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Science Tuesday - Animals
Sexier Posterior Evolves Almost Overnight
By CARL ZIMMER, The New York Times, November 30, 2004
Swallows are getting sexier.
Male barn swallows attract females with long tail feathers, and European researchers have observed that over the last 20 years those feathers have become much longer.
"We've demonstrated quite a dramatic change in a short period of time," said Dr. Anders Pape Moller, an evolutionary biologist at Pierre and Marie Curie University in Paris, who conducted the research with Dr. Tibor Szep of the College of Nyiregyhaza in Hungary. The findings are to be published in The Journal of Evolutionary Biology.
Experiments suggest that the males' tails act as advertising for good genes because males must be in good health to spend the energy growing them. The females, the researchers say, are particularly attracted by the tail's two outer feathers.
Dr. Moller, who has been documenting this preference for more than two decades, found that the outer feathers had lengthened by almost half an inch (11.4 millimeters), an increase of 10 percent, one of the biggest evolutionary shifts ever documented in a living population of wild animals. By contrast, the central tail feathers, which don't produce a reaction in females, haven't changed.
Over the last 30 years, researchers have made more than 1,500 measurements of natural selection in wild populations of animals and plants. Droughts on the Galápagos Islands, for example, have favored larger beaks in finches, because the surviving seeds are harder to crack. But the shift measured by Dr. Moller and Dr. Szep is greater.
Dr. Moller and Dr. Szep suspect that the agent for this is the long-term spread of the Sahara. The barn swallows they are examining migrate from Denmark to South Africa for the winter, then return by way of Algeria in the spring. The reduction of vegetation there around the desert may mean fewer insects for the hungry swallows.
"If they get across the Sahara and there's nothing to eat, it's tough," Dr. Moller said. Weaker male swallows starve; stronger ones reach Denmark. There they pass on their genes to the next generation - including genes for longer tails.
But that explanation has prompted some skepticism.
"I am prepared to believe that the birds are probably evolving, but not that climate change is the cause, simply because there can be so much else going on," said Dr. David Reznick, an evolutionary biologist at the University of California at Riverside.
Dr. Moller plans to search for more evidence.
SIDE EFFECT: Good Dogs, Bad People, and Cats
By JAMES GORMAN, The New York Times, November 30, 2004
Do animals have moral values?
It's a tough question. We can't rely on exit polls. As everyone knows, it's impossible to get a straight answer from a cat.
The question comes to mind because of a report in the Nov. 25 issue of Nature by Karthik Panchanathan and Dr. Robert Boyd of the University of California, Los Angeles. The researchers did a mathematical analysis of how cooperation and punishment might make evolutionary sense.
The problem, from the scientific point of view, is that it's hard to see the advantage to being the one who punishes people who don't cooperate. And it's hard to see how cooperation would evolve without punishment. Why not be a slugabed, or free rider, as the researchers term it, and live off the cooperative people? The analysis showed that one punishment, refusing to help free riders, turns out to be a method that makes survival sense.
Fair enough. But in something of an offhand comment, quoted in a U.C.L.A. news release, Mr. Panchanathan said, "If you put two dogs together, and one dog does something inappropriate, the other dog doesn't care, so long as it doesn't get hurt." He added, "It certainly wouldn't react with moralist outrage. Likewise, it would not experience elation if it saw one dog help out another dog. But humans are very different."
True. I would definitely be elated if I saw one dog help another. More to the point, no one argues that dogs and other animals have the sophisticated moral values of human beings. But that doesn't mean they have no values whatsoever.
I base this conclusion on both art and science. Jack London, in his novels, describes a team of sled dogs as a social group with a leader, a hierarchy and rules. These dogs punish malingerers and teach new dogs what the rules are.
London wasn't a scientist, but Dr. Frans de Waal is. In "Good Natured: The Origin of Right and Wrong in Humans and Other Animals," published in 1996, he argued that the roots of human morality could be found, like the rudiments of language, in animals like primates and canids.
He doesn't go overboard. For instance Dr. de Waal doubts that dogs are displaying guilt when they slink around after they eat the family turkey and then throw up on the new rug. The dogs just know that in a proper household the alpha dog, who had better be human if there's going to be any order at all, always acts very aggressive and dominant when he or she finds a dog's breakfast on the run. So, being of lower rank, the turkey-eating dog slinks around and acts submissive, so as not to be torn to pieces.
But Dr. de Waal does describe instances in which dogs enforce rules like, "Don't pick up my ball." Or, in the case of wolves, he describes older wolves teaching younger wolves lessons on behavior. Again, these are simple lessons, like "Stay near the den when Mom leaves" and "Don't pick up my bone."
Primates have more complex social lives, but I confess that I'm more interested in the dogs because I've spent time with them and the people who train them. I have wondered about the idea that there are "no bad dogs," as the title of a hugely popular book on training dogs proclaimed. If dogs have a sense of right and wrong, then they could do wrong. Right? They may not be capable of carrying guilt around for years and years and years, but they do recognize certain rules about how to act in a social group, and that is sort of a moral value.
The main commandment of dog life and the foundation of dog morality, I suspect, is something like Know Your Place. Dogs live in hierarchies, and everyone agrees (everyone human) that dogs are happiest when the ranking is clear. The second rule is My Food Is Not Your Food. Depending on the pack and how hungry a dog is, the big dog can turn this on its head, so that rule for the submissive animal becomes My Food Is Your Food - Unless I Eat It First. No wonder dogs have no table manners.
Of course, dog morality is to human morality as chimpanzee language is to human language. Humans are able to summon up moral outrage about almost anything, even if it's none of their business. Humans are geniuses at morality and moral outrage. There are so many things we can do wrong, it boggles the mind. And the rules depend on which humans you are with: dancing or no dancing, monogamy or polygamy, card playing or no card playing, sex or celibacy, gay marriage or no gay marriage.
In fact, if moral values and moral outrage are results of evolution, in human beings they may have reached the level of being counterproductive, like the vast antlers that supposedly doomed the Irish elk.
Dogs could presumably evolve into the same morass. It is, however, reserved for social animals, as Dr. de Waal points out. Animals that evolved as solitary predators feel no moral bonds or restrictions on their behavior.
Cats, in other words, are safe. They have no morals, which is one of the reasons so many people love them.
By CARL ZIMMER, The New York Times, November 30, 2004
Swallows are getting sexier.
Male barn swallows attract females with long tail feathers, and European researchers have observed that over the last 20 years those feathers have become much longer.
"We've demonstrated quite a dramatic change in a short period of time," said Dr. Anders Pape Moller, an evolutionary biologist at Pierre and Marie Curie University in Paris, who conducted the research with Dr. Tibor Szep of the College of Nyiregyhaza in Hungary. The findings are to be published in The Journal of Evolutionary Biology.
Experiments suggest that the males' tails act as advertising for good genes because males must be in good health to spend the energy growing them. The females, the researchers say, are particularly attracted by the tail's two outer feathers.
Dr. Moller, who has been documenting this preference for more than two decades, found that the outer feathers had lengthened by almost half an inch (11.4 millimeters), an increase of 10 percent, one of the biggest evolutionary shifts ever documented in a living population of wild animals. By contrast, the central tail feathers, which don't produce a reaction in females, haven't changed.
Over the last 30 years, researchers have made more than 1,500 measurements of natural selection in wild populations of animals and plants. Droughts on the Galápagos Islands, for example, have favored larger beaks in finches, because the surviving seeds are harder to crack. But the shift measured by Dr. Moller and Dr. Szep is greater.
Dr. Moller and Dr. Szep suspect that the agent for this is the long-term spread of the Sahara. The barn swallows they are examining migrate from Denmark to South Africa for the winter, then return by way of Algeria in the spring. The reduction of vegetation there around the desert may mean fewer insects for the hungry swallows.
"If they get across the Sahara and there's nothing to eat, it's tough," Dr. Moller said. Weaker male swallows starve; stronger ones reach Denmark. There they pass on their genes to the next generation - including genes for longer tails.
But that explanation has prompted some skepticism.
"I am prepared to believe that the birds are probably evolving, but not that climate change is the cause, simply because there can be so much else going on," said Dr. David Reznick, an evolutionary biologist at the University of California at Riverside.
Dr. Moller plans to search for more evidence.
SIDE EFFECT: Good Dogs, Bad People, and Cats
By JAMES GORMAN, The New York Times, November 30, 2004
Do animals have moral values?
It's a tough question. We can't rely on exit polls. As everyone knows, it's impossible to get a straight answer from a cat.
The question comes to mind because of a report in the Nov. 25 issue of Nature by Karthik Panchanathan and Dr. Robert Boyd of the University of California, Los Angeles. The researchers did a mathematical analysis of how cooperation and punishment might make evolutionary sense.
The problem, from the scientific point of view, is that it's hard to see the advantage to being the one who punishes people who don't cooperate. And it's hard to see how cooperation would evolve without punishment. Why not be a slugabed, or free rider, as the researchers term it, and live off the cooperative people? The analysis showed that one punishment, refusing to help free riders, turns out to be a method that makes survival sense.
Fair enough. But in something of an offhand comment, quoted in a U.C.L.A. news release, Mr. Panchanathan said, "If you put two dogs together, and one dog does something inappropriate, the other dog doesn't care, so long as it doesn't get hurt." He added, "It certainly wouldn't react with moralist outrage. Likewise, it would not experience elation if it saw one dog help out another dog. But humans are very different."
True. I would definitely be elated if I saw one dog help another. More to the point, no one argues that dogs and other animals have the sophisticated moral values of human beings. But that doesn't mean they have no values whatsoever.
I base this conclusion on both art and science. Jack London, in his novels, describes a team of sled dogs as a social group with a leader, a hierarchy and rules. These dogs punish malingerers and teach new dogs what the rules are.
London wasn't a scientist, but Dr. Frans de Waal is. In "Good Natured: The Origin of Right and Wrong in Humans and Other Animals," published in 1996, he argued that the roots of human morality could be found, like the rudiments of language, in animals like primates and canids.
He doesn't go overboard. For instance Dr. de Waal doubts that dogs are displaying guilt when they slink around after they eat the family turkey and then throw up on the new rug. The dogs just know that in a proper household the alpha dog, who had better be human if there's going to be any order at all, always acts very aggressive and dominant when he or she finds a dog's breakfast on the run. So, being of lower rank, the turkey-eating dog slinks around and acts submissive, so as not to be torn to pieces.
But Dr. de Waal does describe instances in which dogs enforce rules like, "Don't pick up my ball." Or, in the case of wolves, he describes older wolves teaching younger wolves lessons on behavior. Again, these are simple lessons, like "Stay near the den when Mom leaves" and "Don't pick up my bone."
Primates have more complex social lives, but I confess that I'm more interested in the dogs because I've spent time with them and the people who train them. I have wondered about the idea that there are "no bad dogs," as the title of a hugely popular book on training dogs proclaimed. If dogs have a sense of right and wrong, then they could do wrong. Right? They may not be capable of carrying guilt around for years and years and years, but they do recognize certain rules about how to act in a social group, and that is sort of a moral value.
The main commandment of dog life and the foundation of dog morality, I suspect, is something like Know Your Place. Dogs live in hierarchies, and everyone agrees (everyone human) that dogs are happiest when the ranking is clear. The second rule is My Food Is Not Your Food. Depending on the pack and how hungry a dog is, the big dog can turn this on its head, so that rule for the submissive animal becomes My Food Is Your Food - Unless I Eat It First. No wonder dogs have no table manners.
Of course, dog morality is to human morality as chimpanzee language is to human language. Humans are able to summon up moral outrage about almost anything, even if it's none of their business. Humans are geniuses at morality and moral outrage. There are so many things we can do wrong, it boggles the mind. And the rules depend on which humans you are with: dancing or no dancing, monogamy or polygamy, card playing or no card playing, sex or celibacy, gay marriage or no gay marriage.
In fact, if moral values and moral outrage are results of evolution, in human beings they may have reached the level of being counterproductive, like the vast antlers that supposedly doomed the Irish elk.
Dogs could presumably evolve into the same morass. It is, however, reserved for social animals, as Dr. de Waal points out. Animals that evolved as solitary predators feel no moral bonds or restrictions on their behavior.
Cats, in other words, are safe. They have no morals, which is one of the reasons so many people love them.