December 7, 2011 8:22:00 AM
I think of insects as robots. A fantastically successful class of animal, insects are creatures that almost everybody encounters almost every day. Like robots, though, they very often exhibit an obvious response to a stimulus. Shine a light and a moth goes for it; shine a light and a roach runs away; waft a specific pheromone and specific insects swarm to the source. Insects are far more complicated than just that, of course, because they have so many hard-wired responses, but surely they are just tiny robots whose complexity far surpasses anything we have been able to build. Humans, of course, are different: we are not automatons, and we have personalities and each of us is an individual with particular characteristics. If insects are robots, however, they are pretty sophisticated ones, and they might even have personalities (and if you are stickler who thinks only persons can have personalities, let's say insects can have different temperaments). This is one of the surprising lessons in Sex on Six Legs: Lessons on Life, Love, & Language from the Insect World (Houghton Mifflin Harcourt) by biologist Marlene Zuk. Robots might have personalities, too, someday, I suppose, and I suppose that at least initially they will be rudimentary ones like those of the insects Zuk describes. Nonetheless, Zuk's delightful book, full of behavior so strange, and sometimes so gruesome it is beyond the power of any Hollywood horror screenwriter to imagine, makes a reader look anew at how complicated these little robots are; if they are robots, then our robots have lots of catching up to do.
Insects are here to stay, and Zuk is enthusiastic about how much they can accomplish. It's not just that they provide pollination without which the whole system of plants would collapse, and it isn't just that they break down and recycle plant and animal matter and excrement so that all of nature's cycles are renewed, and it isn't just that scientists might coax them to supply genetic information to fight malaria. Such things are vital, Zuk says, but just practical. Insects, she says, "can help us see another way of life, like a gloriously overblown version of cultural exchange." Watch insects, and you learn "that it is possible to be unselfish without a moral code, sophisticated without an education, and beautiful wearing a skeleton on the outside." We marvel at the different behavior of people in other societies, but they get along fine in their way; insects do that in spades, and they help us see that our way of life might be successful, but hugely different ways are no less so.
First, about the personalities of insects. You would surely agree that some people are shy and some people are bold, and that neither personality guarantees success in the world but either might be useful in different situations. Crickets (a species to which Zuk admits fondness because of her studies of them) have different degrees of boldness or shyness, even within the same species; the Chinese have even a sort of miniature cockfighting competition, with crickets instead of cocks, and winners earn tributary poems about their victories, and, I assume, cash for their owners. Water striders also have different amounts of aggressiveness. You might think that the aggressive males would be more successful in mating, but the females have ways of responding to aggressive pursuits, and they mate more often with males that don't use the hard sell. There are plenty of other examples here. It turns out that fruit flies have a gene that makes their larval forms either move around a lot or sit around a lot; they are called respectively "rovers" and "sitters," and the behavior is of course not something they learn by watching their parents. Having a population with a range of personalities is a good survival strategy; variation in this and in physical traits is, of course, one of the essentials for evolution.
Having shown that insects have personalities, in their way, Zuk gives examples of other sophisticated behavior. All wasps of one species look pretty much alike to us, but some species can recognize faces of other wasps. Not only that, but bees can recognize individual human faces. This has implications for humans with the condition known as prosopagnosia or "face blindness," and maybe for computer face recognition programs. After all, if humans have a special part of the brain devoted to that task (the part that fails in patients with the condition), then how can bees with tiny specks of brain manage it? Ants can by group behavior, and not by communicating with each other, find the shortest path to get back and forth to food. Bees do communicate; they famously dance to show where sources of nectar are, but they also dance to show potential sites for making a home. "One swarm took about 16 hours of dancing, spread over three days, to reach a decision, with eleven different potential sites taken under consideration before the winner was determined."
Naturally in a book of this title, insects' sex is covered here. "There is nothing like a view of the genitalia of insects," Zuk writes, "to convince you that the male equipment in human beings is rather dull and pedestrian in its appearance." These penises have knobs and curves and kinks that not only ensure that there is a lock-and-key fit to keep the equivalent of bestiality from happening. Many of these penises have all those attachments as a way of displacing the sperm deposited by a previous male. (Zuk does not mention it, but research has shown that human penises do the same thing.) Some male katydids produce a nutritive blob called a spermatophylax and it might be a third of the male's body weight. When it comes time for mating, he presents it to the female (he would not stand a chance without the gift) and while she eats, he gets the sperm into her. The bigger the spermatophylax, the longer she eats and the longer he has to drain sperm. Scorpionflies catch prey to give to their females in the same situation, but some just produce a ball of saliva that serves the same purpose.
There is plenty of bizarre and icky stuff here, the type of thing that Darwin knew would inspire a sermon from a devil's chaplain. Plenty of mothers eat their babies, often the mothers that tend their young. Like everything else, it's a tradeoff; if the mother cannot find enough food for herself, she eats some of the babies and keeps herself going so that the ones that remain get her continued protection. The genitalia of the male honeybee explodes after sex. Flies deposit eggs into crickets and the larvae eat the cricket's fat and then colonize the entire body of the cricket until it is just a zombie, "a shell that looks like a cricket but is pulsing inside with fly."
Insects aren't cuddly, and we don't risk anthropomorphizing them. They are almost completely alien. They do not have our huge and complicated brains, and they also do not have pituitary or other hormones that are essential to our beings. Yet as Zuk shows they often manage to do the same things we do, tending animals, communicating information, courting, and learning. This makes them wonderful objects of experimentation and study for biologists, entomologists, and even psychologists. For the rest of us, Zuk's book of astonishing facts and insights, presented with infectious enthusiasm and welcome good humor, is an instructive read not just about what insects do, but also about how much humans do in common with them.