Wednesday, February 01, 2012

Ants, flies and bees, if you please

kw: book reviews, nonfiction, natural science, insects

An ant colony in an acorn. A bedbug with a penis that is more of a spear. Talking bees. Crickets that sing, and some that don't. If we really make the effort to get down and look, we find that insects are even weirder than we could imagine. Marlene Zuk, arthropod amateuse extraordinaire, has done us all a great favor with her book Sex on Six Legs: Lessons on Life, Love, and Language from the Insect World. I must say she has also produced the champion of provocative titles!

Indeed, in matters of sex, we vertebrates must seem quite prosaic and limited. One fly has a penis longer than his body, so he can mate with a female that is still in cocoon. Many of the "organs" of male insects are quite elaborate, with spikes, scrapers and spoons for rummaging around to dig out other males' sperm before depositing his own. You could call it sperm competition with weapons. Half of one chapter investigates same-sex courtship and its implications for our understanding of homosexual behavior. Even the insect variety elicits strong political statements from most proponents or opponents of human homosexual freedom. But the big lesson here is that, in sex as in all things, insects exhibit more variety by a huge factor than is found in all the rest of the animal world.

This is true of communication. When finding a new colonial home, some species of ant reach a partial consensus by "quorum sensing" of signals that are still not wholly known to us, then picking up their nestmates and carrying them ignominiously to the new digs. Swarming bees, on the other hand, may have a dozen or more competing selections to choose from, each supported by one or more "waggle dancers", and the entire swarm will grow toward consensus until they are in full agreement, upon which they all head straight for their target. Other means of communication seem to guide the swarm, as led by faster-flying "leaders".

Is such communication really a language? Let's not be too chauvinistic about our own language abilities. As means of conveying emotion, our words are rich and evocative, but as means of conveying information, not so much. We need lots of reinforcement, not unlike the ants that need to be carried. This is why it takes four to six years to get a B.S. or B.A. degree by attending lectures, when the same material can be learned via correspondence about twice as fast. My father enrolled in course after course through ICS (International Correspondence School) while my brothers and I were growing up, earning certificates galore; the school was not accredited to offer degree diplomas, but companies knew that a suitable collection of certificates was worth more than the degree any day. If insect communication gets the job done, what more can one ask?

Why is the sex ratio of most mammals about 50:50, while for social insects females outnumber males by thousands to one? This is no utopia for the guys, though. After a single sex act, they die. Further, that means that popular conceptions are typically wrong. The film Antz portrays male worker ants; all worker ants of all species are female. An ad for an antihistamine spray portrays a male worker bee courting a flower; all worker bees are female. So are the wasps that sting you when you tread on their nest or knock it out of the tree. And the spiders you see are nearly all female; the males are so small they are easily mistaken for offspring. The big exception to this is tarantulas. The migrating tarantulas are nearly all male. The females, which live ten times as long, stay in their nests awaiting males to find them and court them.

The book is filled with many more examples behavior of insects and other arthropods. Their range of behavior exposes their range of genetic diversity. Genetically, two species of beetle may be as diverse from one another as horses are from hummingbirds. And there are about a million known beetle species. But do any of them think? The opening chapter discusses "bug smarts", and the answer is, we don't know yet, but the more we study it the more likely it seems to be. Bees and wasps can recognize faces, and some kinds are reliable enough that it has been soberly suggested that a wasp in a cage could indicate when it sees a familiar face on a security monitor. Trouble is, you'd need to train a lot of wasps, and somehow overcome their impulses to do things like hunt caterpillars while they were watching the screen. We are probably closer to a reliable computer solution to this dilemma; viz. Picasa and other image-recognition photo album programs. They do a surprisingly good job picking out a person photographed at a new angle or even at a different age.

The author's primary interest is crickets. She has a cool story about them also. In one place, she could easily find crickets, but could not hear any. Usually, if there is a cricket within a half mile, you know it is there! It happens that parasitic wasps were using the cricket's songs to locate them. So the crickets had quit singing and were using other means to find one another. No matter what you think you know about insects, there is a species somewhere doing just the opposite. Learning their ways could occupy a lifetime, which is why there are entomologists, of course.

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