Evolution: Change Over Time The Evidence The Evidence Evolution: Change Over Time Evolution: Change Over Time The Evidence The Evidence

Fossil Record Defined: Collection of every known fossil Most fossils found in sedimentary rock

. . Over time, wind and rain carry dirt. Slowly the dead alligator is covered. This dirt is called “sediment”. . . Over time, the dirt hardens into rock. Each layer is called “sedimentary rock”. . . . . . . Younger rock layer Older rock layer

Fossil Record Defined: Collection of every known fossil Most fossils found in sedimentary rock Age determined by depth Law of Superposition: new rock forms on top of older rock Evidence Conclusions: 1) Newer fossils are more complex 2) Common ancestors: relationships between ancient & modern life

Comparing old fossils to modern life shows similarities and differences

Radiometric Dating Helps determine absolute age of fossils

Radiometric Dating 6 electrons 6 electrons 6 protons 6 C 12 14 ISOTOPES 6 protons p = ____ e = ____ n = ____ 6 p = ____ e = ____ n = ____ 6 6 6 6 8 protons + neutrons = 12 protons + neutrons = 14 Helps determine absolute age of fossils Isotopes: atoms of the same element with differing neutrons Ex: 12C and 14C 12C = 6 protons + 6 neutrons 14C = 6 protons + 8 neutrons When organism dies: 14C starts to decay into 14N Fossil age determined by comparing ratio of C to N Both are found in organisms

Dating Fossils

Ratio of 14N to 14C fairly equal Much more 14N compared to 14C

Timelines like this are accurate, but the scale of time it too massive for us to visualize…So let’s try a different scale of time

24 Hour Life Timeline Scale: 1 minute = 3 million years This timeline shrinks Earth’s existence to a 24 hour day. The Point? We can comprehend what 24 hours is like.

Fossils show that the oldest life is ~3.5 byo…bacteria

24 Hour Life Timeline Scale: 1 minute = 3 million years Bacteria (3.5 billion)

Fossils show the first vertebrates (fish) lived ~510mya.

24 Hour Life Timeline Scale: 1 minute = 3 million years Fish (510 million) Bacteria (3.5 billion)

Fossils show the first land animals (amphibians) lived ~340mya

24 Hour Life Timeline Scale: 1 minute = 3 million years Amphibians (340 million) Fish (510 million) Bacteria (3.5 billion)

Fossils show that reptiles first lived ~310mya

24 Hour Life Timeline Scale: 1 minute = 3 million years Reptiles (310 million) Scale: 1 minute = 3 million years Amphibians (340 million) Fish (510 million) Bacteria (3.5 billion)

Fossils show that mammals and dinosaurs first lived ~250mya

24 Hour Life Timeline Scale: 1 minute = 3 million years Dinosaurs & mammals (250m) Reptiles (310 million) Scale: 1 minute = 3 million years Amphibians (340 million) Fish (510 million) Bacteria (3.5 billion)

Fossils show that flowering plants and birds first lived ~175mya

24 Hour Life Timeline Scale: 1 minute = 3 million years Dinosaurs & mammals (250m) Reptiles (310 million) Scale: 1 minute = 3 million years Flowers and birds (175 m) Amphibians (340 million) Fish (510 million) Bacteria (3.5 billion)

Fossils show that humans first lived ~200,000 years ago

24 Hour Life Timeline 1 second = 50,000 years Dinosaurs & mammals (250m) Reptiles (310 million) Humans (200,000) Scale: 1 minute = 3 million years Flowers and birds (175 m) Amphibians (340 million) 1 second = 50,000 years So if humans have been around for 200,000 years, how many seconds before midnight did we evolve? Fish (510 million) Bacteria (3.5 billion)

Other Notable Events Obvious conclusion: Dinosaurs & mammals (250m) First plants (aquatic) Reptiles (310 million) Obvious conclusion: Life began very simple and gradually became more complex Humans (200,000) Scale: 1 minute = 3 million years Flowers and birds (175 m) Amphibians (340 million) Fish (510 million) Dinosaurs extinct Bacteria (3.5 billion) Unicellular eukaryotes

Missing Link Fossils AKA: Transition Fossils Whale Evidence Long spine Found in dried up oceans Reptile Evidence Teeth Bony tail Fish evidence Scales Fins Found in dried-up oceans Amphibian evidence Eyes on top of head Wrist bones Bird Evidence Wishbone Feathers Land Evidence Wolf-like teeth Hind legs AKA: Transition Fossils Archaeopteryx: shares both bird & reptile features Basilosaurus: shares whale & land mammal features Tiktaalik: shares fish & amphibian features Evidence Conclusion : Indicates common ancestry

#3: How do we know evolution happens?

Vestigial Structures Defined: Organs which have lost most or all their original function Vestigial Human Parts: Gill slits = once used to breath oxygen in water Yolk sac = once used to nourish developing embryo Tailbone = once used for balance Appendix = once used to digest plants Wisdom teeth = once used to grind plant tissue Evidence Conclusion : Indicates common ancestry

Human Embryo w/ Vestigial Structures

Pythons have tiny femurs (leg bone)

flipper arm leg wing Homologous Structures walking grasping swimming flight Defined: similar body structures with very different functions Different environments lead to adaptations Ex: The forelimbs of animals Evidence Conclusion : Indicates common ancestry

Biochemical Evidence DNA, RNA, proteins compared

Biochemical Evidence DNA, RNA, proteins compared Amino acid Amino acid Amino acid Amino acid Amino acid Amino acid Amino acid Amino acid Amino acid Amino acid Amino acid protein DNA, RNA, proteins compared Genetic code same for most life More related species have more similar biochemistry

Biochemical Evidence DNA, RNA, proteins compared Amino acid 1 Amino acid 2 Amino acid 3 Amino acid 4 Amino acid 5 Amino acid 6 Amino acid 7 Amino acid 8 Amino acid 9 Amino acid 10 Amino acid 11 Here is the protein “Cytochrome C”… Amino acid 20 Amino acid 19 Amino acid 18 Amino acid 17 Amino acid 16 Amino acid 15 Amino acid 14 Amino acid 13 Amino acid 12 Amino acid 21 Cytochrome C is made from105 amino acids. Amino acid 22 Amino acid 23 Amino acid 23 Amino acid 24 Amino acid 25 Amino acid 26 Amino acid 27 Amino acid 28 DNA, RNA, proteins compared Genetic code same for most life More related species have more similar biochemistry

Biochemical Evidence DNA, RNA, proteins compared This table compares the amino acids of human cytochrome C… to the cytochrome C of nine other species. DNA, RNA, proteins compared Genetic code same for most life More related species have more similar biochemistry Evidence Conclusion: Indicates common ancestry

Video: Did humans evolve?

Embryo Development Different species show similar development patterns Different body plans become noticeable later in development Evidence Conclusion : Indicates common ancestry Embryo Development

Review How does antibiotic and pesticide resistance show natural selection? Explain how the following topics demonstrate that life likely has changed over time. Fossils Homologous structures Vestigial structures Resistant organisms Embryo development Biochemical evidence Fossil age can be determined two ways. What are they? How does radiometric dating work?