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Ant Amputations: Wound Surgery in Carpenter Ant Colonies

1:23:56 recording · AUTO · 2 speakers

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Brief overview

Florida carpenter ants amputate injured legs to stop infection, a surgical behavior only humans were known to perform.

  1. The injury site decides the surgeryFemur wounds are amputated at the trochanter; tibia wounds get wound care but never a cut.
  2. Anatomy sets the deadlineThe femur's narrow hemolymph channel leaves time to cut; the tibia's wide one lets infection spread first.
  3. Ants never check for bacteriaThey amputate infected and sterile femur wounds alike, so evolution added no extra layer of discernment.
Executive Summary AI
  • Nels Elde brings Vincent Racaniello a July Current Biology report, "Wound-dependent leg amputations to combat infections in an ant society," in which Florida carpenter ants (Camponotus floridanus) go from carpenters to surgeons on their injured nest mates.13:24
  • Whether they operate depends entirely on where the wound is: a femur injury gets amputated upstream at the trochanter, a roughly hour-long job, while a tibia injury gets hours of licking and probing with mouthparts but no cut.24:46
  • Micro-CT cross-sections explain the rule — the femur carries a tiny hemolymph channel among muscle bundles, so amputation can still block the infection, whereas the tibia's wide hemolymph access means the bacteria reach the circulatory system long before an amputation could finish.31:36
  • The authors infected injured ants with Pseudomonas aeruginosa (about 10,000 cells) and saw 95% of isolated ants die, while ants returned to subcolonies of roughly 200 nest mates survived far better and carried lower pathogen loads — and they amputate whether or not bacteria are present, so no microbiologist's extra step evolved.42:17
  • Vincent's pick of the week is the January 20th executive order withdrawing the United States from the World Health Organization, which he calls a science stupid move that will cut off US access to outbreak information on H5N1 and SARS-CoV-2 variants.1:08:24
Key Quote
“So the carpenter ants here, Vincent, are going from carpenters to surgeons.”
— Nels Elde13:29
Key Quote
“And 95% of those ants die of that infection.”
— Nels Elde42:17
Key Quote
“I mean, the ants would be laughing at us at our sort of behaviors here.”
— Nels Elde1:00:55