Cheaters are everywhere in the biological world, according to our broadened definition of cheating. Monkeys sneak around for sex; possums, well, play "possum," as they are famous for when pursued by a predator; birds scare rivals away from contested food by crying wolf—emitting alarm calls that are normally used to warn others about an approaching predator; amphibians and reptiles are master impostors, altering their body color to blend into their backgrounds; stickleback fish protect their eggs and babies by misdirecting their cannibal peers away from their nests; defenseless caterpillars ward off predators by masquerading as dangerous animals such as snakes with big false eyes (see color plate 1); squids escape from predators by ejecting ink to create a "smoke screen" in the water.
Examples of lying and deceiving behavior in animals can go on and on.#2399•
Fungi cheat too. For example, truffles—mushroom-like species that form fruiting bodies underground—emit a steroid called androstenol that mimics the pheromone of wild boars. Androstenol is produced in the testes of adult boars and has a musty odor to the human nose. When female pigs sense the truffle aroma, they will dig exuberantly for the source.
What they don't know is that they are being suckered by something bearing no resemblance to the swine beau they are hoping for.#2398•
Bacteria also suffer from this social dilemma. There is no shortage of free riders that contribute less than their fair share to the production of siderophores yet still devour the catch—iron—along with all the others who've done the work. Obviously, cheaters can sabotage the collective effort. If they are too numerous, productivity of siderophores will drop, and the amount of iron collected will decline, which in turn will put the livelihood of the entire community at risk.
Threatened by this potentially fatal consequence, honest producers have evolved an arsenal of anti-fraud strategies.
Some bacteria, for example, can band together with their genetic look-alikes to prevent free riders from infiltrating their community.
They may even use toxins to kill the cheaters.#2397•
Cheating can also take place within the same individual. Cancer cells, for example, are cheating cells that shirk the duty of cooperation with other cells in the body. They instead gobble up all the resources, proliferate, and refuse to commit suicide when commanded to do so.#2395•
Even inside a typical cell, cheating is part of life. For instance, the B chromosome ekes out a living by cheating. In sharp contrast to the normal "A" chromosomes that are familiar to us, B chromosomes are smaller and can be common, and they can be found in varying numbers within a cell (fig. 1.2). What makes them stand out is their ability to tag along without doing any work.
In other words, they are passed on, generation after generation, by hitchhiking without contributing to cell functionality, akin to party crashers living on free food while enjoying themselves at their host's expense.#2402•
These genes code for enzymes called homing endonucleases, which can cut open a DNA chain at specific locations. They then add a replica of themselves into the breach. It's like a rogue physician who uses his own sperm to inseminate eggs from women who come to him seeking artificial fertilization.#2401•