[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:08.16,0:00:12.31,Default,,0000,0000,0000,,The evolutionary tango \Nof animal genitalia.
Dialogue: 0,0:00:12.31,0:00:14.70,Default,,0000,0000,0000,,Can you guess what you're looking at?
Dialogue: 0,0:00:14.70,0:00:18.46,Default,,0000,0000,0000,,If you answered "duck vagina,"\Nyou'd be right.
Dialogue: 0,0:00:18.46,0:00:22.12,Default,,0000,0000,0000,,Although the bird's outward appearance\Nmay not strike you as especially odd,
Dialogue: 0,0:00:22.12,0:00:24.16,Default,,0000,0000,0000,,it uses this strange, intricate,
Dialogue: 0,0:00:24.16,0:00:28.15,Default,,0000,0000,0000,,cork-screw shaped contraption \Nto reproduce.
Dialogue: 0,0:00:28.15,0:00:31.08,Default,,0000,0000,0000,,We see similarly unbelievable genitalia\Nin insects,
Dialogue: 0,0:00:31.08,0:00:32.00,Default,,0000,0000,0000,,mammals,
Dialogue: 0,0:00:32.00,0:00:32.88,Default,,0000,0000,0000,,reptiles,
Dialogue: 0,0:00:32.88,0:00:33.78,Default,,0000,0000,0000,,fish,
Dialogue: 0,0:00:33.78,0:00:34.58,Default,,0000,0000,0000,,spiders,
Dialogue: 0,0:00:34.58,0:00:36.58,Default,,0000,0000,0000,,and even snails.
Dialogue: 0,0:00:36.58,0:00:40.92,Default,,0000,0000,0000,,Apparently, no organs evolve\Nfaster and into more variable shapes
Dialogue: 0,0:00:40.92,0:00:44.06,Default,,0000,0000,0000,,than those involved in procreation.
Dialogue: 0,0:00:44.06,0:00:49.55,Default,,0000,0000,0000,,Superficially, it makes sense\Nbecause evolution works via reproduction.
Dialogue: 0,0:00:49.55,0:00:53.54,Default,,0000,0000,0000,,When an animal leaves more offspring,\Nits genes will spread.
Dialogue: 0,0:00:53.54,0:00:57.28,Default,,0000,0000,0000,,And since genitalia are an animal's tools\Nfor reproduction,
Dialogue: 0,0:00:57.28,0:01:01.58,Default,,0000,0000,0000,,any improvement there \Nwill have immediate effect.
Dialogue: 0,0:01:01.58,0:01:05.95,Default,,0000,0000,0000,,And yet, what's the point of having\Nsuch decorative nether regions?
Dialogue: 0,0:01:05.95,0:01:08.99,Default,,0000,0000,0000,,After all, the function \Nof genitalia seems simple.
Dialogue: 0,0:01:08.99,0:01:11.11,Default,,0000,0000,0000,,A penis deposits a bit of sperm
Dialogue: 0,0:01:11.11,0:01:15.16,Default,,0000,0000,0000,,and a vagina receives it \Nand delivers it to the egg.
Dialogue: 0,0:01:15.16,0:01:17.13,Default,,0000,0000,0000,,A pipette-like thingy on the male
Dialogue: 0,0:01:17.13,0:01:22.51,Default,,0000,0000,0000,,and a funnel-like gizmo on the female\Nshould do just fine for any animal.
Dialogue: 0,0:01:22.51,0:01:25.69,Default,,0000,0000,0000,,And yet, that's not what we see.
Dialogue: 0,0:01:25.69,0:01:30.08,Default,,0000,0000,0000,,The penis of a chicken flea, for example,\Nlooks nothing like a pipette,
Dialogue: 0,0:01:30.08,0:01:33.01,Default,,0000,0000,0000,,more like an exploded grandfather clock.
Dialogue: 0,0:01:33.01,0:01:35.65,Default,,0000,0000,0000,,And the vagina of a featherwing beetle
Dialogue: 0,0:01:35.65,0:01:39.39,Default,,0000,0000,0000,,resembles something you'd find\Nin a Dr. Seuss book.
Dialogue: 0,0:01:39.39,0:01:40.84,Default,,0000,0000,0000,,Throughout the animal kingdom,
Dialogue: 0,0:01:40.84,0:01:43.68,Default,,0000,0000,0000,,genitalia are very complex things,
Dialogue: 0,0:01:43.68,0:01:48.05,Default,,0000,0000,0000,,much more complicated than seems\Nnecessary for what they're meant to do.
Dialogue: 0,0:01:48.05,0:01:53.04,Default,,0000,0000,0000,,That's because genitalia do more than just\Ndeposit and receive sperm.
Dialogue: 0,0:01:53.04,0:02:00.61,Default,,0000,0000,0000,,Many male animals also use the penis\Nas courtship device, like crane flies.
Dialogue: 0,0:02:00.61,0:02:02.59,Default,,0000,0000,0000,,In some South American species,
Dialogue: 0,0:02:02.59,0:02:05.67,Default,,0000,0000,0000,,males have a tiny washboard and scraper\Non their penis,
Dialogue: 0,0:02:05.67,0:02:09.99,Default,,0000,0000,0000,,which produces a song that reverberates\Nthroughout the female's body
Dialogue: 0,0:02:09.99,0:02:11.83,Default,,0000,0000,0000,,when they mate.
Dialogue: 0,0:02:11.83,0:02:15.46,Default,,0000,0000,0000,,It's thought that if female crane flies\Nenjoy this unusual serenade,
Dialogue: 0,0:02:15.46,0:02:18.88,Default,,0000,0000,0000,,they'll allow the male \Nto father their offspring.
Dialogue: 0,0:02:18.88,0:02:22.72,Default,,0000,0000,0000,,This way, the genes of the most\Nmusical penises spread,
Dialogue: 0,0:02:22.72,0:02:27.51,Default,,0000,0000,0000,,leading to rapid evolution\Nof insects' phalluses.
Dialogue: 0,0:02:27.51,0:02:31.82,Default,,0000,0000,0000,,Similarly, some beetles have two little\Ndrumsticks on either side of the penis.
Dialogue: 0,0:02:31.82,0:02:36.68,Default,,0000,0000,0000,,During mating, they'll rub, slap, or tap\Nthe female with these.
Dialogue: 0,0:02:36.68,0:02:40.43,Default,,0000,0000,0000,,And some hoofed mammals,\Nlike rams and bulls,
Dialogue: 0,0:02:40.43,0:02:43.52,Default,,0000,0000,0000,,use a whip-like extension \Non the penis's left side
Dialogue: 0,0:02:43.52,0:02:46.82,Default,,0000,0000,0000,,to create a sensation during mating.
Dialogue: 0,0:02:46.82,0:02:50.28,Default,,0000,0000,0000,,But how can females really choose\Nbetween males
Dialogue: 0,0:02:50.28,0:02:53.69,Default,,0000,0000,0000,,if she can only assess them after mating?
Dialogue: 0,0:02:53.69,0:02:57.98,Default,,0000,0000,0000,,This is where the power\Nof female adaptation comes into play.
Dialogue: 0,0:02:57.98,0:03:00.97,Default,,0000,0000,0000,,In fact, insemination is different\Nto conception,
Dialogue: 0,0:03:00.97,0:03:04.48,Default,,0000,0000,0000,,and the female genitalia exploit\Nthis distinction.
Dialogue: 0,0:03:04.48,0:03:06.16,Default,,0000,0000,0000,,For instance, in some dung flies,
Dialogue: 0,0:03:06.16,0:03:11.05,Default,,0000,0000,0000,,the vagina contains pockets\Nfor separating sperm from different males
Dialogue: 0,0:03:11.05,0:03:14.63,Default,,0000,0000,0000,,depending on how appealing they were.
Dialogue: 0,0:03:14.63,0:03:16.74,Default,,0000,0000,0000,,Males using their penises for courtship
Dialogue: 0,0:03:16.74,0:03:19.61,Default,,0000,0000,0000,,and females controlling \Ntheir own sperm management
Dialogue: 0,0:03:19.61,0:03:24.86,Default,,0000,0000,0000,,are two reasons why genitalia evolve\Ninto such complex shapes.
Dialogue: 0,0:03:24.86,0:03:25.97,Default,,0000,0000,0000,,But there are others
Dialogue: 0,0:03:25.97,0:03:30.37,Default,,0000,0000,0000,,because genitalia are also where\Na sexual conflict is played out.
Dialogue: 0,0:03:30.37,0:03:34.03,Default,,0000,0000,0000,,A female's interests are best served if\Nshe fertilizes her eggs
Dialogue: 0,0:03:34.03,0:03:36.86,Default,,0000,0000,0000,,with the sperm of the best fathers
Dialogue: 0,0:03:36.86,0:03:40.90,Default,,0000,0000,0000,,and creates genetic variability amongst\Nher offspring.
Dialogue: 0,0:03:40.90,0:03:44.38,Default,,0000,0000,0000,,For a male, on the other hand,\Nthis is bad news.
Dialogue: 0,0:03:44.38,0:03:47.52,Default,,0000,0000,0000,,For him, it would be best if a female\Nused his sperm
Dialogue: 0,0:03:47.52,0:03:51.33,Default,,0000,0000,0000,,to fertilize all of her eggs.
Dialogue: 0,0:03:51.33,0:03:55.51,Default,,0000,0000,0000,,So we see cycles of adaptation\Nin an evolutionary arms race
Dialogue: 0,0:03:55.51,0:03:57.98,Default,,0000,0000,0000,,to retain control.
Dialogue: 0,0:03:57.98,0:04:00.98,Default,,0000,0000,0000,,Black widow spiders \Nhave a disposable penis tip
Dialogue: 0,0:04:00.98,0:04:06.01,Default,,0000,0000,0000,,that breaks off inside the vagina\Nblocking the attempts of his rivals,
Dialogue: 0,0:04:06.01,0:04:09.52,Default,,0000,0000,0000,,and bed bug males bypass a female's\Ngenitalia altogether
Dialogue: 0,0:04:09.52,0:04:16.76,Default,,0000,0000,0000,,using a syringe-like penis to inject\Nsperm cells directly into her belly.
Dialogue: 0,0:04:16.76,0:04:18.14,Default,,0000,0000,0000,,Not to be outdone,
Dialogue: 0,0:04:18.14,0:04:21.25,Default,,0000,0000,0000,,females have evolved \Ntheir own countermeasures.
Dialogue: 0,0:04:21.25,0:04:22.77,Default,,0000,0000,0000,,In some bed bug species,
Dialogue: 0,0:04:22.77,0:04:26.00,Default,,0000,0000,0000,,the females have evolved an entirely\Nnew set of genitalia
Dialogue: 0,0:04:26.00,0:04:30.91,Default,,0000,0000,0000,,on their right hand flanks\Nwhere the males usually pierce them.
Dialogue: 0,0:04:30.91,0:04:35.24,Default,,0000,0000,0000,,That allows them to maintain\Nthe power to filter out unwanted sperm
Dialogue: 0,0:04:35.24,0:04:37.40,Default,,0000,0000,0000,,with their genitalia.
Dialogue: 0,0:04:37.40,0:04:40.70,Default,,0000,0000,0000,,And duck vaginas are shaped\Nlike a clockwise spiral
Dialogue: 0,0:04:40.70,0:04:46.60,Default,,0000,0000,0000,,so that when the male inflates his long,\Ncounterclockwise coiled penis into her,
Dialogue: 0,0:04:46.60,0:04:48.20,Default,,0000,0000,0000,,and she disapproves,
Dialogue: 0,0:04:48.20,0:04:51.36,Default,,0000,0000,0000,,all she needs to do \Nis flex her vaginal muscles
Dialogue: 0,0:04:51.36,0:04:55.06,Default,,0000,0000,0000,,and the penis just flubs out.
Dialogue: 0,0:04:55.06,0:04:59.42,Default,,0000,0000,0000,,So, genitalia differs so much,\Nnot just to fascinate us,
Dialogue: 0,0:04:59.42,0:05:01.33,Default,,0000,0000,0000,,but because in every species,
Dialogue: 0,0:05:01.33,0:05:05.40,Default,,0000,0000,0000,,they're the result of \Na furious evolutionary tango of sex
Dialogue: 0,0:05:05.40,0:05:08.38,Default,,0000,0000,0000,,that has been going on\Nfor millions of years
Dialogue: 0,0:05:08.38,0:05:11.45,Default,,0000,0000,0000,,and will continue for millions \Nof years to come.