Transcript Evolution Recap

Evolution Recap
What is it?
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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
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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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