full transcript

From the Ted Talk by Menno Schilthuizen: The evolution of animal genitalia

Unscramble the Blue Letters

The evolutionary tango of animal genitalia. Can you guess what you're looking at? If you aeswrend "duck vgniaa," you'd be right. Although the bird's outward appearance may not stirke you as especially odd, it uses this strange, intricate, cork-screw shaped contraption to reproduce. We see similarly unbelievable genitalia in iscetns, mammals, reptiles, fish, spiders, and even snails. Apparently, no ogarns eolvve fatser and into more variable shapes than those ivnvleod in procreation. Superficially, it makes sense because evolution works via reproduction. When an animal leaves more offspring, its genes will spread. And since genitalia are an animal's tools for reproduction, any improvement there will have immediate effect. And yet, what's the point of having such decorative nehter regions? After all, the function of genitalia seems simple. A penis deposits a bit of sperm and a vagina receives it and delivers it to the egg. A pipette-like thingy on the male and a funnel-like gizmo on the female should do just fine for any animal. And yet, that's not what we see. The penis of a chicken flea, for example, looks nothing like a pipette, more like an exoelpdd grandfather clock. And the vagina of a featherwing beetle resembles something you'd find in a Dr. Seuss book. Throughout the animal kniodgm, gtailinea are very clmoepx things, much more complicated than seems necessary for what they're meant to do. That's because genitalia do more than just deposit and receive sperm. Many male animals also use the penis as courtship device, like crane flies. In some South American species, males have a tiny washboard and spaecrr on their pneis, which pueodrcs a song that reverberates throughout the female's body when they mate. It's thought that if female crane fleis enjoy this uuansul serenade, they'll allow the male to father their offspring. This way, the genes of the most musical penises spread, leading to rapid etulovion of insects' phalluses. Similarly, some beetles have two little drumsticks on either side of the penis. During mating, they'll rub, slap, or tap the fealme with these. And some hoofed mammals, like rams and bulls, use a whip-like extension on the penis's left side to create a sotansein during mating. But how can females really choose between males if she can only assess them after mating? This is where the power of female adaptation comes into play. In fact, insemination is different to conception, and the female genitalia exploit this distinction. For instance, in some dung flies, the vagina contains pockets for separating sperm from different males depending on how appealing they were. maels using their penises for curotishp and females controlling their own serpm management are two rseonas why genitalia evolve into such complex saephs. But there are others because genitalia are also where a sexual conflict is played out. A female's interests are best served if she fertilizes her eggs with the sperm of the best fathers and creeats ginteec variability amongst her ofnisfprg. For a male, on the other hand, this is bad news. For him, it would be best if a female used his sperm to fertilize all of her eggs. So we see ceycls of adaptation in an evolutionary arms race to retain cntorol. Black widow spiders have a disposable penis tip that breaks off inside the vagina blocking the attempts of his rivals, and bed bug males bypass a female's genitalia atothlgeer using a syringe-like penis to inject sperm clels directly into her belly. Not to be oudntoe, falmees have evolved their own countermeasures. In some bed bug species, the females have evolved an entirely new set of genitalia on their right hand flanks where the males usually pierce them. That allows them to maintain the power to filter out unwanted sperm with their genitalia. And duck vniaags are shaped like a clwskioce spiral so that when the male inflates his long, crlotsnuoikcwcee celoid penis into her, and she disapproves, all she needs to do is flex her vaginal muscles and the penis just flubs out. So, genitalia differs so much, not just to fascinate us, but because in every species, they're the result of a furious evolutionary tango of sex that has been going on for millions of years and will continue for millions of years to come.

Open Cloze

The evolutionary tango of animal genitalia. Can you guess what you're looking at? If you ________ "duck ______," you'd be right. Although the bird's outward appearance may not ______ you as especially odd, it uses this strange, intricate, cork-screw shaped contraption to reproduce. We see similarly unbelievable genitalia in _______, mammals, reptiles, fish, spiders, and even snails. Apparently, no ______ ______ ______ and into more variable shapes than those ________ in procreation. Superficially, it makes sense because evolution works via reproduction. When an animal leaves more offspring, its genes will spread. And since genitalia are an animal's tools for reproduction, any improvement there will have immediate effect. And yet, what's the point of having such decorative ______ regions? After all, the function of genitalia seems simple. A penis deposits a bit of sperm and a vagina receives it and delivers it to the egg. A pipette-like thingy on the male and a funnel-like gizmo on the female should do just fine for any animal. And yet, that's not what we see. The penis of a chicken flea, for example, looks nothing like a pipette, more like an ________ grandfather clock. And the vagina of a featherwing beetle resembles something you'd find in a Dr. Seuss book. Throughout the animal _______, _________ are very _______ things, much more complicated than seems necessary for what they're meant to do. That's because genitalia do more than just deposit and receive sperm. Many male animals also use the penis as courtship device, like crane flies. In some South American species, males have a tiny washboard and _______ on their _____, which ________ a song that reverberates throughout the female's body when they mate. It's thought that if female crane _____ enjoy this _______ serenade, they'll allow the male to father their offspring. This way, the genes of the most musical penises spread, leading to rapid _________ of insects' phalluses. Similarly, some beetles have two little drumsticks on either side of the penis. During mating, they'll rub, slap, or tap the ______ with these. And some hoofed mammals, like rams and bulls, use a whip-like extension on the penis's left side to create a _________ during mating. But how can females really choose between males if she can only assess them after mating? This is where the power of female adaptation comes into play. In fact, insemination is different to conception, and the female genitalia exploit this distinction. For instance, in some dung flies, the vagina contains pockets for separating sperm from different males depending on how appealing they were. _____ using their penises for _________ and females controlling their own _____ management are two _______ why genitalia evolve into such complex ______. But there are others because genitalia are also where a sexual conflict is played out. A female's interests are best served if she fertilizes her eggs with the sperm of the best fathers and _______ _______ variability amongst her _________. For a male, on the other hand, this is bad news. For him, it would be best if a female used his sperm to fertilize all of her eggs. So we see ______ of adaptation in an evolutionary arms race to retain _______. Black widow spiders have a disposable penis tip that breaks off inside the vagina blocking the attempts of his rivals, and bed bug males bypass a female's genitalia __________ using a syringe-like penis to inject sperm _____ directly into her belly. Not to be _______, _______ have evolved their own countermeasures. In some bed bug species, the females have evolved an entirely new set of genitalia on their right hand flanks where the males usually pierce them. That allows them to maintain the power to filter out unwanted sperm with their genitalia. And duck _______ are shaped like a _________ spiral so that when the male inflates his long, ________________ ______ penis into her, and she disapproves, all she needs to do is flex her vaginal muscles and the penis just flubs out. So, genitalia differs so much, not just to fascinate us, but because in every species, they're the result of a furious evolutionary tango of sex that has been going on for millions of years and will continue for millions of years to come.

Solution

  1. faster
  2. genitalia
  3. flies
  4. answered
  5. evolve
  6. complex
  7. scraper
  8. altogether
  9. evolution
  10. insects
  11. involved
  12. offspring
  13. clockwise
  14. kingdom
  15. vagina
  16. outdone
  17. cells
  18. sperm
  19. genetic
  20. females
  21. reasons
  22. strike
  23. counterclockwise
  24. coiled
  25. nether
  26. organs
  27. unusual
  28. males
  29. cycles
  30. creates
  31. produces
  32. sensation
  33. vaginas
  34. penis
  35. courtship
  36. exploded
  37. control
  38. female
  39. shapes

Original Text

The evolutionary tango of animal genitalia. Can you guess what you're looking at? If you answered "duck vagina," you'd be right. Although the bird's outward appearance may not strike you as especially odd, it uses this strange, intricate, cork-screw shaped contraption to reproduce. We see similarly unbelievable genitalia in insects, mammals, reptiles, fish, spiders, and even snails. Apparently, no organs evolve faster and into more variable shapes than those involved in procreation. Superficially, it makes sense because evolution works via reproduction. When an animal leaves more offspring, its genes will spread. And since genitalia are an animal's tools for reproduction, any improvement there will have immediate effect. And yet, what's the point of having such decorative nether regions? After all, the function of genitalia seems simple. A penis deposits a bit of sperm and a vagina receives it and delivers it to the egg. A pipette-like thingy on the male and a funnel-like gizmo on the female should do just fine for any animal. And yet, that's not what we see. The penis of a chicken flea, for example, looks nothing like a pipette, more like an exploded grandfather clock. And the vagina of a featherwing beetle resembles something you'd find in a Dr. Seuss book. Throughout the animal kingdom, genitalia are very complex things, much more complicated than seems necessary for what they're meant to do. That's because genitalia do more than just deposit and receive sperm. Many male animals also use the penis as courtship device, like crane flies. In some South American species, males have a tiny washboard and scraper on their penis, which produces a song that reverberates throughout the female's body when they mate. It's thought that if female crane flies enjoy this unusual serenade, they'll allow the male to father their offspring. This way, the genes of the most musical penises spread, leading to rapid evolution of insects' phalluses. Similarly, some beetles have two little drumsticks on either side of the penis. During mating, they'll rub, slap, or tap the female with these. And some hoofed mammals, like rams and bulls, use a whip-like extension on the penis's left side to create a sensation during mating. But how can females really choose between males if she can only assess them after mating? This is where the power of female adaptation comes into play. In fact, insemination is different to conception, and the female genitalia exploit this distinction. For instance, in some dung flies, the vagina contains pockets for separating sperm from different males depending on how appealing they were. Males using their penises for courtship and females controlling their own sperm management are two reasons why genitalia evolve into such complex shapes. But there are others because genitalia are also where a sexual conflict is played out. A female's interests are best served if she fertilizes her eggs with the sperm of the best fathers and creates genetic variability amongst her offspring. For a male, on the other hand, this is bad news. For him, it would be best if a female used his sperm to fertilize all of her eggs. So we see cycles of adaptation in an evolutionary arms race to retain control. Black widow spiders have a disposable penis tip that breaks off inside the vagina blocking the attempts of his rivals, and bed bug males bypass a female's genitalia altogether using a syringe-like penis to inject sperm cells directly into her belly. Not to be outdone, females have evolved their own countermeasures. In some bed bug species, the females have evolved an entirely new set of genitalia on their right hand flanks where the males usually pierce them. That allows them to maintain the power to filter out unwanted sperm with their genitalia. And duck vaginas are shaped like a clockwise spiral so that when the male inflates his long, counterclockwise coiled penis into her, and she disapproves, all she needs to do is flex her vaginal muscles and the penis just flubs out. So, genitalia differs so much, not just to fascinate us, but because in every species, they're the result of a furious evolutionary tango of sex that has been going on for millions of years and will continue for millions of years to come.

Frequently Occurring Word Combinations

ngrams of length 2

collocation frequency
evolutionary tango 2
crane flies 2
bed bug 2

Important Words

  1. adaptation
  2. altogether
  3. american
  4. animal
  5. animals
  6. answered
  7. apparently
  8. appealing
  9. appearance
  10. arms
  11. assess
  12. attempts
  13. bad
  14. bed
  15. beetle
  16. beetles
  17. belly
  18. bit
  19. black
  20. blocking
  21. body
  22. book
  23. breaks
  24. bug
  25. bulls
  26. bypass
  27. cells
  28. chicken
  29. choose
  30. clock
  31. clockwise
  32. coiled
  33. complex
  34. complicated
  35. conception
  36. conflict
  37. continue
  38. contraption
  39. control
  40. controlling
  41. counterclockwise
  42. countermeasures
  43. courtship
  44. crane
  45. create
  46. creates
  47. cycles
  48. decorative
  49. delivers
  50. depending
  51. deposit
  52. deposits
  53. device
  54. differs
  55. disapproves
  56. disposable
  57. distinction
  58. dr
  59. drumsticks
  60. duck
  61. dung
  62. effect
  63. egg
  64. eggs
  65. enjoy
  66. evolution
  67. evolutionary
  68. evolve
  69. evolved
  70. exploded
  71. exploit
  72. extension
  73. fact
  74. fascinate
  75. faster
  76. father
  77. fathers
  78. featherwing
  79. female
  80. females
  81. fertilize
  82. fertilizes
  83. filter
  84. find
  85. fine
  86. fish
  87. flanks
  88. flea
  89. flex
  90. flies
  91. flubs
  92. function
  93. furious
  94. genes
  95. genetic
  96. genitalia
  97. gizmo
  98. grandfather
  99. guess
  100. hand
  101. hoofed
  102. improvement
  103. inflates
  104. inject
  105. insects
  106. insemination
  107. instance
  108. interests
  109. intricate
  110. involved
  111. kingdom
  112. leading
  113. leaves
  114. left
  115. long
  116. maintain
  117. male
  118. males
  119. mammals
  120. management
  121. mate
  122. mating
  123. meant
  124. millions
  125. muscles
  126. musical
  127. nether
  128. news
  129. odd
  130. offspring
  131. organs
  132. outdone
  133. outward
  134. penis
  135. penises
  136. phalluses
  137. pierce
  138. pipette
  139. play
  140. played
  141. pockets
  142. point
  143. power
  144. procreation
  145. produces
  146. race
  147. rams
  148. rapid
  149. reasons
  150. receive
  151. receives
  152. regions
  153. reproduce
  154. reproduction
  155. reptiles
  156. resembles
  157. result
  158. retain
  159. reverberates
  160. rivals
  161. rub
  162. scraper
  163. sensation
  164. sense
  165. separating
  166. serenade
  167. served
  168. set
  169. seuss
  170. sex
  171. sexual
  172. shaped
  173. shapes
  174. side
  175. similarly
  176. simple
  177. slap
  178. snails
  179. song
  180. south
  181. species
  182. sperm
  183. spiders
  184. spiral
  185. spread
  186. strange
  187. strike
  188. superficially
  189. tango
  190. tap
  191. thingy
  192. thought
  193. tiny
  194. tip
  195. tools
  196. unbelievable
  197. unusual
  198. unwanted
  199. vagina
  200. vaginal
  201. vaginas
  202. variability
  203. variable
  204. washboard
  205. widow
  206. works
  207. years