CHAPTER 2: EVOLUTION- CHANGE ACROSS TIME Examining the evidence of change across time.
WHERE DID THE THEORY OF EVOLUTION COME FROM? The theory of evolution was created in response to observations and discoveries that were not explained by current beliefs: The common belief was based on Divine Creation. Fossil evidence did not support that belief.
What is some of this evidence? A. The fossil record shows us a history of the organisms that once lived on earth, but are no longer alive.
What is some of this evidence? B.The fossil record also shows us that things that are alive today, were not alive in the geologic past, but resemble organisms that are no longer alive.
What Types of Fossils? We typically think of animals like dinosaurs, but there is far more in the fossil record than that. 1. Plants 2. Insects 3. Fish, shellfish and other marine organisms. 4. Animal evidence (eggs, footprints, scat (poo), feathers and skin. 5. Bacteria
Other types of fossils Dinosaur eggs Embryo in egg Footprints Fern imprint Spider, 65 mya Insects in amber
To help protect your privacy, PowerPoint prevented this external picture from being automatically downloaded. To download and display this picture, click Options in the Message Bar, and then click Enable external content. What is some of this evidence? The change in horses over time 1.Specific changes in horses such as the size and structure of their forelegs. 2. The original horse was about 1 foot tall, had 4 toes on the front feet and 3 toes on hind feet.
What is some of this evidence? Horses started as small & dog sized According to the fossil record: Equus, the current and last surviving member of the horse family appeared 5 million years ago
Archaeopteryx: Full set of teeth, long bony tail, and claws on wings are not common bird characteristics Further fossil evidence More organisms that were once alive but no longer are
How do fossils form? 1. Some animals were buried by mud or sediment quickly after dying. 2. Over time, more sediment covered the corpse. 3. The soft parts of the animal rotted (skin, muscle, organs), hard parts remained. 4. Eventually, minerals in the water replace the minerals that make up bone. 5. This turns what used to be bone into a rock-like substance.
How do scientists establish the age of fossils? Scientists establish the age of fossils in 2 ways: 1. Relative dating: Is a way of establishing a non-specific age based on it s location in the fossil record 2. Absolute(Direct) dating: A specific age is established by using radioactive elements.
Relative dating By studying the strata (layers) of earth, you can identify what is older or younger based on its relative depth.
Radiometric dating Geologists use radiometric dating to estimate how long ago rocks formed, and to infer the ages of fossils contained within those rocks This is done by calculating the radioactive half-life of the rock or fossil.
Radiometric dating: How it Works The universe is full of naturally occurring radioactive elements such as Uranium isotopes. Radioactive atoms are inherently unstable; over time, radioactive parent atoms decay into stable daughter atoms. When molten rock cools, forming what are called igneous rocks, radioactive atoms are trapped inside. Afterwards, they decay at a predictable rate. By measuring the quantity of unstable atoms left in a rock and comparing it to the quantity of stable daughter atoms in the rock, scientists can estimate the amount of time that has passed since that rock formed.
Radiometric dating Half Life: The amount of time required for a substance to lose half of it s radioactive value
WHAT IS EVOLUTION This misconception exists that evolution means that humans came from monkeys. The accurate definition is: 1.The gradual change in a species over time. a. Evolution refers to the life history of ALL living organisms, including plants, insects, fish.you name it.
How is evolution possible? Four concepts explain how evolution works: 1. More offspring are produced than the environment can support. 2. There is variation in the genes of all organisms. 3. Because of that, some are better suited to survive (survival of the fittest). 4. The individuals best able to survive will reproduce and pass on those successful traits to their offspring.
WHAT CONTROLS EVOLUTION? The environment The environment places many stresses and challenges on individuals Climate (weather) Availability of food Natural disasters Ability to find habitat Ability to escape predators or find prey
A brief glimpse of life on earth A look at how long things have been around.