魔道祖师香炉3 大和谐:受虐雏鸟长大后变成施虐者

        在秘鲁鹈鹕鸟繁殖栖息地纳斯卡，我们天天都能看到这样的场景：成年的鸟儿大摇大摆走向邻居鸟巢，并开始啄咬那里的雏鸟，有时候造成的伤害致使雏鸟死亡。研究人员说，如果雏鸟没有被啄死，等它成年后，就会变成像向它施虐的成鸟一样残忍，去攻击其他雏鸟，传承这一永久的“暴力的怪圈”。这一现象在人类被称作“虐童”。在野生动物群体中这种“暴力怪圈”还是第一次被发现。

         人们都知道，受到过成年人暴力攻击的儿童，成年后往往会虐待他们的孩子。在人类以外的动物或豢养动物如恒河猴之外，类似行为也有出现，但是却很难去研究，因为这种现象很少，起码很难见到。但在西班牙的加拉帕戈斯島，成年鹈鹕袭击雏鸟的行为达到了惊人的程度。研究者说鸟类的这一行为有点类似于人类。他们说鸟对人类观察它们的行动置若罔闻，所以很容易看到，并且能够记录下整个过程。

        设在北卡罗来纳州温斯顿-赛伦的威克森林大学的生态进化学家戴维 安德孙从1984年起就开始观察鹈鹕鸟。他说这是“是首次发现的海鸟虐雏实例之一。它是那样的明显而使人不安。”这种行为令人感到吃惊，“当海鸟有时间做其他事情时，比如找个伴侣，你却意外发现它们耗费时间，去袭扰邻居的幼雏。”

        为了了解这种行为为什么会发生在鹈鹕当中，安德孙和他的研究生，包括论文的第一作者马提娜 穆勒，搜集了三个繁殖季节的资料。他们锁定了24个鹈鹕，其中一些在幼雏时曾受到过攻击，另外的没有受到攻击。他们把这些鹈鹕用瓦蓝色脚环打上标记，在长大之后再一次追踪它们，发现在还是雏鸟时受虐最严重的那些鹈鹕也是最严重的施虐者。安德孙说：“在成长历史上曾经是施虐目标的鸟，可以预言它们变成成鸟后的行为。”他补充说，在这方面鸟的行为和人类是相似的，但是有关键的一点不同。人类的施虐这往往和孩子有亲缘关系，而鹈鹕攻击的则是没有关系的雏鸟。

        鹈鹕的行为起码有一部分是和自己的历史有关的。鹈鹕通常都是下两枚蛋，即便这样，父母也只能抚养其中的一只幼鸟。如果两枚蛋都孵化出来，他们也会相互争斗使其中一只致死，这一行为是由所受激素决定的。

        最近发现成活下来的受虐者成年后往往成为施虐，其原因可能是源自于过去的行为，或所受刺激仍在起作用。安德孙说，因为科学家还没有找到用进化来解释鸟的这一行为原因，所以提出  

       “假设施虐者对幼鸟有强烈的兴趣，那就是某种心理因素在起作用。”因为受到没有亲缘关系的成鸟施虐和兄妹相残相似，加拿大温尼伯大学的生物学家司各特 福布斯说，或许存在一种“行为不良的副作用”。福布斯同意安德孙的看法，鹈鹕的例子可以为研究人类虐童提供一种“有用的模式”。然而，另外也有人不认为鹈鹕虐童和人类虐童相似，不应该用对鸟的研究作为一种模式。美国伊利诺斯的芝加哥大学的生物学家达里奥 马埃斯特里皮耶里说： “在动物中两代之间的经历和刺激所产生的作用很有意思。但是在人类产生的现象却是病理学的原因。”他继续说道：“雏鸟兄妹相残是一种程式，”因为父母只能只能抚育一个孩子。

 Abused Chicks Grow Up to Be Abusers

 by Virginia Morell on 11 October 2011, 5:10 PM | 7 Comments 

 Bird attacks. A Nazca booby adult begins an unwelcome visit with an unguarded nestling. Most such visits include aggressive bites by the adult to the nestling's head and neck.

 Credit: Jacquelyn Grace

 It's a scene that occurs daily among nesting colonies of Nazca boobies: A young adult bird struts over to a neighbor's chick and begins biting and pecking it, sometimes causing injuries that lead to the nestling's death. But if the chick survives, it's likely to become just like its tormentor, attacking other nestlings when it reaches maturity and perpetuating this "cycle of violence," researchers report. It's one of the first times that the cycle, which is normally used to explain child abuse in humans, has been discovered in a population of wild animals. The study appears in the October issue of The Auk.

 It's well known that children who suffer attacks by adults often grow up to abuse their own kids. But it's been difficult to study this cycle outside of humans or captive species, such as rhesus monkeys, that may exhibit some similar behaviors—because it is apparently rare, or at least seldom witnessed. On Espa?ola Island in the Galápagos, however, adult Nazca boobies attack chicks at an alarming rate, and the researchers say the birds' behavior offers a somewhat parallel model to that of humans. The birds are indifferent to human observers, so it's easy to spot and record the entire sequence of events, the researchers say.

 The sea birds' chick abuse is "one of the first things you notice; it's that obvious and disturbing," says David Anderson, an evolutionary ecologist at Wake Forest University in Winston-Salem, North Carolina, and one of the study's co-authors, who has been observing the boobies since 1984. The behavior is also surprising. "You don't expect to see animals wasting time, bothering with a neighbor's chick, when it could be doing something that benefits its fitness, like finding a mate." 

 To understand more about how this behavior arises in the boobies, Anderson and his graduate students, including first author Martina Muller, collected data over three breeding seasons. They identified 24 individuals, some of which were attacked as nestlings and some of which weren't. They tagged these birds with bright blue leg bands and tracked them again when they were adults. The scientists discovered that those adults that had suffered the most abuse as nestlings were themselves the worst chick abusers as adults. "A bird's history as a target of abuse proved to be a strong predictor of its adult behavior," Anderson says. The bird's behavior is thus similar to that of humans—but with a key difference, he adds. In humans, the abuser is most often related to the child. The boobies, however, are attacking unrelated chicks.

 The boobies' behavior seems to be at least partly linked to the birds' natural history. Boobies often lay two eggs, even though the parents can care for only one chick. If both eggs hatch, the nestlings fight each other to the death—a behavior that is governed by hormones.

 The latest find—that these survivors often become abusers as adults—may be due to this previous behavior or to lingering hormonal effects. Because the scientists have not yet found an evolutionary explanation for the birds' behavior, they suggest there may be "some psychological element at play," given the abusers' "intense interest in the chicks," Anderson says. 

 Because the attacks by unrelated adults are similar to the sibling attacks, there may be a "maladaptive side effect" of something that makes evolutionary sense, says Scott Forbes, a biologist at the University of Winnipeg in Canada. Forbes agrees with Anderson that the boobies can provide a "useful model system" to study the causes of human child abuse. Others, however, are not yet convinced that the chick-abusing boobies and child-abusing humans are sufficiently similar to warrant using the birds as a model. "It is very interesting to see these intergenerational effects of early experience and hormones in an animal," says Dario Maestripieri, a behavioral biologist at the University of Chicago in Illinois. "But what happens in humans is pathological," he continues, "whereas the birds are programmed to attack each other as siblings," because the parents can handle only one.