CLUES ABOUT EVOLUTION

Mr. Rethman

I CAN’S

• I can identify the importance of fossils as evidence of evolution.

• I can explain how relative and radiometric dating is used to estimate the age of fossils.

• I can list examples of five types of evidence for evolution.

INDIRECT EVIDENCE FOR EVOLUTION

Clues from Fossils

• Paleontologists – scientists who study the past by collecting and examining fossils.

• Plants and Animals covered with silt and mud• Green River Formation in Wyoming, Utah, and

Colorado – one of the richest fossil deposits in the world.

Types of Fossils

• Fossil – remains or imprint or trace of a prehistoric organism

• Found in Sedimentary Rock with layers of silt, sand, clay, mud compacted or when minerals are deposited.

• Examples of rock include: limestone, sandstone, and shale.

Determining Fossil Age

• Relative Dating– Idea of undisturbed areas– Younger rock on top of older rock layers

Compare the ages of rock

Radiometric Dating

• Estimate age of rock using radioactive elements

• Compare the amount of radioactive element with the amount of nonradioactive element in rock.

Embryology

• Study of embryos and their development

Homologous Structures

• Body parts in the same origin and structure

• Also, similar in function

• Indicate more species share common ancestors

Homologous Structures

Vestigial Structures

• Structures with no function

• Example: Manatees, snakes, and whales no longer have back legs but still have pelvic bones.

• Human appendix – helpful for digestion

DNA

• Molecule that directs heredity• Found on genes that make up chromosomes• Dogs close relatives of bears• Apes, gorillas, and chimps = 24 pairs of

chromosomes• Humans = 23 pairs • Match in chromosome # 2• Similar proteins found – such as hemoglobin –

found in red blood cells

DIRECT EVIDENCE FOR EVOLUTION

Direct Evidence

• Antibiotic Resistance• Pesticide Resistance• Genetic Changes in Plants

Evolution of Primates

• Group of Mammals with:– Humans– Apes– Monkeys

I CAN….

• I can describe the differences among living primates

• Identify the adaptations of primates• Discuss the evolutionary history of modern

primates

Characteristics of Primates

• Opposable thumbs – grasp and hold things• Binocular vision – judge distance• Flexible shoulders - swimming

• Indicate all share a common ancestor

Two groups of Primates

• Strepsirhines

• Lemurs• Tarsiers

• Haplorhines

• Monkeys• Apes• Humans

Hominids

• 4-6 million years ago• Both plant and animal eating• Walked upright on two legs…bipedal

African Origins

• 1920 – fossil skull found in South Africa• Small brain• Humanlike jaw and teeth• Australopithecus – oldest hominid• “Lucy” – full skeleton found in 1974. – Found to be 2.9 to 3.4 million years old

Homo Habilis “Handy Man”

• Simple stones found near him• 1.5 to 2 million years old• Gave rise to Homo Erectus – larger brain• Traveled from Africa to Southeast Asia and

Europe

Homo Sapiens “wise human”

• 400,000 years ago

• 125,000 – two groups lived Neanderthals and Cro-Magnon humans

Neanderthals

• Short, heavy bodies with thick bones• Small chins• Heavy browridges• Lived in caves• Well-made stone tools• Disappeared 30,000 yrs ago• Side branch of evolution – not direct ancestors

Cro-Magnon Humans

• Found in Europe, Asia, and Australia• 10,000 to 40,000 years ago• Stood 1.6 or 1.7 m high• Lived in Caves• Made Stone Carvings• Buried their dead

• Modern Human – Homo Sapiens sapiens evolved from Homo Sapiens