Evolution Recap

What is it? Species – can reproduce to produce new generations Population – number of a species in an area Trait – distinguishing feature of an animal Variation – differences in a trait between individuals from: Mutation Sex – brothers and sisters rather than clones Selection Reproduction Selection of a variation of a trait that is passed onto the next generation of a species Variation + Selection + Reproduction = Evolution Isolated populations + Selection = New Species

History of the Idea Old idea from ancient times animals change over time Grandfather Darwin – All creatures have one Great Great…. Great Grandmother – little evidence and no reason why – not a scientific theory Darwin – Natural Selection - Children are variation of parents then Survivors reproduce – But Darwin was upper class, and Evolution supporters were being laughed at by upper class for lack of evidence and reason why – Darwin built his case for 20 years Wallace – Struggle for Existence – Working class selling stuffed animals to Upper class. Ship got burnt, then in fever of Malaria worked it out. Wrote to Darwin and they “Co-published” Lamark – Had a wrong reason why – stretching your neck makes it longer, then have sex and your baby will have a longer neck.

Evidence Similarities of existing animals – slugs and snails Fossils (1970 – good, 2009 – excellent) Feature evolved to do different jobs – hands and wings Different features evolved to do the same job – jaws and ears Vestigial Organs – appendix, Embryos all look the same – we have a tail and gills at 20 days. DNA – work out who are you parents, then grandparents then their grandparents ….. Traced to an Adam, then back to chimpanzee ancestor, female line tracked back to bacteria. David A – says proven. 8 Years read Human DNA is 2003 – now species are sequenced every few hours to build the complete evolutionary map Evolution is diseases of Flu and HIV – now accepted Evolution now in Computer games, and modern products.

History of Life 4.5 Ga– earth made 3 Ga – single cell 2.3 Ga – Snowball 1 Oxygen! 0.65 Snowball – multicell 0.53 Eyes – Sex – Cambrian explosion 0.38 Ga land animals 0.23 – 0.06 Ga Dinosaurs

How old is that rock? Layer of rock, dated by fossils. Old ones are at the bottoms 50% Element A decays to element B over 1 G years, and rock has no B then 100 % A – 0% B = 0 yr. 50 % A – 50 % B = 1 Gyr 25 % A - 75% B = 2 Gyr 6.25 % A – 93.75% = 4 Gyr

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