PSY 304 evolution video notes PDF

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PSY 304: Video Notes Evolution - What Darwin Never Knew - NOVA PBS Documentary • • • ◦ • • • ◦ ◦ • ◦ ◦ • ◦ • • ◦

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how does evolution work? why is there an amazing variety of animals? many questions unanswered with the theory of evolution he didn’t understand the physical forces in which species appear a fish is the ancestor of all animals, even humans Sean Carol was just like Darwin when it came to his interest in animals Darwin’s first important discovery was in Argentina on his Voyage he found fossils of extinct creatures and tried to find a correlation between them and the animals we have today Galapagos Islands; he found penguins that live on the equator, tortious, iguanas that live in the sea all the birds he collected were variations of the same one depends on what island they lived on reminded him of the tortious and their different shells from island to island (mental rioting) Darwin discovered species CHANGE one type of animal changes into different kinds depending on the island the fossils he found were extinct but there were smaller versions of the same animals that still exist; which backed up his theory that species change they study animals in an embryonic stage (embryos) for example, they saw snakes had legs as embryos but when they hatch they don’t have legs, so they may have come from creatures with legs whales had teeth has embryos for humans, we have gill like lines on our necks, that turn into ears when born meaning we probably came from fish Darwin’ Tree of Life - all species were eventually connected decent with modification- adding or dropping body features (change in creatures) Darwin founds clues in dogs; there are so many types! big small tall (England) can natural selection explain the great diversity in life? is there animal breeding in nature without human guide? for Darwin, nature was savage, all creatures were locked in a desperate struggle for survival theres a lottttt of death, especially unpleasant death Darwin saw that everything was a competition in nature

• finches on the galapagos have many different kinds of beaks that interested Darwin ◦ he saw a clue in his family, no two children are exactly the same; he called it variation ◦ variation must be the starting point for change in nature this will allow the fit to get fitter and the less fit to die; natural selection- how new species are formed • in 1859, Darwin published The Origin of Species ◦ evolution on how natural selection works ◦ Darwin acknowledged there were holes in his theory; didn’t know how it worked what happens in their bodies that make them change modern science will answer these questions • in Arizona, mice were eaten by everything, there were light and dark mice, living on the light and dark rocks ◦ all the dark mice had light fur on their belly; scientists today looked at DNA (which Darwin couldn’t do) ◦ DNA doesn’t stay the same it can also change by mutation; without it, all generations will stay constant ◦ humans have 23,000 genes, same as a chicken, less than an ear of corn • looked back at embryos, how can they all start off looking so similar but end up so different ◦ it is the platform of diversity ◦ they use the same set of key genes to build their bodies; where the head goes, legs go ◦ it’s not the number of genes you have, it’s how you use them! • Sean Carol studied the fruit fly in his lab ◦ one type had spots on their wings, the other didn’t (in males) ◦ paintbrush gene- gene that causes the black spots but both types of flies had the paintbrush gene but only had spots so that shows it’s about how they use it, not if you have it junk- dark matter of genome switch- (DNA) they turn on and off genes switching answered a lot of questions about how species change • in British Columbia, stickle back fish were found in a lake, usually they live in the ocean ◦ over the years they have evolved; in the ocean their bellies have spikes, but in the lakes they lost their spikes there was a mutation that broke the switch in the DNA for it’s

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spikes they saw a lopsided pattern of where bones use to be so they looked for the same switch in manatees (also to explain whales and snakes) the differences in finches beaks were not in the genes, it was the timing in the embryos there were genes that boss other genes around; making not all genes not equal Neil Shubin tackled the problem of how sea creatures turned into land creatures his team found a fossil; called it tictolic; found small arms and a flat head (prey) looked at paddle fish for common genes found haux genes; gives orders to genes in a developing embryo; critical for form of developing creature all it needed were a few mutations, timing, and order human DNA is 99% identical to chimps how can closely related species be so different? sequence was different in 13 places compared to chimp DNA inserted into a mouse to see what the genes did active in the thumb and big toe need to know how to use it; so you need a human brain! they found a muscle making gene where two letters in the DNA were missing (mutation) this was common in humans and apes for apes this was the muscle for chewing (closing the jaw) humans only chew with a fraction of the force that apes use; tried to draw conclusion to the human brain muscle for chewing pulls on the bones for the skull, puts limits on how much the brain can grow in apes because it closes the skull for growth because the muscle is as strong as quadricep muscles so human jaw muscles are mutation so we can grow a bigger brain (until about age 30) microcephaly- brain disorder usually leading to down syndrome, basically meaning you have half a brain gene for this disorder tells the brain when to stop gene that help direct brain growth, it was defective (stop braincells from dividing at early development) now compared to chimps; the gene is humans were radically different from the one in chimps; major factor in evolution in our huge brains new program to find the difference in DNA between humans, chimps, and other animals

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the differences weren’t in genes, it was the switches cortex- outer layer of brain (language, math) different in 1 letter in apes and chickens; 18 letter difference in humans (mutation)...