Paleofantasy: What Evolution Really Tells Us about Sex, Diet, and How We Live by Marlene Zuk
Authors: Marlene Zuk
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two decades trying to figure out how the crickets resolved their evolutionary conundrum.
My colleagues and I discovered many interesting parts to the solution, but the real stunner happened during what I thought would be a somewhat rushed and routine visit to Kauai. We had been doing our research on the Big Island, Oahu, and Kauai, and for several years I had been catching and dissecting crickets in each place to see how the males infested with parasites might differ from the ones that had escaped. It was always a small thrill to open up the body cavity under the microscope and see, in addition to all the normal cricket organs and tissue, a plump white maggot glistening under the cold fiber-optic light we use for dissection. The tiniest maggots have little black racing stripes along the sides, giving them a cheerful perkiness that belies their more sinister character.
None of my colleagues saw the charm of any of the fly larvae, large or small, but we all could see that the percentage of males harboring the maggots was always highest on Kauai. Nearly a third of all the males we caught were infested, and we wondered for years whether the relentless hunting by so many flies would eventually wipe out the cricket population entirely. We don’t know how long the flies have been on the islands, but we know the crickets did not evolve there, so the relationship is relatively recent, suggesting that it might not be stable.
Indeed, starting in the late 1990s, it became increasingly difficult to find any crickets at all on Kauai. A field that once held dozens grew more and more silent, and by 2001 we heard only a single cricket calling in our usual field site. That doesn’t mean others weren’t around, of course, but the relative silence was symptomatic of a major decline in the population.
Thus, when my husband and I returned to Kauai in 2003, I was not optimistic. It was certainly possible that the flies had finally proven the death knell for the crickets on the island. And sure enough, when we drove up to the field where we usually found our samples, the night was silent. But having come so far, I figured we might as well get out of the car and take a look. We put on our headlamps and started walking up the road.
And that’s when I felt like William the cat. Because in front of me, on each side, hopping on the ground and perching on the grass, were crickets. Lots of crickets. More crickets than I had seen on Kauai for years—maybe ever. I caught one. It was one of our species all right, and it was even a male, easily distinguishable from the females by the absence of a long, straw-like ovipositor used to lay eggs. But I didn’t hear a thing.
Remember that singing is, well, what crickets do. Except for a few oddball species that definitely did not include my study subjects, the definition of a male cricket is an animal that gets out there every night, lifts his wings, and rubs them together to make noise. Individuals may refrain from calling sometimes for one reason or another—it’s too cold, they are injured, or they mated so recently that they cannot produce sperm for the next female—but chirping is part of the cricket identity. So my mind started going through puzzled loops, much as I imagine William’s had done years before: These can’t be crickets, because they aren’t calling. But look, there are lots of crickets. Maybe they are a different kind of cricket that just suddenly appeared here on Kauai? Nope, they are my kind of crickets. But these can’t be crickets, because they aren’t calling. Maybe I’ve gone deaf? No, that’s not it. But these can’t be . . . etc.
I would like to be able to say that I resolved the disharmony of the situation more quickly than William had done in giving up his futile perusal of the motel bed and falling asleep, but the truth is that although I shook myself out of my own cognitive dissonance and actually tried to use science to solve the puzzle, it took a few months
My colleagues and I discovered many interesting parts to the solution, but the real stunner happened during what I thought would be a somewhat rushed and routine visit to Kauai. We had been doing our research on the Big Island, Oahu, and Kauai, and for several years I had been catching and dissecting crickets in each place to see how the males infested with parasites might differ from the ones that had escaped. It was always a small thrill to open up the body cavity under the microscope and see, in addition to all the normal cricket organs and tissue, a plump white maggot glistening under the cold fiber-optic light we use for dissection. The tiniest maggots have little black racing stripes along the sides, giving them a cheerful perkiness that belies their more sinister character.
None of my colleagues saw the charm of any of the fly larvae, large or small, but we all could see that the percentage of males harboring the maggots was always highest on Kauai. Nearly a third of all the males we caught were infested, and we wondered for years whether the relentless hunting by so many flies would eventually wipe out the cricket population entirely. We don’t know how long the flies have been on the islands, but we know the crickets did not evolve there, so the relationship is relatively recent, suggesting that it might not be stable.
Indeed, starting in the late 1990s, it became increasingly difficult to find any crickets at all on Kauai. A field that once held dozens grew more and more silent, and by 2001 we heard only a single cricket calling in our usual field site. That doesn’t mean others weren’t around, of course, but the relative silence was symptomatic of a major decline in the population.
Thus, when my husband and I returned to Kauai in 2003, I was not optimistic. It was certainly possible that the flies had finally proven the death knell for the crickets on the island. And sure enough, when we drove up to the field where we usually found our samples, the night was silent. But having come so far, I figured we might as well get out of the car and take a look. We put on our headlamps and started walking up the road.
And that’s when I felt like William the cat. Because in front of me, on each side, hopping on the ground and perching on the grass, were crickets. Lots of crickets. More crickets than I had seen on Kauai for years—maybe ever. I caught one. It was one of our species all right, and it was even a male, easily distinguishable from the females by the absence of a long, straw-like ovipositor used to lay eggs. But I didn’t hear a thing.
Remember that singing is, well, what crickets do. Except for a few oddball species that definitely did not include my study subjects, the definition of a male cricket is an animal that gets out there every night, lifts his wings, and rubs them together to make noise. Individuals may refrain from calling sometimes for one reason or another—it’s too cold, they are injured, or they mated so recently that they cannot produce sperm for the next female—but chirping is part of the cricket identity. So my mind started going through puzzled loops, much as I imagine William’s had done years before: These can’t be crickets, because they aren’t calling. But look, there are lots of crickets. Maybe they are a different kind of cricket that just suddenly appeared here on Kauai? Nope, they are my kind of crickets. But these can’t be crickets, because they aren’t calling. Maybe I’ve gone deaf? No, that’s not it. But these can’t be . . . etc.
I would like to be able to say that I resolved the disharmony of the situation more quickly than William had done in giving up his futile perusal of the motel bed and falling asleep, but the truth is that although I shook myself out of my own cognitive dissonance and actually tried to use science to solve the puzzle, it took a few months
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