Version classiqueVersion mobile
OpenEdition Books

Behaviour, Development and Evolution

 | 
Patrick Bateson

9. Active Role of Behaviour

Texte intégral

  • 1 Fitzgibbon, C.D. & Fanshawe, J.H. (1988), Stotting in Thomson’s gazelles: an honest signal of condi (...)
  • 2 Cresswell, W. (1994), Song as a pursuit-deterrent signal, and its occurrence relative to other anti (...)

1The ability of animals to respond differentially to one of several options is an important part of adaptive behaviour. In colloquial terms they make a choice. Charles Darwin suggested that members of one sex choose to mate with individuals with a striking feature such as the tail of the male peacock. Choice can take many different forms. One is involved in predators’ choice of prey. When gazelle see a predator like a cheetah they jump into the air, a behaviour pattern called ‘stotting’. Cheetah seem to learn not to chase jumping gazelle.1 A similar case is the small falcon, the merlin, which takes other small birds on the wing.2 When it hunts flying skylarks, its potential prey start singing. The more the skylark sings, the more likely is the merlin to abandon the chase and hunt for other skylarks that don’t sing so much. The merlin has probably learned that the skylark singing a lot is more vigorous and more difficult to catch and chooses to attack other individuals.

2Apparent design emerges, even when it is at the end of the long and complicated process of development. Development depends on the constancy of many genetic and environmental conditions. If any of these conditions changes, as can happen to environmental conditions when organisms move away from the natal area, the characteristics of the organism can also change. High mobility by organisms would have frequently placed them in conditions that revealed heritable variation not previously apparent in the population. By their mobility, in the case of animals, or facility to disperse their seeds in the case of plants, organisms would have exposed themselves to new conditions that might reveal heritable variability.

  • 3 Laland, K.N., Odling Smee, J. & Gilbert, S.F. (2008), Evo-devo and niche construction: building bri (...)

3The environment does not simply set a problem to which the organism has to find a solution. The organism can do a great deal to select or create an environment to which it is best suited. For example beavers dam rivers, flood valleys and create private lakes for themselves. The concepts derived from such examples have been developed extensively and they are now referred to collectively as ‘niche construction’.3 The effects of behavioural control can be especially great when a major component of the environmental conditions with which animals have to cope is provided by their social environment. When individuals compete with each other within a social group, the outcome of the competition depends in part on each individual’s capacity to predict what the other will do.

  • 4 A full discussion of play is given in Bateson, P. & Martin, P. (2013), Play, Playfulness, Creativit (...)

4Play behaviour, prominent in young mammals and some birds, is spontaneous and rewarding to the individual; it is intrinsically motivated and its performance serves as a goal in itself. The player is to some extent protected from the normal consequences of serious behaviour. The behaviour appears to have no immediate practical goal or benefit. Playing with other individuals may be preceded or accompanied by specific signals or facial expressions indicating that the behaviour is not to be taken as a threat. Play is the antithesis of ‘work’ or ‘serious’ behaviour. The behaviour consists of actions and, in the case of humans, thoughts, expressed in novel combinations. When playing with others, a normally dominant individual may become temporarily subordinate. Individual actions or thoughts are performed repeatedly; they may also be incomplete or exaggerated relative to non-playful behaviour in adults; play looks different. Play is sensitive to prevailing conditions and occurs only when the player is free from illness or stress. Play is an indicator of well-being. Playful play is accompanied by a particular positive mood state in which the individual is more inclined to behave in a spontaneous and flexible way.4

  • 5 Gomendio, M. (1988), The development of different types of play in gazelles: implications for the n (...)

5When young animals playfully practise the stereotyped movements they will use in earnest later in life, they are likely to improve the coordination and effectiveness of these behaviour patterns. The short dashes and jumps of a young gazelle when it is playing bring benefits that may be almost immediate, as it faces the threat of predation from cheetah or other carnivores and needs considerable skill when escaping.5 Even though the benefits may be immediate in such cases, they may also persist into adult life.

6Many theories of the functions of play have continued to focus on its role in enabling the developing individual to acquire and practise complex physical skills and, by so doing, fine tune neuromuscular systems. Others theories, derived from observing how much young animals play with each other, have emphasised how individuals also develop social skills and cement their social relationships; play may also serve to improve the individual’s capacity to compete and cooperate with other members of their own species. Play can make an individual more resistant to stress, and enlarge its repertoire. Play may enhance an individual’s resourcefulness and flexibility and make it able to adjust to new conditions. Play may enhance its ability to cooperate with others and to co-exist with older members of its own species. Play may increase its knowledge of its home range. Play, or at least some components of it, allows young animals to simulate, in a relatively safe context, potentially dangerous situations that will arise in their adult life. They learn from their mistakes, but do so in relative safety. On this view, play exerts its most important developmental effects on risky adult behaviour such as fighting, mating in the face of serious competition, catching dangerous prey, and avoiding becoming someone else’s prey. Indeed, the behaviour patterns of fighting and prey-catching are especially obvious in the play of cats and other predators, whereas safe activities such as grooming, defecating and urinating have no playful counterparts.

Dog soliciting play with a bow. Photo by Thomas Zimmermann (2015), Wikimedia, https://commons.wikimedia.org/​wiki/​File:Vorderkoerpertiefstellung_THWZ.jpg, CC BY 3.0.

  • 6 Kahlenberg, S.M. & Wrangham, R.W. (2010), Sex differences in chimpanzees’ use of sticks as play obj (...)

7When differences between the sexes arise in play, as they often do, these are reflected in differences between the sexes in the activities of adults. For instance young female chimpanzees seem to behave maternally towards sticks, doing so much more than males and ceasing to do so when they have real offspring to care for.6 One study showed that stick-carrying consisted of holding or cradling detached sticks pieces of bark, small logs or woody vine with their hand or mouth, underarm or, most commonly, tucked between the abdomen and thigh. Individuals sometimes carried sticks for periods of up to four hours or more during which they rested, walked, climbed, slept and fed as usual. The occurrence of stick-carrying peaked among juveniles and was higher in females than males. This sex difference could not be explained by a general propensity for females to play with objects more than males, because several types of object such as weapons were played with more by males. Males in many species, including humans, perform more rough and tumble play than females and engage in more violent activities when adult.

Siberian tiger mum and daughter play-fighting. Photo by Tambako The Jaguar (2011), Flickr, https://www.flickr.com/​photos/​tambako/​6831507351, CC BY-ND 2.0.

8Play has features that are likely to make it suitable for finding the best way forward in a world of conflicting demands. In acquiring cognitive skills, individuals are in danger of finding sub-optimal solutions to the many problems that confront them. In deliberately moving away from what might look like the final end state, each individual may arrive somewhere that is better. Play may therefore fulfil an important probing role that enables the individual to escape from false end-points or ‘local optima’. An analogy is a mountain surrounded by lesser peaks.

9A climber might get to the top of a lesser peak only to discover that he or she had to descend before scaling a higher one. When the metaphorical climber is on a lower peak, active ways of getting off it can be highly beneficial. In practice what this could mean that the activities involved in play discover possibilities that are better than those obtained without play.

  • 7 Bateson, P. & Nettle, D. (2014), Playfulness, ideas, and creativity: a survey. Creativity Research (...)

10All short-term quantitative studies of play in animals find that some individuals play more than others. In humans, five main dimensions have been used to describe the variation in personalities. Many of these are not usually regarded as attributes of cognitive ability, but the dimension ‘Openness to Experience’ is one that could have developed as the result of play. The descriptions of people on one dimension range from Creativity to Analytical Ability. In a survey of humans, the individuals who believed that they were playful also believed that they were creative.7 Respondents were asked to offer ideas for the uses of two items, a jam jar and a paperclip. In the literature on creativity, those individuals who produce few answers are referred to as ‘convergers’ and those who produce many suggestions are known as ‘divergers’. The typical sole response from a converger when asked for uses for a paper clip was ‘Clip paper together’. The response from one diverger in the survey was: ‘Clip papers, unfold to clean fingernails, general clothes fixing in an emergency, put on a magnet for a science experiment for children, make a mobile with lots of them, make a sculpture with one or more of them, earrings, pick a lock’. If there had no been a cut-off after ten answers, this person would probably have gone on. Most of the respondents provided a relatively small number of uses for the objects and only a few offered many uses. The respondents who regarded themselves as playful and producers of new ideas were much more likely to give lots of uses.

  • 8 The distinction between creativity and innovation is emphasised in Bateson, P. & Martin, P. (2013),(...)

11The differences between individuals might reflect the variation in almost every character of body and behaviour. It might instead (or in addition) reflect the benefits of being different from others. In a population that consists mostly of females it is advantageous to be a male — and vice versa. In cooperative species, providing a particular set of skills may complement a different set possessed by others. In humans those who suggest new ways of looking at the world are complemented by others who put such ideas to good use. Creativity and innovation are mutually beneficial but not necessarily found in the same person.8

Environmental change

12The environment does not cease to be important even if it normally remains constant. Change the environment and the outcome of an individual’s development may be utterly different. Indeed, if an individual does not inherit its parents’ environment along with their genes and other transmittable factors, it may not be well adapted to the conditions in which it now finds itself. Its behaviour may enable it to cope.

13A rule for learning, or for any other kind of developmental process, is not simply a gene written large. A straightforward correspondence between a gene and a rule for changing behaviour is no more likely than a straightforward relationship between gene and behaviour (see Chapter 8). The same point applies with equal force to all the other epigenetic rules that bring order to development. Presumably, if the rules have any universality in natural conditions, the experience that affects them must be a common feature of all the animals having those rules. Alternatively, they must be well buffered against change by the particular conditions in which an individual finds itself.

14When behaviour changes in response to alterations in the environment, it seems likely that the specific ways in which animals tune their behaviour to local conditions are themselves the products of Darwinian evolution. If rules for learning fit the animal’s information-gathering equipment to particular problems and which may have been subject to Darwinian evolution, then the conditions necessary for their development must pass in some way from one generation to the next. While the mode of transmission may commonly involve genes, the rules for modifying behaviour are hardly likely to spring fully armed out of the genome. Criticism of the assertion that genes code for behaviour that is not learned applies just as forcibly to the rules that are involved in the development of behaviour. Such rules represent the workings of an already functional nervous system and body. They themselves have to develop and depend on structures that require for their development a complex interplay between the products of many genes and many conditions external to the genome.

15Many features of the inferred rules for learning seem to be profoundly modified by experience. For instance, whether or not initially neutral cues are treated as potentially relevant or ignored is greatly affected by the animal’s prior history. Such selectivity in responsiveness to external conditions can be of great use to the animal. In many experiments on associative learning monkeys are rewarded with food. The machines that dispense the food are commonly designed to drop peanuts into a cup when the monkey is to be rewarded. Many monkeys do not like the peanuts at first. They have to be deprived of their regular food and accustomed to the peanuts for weeks before they will take them with any readiness, let alone treat the nuts as rewards for appropriate behaviour. In such cases, which are not exceptional, experience expands the range of what the monkeys regard as acceptable food.

16It might be argued that a spontaneously expressed rule could still be detected at work behind the scenes, since the general category of food, and its effectiveness as a reward, was in some sense built in. In other cases, though, it becomes more difficult to pinpoint what might or might not act as a reward without extensive knowledge of the animal’s previous experience. For instance, the condition in which it becomes possible for an animal to perform an act that would bring it food becomes rewarding in itself. So the animal will work in order to provide itself with those conditions. In this way, lengthy chains of behaviour can be developed with one event providing the terminating condition for one action and the enabling condition for the next. This is the basis for many complex circus acts performed by animals.

17An adaptation of an animal’s behaviour to the environment in which it lives gives the appearance of good design. The adaptations are often the result of Darwinian evolution, but the adaptability of organisms will mean that the adaptations may have developed during the lifetime of the individual. An individual whose body has been damaged in an accident or who is burdened with a mutation that renders its body radically different from other individuals may be able to accommodate to such abnormality. In doing so, the individual may develop novel structures and behaviour not seen in other individuals of the same species. Such accommodation can be particularly marked when it occurs early in development. A goat born without forelimbs walked about on its hind legs and developed a peculiar musculature and skeleton. A modern instance is a bipedal domestic dog.9 The animals have coped with an abnormality by accommodating to it, producing coordinated changes in functionally related characters. Similarly, humans born with limb abnormalities as a result of exposure to a teratogen such as thalidomide develop strategies to cope, for example, by handling objects using their feet or teeth in ways for which others might use their hands.

18The capacity of the individual to respond to neural damage is remarkable, particularly when the damage occurs early in life. In such cases described in humans, the brain reorganises and morphologically can look markedly different from the brain of a normal individual. Even so, the effects on behaviour may be scarcely detectable and the plasticity at the neural level may be accompanied by robust development at the behavioural level.

19Another form of ‘coping’, found especially during early development, arises when the organism must make immediate responses to survive a challenge but, in contrast to accommodation responses, the normal developmental sequence is not necessarily disrupted. Although these responses may involve either structural or temporal changes in the course of development, they do not entail a fundamental change in the normal pattern of development. Thus, the phenotypic consequences are not as marked as those that involve accommodation, but they may have a costs and become disadvantageous to the individual later in life.

Conclusions

20Individuals differ for a variety of reasons, some genetic and some stochastic. Undoubtedly their plasticity, which comes in many forms, also contributes greatly to the variation commonly found in most populations. The processes involved in plasticity can operate at many different levels, ranging from the molecular to the behavioural, some involving adaptability to what may be novel challenges and some responding conditionally to local circumstances. Differences between individuals can be triggered in a variety of ways, some mediated through the parent’s characteristics. Sometimes phenotypic variation arises because the environment triggers a developmental response that is appropriate to those ecological conditions. Sometimes the organism ‘makes the best of a bad job’ in suboptimal conditions. Sometimes the buffering processes of development may not cope with what has been thrown at the organism, and a bizarre phenotype is generated. Whatever the appearance of a well-designed organism’s characteristics, the various forms of plasticity illustrate why individuals of the same species can differ so much.

Notes

1 Fitzgibbon, C.D. & Fanshawe, J.H. (1988), Stotting in Thomson’s gazelles: an honest signal of condition. Behav. Ecol. Sociobiol. 23.2, 69–74, https://doi.org/10.1007/bf00299889

2 Cresswell, W. (1994), Song as a pursuit-deterrent signal, and its occurrence relative to other anti-predation behaviours of skylark (Alauda arvensis) on attack by merlins (Falco columbarius). Behav. Ecol. Sociobiol. 34.3, 217–223, https://doi.org/10.1007/bf00167747

3 Laland, K.N., Odling Smee, J. & Gilbert, S.F. (2008), Evo-devo and niche construction: building bridges. Journal of Experimental Evolution 310B, 549-566.

4 A full discussion of play is given in Bateson, P. & Martin, P. (2013), Play, Playfulness, Creativity and Innovation. Cambridge: Cambridge University Press. ‘Playfulness’ is a positive mood state that facilitates and accompanies ‘playful play’, a subset of broadly defined play. A distinction is drawn between playful play and non-playful play. Playfulness, the defining feature of playful play, is a positive mood state that is not always detectable in observable behaviour. The behaviour of a playful human is captured by numerous synonyms, including cheerful, frisky, frolicsome, good-natured, joyous, merry, rollicking, spirited, sprightly and vivacious. Some of these terms relate to human emotions that could not be readily identified in animals without much anthropomorphic projection. Some, though, are descriptive of visible behaviour and can be defined ostensively, such as when two kittens engage vigorously in social play. In animals, as in humans, playfulness may be inferred from the context in which it occurs. What the animals do may vary — from playing with objects at one moment to playing with another individual at the next — but the playful state underlying their behaviour is the same.

5 Gomendio, M. (1988), The development of different types of play in gazelles: implications for the nature and functions of play. Anim. Behav. 36.3, 825–836, https://doi.org/10.1016/S0003-3472(88)80165-9

6 Kahlenberg, S.M. & Wrangham, R.W. (2010), Sex differences in chimpanzees’ use of sticks as play objects resemble those of children. Current Biol. 20.24, R1067-R1068, https://doi.org/10.1016/j.cub.2010.11.024

7 Bateson, P. & Nettle, D. (2014), Playfulness, ideas, and creativity: a survey. Creativity Research J. 26.2, 219–222, https://doi.org/10.1080/10400419.2014.901091

8 The distinction between creativity and innovation is emphasised in Bateson, P. & Martin, P. (2013), Play, Playfulness, Creativity and Innovation.

9 The remarkable ability of Faith, the two-legged dog, can be viewed on YouTube https://www.youtube.com/watch?v=5QKG3CKZTYU

Table des illustrations

Légende Lake created by beavers damming a river (2005), Wikimedia, https://commons.wikimedia.org/​wiki/​Algonquin_Provincial_Park/​media/​File:Biberdamm_2_db.jpg, Public Domain.
URL http://books.openedition.org/obp/docannexe/image/3893/img-1.jpg
Fichier image/jpeg, 96k
Légende Dog soliciting play with a bow. Photo by Thomas Zimmermann (2015), Wikimedia, https://commons.wikimedia.org/​wiki/​File:Vorderkoerpertiefstellung_THWZ.jpg, CC BY 3.0.
URL http://books.openedition.org/obp/docannexe/image/3893/img-2.jpg
Fichier image/jpeg, 32k
Légende Siberian tiger mum and daughter play-fighting. Photo by Tambako The Jaguar (2011), Flickr, https://www.flickr.com/​photos/​tambako/​6831507351, CC BY-ND 2.0.
URL http://books.openedition.org/obp/docannexe/image/3893/img-3.jpg
Fichier image/jpeg, 39k

Acheter