The Theory of Evolution

Evolution: The most famous scientist that studied and discussed evolution is Charles Darwin. In 1831 Charles Darwin undertook a five year scientific study on the H.M.S. Beagle. He traveled to the Galapagos Islands where he discovered his greatest proof to support evolution. On the Galapagos islands Darwin discovered an interesting bird, the Finch.

Evolution continued: Darwin observed that Finches had different beak sizes on different islands dependent on the food resources available to them.

What is a theory? In everyday use, the word "theory" often means an untested hunch, or a guess without supporting evidence. But for scientists, a theory has nearly the opposite meaning. A theory is a well-substantiated explanation of an aspect of the natural world. It can incorporate laws, hypotheses and facts.

What is evolution: Evolution is the genetic change of organisms over time. This genetic change may give the organism a survival and/or reproductive advantage in their local environments. Population increases usually accompany these changes and this increased rate of survival is known as natural selection.

The Theory of Evolution: Supporters of the theory of evolution believe that all living things developed from one simple form of life. From this ‘unknown’ ancestor organisms adapted according to their environment and gave birth to the diverse species seen in the fossil record.

The Theory of Evolution: There are four essential requirements of evolution: – V = Variation: All life forms vary genetically within a population. It is this genetic variation upon which selection works. –I = Inheritance: Genetic traits are inherited from parents and are passed on to offspring. –S = Selection: Organisms with traits that are favorable to their survival get to live and pass on their genes to the next generation. –T = Time: Evolution takes time. Evolution can happen in a few generations, but major change, such as speciation, often takes long periods of time.

The Theory of Evolution: There are also four ways in which evolution occurs: –Mutation: a change in an organisms DNA usually caused by an error in repair or duplication –Migration: occurs when an organism inserts its DNA in a different species pool –Genetic Drift: random changes in gene frequencies of a species (could be caused by environmental factors) –Natural Selection: process in which some individuals have genetically-based traits that improve survival or reproduction and and thus have more offspring

The Theory of Creation: Many people believe in creationism. This is the belief that man (and all other beings) were placed on earth by a higher being, God. For many this belief is grounded in the book of Genesis. –Chapter 1, Verse 27: “So God created man in his own image, in the image of God created them; male and female created them.”

The Theory of Creation: Believers in creation suggest that the major plants and animals on earth were placed on the earth in their final form. This also suggests that man/women were placed on the earth in his/her current fully human form. In this view, earth was not a spontaneous creation but rather a specific and planned event by our creator.

Theories on the Origin of Humankind – Pre-Darwinism Diluvial Theory: –supported the Bible –fossils of extinct animals formed by Noah’s flood Objections: –no single event like Flood could account for progression of fossils in layers, each lower level is older –discovery of pre-flood fossils related to animals living after the flood

Theories on the Origin of Humankind – Pre-Darwinism Catastrophe Theory – George Cuvier ( ) –explained sequence of fossil layers by proposing a corresponding series of major catastrophes interspersed with periods of calm when plant and animal populations restocked the Earth –Noah’s flood just one of many catastrophes (between 27-32) Objection: –fossil record looks like “jerky” catastrophes but change was much more gradual

Contemporary Creationism Intelligent Design –promotes the idea that natural processes and living things are best explained by an intelligent cause and not undirected, Darwinian natural selection Common Objection: not scientifically verifiable, should not be considered a “scientific theory”

What is the big deal anyways? Why was (is) the theory of evolution so controversial? –At the time of Darwin’s publication of the Origin of Species (1859) creation was the most widely accepted version of how the earth and all life on it was created. –To many it seemed that the theory of evolution was an attempt to contradict religious belief. –But, Darwin himself was deeply religious. –The idea that humans came from apes was also offensive to some people.

Misconceptions about the theory of Evolution: 1. Evolution is a theory about the origin of life.

Misconceptions continued: 2. E volution is like a climb up a ladder of progress; organisms are always getting better.

3. Evolution means that life changed ‘by chance’.

4. Natural selection involves organisms ‘trying’ to adapt.

5. Natural selection gives organisms what they ‘need’.

Origin of Species Synopsis 1. IF you have creatures that vary… 2. IF there is a struggle for life that killed most species that ever lived… 3. IF the few that do survive pass on whatever genes helped them to survive… THEN YOU GET…

The Evolutionary Algorithm: If you have: –Variation –Inheritance –Selection And -Time Then you get evolution

Activity: Think about this question: At what point in ‘the evolution of humans’ do you believe that these primates begin to become human? (Ex. when they begin to walk on two feet or use tools) Why?