BitTorrent and Vampire Bats

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BitTorrent and Vampire Bats

• Miranda Mowbray, HP Labs
• miranda_mowbray_at_hp.com

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BitTorrent and Vampire Bats

• BitTorrent
• Ideas from animal sharing behaviour
• Vampire bats
• Aquatic worms (ophryotrocha diadema)
• Brown capuchin monkeys
• Conclusions/Questions

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BitTorrent

• File distribution tool
• Created by Bram Cohen
• Downloading peers share bandwidth
• Open source software, pirate movies,
• videos of lectures, podcasts, TV episodes,
• interactive games
• Tit-for-tat incentive for uploading

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Vampire bats

• Need to drink 50-100 of their weight in blood
  each night
• If they dont get blood for 60 hours, they die
• Estimated one-year survival rate 16
• Actual survival rate 76
• Share blood meals with unrelated bats close to
  starvation
• G. S. Wilkinson, Reciprocal food sharing in the
  vampire bat, Nature 308183, 1984
• Idea harsh environment for uncooperative
  BitTorrent peers sharing ratio enforcement
• Idea preferentially upload pieces of files to
  peers closer to starvation

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Ophryotrocha diadema

• Aquatic worm
• Hermaphroditic, not self-fertilizing
• Alternates roles in mating, tit-for-tat-like
• Apparently no punishment of cheats
• Long courtship ritual (for a worm)
• Gabriella Sella and M. Cristina Lorenzi, Partner
  fidelity and egg reciprocation in the
  simultaneously hermaphroditic polychaete worm
  Ophryotrocha diadema, Behavioural Ecology
  11260-4, 2000
• Idea hysteresis for BitTorrent uploading

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Brown Capuchin Monkeys

• Tit-for-tat-like behaviour in food sharing
• Remembers whether a particular monkey was
  generous in the past, behaves accordingly
• But doesnt remember exact amount of food shared
• May reject ungenerous offers
• Frans de Waal, Attitudinal reciprocity in food
  sharing among brown capuchin monkeys. Animal
  Behaviour 60253-61, 2000.
• Idea upload only to generous peers

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BitTorrent and Vampire Bats

• BitTorrent
• Ideas from animal sharing behaviour
• Vampire bats
• Aquatic worms (ophryotrocha diadema)
• Brown capuchin monkeys
• Conclusions/Questions

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