Evolution Recap

1. Evolution Recap

2. 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

3. 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.

4. 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.

6. 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

7. 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

9. video