1. Adaptations over Time Section 1: Ideas about Evolutions
Section 2: Clues about Evolution
Section 3: Evolution of Primates

2. Early Models of Evolution
There are millions of species on earth
Species is a group of organisms that share similar characteristics and can reproduce among themselves to produce fertile off springs
Changes in inherited characteristics over time is evolution
Modern day horse has changed in size and hoof shape in the past 50 million years

3. Hypothesis of Acquired Characteristics
1809, Babtiste Lamarck proposed hypothesis to explain how species change over time
His proposal became known as inheritance of acquired characteristics which states that characteristics or traits developed during a parent organisms’ lifetime are inherited by its offspring
If cut tail on dog, its offspring will not have a tail
If lift weights and build muscles, offspring will have large muscles

4. Darwins Model of Evolution
Charles Darwin ( ) traveled around world taking samples of over 2000 species
He drew pictures of organisms, tried to classify them and noticed small but obvious changes in organism on his trip
Galapagos Island was visited by his ship where he noticed 13 species of finches were similar but had slight differences in body size, beak shape, and eating habits and were similar to one species he had seen on continent of South American Coast

5. Darwin’s Observations
Darwin reasoned that the Galapagos finches must have had to compete for food.
Finches with beak shapes that allowed them to eat available food survived longer and produced more offspring than finches without those beak shapes
After many generations these groups of finches became separate species

6. Natural Selection
Darwin returned to England and wrote a book that changed our thought of how and why traits are passed on the offspring
He developed the Theory of Evolution by Natural Selection
It states that organisms with traits best suited to their environment are more likely to survive and reproduce
Page 337 (applying science)

7. Variations and Adaptations
Darwins Theory emphasizes differences among individuals
These differences are called variations
Variations are inherited traits that make an individual different from other members of its species
Variations result from mutations and may be small (shape of human hairlines) or large (albino)

8. Variations and Adaptations
Those variations over time allow a gene pool that is a little different
Those differences can be beneficial and if so those traits are carried thru to offspring
An adaptation is any variation that makes an organism better suited to its environment
Variations can result in changes of color, shape, behavior, or chemical makeup

9. Changes in the Source of Genes
When organisms move into an area or leave they bring or take with them characteristics that may change the gene pool

10. Geographic Isolation
When separated geographically from other organisms of the same species, variations of the isolated species may occur due to gene mutations
Overtime to two populations may become different so they can not reproduce amongst themselves

11. Speed of evolution
Gradualism: slow process of change where one species changes to a new species
Punctuated equilibrium: one species changes rapidly to another (penicillin resistant bacteria)

12. Clues about Evolution Section 2
Clues From Fossils
Study of Embryology
Homologous structures
Vestigal structures
DNA evidence
Fossils are living organisms preserved by natural means
They tell us a lot about the climate, how they obtain their food, sometimes how they died

13. Types of Fossils Fossils can be preserved by
Petrified remains caused by minerals replacing wood or bone.
Imprint fossils are caused by organisms leaving imprint in sedimentary rock that later hardens.
Casts and Molds where minerals fill in the area of a dead organism and tracks are recorded.
Ice trapped organisms preserved in whole form.
Amber or Tar pits preserve whole organisms trapped and hardened.
Most fossils are found in sedimentary rock(layers of sediment cemented together or mineral deposits from a solution

14. Determining Age of Fossils
Relative Dating: Dating of fossils by looking at position fossils lies in relation to each other
Layers of rock are deposited in layers and lower layers will be older than layers above
It is not an accurate time but relative, so fossils at lower levels were deposited before fossils found above and are older than those above

15. Radiometric Dating
Accurate dating of fossils based on radioactive decay of certain radioactive rocks
Radioactive elements give off a steady amount of radiation and they decay are steady rates
Scientist can determine age of rock that fossils are found by calculating that decay
This method gives more accurate dates of fossil preservation

16. Fossils and Evolution Fossils can show a gradual change of an organism
Those changes are preserved in rock and you can follow the evolutionary development of them
Fossils can also show extinction of some species

17. Other Clues of Evolution
Embryology: study of embryos and their development
Relationship among species (vertebrates) have similar embryo development

18. Embryology similarities

19. Homologous Structure
Homologous structures: body parts that are similar in origin and structure are call homologous
Scientists studies these similarities in structure and function to see if two or more species share common ancestors (thus indicating similar evolutionary paths)

20. Homologous structures

21. Vestigal Structures
Vestigal structures: structures that no longer seem to have a function (appendix, tail bone in humans, ear wiggling, wisdom teeth)
Thought that in earlier times they did have a function, but no longer was needed in an organism and could be related to ancestors with similar structures
This can track evolutionary changes from a species ancestors

23. DNA Evidence
By comparing DNA amongst species, similarities are shown between organism
Scientists can determine how closely related organisms are to each other
Similar DNA suggest common ancestry
Humans and other primates
Humans have 23 pairs, primates have 24, but two of an apes chromosomes when laid side by side match chromosome #2 on the human genome
Blood proteins are similar between humans and apes

24. Evolution of Primates
The Order of the Primates are composed of apes, monkeys, and humans
Characteristics they share
Opposable thumb, binocular vision, flexible shoulders
Believed to share common ancestor
Primates are divided into 2 groups
Strepsirhines: lemurs and tarpsier
Haplorhines : monkeys, apes, humans

25. Early Humans
Hominids: early human-like ancestors that shared characteristics with gorillas, orangutans but had larger brains (4-6 millions years ago)
African origins: Lucy (Australopithecus) oldest hominid found ( mya) in Africa : small brain, walked upright indicating ancestors to present humans

26. Early Humans Homo habilis: handy man who used tools ( 1.5-2 mya)
Gave rise to Homo erectus had larger brain (1.6 mya) traveled from Africa to SE Asia, China and maybe Europe
Larger brain and more human like than Lucy

27. Humans
Homo sapiens: (400,000 ya) evolved and broke into two early human groups Neantherthal and Cro-Magnon and lived during the same time
Neanderthal: lived in caves, used stone tools, hunted large animals, disappeared 30,000 ya, short, thick bones, small chins and heavy browridges. Probably not direct ancestor of humans but a branch
Cro-Magnon: fossil found between 10,000-40,000 ya : Thought to be ancestor of human, walk upright, tall, used tools, buried their dead
Homo sapiens means wise human