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The Handicap Principle: A Missing Piece of Darwin's Puzzle
Ever since Darwin, animal behavior has intrigued and perplexed human observers. The elaborate mating rituals, lavish decorative displays, complex songs, calls, dances and many other forms of animal signaling raise fascinating questions. To what degree can animals communicate within their own species and even between species? What evolutionary purpose do such communications serve? Perhaps most importantly, what can animal signaling tell us about our own non-verbal forms of communication? In The Handicap Principle , Amotz and Ashivag Zahavi offer a unifying theory that brilliantly explains many previously baffling aspects of animal signaling and holds up a mirror in which ordinary human behaviors take on surprising new significance.
The wide-ranging implications of the Zahavis' new theory make it arguably the most important advance in animal behavior in decades. Based on 20 years of painstaking observation, the Handicap Principle illuminates an astonishing variety of signaling behaviors in animals ranging from ants and ameba to peacocks and gazelles. Essentially, the theory asserts that for animal signals to be effective they must be reliable, and to be reliable they must impose a cost, or handicap, on the signaler. When a gazelle sights a wolf, for instance, and jumps high into the air several times before fleeing, it is signaling, in a reliable way, that it is in tip-top condition, easily able to outrun the wolf. (A human parallel occurs in children's games of tag, where faster children will often taunt their pursuer before running). By momentarily handicapping itself--expending precious time and energy in this display--the gazelle underscores the truthfulness of its signal. Such signaling, the authors
suggest, serves the interests of both predator and prey, sparing each the exhaustion of a pointless chase. Similarly, the enormous cost a peacock incurs by carrying its elaborate and weighty tail-feathers, which interfere with food gathering, reliably communicates its value as a mate able to provide for its offspring. Perhaps the book's most important application of the Handicap Principle is to the evolutionary enigma of animal altruism. The authors convincingly demonstrate that when an animal acts altruistically, it handicaps itself--assumes a risk or endures a sacrifice--not primarily to benefit its kin or social group but to increase its own prestige within the group and thus signal its status as a partner or rival. Finally, the Zahavis' show how many forms of non-verbal communication among humans can also be explained by the Handicap Principle. Indeed, the authors suggest that non-verbal signals--tones of voice, facial expressions, body postures--are quite often more reliable
indicators of our intentions than is language.
Elegantly written, exhaustively researched, and consistently enlivened by equal measures of insight and example, The Handicap Principle illuminates virtually every kind of animal communication. It not only allows us to hear what animals are saying to each other--and to understand why they are saying it--but also to see the enormously important role non-verbal behavior plays in human communication.
The wide-ranging implications of the Zahavis' new theory make it arguably the most important advance in animal behavior in decades. Based on 20 years of painstaking observation, the Handicap Principle illuminates an astonishing variety of signaling behaviors in animals ranging from ants and ameba to peacocks and gazelles. Essentially, the theory asserts that for animal signals to be effective they must be reliable, and to be reliable they must impose a cost, or handicap, on the signaler. When a gazelle sights a wolf, for instance, and jumps high into the air several times before fleeing, it is signaling, in a reliable way, that it is in tip-top condition, easily able to outrun the wolf. (A human parallel occurs in children's games of tag, where faster children will often taunt their pursuer before running). By momentarily handicapping itself--expending precious time and energy in this display--the gazelle underscores the truthfulness of its signal. Such signaling, the authors
suggest, serves the interests of both predator and prey, sparing each the exhaustion of a pointless chase. Similarly, the enormous cost a peacock incurs by carrying its elaborate and weighty tail-feathers, which interfere with food gathering, reliably communicates its value as a mate able to provide for its offspring. Perhaps the book's most important application of the Handicap Principle is to the evolutionary enigma of animal altruism. The authors convincingly demonstrate that when an animal acts altruistically, it handicaps itself--assumes a risk or endures a sacrifice--not primarily to benefit its kin or social group but to increase its own prestige within the group and thus signal its status as a partner or rival. Finally, the Zahavis' show how many forms of non-verbal communication among humans can also be explained by the Handicap Principle. Indeed, the authors suggest that non-verbal signals--tones of voice, facial expressions, body postures--are quite often more reliable
indicators of our intentions than is language.
Elegantly written, exhaustively researched, and consistently enlivened by equal measures of insight and example, The Handicap Principle illuminates virtually every kind of animal communication. It not only allows us to hear what animals are saying to each other--and to understand why they are saying it--but also to see the enormously important role non-verbal behavior plays in human communication.
304 pages, Paperback
First published January 1, 1997
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September 3, 2019
Best book on evolution in many years
Why does the peacock grow that tail? Why does the springbok leap straight up into the air when it sees a predator? Why do people behave heroically? The handicap principle answers these questions, eloquently, simply and with an overwhelming sense of conviction. The peacock is advertising his fitness. He is saying to the female in essence, I am so fit I can carry around this cumbersome adornment and still scratch out a very fine living. The springbok is saying to the predator: don't even think about going after me. I am in such good shape I can waste energy jumping up and down and still have plenty of reserves to outrun you. Save us both the bother and go after someone weaker. (By the way, the springbok jumps straight up instead of sideways because by jumping straight up its performance can be effectively judged by a predator from any direction.) And the man who dives into the swiftly flowing river to save a drowning child is actually advertising his fitness and improving his station in society. He is so fit he can take chances that others dare not. He's the man the women want to mate with.
The Handicap Principle thus is about signals, signals between prey and predator, between one sex and the other, and between the individual and the group. The purpose of these signals is to display in an unequivocal way the fitness of the signaler. Note that such signals have to be "fake proof." They have to be what the authors call "reliable." An animal that can't run fast and has limited resources of energy can't waste them jumping in the air. It needs to get going immediately or to stay hidden if it is to have any chance of survival. A man leads with his chin. That's a signal that he's confident. When men had beards it was a little dangerous to stick your chin out since the other guy might grab your beard and you could be in trouble. People demonstrate wealth by wasting money. This is a "reliable" (if ugly) signal because without an ample supply of money, you can't afford to waste it.
Part of the beauty of this book comes from the personality of the authors, who spent a large part of their lives studying little babbler birds in Israel. I feel I know these little social birds just from the loving descriptions in the text. One can see that even though the Zahavis made their discovery of the handicap principle in 1975 and waited almost two decades before it was generally accepted in the scientific community, they harbor no bitterness, nor is their tone at all gloating. They come across as hard-working field scientists who love their work and nature.
Besides being full of exciting and original ideas, The Handicap Principle is also extremely well written. Each sentence is clear and to the point without the burden of unnecessary jargon or the wordy clumsiness sometimes found in such books. Amotz and Avishag Zahavi took great pride in effectively communicating their ideas to a wide audience. Additionally there are scores of exquisite, loving little black and white drawings by illustrator Amir Balaban of animals, birds, insects and people, etc., illuminating the text.
If you're interested in evolutionary theory, this is a book not to be missed. As Jared Diamond says on the cover, "Read this fine book, and discover what the excitement is all about."
--Dennis Littrell, author of “Understanding Evolution and Ourselves”
Why does the peacock grow that tail? Why does the springbok leap straight up into the air when it sees a predator? Why do people behave heroically? The handicap principle answers these questions, eloquently, simply and with an overwhelming sense of conviction. The peacock is advertising his fitness. He is saying to the female in essence, I am so fit I can carry around this cumbersome adornment and still scratch out a very fine living. The springbok is saying to the predator: don't even think about going after me. I am in such good shape I can waste energy jumping up and down and still have plenty of reserves to outrun you. Save us both the bother and go after someone weaker. (By the way, the springbok jumps straight up instead of sideways because by jumping straight up its performance can be effectively judged by a predator from any direction.) And the man who dives into the swiftly flowing river to save a drowning child is actually advertising his fitness and improving his station in society. He is so fit he can take chances that others dare not. He's the man the women want to mate with.
The Handicap Principle thus is about signals, signals between prey and predator, between one sex and the other, and between the individual and the group. The purpose of these signals is to display in an unequivocal way the fitness of the signaler. Note that such signals have to be "fake proof." They have to be what the authors call "reliable." An animal that can't run fast and has limited resources of energy can't waste them jumping in the air. It needs to get going immediately or to stay hidden if it is to have any chance of survival. A man leads with his chin. That's a signal that he's confident. When men had beards it was a little dangerous to stick your chin out since the other guy might grab your beard and you could be in trouble. People demonstrate wealth by wasting money. This is a "reliable" (if ugly) signal because without an ample supply of money, you can't afford to waste it.
Part of the beauty of this book comes from the personality of the authors, who spent a large part of their lives studying little babbler birds in Israel. I feel I know these little social birds just from the loving descriptions in the text. One can see that even though the Zahavis made their discovery of the handicap principle in 1975 and waited almost two decades before it was generally accepted in the scientific community, they harbor no bitterness, nor is their tone at all gloating. They come across as hard-working field scientists who love their work and nature.
Besides being full of exciting and original ideas, The Handicap Principle is also extremely well written. Each sentence is clear and to the point without the burden of unnecessary jargon or the wordy clumsiness sometimes found in such books. Amotz and Avishag Zahavi took great pride in effectively communicating their ideas to a wide audience. Additionally there are scores of exquisite, loving little black and white drawings by illustrator Amir Balaban of animals, birds, insects and people, etc., illuminating the text.
If you're interested in evolutionary theory, this is a book not to be missed. As Jared Diamond says on the cover, "Read this fine book, and discover what the excitement is all about."
--Dennis Littrell, author of “Understanding Evolution and Ourselves”
February 17, 2024
Summary:
- Signal selection
They define signals as traits whose value to the signaler is that they convey information to those who receive them. There is a difference between traits that evolved for other reasons, such as body size or a kangaroo's gait, that can and do convey information; and signals, which evolved solely to convey information. For example, one can judge the direction of another's gaze by watching its eyes—yet eye movement is not primarily a signal. But eye rings and small tufts of hair or feathers whose only function is to show an observer the direction of an individual's gaze more clearly, or from a greater distance, are signals. The evolution of signals—signal selection—is thus fundamentally different from the evolution of no-fall other adaptations. In traits other than signals, the cost of the trait is an unavoidable side effect. In signals, cost is of the very essence; it is necessary for the existence of the signal.
!! - If there is no cost, nothing prevents cheaters from using a signal to their benefit and the detriment of the receivers, and that signal will lose its value as a signal. This has happened not infrequently in human history. When money is easier to get, it loses value through inflation. Ornaments that were prized as tokens of wealth when rare became worthless when easy to obtain.
- Evolution of signaling
The message can be conveyed only if the other individual is interested in the message and understands it. The process therefore cannot start with a mutation in the signaler; because that would require two simultaneous, coordinated mutations: 1. which caused the signaler to perform the signal, 2. causing the observer to take interest in it. For instance, preparatory movements are made regardless of whether or not anybody is watching them, because of their intrinsic usefulness, rather than to convey any message. The ability to watch for specific movements other than signals can then evolve and spread through a population - once observers respond to specific observed movements, mutations that exaggerate these movements may spread among the ones observed. Then mutations are an advantage to their bearers because they intensify the movement in the eyes of observers who already understand its meaning. Exaggerated movements used as signals are constantly tested by natural selection.
- Species, age, and gender-specific marks
But did these markings evolve to enable animals to identify members of their species? Not necessarily. We identify a kangaroo by its special shape and gait. Kangaroos themselves likely do the same. Yet no one suggests that the shape and gait of kangaroos evolved to help kangaroos recognize each other as kangaroos. The fact that features are used by animals to identify the species, age, or gender of other animals does not prove that the features evolved for that purpose. Would anybody suggest that women use eyeliner to let men know that they are women? Men can figure that much out long before they see a woman's face, let alone her eyes. We were thus led to the conclusion that the different colors of the male and female babbler's eyes evolved not to indicate gender but for some other reason. They suggest a very different explanation: these markings evolve through the competition that members of the species engage in to determine their relative quality.
- Signals for sexual selection
A) Beauty: The correlation of symmetry to quality, both in animals and in humans, has been studied recently by several researchers; the term used in current literature is "fluctuating asymmetry. " Moller found that the male swallows preferred by females had both longer and more symmetrical tails (that is, the left and right parts were evenly matched) than males who took longer to find mates. Research confirms that humans consider symmetrical faces to be more beautiful than somewhat asymmetrical faces. The symmetry signals good development and health - and is connected to genetics and nutrition. As bright and colorful plumage of birds reflects both.
B) Decoration: The relationship between decoration and its message explains why it so often happens that unrelated species who occupy a similar ecological niche look alike. The decoration of the desert agamidae of the Middle East is very similar to that of desert iguanas in the Americas, as is the decoration of rattlesnakes in America and that of vipers in the Old World. On the other hand, as this theory predicts, - in Australia, male satin bowerbirds especially favor blue objects; in their usual habitat, such objects consist of blue feathers, which are rare, and blue flowers that need constant replacement. Borgia found on average five blue feathers per bower. Near human habitats or picnic grounds, however, blue artifacts—mostly blue plastic—are fairly common, and satin bowerbirds ca n collect as many as a hundred per bower. In most areas, male satin bowerbirds compete both by stealing blue objects from one another and by destroying each other's bowers. Hunter and Dwyer recently found, however, that where blue objects are abundant, the males direct less effort into stealing such objects from one another, and more into the destruction of their competitors' bowers, than they do in areas where such objects are rare. Blue objects, where abundant, are no longer significant marks of quality.
C) Male courtship movements (Dance): These are often extremely elaborate and difficult to perform. This does not make the movements any clearer, but it does make them more difficult to perform, and thus stronger proof of the male's physical ability and his motivation to court females. Doves usually walk when on the ground, but when courting, male doves hop on both legs. The hop is probably more difficult and demonstrates the male's prowess.
D) Fighting: Much of the fighting that goes on between rivals of the same species is ritual fighting; the goal is not to injure or kill the opponent, but to convince it and others that it is the weaker and should withdraw from the contest - only after its opponent has assumed the appropriate stance does the aggressor strike—and then only a well-protected and "legitimate" target, such as antlers. As the horns of a male gazelle are strong, sharp, lethal weapons...
E) Vocalization (Singing): Scherer pointed out that vocalizations express the motivation of their producers because their tonal quality is affected by the stance typical of that motivation. But nobody saw in this connection a key to reliability in vocal communication in general. The variations that the listener is interested in seem to be displayed better by some vocalization patterns than by others. Lambrechts and Dhondt found that the more successful great tits—the ones who produced more offspring—had songs that contained more syllables and were more rhythmical than the songs of other great tits.
F) Pheromones: Male pheromones vary greatly from species to species, reflecting to a degree the varieties of plants they eat. Female pheromones, on the other hand, are much more similar. The pheromone has to be a chemical that would harm a female who overproduced it—and correlate to qualities that are of interest to males. At this stage, authors believe that the pheromones concentrate around the female that produces them, penetrate her sensory cells, and impair them - dulling of the senses would impair her ability to evaluate the males.
- Body parts that serve as the signal
The comb of a rooster is a delicate organ and it is full of blood vessels—which advertise the health of the bird. In the wild an intact comb on a cock's head is evidence that despite such a handicap, no rival has managed to injure him: the comb advertises that no rival overcame the rooster. Holder and Montgomerie found that ptarmigan males attack each other's combs, and also found a correlation between the state of males' combs and the number of females who chose to breed with them. The beard of the male ibex puzzled scientists for many years. It is a signal: adult males have them, but not females or young. A leopard can overcome even a large ibex - it grabs the ibex by its face. Anything, such as a beard, that makes it easier for a leopard to grab hold of the ibex's face makes it more difficult for the ibex to escape - the ibex's beard is showing off its confidence in its ability to escape the leopard.
Stages of the evolution of horns and antlers: 1. Originally, structures that signaled the direction of an animal's gaze evolved by signal selection, and their shape and position were determined by this function. 2. Then these structures became progressively stronger, evolving by utilitarian selection into weapons. 3. They continued to change, becoming larger and more elaborate as they evolved into handicaps and instruments of ritual rather than actual combat.
The use of color as a signal
There are cases in which coloring itself signals health, as do the red of cocks' combs, the color of human lips, and similar structures that show off blood circulation,
Female dominance
Female dominance evolves in specific ecological conditions: for example, when on the one hand two adults are needed to take care of the offspring, and on the other hand the "bottleneck" in reproduction is not the female's ability to bear young or lay eggs but occurs at a later stage in the breeding cycle.
Note: As we have seen already, copulation can serve to test the social bond between males and females, and that bond does not necessarily have to do with procreation. For example, some birds, such as stone chats and wagtails, pair up in their winter habitats—not to breed, but rather to defend what is temporarily their mutual territory. In such cases, one often finds that the same courtship mechanism that helps two individuals form a partnership in the breeding season serves them at other times to form a partnership solely for defense. One who doesn't know that these partners have no intention of reproducing and will split up in a few months might think they are going through regular courtship.
- Signal selection
They define signals as traits whose value to the signaler is that they convey information to those who receive them. There is a difference between traits that evolved for other reasons, such as body size or a kangaroo's gait, that can and do convey information; and signals, which evolved solely to convey information. For example, one can judge the direction of another's gaze by watching its eyes—yet eye movement is not primarily a signal. But eye rings and small tufts of hair or feathers whose only function is to show an observer the direction of an individual's gaze more clearly, or from a greater distance, are signals. The evolution of signals—signal selection—is thus fundamentally different from the evolution of no-fall other adaptations. In traits other than signals, the cost of the trait is an unavoidable side effect. In signals, cost is of the very essence; it is necessary for the existence of the signal.
!! - If there is no cost, nothing prevents cheaters from using a signal to their benefit and the detriment of the receivers, and that signal will lose its value as a signal. This has happened not infrequently in human history. When money is easier to get, it loses value through inflation. Ornaments that were prized as tokens of wealth when rare became worthless when easy to obtain.
- Evolution of signaling
The message can be conveyed only if the other individual is interested in the message and understands it. The process therefore cannot start with a mutation in the signaler; because that would require two simultaneous, coordinated mutations: 1. which caused the signaler to perform the signal, 2. causing the observer to take interest in it. For instance, preparatory movements are made regardless of whether or not anybody is watching them, because of their intrinsic usefulness, rather than to convey any message. The ability to watch for specific movements other than signals can then evolve and spread through a population - once observers respond to specific observed movements, mutations that exaggerate these movements may spread among the ones observed. Then mutations are an advantage to their bearers because they intensify the movement in the eyes of observers who already understand its meaning. Exaggerated movements used as signals are constantly tested by natural selection.
- Species, age, and gender-specific marks
But did these markings evolve to enable animals to identify members of their species? Not necessarily. We identify a kangaroo by its special shape and gait. Kangaroos themselves likely do the same. Yet no one suggests that the shape and gait of kangaroos evolved to help kangaroos recognize each other as kangaroos. The fact that features are used by animals to identify the species, age, or gender of other animals does not prove that the features evolved for that purpose. Would anybody suggest that women use eyeliner to let men know that they are women? Men can figure that much out long before they see a woman's face, let alone her eyes. We were thus led to the conclusion that the different colors of the male and female babbler's eyes evolved not to indicate gender but for some other reason. They suggest a very different explanation: these markings evolve through the competition that members of the species engage in to determine their relative quality.
- Signals for sexual selection
A) Beauty: The correlation of symmetry to quality, both in animals and in humans, has been studied recently by several researchers; the term used in current literature is "fluctuating asymmetry. " Moller found that the male swallows preferred by females had both longer and more symmetrical tails (that is, the left and right parts were evenly matched) than males who took longer to find mates. Research confirms that humans consider symmetrical faces to be more beautiful than somewhat asymmetrical faces. The symmetry signals good development and health - and is connected to genetics and nutrition. As bright and colorful plumage of birds reflects both.
B) Decoration: The relationship between decoration and its message explains why it so often happens that unrelated species who occupy a similar ecological niche look alike. The decoration of the desert agamidae of the Middle East is very similar to that of desert iguanas in the Americas, as is the decoration of rattlesnakes in America and that of vipers in the Old World. On the other hand, as this theory predicts, - in Australia, male satin bowerbirds especially favor blue objects; in their usual habitat, such objects consist of blue feathers, which are rare, and blue flowers that need constant replacement. Borgia found on average five blue feathers per bower. Near human habitats or picnic grounds, however, blue artifacts—mostly blue plastic—are fairly common, and satin bowerbirds ca n collect as many as a hundred per bower. In most areas, male satin bowerbirds compete both by stealing blue objects from one another and by destroying each other's bowers. Hunter and Dwyer recently found, however, that where blue objects are abundant, the males direct less effort into stealing such objects from one another, and more into the destruction of their competitors' bowers, than they do in areas where such objects are rare. Blue objects, where abundant, are no longer significant marks of quality.
C) Male courtship movements (Dance): These are often extremely elaborate and difficult to perform. This does not make the movements any clearer, but it does make them more difficult to perform, and thus stronger proof of the male's physical ability and his motivation to court females. Doves usually walk when on the ground, but when courting, male doves hop on both legs. The hop is probably more difficult and demonstrates the male's prowess.
D) Fighting: Much of the fighting that goes on between rivals of the same species is ritual fighting; the goal is not to injure or kill the opponent, but to convince it and others that it is the weaker and should withdraw from the contest - only after its opponent has assumed the appropriate stance does the aggressor strike—and then only a well-protected and "legitimate" target, such as antlers. As the horns of a male gazelle are strong, sharp, lethal weapons...
E) Vocalization (Singing): Scherer pointed out that vocalizations express the motivation of their producers because their tonal quality is affected by the stance typical of that motivation. But nobody saw in this connection a key to reliability in vocal communication in general. The variations that the listener is interested in seem to be displayed better by some vocalization patterns than by others. Lambrechts and Dhondt found that the more successful great tits—the ones who produced more offspring—had songs that contained more syllables and were more rhythmical than the songs of other great tits.
F) Pheromones: Male pheromones vary greatly from species to species, reflecting to a degree the varieties of plants they eat. Female pheromones, on the other hand, are much more similar. The pheromone has to be a chemical that would harm a female who overproduced it—and correlate to qualities that are of interest to males. At this stage, authors believe that the pheromones concentrate around the female that produces them, penetrate her sensory cells, and impair them - dulling of the senses would impair her ability to evaluate the males.
- Body parts that serve as the signal
The comb of a rooster is a delicate organ and it is full of blood vessels—which advertise the health of the bird. In the wild an intact comb on a cock's head is evidence that despite such a handicap, no rival has managed to injure him: the comb advertises that no rival overcame the rooster. Holder and Montgomerie found that ptarmigan males attack each other's combs, and also found a correlation between the state of males' combs and the number of females who chose to breed with them. The beard of the male ibex puzzled scientists for many years. It is a signal: adult males have them, but not females or young. A leopard can overcome even a large ibex - it grabs the ibex by its face. Anything, such as a beard, that makes it easier for a leopard to grab hold of the ibex's face makes it more difficult for the ibex to escape - the ibex's beard is showing off its confidence in its ability to escape the leopard.
Stages of the evolution of horns and antlers: 1. Originally, structures that signaled the direction of an animal's gaze evolved by signal selection, and their shape and position were determined by this function. 2. Then these structures became progressively stronger, evolving by utilitarian selection into weapons. 3. They continued to change, becoming larger and more elaborate as they evolved into handicaps and instruments of ritual rather than actual combat.
The use of color as a signal
There are cases in which coloring itself signals health, as do the red of cocks' combs, the color of human lips, and similar structures that show off blood circulation,
Female dominance
Female dominance evolves in specific ecological conditions: for example, when on the one hand two adults are needed to take care of the offspring, and on the other hand the "bottleneck" in reproduction is not the female's ability to bear young or lay eggs but occurs at a later stage in the breeding cycle.
Note: As we have seen already, copulation can serve to test the social bond between males and females, and that bond does not necessarily have to do with procreation. For example, some birds, such as stone chats and wagtails, pair up in their winter habitats—not to breed, but rather to defend what is temporarily their mutual territory. In such cases, one often finds that the same courtship mechanism that helps two individuals form a partnership in the breeding season serves them at other times to form a partnership solely for defense. One who doesn't know that these partners have no intention of reproducing and will split up in a few months might think they are going through regular courtship.
December 10, 2021
نبدأ بمشهد غزال يستريح أو يرعى في البرية. يكاد يكون غير مرئي. يمتزج لون جسده جيدًا مع البيئة المحيطة. يظهر الذئب. في حالة التعرض للخطر ، يجب تفضيل الانحناء والقيام بأقصى ما في وسعك لتجنب رؤيتك. لكن لا: إنه يرتفع ، ويضرب الأرض بقدمه الأمامية ، كل ذلك أثناء مشاهدة الذئب. تنتقل ضربات حوافر الغزال عبر الأرض لمسافات طويلة ؛ تظهر قرونه المنحنية والنظرة على وجهه بوضوح أن الغزال في الواقع ينظر إلى عدوه.
إذا اقترب الذئب ، فسيتوقع المرء أن يهرب الغزال بأسرع ما يمكن.
لكن مرة أخرى لا يفعل : غالبًا ما يقفز الغزال عالياً على جميع الأرجل الأربع عدة مرات ، وعندها فقط يبدأ في الجري ، ويهز ذيله القصير . من الواضح جدًا أن هذه القفزات العالية مرتبطة بنهج الذئب. ومع ذلك ، فإن الغزال الذي يهرب من خطر فوري وعاجل - مثل خطر صيادين في سيارة جيب - يفر بطريقة مختلفة تمامًا: فهو يهرب بصمت وبسرعة كبيرة ، مستفيدًا من التضاريس لإخفاء هروبه.
لماذا يكشف الغزال عن نفسه لحيوان مفترس قد لا يكتشفه بطريقة أخرى؟ لماذا يضيع الوقت والطاقة في القفز صعودًا وهبوطًا ، ثم الهرب بأسرع ما يمكن؟
يوجّه الغزال إلى المفترس رسالة مفادها أنه قد شاهده ؛ من خلال "إضاعة" الوقت والقفز عالياً في الهواء بدلاً من الانطلاق بعيدًا ، فإنه يوضح بطريقة موثوقة قدرته على تجاوز الذئب. عندما علم الذئب أنه فقد فرصته في مفاجأة فريسته ، وأن هذا الغزال في حالة بدنية عالية ، قرر الانتقال إلى منطقة أخرى ؛ أو ربما قرر البحث عن فرائس واعدة أكثر.
حتى الأطراف في العلاقات الأكثر عدائية ، مثل الفريسة والمفترس ، قد تتواصل ، بشرط أن يكون لديهم مصلحة مشتركة: في هذه الحالة ، كلاهما يريد تجنب مطاردة لا طائل من ورائها. يحاول الغزال إقناع الذئب بأنه ليس الفريسة السهلة التي يبحث عنها الذئب ، وأن الذئب سيضيع وقته وطاقته بمطاردته. حتى لو كان الغزال متأكدًا من أنه يمكنه تجاوز الذئب ، فإنه يفضل أيضًا تجنب مطاردة مرهقة. ولكن من أجل إقناع الذئب بعدم المطاردة ، يجب على الغزال أن يبذل وقتًا ثمينًا وطاقة يحتاجها إذا تجاهل الذئب إشاراته وقرر مطاردته على أي حال.
يجسد اللقاء بين الغزال والذئب الفكرة الأساسية التالية : لكي تكون الإشارات فعالة ، يجب أن تكون موثوقة ؛ لكي تكون الإشارات موثوقة ، يجب أن تكون مكلفة.
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Amotz Zahavi
The Handicap Principle
Translated By #Maher_Razouk
إذا اقترب الذئب ، فسيتوقع المرء أن يهرب الغزال بأسرع ما يمكن.
لكن مرة أخرى لا يفعل : غالبًا ما يقفز الغزال عالياً على جميع الأرجل الأربع عدة مرات ، وعندها فقط يبدأ في الجري ، ويهز ذيله القصير . من الواضح جدًا أن هذه القفزات العالية مرتبطة بنهج الذئب. ومع ذلك ، فإن الغزال الذي يهرب من خطر فوري وعاجل - مثل خطر صيادين في سيارة جيب - يفر بطريقة مختلفة تمامًا: فهو يهرب بصمت وبسرعة كبيرة ، مستفيدًا من التضاريس لإخفاء هروبه.
لماذا يكشف الغزال عن نفسه لحيوان مفترس قد لا يكتشفه بطريقة أخرى؟ لماذا يضيع الوقت والطاقة في القفز صعودًا وهبوطًا ، ثم الهرب بأسرع ما يمكن؟
يوجّه الغزال إلى المفترس رسالة مفادها أنه قد شاهده ؛ من خلال "إضاعة" الوقت والقفز عالياً في الهواء بدلاً من الانطلاق بعيدًا ، فإنه يوضح بطريقة موثوقة قدرته على تجاوز الذئب. عندما علم الذئب أنه فقد فرصته في مفاجأة فريسته ، وأن هذا الغزال في حالة بدنية عالية ، قرر الانتقال إلى منطقة أخرى ؛ أو ربما قرر البحث عن فرائس واعدة أكثر.
حتى الأطراف في العلاقات الأكثر عدائية ، مثل الفريسة والمفترس ، قد تتواصل ، بشرط أن يكون لديهم مصلحة مشتركة: في هذه الحالة ، كلاهما يريد تجنب مطاردة لا طائل من ورائها. يحاول الغزال إقناع الذئب بأنه ليس الفريسة السهلة التي يبحث عنها الذئب ، وأن الذئب سيضيع وقته وطاقته بمطاردته. حتى لو كان الغزال متأكدًا من أنه يمكنه تجاوز الذئب ، فإنه يفضل أيضًا تجنب مطاردة مرهقة. ولكن من أجل إقناع الذئب بعدم المطاردة ، يجب على الغزال أن يبذل وقتًا ثمينًا وطاقة يحتاجها إذا تجاهل الذئب إشاراته وقرر مطاردته على أي حال.
يجسد اللقاء بين الغزال والذئب الفكرة الأساسية التالية : لكي تكون الإشارات فعالة ، يجب أن تكون موثوقة ؛ لكي تكون الإشارات موثوقة ، يجب أن تكون مكلفة.
.
Amotz Zahavi
The Handicap Principle
Translated By #Maher_Razouk
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September 3, 2022The handicap hypothesis (which is not a principle) was important in the history of sexual selection research. It has, however, outlived its usefulness and is now recognized as nothing more than a ‘sexy’, though erroneous hypothesis.
I was looking forward to reading this book, which, I presume, is Zahavi and Zahavi’s best attempt to make a case for the handicap hypothesis after more than 20 years since the hypothesis was first developed in 1975.
It was painful to read. It’s thesis is based on the most superficial understanding of a wide range of species and not the slightest attempt had been made to discuss alternative hypotheses.
I would have appreciated this book much more, had it been phrased as a speculative account of nature. Indeed, wrong explanations can still stimulate productive scientific discourse. However, the Zahavis incessantly and arrogantly use the word “principle”, rather than hypothesis, to describe the handicap model, while every bit of “evidence” they use to support it is preliminary. Nothing more.
Today (2022) this book has two purposes:
1. To educate new researchers about historical models of sexual selection and
2. To serve as an example of bad, dogmatic science.
I was looking forward to reading this book, which, I presume, is Zahavi and Zahavi’s best attempt to make a case for the handicap hypothesis after more than 20 years since the hypothesis was first developed in 1975.
It was painful to read. It’s thesis is based on the most superficial understanding of a wide range of species and not the slightest attempt had been made to discuss alternative hypotheses.
I would have appreciated this book much more, had it been phrased as a speculative account of nature. Indeed, wrong explanations can still stimulate productive scientific discourse. However, the Zahavis incessantly and arrogantly use the word “principle”, rather than hypothesis, to describe the handicap model, while every bit of “evidence” they use to support it is preliminary. Nothing more.
Today (2022) this book has two purposes:
1. To educate new researchers about historical models of sexual selection and
2. To serve as an example of bad, dogmatic science.
July 28, 2020
One of the most detailed, clear, eye opening reads one can have on the subject of complex structures in their natural habitat. The results of three decades of concise observation leads to such a simple and profound theorem that can be and should be taken into account by researchers and curious individuals alike. Highly recommended to all. Zahavi and his wife are pioneers and the work they did is aspiring. I commend them utmost respect and admiration.
January 11, 2021
I thought this was a very clear explanation of an interesting part of evolutionary theory. The text was arranged in palatable bites and each topic was explained well. I found the arguments to be very compelling.
August 27, 2020
Eye opening book which puts many behaviors (rather signals) of daily life in a new perspective.
November 10, 2020
Astounding
January 15, 2024
cool look at underlooked part of evolutionary psych
January 24, 2024
Has some very interesting anecdotes. The best one was how the 👶 blackmails parents by crying (i.e. feed me or I ll tell the predators where we are)
February 23, 2012
A bit long winded and technical, the overall message--that animals evolve to "waste", that is to directly handicap themselves, in an effort to show both potential mates, and potential predators that they are fit--is mind blowing, and grounds a lot of behavior. By providing basic examples, the authors move us through the animal kingdom. "Wasting" is, in short, a way to signal to others, and it happens all over, as this book describes. There's probably too much here, though, to make it a really compelling read for everyone. It is simply too detailed at times.
December 24, 2007
I've the Israeli copy of Zahavi's book and have taken his course on The Handicap Principle in university (I even have his autograph on my copy >.< sorry, I had to brag), this book is an even more extensive report of Zahavi's theory with solid evidence and explanations while siting studies in the subject from a wide variety of sources.
It's a very good book on the Principle and a good read, in general, about behavior in both animals and humans.
It's a very good book on the Principle and a good read, in general, about behavior in both animals and humans.
May 6, 2012
The Handicap Principle: A missing piece of Darwin’s puzzle is a 1997 book that describes the application of a particular principle to explain several aspects of animal behaviour including prey-predator interactions, mate selection as well as altruism among social animals. Some of the ideas in the book connect it with other fields such as game theory and semiotics. Moreover, it’s a fascinating look at some of the puzzles in the study of evolution
August 26, 2012
I haven't finish the book yet, but it has some very interesting ideas about animal behaviour that could be borrowed to explain aspects of human behaviour as well. The handicap principle reminds me of the childhood times when, sure of my physical superiority, I used to offer other children a "handicap" before racing them, to dissuade them from making the challenge. It's very much the same thing as the main idea of this book.
January 9, 2013
I found the basis for this book a revelation: it made so many things fall into place. Basically, the book demonstrates how honest signals (signals that cannot easily be faked) cause all of us, humans and animals, to do things that otherwise don't make sense. Please read it. You'll be glad you did.
March 3, 2009
I had the honor to document and observe the field work of the brilliant, witty and caring Dr. Amotz Zohavi in the Israeli desert.
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