We're All Giant Crab-Men, I Tell You!

Scott Hardie | April 10, 2002
Kelly and I saw this nature/science show on PBS last night about researchers who were trying to find the first creature to walk on land. They started by looking in our DNA, since there's a record there of everything we've evolved from, and they got it back about as far as flatworms before they realized they lost track of ocean vs. land somewhere along the way.

So then they started looking for fossilized tracks. There's this place in Wales where humans have never been and where there are apparently lots of fossils, and they indeed found a bunch of fossilized tracks of some of the earliest explorers of land. They found that instead of being flat like a worm, they found that it was something with legs.

And it made sense. Carnivorism developed long before land mobility, and the most efficient carnivores by far (underwater) are crustaceans, who have legs to move around quickly and sneak up on their prey. According to the scientists, they were the first creatures to evolve legs, joints in their legs, skeletons of any kind (exo or not), eyes, adaptable limbs (claws vs. feet), and antennae. So when some of them, starting possibly with horseshoe crabs, came up on the beach to lay their eggs in the sand, over time some of them may have stayed. And what did they become? Insects. Insects have the same biological structure as crustaceans. Scorpions are an awful lot like lobsters, beetles are an awful lot like horseshoe crabs, etc.

I don't know if all of this was theory or if it was fact, but it was damn cool to think about. The first land explorers were not amphibians, but crustaceans, who became insects, who evolved wings and spread out all over the world, and evolved into other animals. Weird. I guess the biggest block is that we think of bugs as tiny, when many of them are quite large, so it could make sense. Maybe.

Incidentally, The Onion today ran an article, Ask a Guy Trying to Explain What He Saw on NOVA Last Night.