CHAPTER 8 BHISTORY OF EVOLUTIONARY THEORY EVOLUTION What

CHAPTER 8 BHISTORY OF EVOLUTIONARY THEORY

EVOLUTION • What is evolution? – Gradual change that makes something improve – The natural events that supposedly formed and changed the universe

EVOLUTION • Biological evolution – Change of one kind of organism into another kind over many generations • To happen: – First- Offspring must inherit new traits to be different from their parents – Second- new traits must make it easier to survive

LAMARCK’S THEORY: INHERITANCE OF ACQUIRED CHARACTERISTICS • Jean Baptiste Lamarck. French biologist in early 1800’s – Proposed theory of inheritance of acquired characteristics • Physical changes caused by an organism’s environment can be passed on to offspring

LAMARCK’S THEORY: INHERITANCE OF ACQUIRED CHARACTERISTICS • Thought that long ago, giraffes had short necks – Lots of animals ate lower leaves, so giraffes had to streeeeetch their necks • Necks became longer – Offspring’s necks were long too

LAMARCK’S THEORY: INHERITANCE OF ACQUIRED CHARACTERISTICS • Also, loss of a feature through not using or disease – Like the hamster’s really bad eyes – Most of the time they are awake, it is dark or they are underground

DARWIN’S THEORIES: NATURAL SELECTION AND DESCENT WITH MODIFICATION • Charles Darwin- lived in England 1800 s • Traveled to Galapagos Islands – Noticed animals on some islands different from animals on other islands

DARWIN’S THEORIES: NATURAL SELECTION AND DESCENT WITH MODIFICATION • Island A – Finches had large, strong beaks for cracking large seeds • Island B – Finches had small beaks for cracking smaller seeds

DARWIN’S THEORIES: NATURAL SELECTION AND DESCENT WITH MODIFICATION • Described theory of natural selection – Individuals in a species compete for food, shelter, survival – Some are better at competing – They have traits that help them win • Survival of the fittest – Pass on the good traits to children

DARWIN VS LAMARCK

ANALYSIS • Natural Selection is like selective breeding – Environment “chooses” the best trait • There be descent with modification – Newer organisms are the modified descendants of older organisms

DE VRIES’S THEORY: EVOLUTION BY MUTATION • Early 1900’s- modern genetics was discovered • Dutch botanist Hugo de Vries proposed the mutation theory of evolution – Mutations could produce the genetic changes needed for

ANALYSIS • Chromosomal mutations • How many mutations change organisms, but needed for a new structure? do not create new Leaf design, extra eye for genes spider, …? • Gene mutations do create new genes • But!!! Genes mutate every 10, 000 cell divisions – MILLIONS – Math shows it is nearly impossible for mutations to have produced changes for evolution

NEO-DARWINISM • Modern Evolutionary Theory: mutationselection theory – Mutations produce variations and natural selection determines which variations will survive for biological evolution • 3 main points: – Mutations supply new traits – Organisms produce more offspring than numbers that survive – Natural selection allows only organisms with the best traits to survive

INTELLIGENT DESIGN • Intelligent Design– Theory that living things show such complexity that they couldn’t have evolved by chance – Intelligent outside force (such as God) that is responsible for how things started and evolved • Not same as creationism, but a step in the right direction

QUESTIONS?