Module · 4

Forty-plus independent eyes.

Each dot below is a known independent origin of a major trait, plotted on a 600-million-year axis. The clusters tell you which problems are easy to find, and which ones — like photosynthesis — happened only once.

MYA · log scale

3500

1000

500

250

100

10k

Photosynthesis×1

Cyanobacteria~3500 MYA

Venom×5

Cnidarians~600 MYA

Spiders & scorpions~400 MYA

Stinging hymenopterans~150 MYA

Advanced snakes~60 MYA

Cone snails~55 MYA

Camera eye×5

Vertebrates~530 MYA

Box jellyfish~500 MYA

Cephalopods~480 MYA

Annelid worms~400 MYA

Spiders~150 MYA

Powered flight×4

Insects~410 MYA

Pterosaurs~228 MYA

Birds~150 MYA

Bats~52 MYA

Streamlined aquatic body×5

Sharks~400 MYA

Ichthyosaurs~250 MYA

Penguins~60 MYA

Tuna~50 MYA

Dolphins~30 MYA

Endothermy×2

Mammals~250 MYA

Birds~150 MYA

Eusociality×4

Termites~150 MYA

Ants~140 MYA

Honeybees~80 MYA

Naked mole-rats~30 MYA

Agriculture×4

Leaf-cutter ants~60 MYA

Ambrosia beetles~50 MYA

Termites~30 MYA

Humans~12 KYA

Echolocation×3

Microbats~50 MYA

Toothed whales~30 MYA

Oilbird & swiftlets~20 MYA

Tool use×4

Genus Homo (and earlier)~3.3 MYA

Chimpanzees~2 MYA

Corvids~1 MYA

Octopus, dolphin~recent

Read it like this

Each row is one trait. Each dot is one independent origin of that trait. When dots cluster on a row, the trait is convergent — easy for selection to find. When a row has just one dot, the trait is rare or required a specific accident.

The exception

Photosynthesis. One dot, 3.5 billion years ago, in cyanobacteria. Every other green thing on Earth got it sideways, by swallowing one of those bacteria and keeping it. Convergence is the rule; this is what its absence looks like.