{
  "wireMagic": "pb3",
  "pens": [ {
  
  } ],
  "wsWinStyles": [ {
  
  } ],
  "wpWinPositions": [ {
  
  } ],
  "events": [ {
    "tStartMs": 3600,
    "dDurationMs": 2719,
    "segs": [ {
      "utf8": "Evolution is all about reproduction, right?"
    } ]
  }, {
    "tStartMs": 6319,
    "dDurationMs": 2361,
    "segs": [ {
      "utf8": "It’s like...the whole point."
    } ]
  }, {
    "tStartMs": 8680,
    "dDurationMs": 4840,
    "segs": [ {
      "utf8": "So try to explain this: Male elephant seals\nare pretty unlucky in love."
    } ]
  }, {
    "tStartMs": 13520,
    "dDurationMs": 2740,
    "segs": [ {
      "utf8": "Most never get a chance to reproduce."
    } ]
  }, {
    "tStartMs": 16260,
    "dDurationMs": 4170,
    "segs": [ {
      "utf8": "Just four percent of males can account for\neighty-eight percent of mating."
    } ]
  }, {
    "tStartMs": 20430,
    "dDurationMs": 5080,
    "segs": [ {
      "utf8": "The other 96% of male elephant seals just\nuse up resources and don’t contribute anything"
    } ]
  }, {
    "tStartMs": 25510,
    "dDurationMs": 1720,
    "segs": [ {
      "utf8": "to the next generation."
    } ]
  }, {
    "tStartMs": 27230,
    "dDurationMs": 4770,
    "segs": [ {
      "utf8": "Yet even though it would be a lot more efficient\nto have just a few males, and a bunch of females,"
    } ]
  }, {
    "tStartMs": 32000,
    "dDurationMs": 3730,
    "segs": [ {
      "utf8": "roughly equal numbers of each sex are born\nevery season."
    } ]
  }, {
    "tStartMs": 35730,
    "dDurationMs": 3009,
    "segs": [ {
      "utf8": "We see this in almost every animal species\non Earth."
    } ]
  }, {
    "tStartMs": 38739,
    "dDurationMs": 7111,
    "segs": [ {
      "utf8": "Why do most animals, from eagles to armadillos\nto blue whales to us, make equal numbers of"
    } ]
  }, {
    "tStartMs": 45850,
    "dDurationMs": 1930,
    "segs": [ {
      "utf8": "males and females?"
    } ]
  }, {
    "tStartMs": 47780,
    "dDurationMs": 6279,
    "segs": [ {
      "utf8": "INTRO\nThe equal ratio of sexes is so common in nature,"
    } ]
  }, {
    "tStartMs": 54059,
    "dDurationMs": 2781,
    "segs": [ {
      "utf8": "most people never wonder why it is that way."
    } ]
  }, {
    "tStartMs": 56840,
    "dDurationMs": 3989,
    "segs": [ {
      "utf8": "And it’s worth pausing here for a second\nto make clear we’re talking about biological"
    } ]
  }, {
    "tStartMs": 60829,
    "dDurationMs": 1480,
    "segs": [ {
      "utf8": "sex, not gender."
    } ]
  }, {
    "tStartMs": 62309,
    "dDurationMs": 3850,
    "segs": [ {
      "utf8": "You probably learned that when male (XY) and\nfemale (XX) chromosomes shuffle and combine,"
    } ]
  }, {
    "tStartMs": 66159,
    "dDurationMs": 2441,
    "segs": [ {
      "utf8": "there’s a 50% probability of either sex."
    } ]
  }, {
    "tStartMs": 68600,
    "dDurationMs": 6140,
    "segs": [ {
      "utf8": "But this just tells us how it IS, not why\nit is this way rather than some other way,"
    } ]
  }, {
    "tStartMs": 74740,
    "dDurationMs": 3040,
    "segs": [ {
      "utf8": "and in biology that’s really what we want\nto know."
    } ]
  }, {
    "tStartMs": 77780,
    "dDurationMs": 4210,
    "segs": [ {
      "utf8": "If getting your genes from one generation\nto the next is the whole point of evolution,"
    } ]
  }, {
    "tStartMs": 81990,
    "dDurationMs": 5050,
    "segs": [ {
      "utf8": "then you’d think the best strategy would\nbe to put a lot of eggs into the female basket."
    } ]
  }, {
    "tStartMs": 87040,
    "dDurationMs": 5469,
    "segs": [ {
      "utf8": "Sperm are really cheap to produce, so males\nmake...a lot of them, and animal males typically"
    } ]
  }, {
    "tStartMs": 92509,
    "dDurationMs": 1781,
    "segs": [ {
      "utf8": "don’t do most of the childcare."
    } ]
  }, {
    "tStartMs": 94290,
    "dDurationMs": 4630,
    "segs": [ {
      "utf8": "So you get a situation in which you only need\na few males to keep a population churning"
    } ]
  }, {
    "tStartMs": 98920,
    "dDurationMs": 1110,
    "segs": [ {
      "utf8": "along."
    } ]
  }, {
    "tStartMs": 100030,
    "dDurationMs": 5390,
    "segs": [ {
      "utf8": "This seems like the ideal situation not just\nfor elephant seals, but for many animal species."
    } ]
  }, {
    "tStartMs": 105420,
    "dDurationMs": 6269,
    "segs": [ {
      "utf8": "Yet elephant seals produce both sexes in equal\nnumber, and the result is a whole lot of mooching"
    } ]
  }, {
    "tStartMs": 111689,
    "dDurationMs": 1920,
    "segs": [ {
      "utf8": "mateless males."
    } ]
  }, {
    "tStartMs": 113609,
    "dDurationMs": 4291,
    "segs": [ {
      "utf8": "As far as evolutionary strategies go, this\none seems like a loser."
    } ]
  }, {
    "tStartMs": 117900,
    "dDurationMs": 2120,
    "segs": [ {
      "utf8": "It’s not survival of the moochiest!"
    } ]
  }, {
    "tStartMs": 120020,
    "dDurationMs": 1989,
    "segs": [ {
      "utf8": "It’s survival of the fittest."
    } ]
  }, {
    "tStartMs": 122009,
    "dDurationMs": 6661,
    "segs": [ {
      "utf8": "Fittest, in biology, means makes-the-most-offspring,\nand 96% of elephant seal males get a big zero"
    } ]
  }, {
    "tStartMs": 128670,
    "dDurationMs": 1120,
    "segs": [ {
      "utf8": "for fitness!"
    } ]
  }, {
    "tStartMs": 129790,
    "dDurationMs": 1820,
    "segs": [ {
      "utf8": "That’s totally bonkers!"
    } ]
  }, {
    "tStartMs": 131610,
    "dDurationMs": 1930,
    "segs": [ {
      "utf8": "So how can we explain it?"
    } ]
  }, {
    "tStartMs": 133540,
    "dDurationMs": 4430,
    "segs": [ {
      "utf8": "Let’s start with a hypothetical population\nof purple people-eaters, in which out of every"
    } ]
  }, {
    "tStartMs": 137970,
    "dDurationMs": 4320,
    "segs": [ {
      "utf8": "10 purple-people-eating babies born, 9 are\nfemale and 1 is a male."
    } ]
  }, {
    "tStartMs": 142290,
    "dDurationMs": 4400,
    "segs": [ {
      "utf8": "When it comes to making adorable people-eating\nbabies, every male will get to mate about"
    } ]
  }, {
    "tStartMs": 146690,
    "dDurationMs": 2750,
    "segs": [ {
      "utf8": "nine times as often as every female."
    } ]
  }, {
    "tStartMs": 149440,
    "dDurationMs": 4290,
    "segs": [ {
      "utf8": "If every mating results in two new purple\npeople-eaters, then in the next generation,"
    } ]
  }, {
    "tStartMs": 153730,
    "dDurationMs": 5371,
    "segs": [ {
      "utf8": "each male’s genes are carried on by 18 offspring,\nbut each female–on average–gets their"
    } ]
  }, {
    "tStartMs": 159101,
    "dDurationMs": 1699,
    "segs": [ {
      "utf8": "genes into just 2."
    } ]
  }, {
    "tStartMs": 160800,
    "dDurationMs": 5020,
    "segs": [ {
      "utf8": "When we count up the “fitness” score,\nevery male in this population has 9 times"
    } ]
  }, {
    "tStartMs": 165820,
    "dDurationMs": 1890,
    "segs": [ {
      "utf8": "the fitness of every female."
    } ]
  }, {
    "tStartMs": 167710,
    "dDurationMs": 4860,
    "segs": [ {
      "utf8": "If, through the random chance of evolution,\none muncher manages to change in a way that"
    } ]
  }, {
    "tStartMs": 172570,
    "dDurationMs": 6550,
    "segs": [ {
      "utf8": "it produces say, 9 male kids for every female\nkid, those offspring would have a huge advantage."
    } ]
  }, {
    "tStartMs": 179120,
    "dDurationMs": 4990,
    "segs": [ {
      "utf8": "WIth this genetic change, one of these new\nmales would produce roughly four and a half"
    } ]
  }, {
    "tStartMs": 184110,
    "dDurationMs": 3040,
    "segs": [ {
      "utf8": "times more grandchildren than a male without\nthe change."
    } ]
  }, {
    "tStartMs": 187150,
    "dDurationMs": 4960,
    "segs": [ {
      "utf8": "This new mutation will spread like gangbusters\nand in a few generations, you’d have more"
    } ]
  }, {
    "tStartMs": 192110,
    "dDurationMs": 2930,
    "segs": [ {
      "utf8": "males than females in the whole purple people\neater population."
    } ]
  }, {
    "tStartMs": 195040,
    "dDurationMs": 6690,
    "segs": [ {
      "utf8": "But at this point, the mutation causing 90%\nmale offspring would no longer be an advantage."
    } ]
  }, {
    "tStartMs": 201730,
    "dDurationMs": 4400,
    "segs": [ {
      "utf8": "The environment has changed, and now females\nare the rarer sex."
    } ]
  }, {
    "tStartMs": 206130,
    "dDurationMs": 5300,
    "segs": [ {
      "utf8": "Now, any parent with a mutation that results\nin extra FEMALE offspring would be favored."
    } ]
  }, {
    "tStartMs": 211430,
    "dDurationMs": 4720,
    "segs": [ {
      "utf8": "Then THAT mutation would spread until the\nsex ratio moves BACK towards more females."
    } ]
  }, {
    "tStartMs": 216150,
    "dDurationMs": 4340,
    "segs": [ {
      "utf8": "Repeat this whole process and we move back\ntowards more males...then more females..."
    } ]
  }, {
    "tStartMs": 220490,
    "dDurationMs": 1260,
    "segs": [ {
      "utf8": "then more males..."
    } ]
  }, {
    "tStartMs": 221750,
    "dDurationMs": 4203,
    "segs": [ {
      "utf8": "The population would be in a constant see-saw\ntowards one sex or the other until, finally,"
    } ]
  }, {
    "tStartMs": 225953,
    "dDurationMs": 6027,
    "segs": [ {
      "utf8": "a mutation arises that results in an equal\nratio of offspring."
    } ]
  }, {
    "tStartMs": 231980,
    "dDurationMs": 6100,
    "segs": [ {
      "utf8": "That magic 50:50 sex ratio is the only one\nthat is evolutionarily stable… and that,"
    } ]
  }, {
    "tStartMs": 238080,
    "dDurationMs": 3540,
    "segs": [ {
      "utf8": "right there, is why we see it again and again\nand again…"
    } ]
  }, {
    "tStartMs": 241620,
    "dDurationMs": 4020,
    "segs": [ {
      "utf8": "Of course, the 50:50 ratio isn’t just about\nnumbers of offspring."
    } ]
  }, {
    "tStartMs": 245640,
    "dDurationMs": 4780,
    "segs": [ {
      "utf8": "It’s really about how much time and resources\nparents invest in offspring."
    } ]
  }, {
    "tStartMs": 250420,
    "dDurationMs": 6029,
    "segs": [ {
      "utf8": "We see 50:50 sex ratios whenever parents invest\nthe equally in their male and female children."
    } ]
  }, {
    "tStartMs": 256449,
    "dDurationMs": 4591,
    "segs": [ {
      "utf8": "If investment is unequal, like, if females\nrequire twice the parental care of males,"
    } ]
  }, {
    "tStartMs": 261040,
    "dDurationMs": 3160,
    "segs": [ {
      "utf8": "you’d expect to see twice as many males\nborn than females."
    } ]
  }, {
    "tStartMs": 264200,
    "dDurationMs": 5640,
    "segs": [ {
      "utf8": "Sure, here each male has less chance to pass\non their genes, but they cost half as much"
    } ]
  }, {
    "tStartMs": 269840,
    "dDurationMs": 2150,
    "segs": [ {
      "utf8": "as females, so it evens out."
    } ]
  }, {
    "tStartMs": 271990,
    "dDurationMs": 8090,
    "segs": [ {
      "utf8": "Australian brushtail possum moms, for example,\ninvest more resources in their daughters,"
    } ]
  }, {
    "tStartMs": 280080,
    "dDurationMs": 4760,
    "segs": [ {
      "utf8": "so when these resources are scarce, they have\nmore male offspring."
    } ]
  }, {
    "tStartMs": 284840,
    "dDurationMs": 4900,
    "segs": [ {
      "utf8": "Like everything in biology, there are lots\nof weird exceptions to this, but it’s amazing"
    } ]
  }, {
    "tStartMs": 289740,
    "dDurationMs": 3370,
    "segs": [ {
      "utf8": "how universal the 50:50 rule actually is."
    } ]
  }, {
    "tStartMs": 293110,
    "dDurationMs": 4640,
    "segs": [ {
      "utf8": "You see it in species where parents care for\ntheir babies and where they don’t, when"
    } ]
  }, {
    "tStartMs": 297750,
    "dDurationMs": 2640,
    "segs": [ {
      "utf8": "they have many partners, or just one."
    } ]
  }, {
    "tStartMs": 300390,
    "dDurationMs": 4700,
    "segs": [ {
      "utf8": "You even see it in species where one sex dies\na lot more than the other."
    } ]
  }, {
    "tStartMs": 305090,
    "dDurationMs": 5350,
    "segs": [ {
      "utf8": "It shows us the incredible power of natural\nselection to shape the characteristics of"
    } ]
  }, {
    "tStartMs": 310440,
    "dDurationMs": 1230,
    "segs": [ {
      "utf8": "a population."
    } ]
  }, {
    "tStartMs": 311670,
    "dDurationMs": 6469,
    "segs": [ {
      "utf8": "After all, if love is a battlefield, at least\neach side is evenly matched."
    } ]
  }, {
    "tStartMs": 318139,
    "dDurationMs": 2861,
    "segs": [ {
      "utf8": "Stay curious."
    } ]
  } ]
}