Section 1: Ideas about Evolutions

Section 2: Clues about Evolution

Section 3: Evolution of Primates

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

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

Charles Darwin (1831-1845) 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

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

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)

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)

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

When organisms move into an area or leave they bring or take with them characteristics that may change the gene pool

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

Gradualism: slow process of change where one species changes to a new species

Punctuated equilibrium: one species changes rapidly to another (penicillin resistant bacteria)

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

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

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

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

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

Embryology: study of embryos and their development

Relationship among species (vertebrates) have similar embryo development

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)

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

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

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

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 (2.9-3.4 mya) in Africa : small brain, walked upright indicating ancestors to present 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

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