[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:14.52,0:00:16.61,Default,,0000,0000,0000,,The Five Fingers of Evolution.
Dialogue: 0,0:00:17.25,0:00:19.38,Default,,0000,0000,0000,,A thorough understanding of biology
Dialogue: 0,0:00:19.41,0:00:23.07,Default,,0000,0000,0000,,requires a thorough understanding\Nof the process of evolution.
Dialogue: 0,0:00:23.09,0:00:26.25,Default,,0000,0000,0000,,Most people are familiar\Nwith the process of natural selection.
Dialogue: 0,0:00:26.27,0:00:28.81,Default,,0000,0000,0000,,However, this is just one\Nof five processes
Dialogue: 0,0:00:28.84,0:00:30.79,Default,,0000,0000,0000,,that can result in evolution.
Dialogue: 0,0:00:30.81,0:00:33.48,Default,,0000,0000,0000,,Before we discuss\Nall five of these processes,
Dialogue: 0,0:00:33.51,0:00:35.38,Default,,0000,0000,0000,,we should define evolution.
Dialogue: 0,0:00:35.40,0:00:39.03,Default,,0000,0000,0000,,Evolution is simply change\Nin the gene pool over time.
Dialogue: 0,0:00:39.05,0:00:40.30,Default,,0000,0000,0000,,But what is a gene pool?
Dialogue: 0,0:00:40.33,0:00:42.77,Default,,0000,0000,0000,,And for that matter, what is a gene?
Dialogue: 0,0:00:42.80,0:00:44.98,Default,,0000,0000,0000,,Before spending any more time on genetics,
Dialogue: 0,0:00:45.00,0:00:46.87,Default,,0000,0000,0000,,let us begin with a story.
Dialogue: 0,0:00:47.68,0:00:49.46,Default,,0000,0000,0000,,Imagine that a boat capsizes,
Dialogue: 0,0:00:49.48,0:00:52.64,Default,,0000,0000,0000,,and 10 survivors\Nswim to shore on a deserted island.
Dialogue: 0,0:00:52.66,0:00:53.84,Default,,0000,0000,0000,,They are never rescued,
Dialogue: 0,0:00:53.87,0:00:57.51,Default,,0000,0000,0000,,and they form a new population\Nthat exists for thousands of years.
Dialogue: 0,0:00:57.53,0:01:00.65,Default,,0000,0000,0000,,Strangely enough,\Nfive of the survivors have red hair.
Dialogue: 0,0:01:00.99,0:01:03.87,Default,,0000,0000,0000,,Red hair is created\Nwhen a person inherits two copies
Dialogue: 0,0:01:03.89,0:01:05.83,Default,,0000,0000,0000,,of the red gene from their parents.
Dialogue: 0,0:01:05.85,0:01:09.10,Default,,0000,0000,0000,,If you only have one copy of the gene,\Nyou won't have red hair.
Dialogue: 0,0:01:09.12,0:01:10.98,Default,,0000,0000,0000,,To make this easier, we will assume
Dialogue: 0,0:01:11.00,0:01:14.52,Default,,0000,0000,0000,,that the five non-redheads\Nare not carriers of the gene.
Dialogue: 0,0:01:14.55,0:01:18.15,Default,,0000,0000,0000,,The initial frequency of the red-hair gene\Nis therefore 50 percent,
Dialogue: 0,0:01:18.18,0:01:20.26,Default,,0000,0000,0000,,or 10 of 20 total genes.
Dialogue: 0,0:01:20.83,0:01:22.61,Default,,0000,0000,0000,,These genes are the gene pool.
Dialogue: 0,0:01:22.100,0:01:25.68,Default,,0000,0000,0000,,The 20 different genes\Nare like cards in a deck
Dialogue: 0,0:01:25.71,0:01:28.90,Default,,0000,0000,0000,,that keep getting reshuffled\Nwith each new generation.
Dialogue: 0,0:01:28.93,0:01:32.23,Default,,0000,0000,0000,,Sex is simply a reshuffling\Nof the genetic deck.
Dialogue: 0,0:01:33.23,0:01:36.89,Default,,0000,0000,0000,,The cards are reshuffled\Nand passed to the next generation;
Dialogue: 0,0:01:36.92,0:01:39.59,Default,,0000,0000,0000,,the deck remains the same, 50 percent red.
Dialogue: 0,0:01:40.22,0:01:43.89,Default,,0000,0000,0000,,The genes are reshuffled\Nand passed to the next generation;
Dialogue: 0,0:01:43.91,0:01:47.15,Default,,0000,0000,0000,,the gene pool remains\Nthe same, 50 percent red.
Dialogue: 0,0:01:47.88,0:01:50.87,Default,,0000,0000,0000,,Even though the population\Nmay grow in size over time,
Dialogue: 0,0:01:50.90,0:01:53.50,Default,,0000,0000,0000,,the frequency should stay\Nat about 50 percent.
Dialogue: 0,0:01:53.87,0:01:57.06,Default,,0000,0000,0000,,If this frequency ever varies,\Nthen evolution has occurred.
Dialogue: 0,0:01:57.08,0:02:00.27,Default,,0000,0000,0000,,Evolution is simply change\Nin the gene pool over time.
Dialogue: 0,0:02:00.72,0:02:02.84,Default,,0000,0000,0000,,Think about it in terms of the cards.
Dialogue: 0,0:02:02.87,0:02:05.78,Default,,0000,0000,0000,,If the frequency of the cards\Nin the deck ever changes,
Dialogue: 0,0:02:05.81,0:02:07.36,Default,,0000,0000,0000,,evolution has occurred.
Dialogue: 0,0:02:07.38,0:02:11.33,Default,,0000,0000,0000,,There are five processes\Nthat can cause the frequency to change.
Dialogue: 0,0:02:11.35,0:02:14.98,Default,,0000,0000,0000,,To remember these processes,\Nwe will use the fingers on your hands,
Dialogue: 0,0:02:15.00,0:02:18.10,Default,,0000,0000,0000,,starting from the little finger\Nand moving to the thumb.
Dialogue: 0,0:02:18.13,0:02:21.72,Default,,0000,0000,0000,,The little finger should remind you\Nthat the population can shrink.
Dialogue: 0,0:02:21.74,0:02:24.50,Default,,0000,0000,0000,,If the population shrinks,\Nthen chance can take over.
Dialogue: 0,0:02:24.99,0:02:28.54,Default,,0000,0000,0000,,For example, if only four\Nindividuals survive an epidemic,
Dialogue: 0,0:02:28.57,0:02:31.36,Default,,0000,0000,0000,,then their genes will represent\Nthe new gene pool.
Dialogue: 0,0:02:31.96,0:02:33.78,Default,,0000,0000,0000,,The next finger is the ring finger.
Dialogue: 0,0:02:33.80,0:02:37.94,Default,,0000,0000,0000,,This finger should remind you of mating,\Nbecause a ring represents a couple.
Dialogue: 0,0:02:38.43,0:02:42.06,Default,,0000,0000,0000,,If individuals choose a mate\Nbased on their appearance or location,
Dialogue: 0,0:02:42.08,0:02:43.76,Default,,0000,0000,0000,,the frequency may change.
Dialogue: 0,0:02:43.79,0:02:47.37,Default,,0000,0000,0000,,If redheaded individuals only mate\Nwith redheaded individuals,
Dialogue: 0,0:02:47.39,0:02:49.56,Default,,0000,0000,0000,,they could eventually\Nform a new population.
Dialogue: 0,0:02:50.08,0:02:52.54,Default,,0000,0000,0000,,If no one ever mates\Nwith redheaded individuals,
Dialogue: 0,0:02:52.57,0:02:54.26,Default,,0000,0000,0000,,these genes could decrease.
Dialogue: 0,0:02:54.28,0:02:56.04,Default,,0000,0000,0000,,The next finger is the middle finger.
Dialogue: 0,0:02:56.07,0:03:00.04,Default,,0000,0000,0000,,The M in the middle finger should remind\Nyou of the M in the word "mutation."
Dialogue: 0,0:03:00.07,0:03:03.69,Default,,0000,0000,0000,,If a new gene is added through mutation,\Nit can affect the frequency.
Dialogue: 0,0:03:04.13,0:03:07.35,Default,,0000,0000,0000,,Imagine a gene mutation\Ncreates a new color of hair.
Dialogue: 0,0:03:07.37,0:03:10.33,Default,,0000,0000,0000,,This would obviously change\Nthe frequency in the gene pool.
Dialogue: 0,0:03:10.35,0:03:12.88,Default,,0000,0000,0000,,The pointer finger\Nshould remind you of movement.
Dialogue: 0,0:03:12.91,0:03:16.18,Default,,0000,0000,0000,,If new individuals\Nflow into an area, or immigrate,
Dialogue: 0,0:03:16.21,0:03:17.74,Default,,0000,0000,0000,,the frequency will change.
Dialogue: 0,0:03:17.76,0:03:20.62,Default,,0000,0000,0000,,If individuals flow out\Nof an area, or emigrate,
Dialogue: 0,0:03:20.65,0:03:22.13,Default,,0000,0000,0000,,then the frequency will change.
Dialogue: 0,0:03:22.15,0:03:25.79,Default,,0000,0000,0000,,In science, we refer to this\Nmovement as gene flow.
Dialogue: 0,0:03:26.36,0:03:31.02,Default,,0000,0000,0000,,All four of the processes represented\Nby our fingers can cause evolution.
Dialogue: 0,0:03:31.05,0:03:34.42,Default,,0000,0000,0000,,Small population size, non-random mating,
Dialogue: 0,0:03:34.44,0:03:36.98,Default,,0000,0000,0000,,mutations and gene flow.
Dialogue: 0,0:03:37.00,0:03:39.90,Default,,0000,0000,0000,,However, none of them lead to adaptation.
Dialogue: 0,0:03:39.92,0:03:42.15,Default,,0000,0000,0000,,Natural selection is the only process
Dialogue: 0,0:03:42.18,0:03:45.73,Default,,0000,0000,0000,,that creates organisms\Nbetter adapted to their local environment.
Dialogue: 0,0:03:46.06,0:03:48.44,Default,,0000,0000,0000,,I use the thumb to remember this process.
Dialogue: 0,0:03:48.46,0:03:52.60,Default,,0000,0000,0000,,Nature votes thumbs up for adaptations\Nthat will do well in their environment,
Dialogue: 0,0:03:52.62,0:03:55.32,Default,,0000,0000,0000,,and thumbs down to adaptations\Nthat will do poorly.
Dialogue: 0,0:03:55.74,0:03:59.57,Default,,0000,0000,0000,,The genes for individuals\Nthat are not adapted for their environment
Dialogue: 0,0:03:59.59,0:04:02.66,Default,,0000,0000,0000,,will gradually be replaced\Nby those that are better adapted.
Dialogue: 0,0:04:03.18,0:04:05.99,Default,,0000,0000,0000,,Red hair is an example\Nof one of these adaptations.
Dialogue: 0,0:04:06.38,0:04:09.07,Default,,0000,0000,0000,,Red hair is an advantage\Nin the northern climates,
Dialogue: 0,0:04:09.10,0:04:13.15,Default,,0000,0000,0000,,because the fair skin\Nallowed ancestors to absorb more light
Dialogue: 0,0:04:13.17,0:04:15.22,Default,,0000,0000,0000,,and synthesize more vitamin D.
Dialogue: 0,0:04:15.24,0:04:16.44,Default,,0000,0000,0000,,Thumbs up!
Dialogue: 0,0:04:16.47,0:04:19.42,Default,,0000,0000,0000,,However, this was a disadvantage\Nin the more southern climates,
Dialogue: 0,0:04:19.45,0:04:24.29,Default,,0000,0000,0000,,where increased UV radiation\Nled to cancer and decreased fertility.
Dialogue: 0,0:04:24.32,0:04:25.58,Default,,0000,0000,0000,,Thumbs down!
Dialogue: 0,0:04:25.60,0:04:27.58,Default,,0000,0000,0000,,Even the thumb itself is an adaptation
Dialogue: 0,0:04:27.61,0:04:29.96,Default,,0000,0000,0000,,formed through the process\Nof natural selection.
Dialogue: 0,0:04:30.69,0:04:34.57,Default,,0000,0000,0000,,The evolution that we have described\Nis referred to as microevolution,
Dialogue: 0,0:04:34.59,0:04:36.62,Default,,0000,0000,0000,,because it refers to a small change.
Dialogue: 0,0:04:36.65,0:04:38.16,Default,,0000,0000,0000,,However, this form of evolution
Dialogue: 0,0:04:38.19,0:04:41.42,Default,,0000,0000,0000,,may eventually lead\Nto macroevolution, or speciation.
Dialogue: 0,0:04:42.04,0:04:46.29,Default,,0000,0000,0000,,Every organism on the planet shares\Nancestry with a single common ancestor.
Dialogue: 0,0:04:46.86,0:04:50.12,Default,,0000,0000,0000,,All living organisms on the planet\Nare connected back in time
Dialogue: 0,0:04:50.14,0:04:51.80,Default,,0000,0000,0000,,through the process of evolution.
Dialogue: 0,0:04:52.42,0:04:53.92,Default,,0000,0000,0000,,Take a look at your own hand.
Dialogue: 0,0:04:53.94,0:04:55.61,Default,,0000,0000,0000,,It's an engineering masterpiece
Dialogue: 0,0:04:55.63,0:04:58.63,Default,,0000,0000,0000,,that was created by the five\Nprocesses I just described,
Dialogue: 0,0:04:58.66,0:05:00.54,Default,,0000,0000,0000,,over millions and millions of years.
Dialogue: 0,0:05:01.10,0:05:04.60,Default,,0000,0000,0000,,Can you recall the five main\Ncauses of evolution from memory?
Dialogue: 0,0:05:04.63,0:05:07.28,Default,,0000,0000,0000,,If you can't, hit rewind\Nand watch that part again.
Dialogue: 0,0:05:07.71,0:05:08.94,Default,,0000,0000,0000,,But if you can,
Dialogue: 0,0:05:08.96,0:05:13.53,Default,,0000,0000,0000,,give yourself or your neighbor\Na big five-fingered high five.