Evolution 8 th Grade Science Mr. Banks

Evolution is a scientific theory Lets discuss for a moment what a scientific theory is.

Hypothesis vs theory vs law Hypothesis - a proposed explanation for a natural occurrence based on observations. Can be disproven via experimentation Can never be proven right, more evidence can be gathered to support the hypothesis, but it can never be definitively proven The term is usually used to describe an explanation that does not have much supporting evidence yet.

Hypothesis vs theory vs law Theory - a hypothesis or group of hypotheses that have been supported repeatedly by different experiments or evidence. Accepted as a good explanation of a phenomenon. A theory is valid as long as significant evidence has not been accumulated to dispute it. Like a hypothesis, it can never be proven right

Hypothesis vs theory vs law Law a description of repeated experimental observations without an explanation of how they occur. The observed phenomenon always occurs without exception under the expected conditions. Can be disproven with evidence that contradicts the law. Yet again, it can never be proven right.

Deep Time The concept that the earth is incredibly, inconceivably old.

For most of modern history until the early 1800 s, most biological thinking was essentialism. This is the idea that every species has characteristics that are unalterable or cannot change. Copyright 2010 Ryan P. Murphy

Geneticists have the ability to actually alter a species by changing genes.

Geneticist have the ability to actually alter a species by changing genes. This is a picture of a beak in a genetically altered chicken that grew teeth. (this is an extreme example)

Geneticist have the ability to actually alter a species by changing genes. I have altered the genes of bacteria many times to make certain proteins that I wanted to create. I have also used selective breeding to create strains of mice that have traits I m interested in studying.

A gene is a unit of heredity that is transferred from a parent to offspring.

A gene is a unit of heredity that is transferred from a parent to offspring. When genes change over time in a population of organisms it is called Evolution

A gene is a unit of heredity that is transferred from a parent to offspring. When genes change over time in a population of organisms it is called

A gene is a unit of heredity that is transferred from a parent to offspring. When genes change over time in a population of organisms it is called Evolution

Jean-Baptiste Lamarck proposed the hypothesis of transmutation of species, which turned out to have some flaws. Nonetheless was the first real theory of evolution. How do you think a giraffe got a long neck? Copyright 2010 Ryan P. Murphy

Charles Darwin and Alfred Russel Wallace published their views of evolutionary theory in 1859, these views are mostly what form our current ideas on evolution.

Natural Selection The gradual process by which traits become more or less common due to their effect on the reproductive success of an organism in its environment.

Survival of the fittest the individuals that are best adapted to their environment are more likely to reproduce.

Survival of the fittest the individuals that are best adapted to their environment are more likely to reproduce. Meaning that the best individuals will reproduce more and spread their successful traits.

Radioactive isotope and carbon dating is an accurate method of determining age. Dating to millions / billions of years ago. May be off by 30,000 years. But when your talking millions that is very close. Copyright 2010 Ryan P. Murphy

Extiction events

Millions of Years Ago Present

Rodhocetus

Picture of fossil and recreation of a very early amphibian, the tiktaalik. Note location of where the fossil was found. Amphibians don t inhabit this colder area (Evidence of continental drift). Copyright 2010 Ryan P. Murphy

The Coelacanth.

The Coelacanth. Believed to have gone extinct with dinosaurs.

The Coelacanth. Believed to have gone extinct with dinosaurs. Rediscovered (living) in 1938 off the coast of South Africa.

The lobe-finned fish are thought to be the start of the terrestrial (land) animals.

The lobe-finned fish are thought to be the start of the terrestrial (land) animals. Picture of lung fish moving across the mud.

How many neck bones (vertebrae) does a giraffe and human have?

They all have Eyes, Nose, Ears, Mouth Warmbloodedness Heart, Lungs, Organs Eat Food, Move Tetrapods (four limbs) Walrus has lost limbs. Some have Teeth, Fur, Hoofs, Smell Glands Eggs Live Birth Copyright 2010 Ryan P. Murphy

The lobe-finned fish are thought to be the start of the terrestrial (land) animals. Picture of lung fish moving across the mud.

The lobe-finned fish are thought to be the start of the terrestrial (land) animals. Picture of lung fish moving across the mud. What we call arms were once legs. We are tetrapods.

One theory suggests that land animals developed when smaller bodies of water periodically dried up.

One theory suggests that land animals developed when smaller bodies of water periodically dried up. Being able to crawl from one pool to the next aided in survival.

One theory suggests that land animals developed when smaller bodies of water periodically dried up. Being able to crawl from one pool to the next aided in survival. This ability was passed on from one generation to the next.

Another theory

Which picture below is a tetrapod?

Alfred Russel Wallace reasoned that the Indonesian archipelago can be divided into two distinct parts. One in which animals are closely related to those of Australia. And one in which the species are largely of Asian origin.

What is so unique about this salamander?

This is a cave angel fish. It has special hooks so that if can hold on to rocks in cave waterfalls. It also doesn t have eyes and has lost the colored pigment in its skin. Copyright 2010 Ryan P. Murphy