Sex on Six Legs_ Lessons on Life, Love, and Language From the Insect World - Marlene Zuk [4]
And yet they do all those things in stunningly different ways from humans, getting to what look like the same destinations without any of the same highway systems or modes of transport. That reflection we recognize is eerily superficial, because what drives the behaviors is not what drives our own. Underneath the maternal care, the language, the system of social favors given and returned is a handful of nerve cells casually strung together in a few small clusters along the body wall. No cerebrum, no right and left hemispheres, not even that so-called reptilian brain part, the cerebellum. They don't have a pituitary gland, or a system of hormones like ours. And yet a sphecid wasp with a body smaller than a kidney bean can dig a burrow in the sand, go off to find a caterpillar just the right size to feed her young, and bring it back to the burrow, remembering where it was and how many other caterpillars she had already brought there. Most of us couldn't find a single caterpillar if we were commanded to do so, much less bring it back to a site the equivalent of a county away. A whole ant colony, with all the drama of the queen suppressing the reproduction of her daughters, can live inside an acorn. A female insect can survey an array of frantically displaying males, select one on the basis of a tiny difference in song, color, or smell, and then store his sperm for weeks or even years before selectively using a particular mate's DNA to fertilize some—and only some—of her eggs.
How is that possible? How can you get what looks like human reasoning, even human love, when you lack not only a human brain but even the chemicals in the blood that drive human emotions? It is easy to endow a fellow warm-blooded creature, for example, a dog or a bird, with motivations and feelings like our own, harder to do so when the entire nervous system of a fruit fly producing a wing-fluttering courtship song of come-hither would fit on a sesame seed.
Insects bring home the uneasy truth that you don't need a big brain to do big things, and that in turn makes us question how the mind and, dare to say it, the spirit, are related to the brain. It even makes us question what it means to be human. What does it mean to have complex behavior? Does it mean you are smart? Is the complexity of a honeybee nest with its exquisitely economical hexagons equal to that of a Park Avenue brownstone? We all have our prejudices, and even scientists can be terribly vertebrate centric about understanding behavior. A huge fuss is made about the behavioral flexibility it takes for a New Caledonian crow to construct a tool from a leaf to poke a grub out of a branch, or a chimp to use a stick to get termites from a hole in the ground. It's that flexibility, we say, that's important—humans and a few other anointed species can change what they do to suit changing circumstances. We aren't little automatons; we are unique individuals. Behavioral flexibility is taken as the hallmark of intelligence and hence the key to human evolution. It is often linked to brain size, and that in turn is said to be important for allowing our complex behavior.
Natural selection can produce what looks uncannily like intelligent thought or emotion but is no more than the relentless culling of minute variations in genetic makeup, generation after generation, for millions of years. Not only that, but insects too have small personalities, with some showing boldness in new situations and some hanging back with what looks an awful lot like shyness. It's turning out that we haven't cornered the market on individuality, either.
Insects make us question virtually every assumption we have about what makes humans human. They lay bare the workings of evolution.
Insects Are a Window
INSTEAD of a mirror, sometimes insects hold up a window, so that we can see through it and imagine life with different ground rules. Insects wear their skeletons on the outside, and they insouciantly transform from egg to grub to gleaming adult in the space of days. Insects use their antennae to smell and hear in ways