Out of the Mouths of Babes

Which came first -- sharks or insects?

This is another question that popped up during class. It came from India; she, her younger sister India and their fabulous mama Nicole are vying for the coveted Most Hopelessly Adorable Family Ever award. You just want to follow them around all day with a tape recorder, or at least a really big piece of paper and a pen, and catch all the unstudied cuteness.

Anyway, this was another one I had to look up after class. Specifically, I checked volumes two and three of A Cartoon History of the Earth, the whole series of which tops my can't-recommend-it-highly-enough list. Written by Jacqui Bailey and Matthew Lilly and published by Kids Can Press, they are that rare combination in children's nonfiction -- appealing and informative. These are science books that my son, generally highly suspicious of any perceived attempts to whip a little learning on him when he isn't looking, repeatedly requests I read to him at bedtime. And no, I don't get anything for endorsing them. And yes, they're available in paperback. 'Nuff said.

To answer India's question: life first came into existence in the ocean, and the simplest fish -- jawless, toothless, boneless, sometimes sporting a touch of exoskeleton at the head and tail -- made their appearance between 505 and 440 million years ago. From these evolved fish with skeletons -- the first vertebrates. Along with bony fish came the cartilaginous sharks. These emerged about 400 million years ago.

The ocean teemed with life, and land was beginning to get its first taste of it as well. Algae was creeping its way ashore sometime around 500 million years ago, and the first true land plants raised their heads between 440 and 410 million years ago. Life will flood into any niche offered it, and land plants were a source of food too tempting to go untouched. As they set down roots, arthropods eagerly made their way ashore. Arthropods make up one of the biggest groups of animals around. These invertebrates include mites, millipedes, crabs, lobsters, arachnids -- and insects.

There is some debate as to when true insects came into existence. If you consider springtails -- wingless creatures so tiny that in the grasslands they favor, some 5000 of them can occupy a single square foot -- to be insects, then the first insects we have any fossil record for emerged some 400 million years ago. Some specialists don't class springtails as insects, however. As a civilian, I don't know the arguments for or against their inclusion, and must stand neutrally by (although it would take the lightest touch in the world to prompt me into some further research on the point). They certainly look like insects (six legs, antennae, disgusting little stinger-looking thing sticking out of their backsides), but as my dear great aunt Hazel used to say regarding her marriage to my not-as-dear-but-all-right-if-you-like-that-sort-of-thing great uncle Chester, looks aren't everything. If you are a member in good standing of the Springtails? Pooh, Pooh! association, then you would say that true insects came into being some hundred million years later than sharks (and springtails) -- that is, about 300 million years ago. Some of these winged insects were recognizably similar to the dragonflies and cockroaches currently gracing our planet.

So, India -- either it's pretty much a tie between sharks and insects, or sharks beat bugs by a tidy hundred million years. Run along and get your degree in entymology and you can settle the question for us one way or the other.

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