated equilibrium.
Gradualism
Involves small changes that add up to major changes over a long period of time.
Punctuated Equilibrium
Short periods of rapid change and then don’t change much.
Primates
A group of mammals that includes humans, apes, monkeys, and prosimians
Characteristics:Opposable thumb (bends opposite index
finger)Binocular vision (eyes at front of head, 3-
D)
Our closest living relative?
Chimpanzee!
97% of our genetic material is identical
Humans did not descend from chimpsInstead, humans and chimps share a common
ancestor• Split approximately 7 mya
Hominids
Hominids include humans and human-like ancestors
Walk upright on two legs for locomotionCalled bipedalism
Prosimians
First primatesAbout 55 mya
Only 1 species, the lemur survives today
Australopithecines
“Southern Man Ape”
Long arms, short legs, small brains
Brains are larger than ape brains, but smaller than modern humans
Lucy (1979) 2 myaFootprints 3.6 myaAustralopithicus afarensis
Homo habilis
“Handy Man”
2.3 mya
Used crude stone tools
Short in size, small brain, and large jaw
Homo habilis
Homo erectus
Survived for nearly 1 million yearsLonger than any other species
Lived in caves, built fires, wore clothing, hunted large animals, made tools
Migrated across the globe
Homo sapiens?Neanderthals
230,000 years ago
Hunted large animals, made fires, wore clothing
Cared for the sick and elderly, buried the dead
Heavy brow rides, larger brain than modern humans
Homo sapiensCro-Magnon
100,000 years old
Smaller and flatter faces, high round skulls, thicker and heavier bones
Made cave paintings, sculptures, and carvings
Complex social organization and civilizations
Cave Paintings