Chap.15 Play 鄭先祐 (Ayo) 教授 國立台南大學 環境與生態學院 生態科學與技術學系 環境生態研究所 + 生態旅遊研究所

Ayo 2010 Ethology2 Play  Defining play  Types and functions of play  Object play  Locomotor play  Social play  A general theory for the function of play  Endocrinological and neurobiological bases of play  A phylogenetic approach to play

Ayo 2010 Ethology3 Sea lions Polar bears

Ayo 2010 Ethology4 Defining play  Play is all motor activity performed that appears to be purposeless, in which motor patterns from other contexts may often be used in modified forms and altered temporal sequencing.  If the activity is directed toward another living being it is called social play.  This definition centers on the structure of play rather than its function.  Purposeless?  不知道，不等於，沒有存在

Ayo 2010 Ethology5 Types and functions of play  Object play  Refers to play that centers on the use of inanimate objects such as sticks, rocks, leaves, feathers, fruit, and human-provided objects, and the pushing, throwing, tearing, or manipulating of such objects.  Locomotor play  Refers to as locomotor-rotational play  Social play  Three functions: (1) long-lasting social bonds, (2) needed physical skills, (3) development of cognitive skills.

Ayo 2010 Ethology6 Leaf-pile pulling. As they go down the slope of a mountain, individuals sometimes walk backwards, pulling handfuls of leaves and then stopping and either walking or somersaulting ( 翻筋斗 ) through the piles of leaves. The (A) photo shows the chimp as he starts to gather a pile of leaves, and the (B) photo shows the same chimp as his leaf pile accumulates.

Ayo 2010 Ethology7 Here a cheetah cub comes upon a novel object: a can. Exploring the can appears designed to address the “what is it?” question, while play appears designed to tackle the “what can I do with this object?” question.

Ayo 2010 Ethology8 Object play in juvenile ravens  Young animals often have more “free time” than adults to engage in object play.  Mind of the Raven (Heinrish, 1999)  Play or exploration? Exploration and play  自然項目有 980items + 44 novel items  Exploration and play were directed at novel items.  Benefit of enabling the juvenile ravens to identify new food sources.

Ayo 2010 Ethology9 Various ”hanging games” Heinrich observed in ravens.

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Ayo 2010 Ethology11 Object play in young cheetahs  Tim Caro examined play in cheetah cubs in the Serengeti National Park in Tanzania for three years (Fig. 15.5).  He observed cubs for more than 2,600 hours and documented many cases of object, social, and locomotor play (Table 15.2).

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Ayo 2010 Ethology14 In cheetahs, play progressively disappears with age.

Ayo 2010 Ethology15 Locomotor play  Two hypotheses: (the function)  Provides both exercise and training for specific motor skills needed later in life.  Provides animals with a better understanding of “ the lay of the land ”.  Pronghorn( 叉角羚 ) play (Fig. 15.7)  Physiological effects of elevated motor activity (Table 15.3)  Play and brain development (Fig. 15.8)

Ayo 2010 Ethology16 “high-speed running”“fast turns” “stots”, jumping with all four legs simultaneously off the ground.

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Ayo 2010 Ethology19 Mice

Ayo 2010 Ethology20 Rats

Ayo 2010 Ethology21 Cats

Ayo 2010 Ethology22 Social play  Social play and bighorn sheep  (Fig. 15.9) Juvenile bighorn sheep who (A) stayed close to their mothers for extended periods of time play less often than (B) other juveniles.  Social play and cognition  Self-assessment Young sable antelope like this pair often engage in play, particularly with same-age partners (Fig )  Play markers (Fig ) (play signals)  Play face in gorillas (Fig )

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Ayo 2010 Ethology25 (A)Play signals override canine aggression. The dog on the right growls, while the dog on the left “paws”. Pawing is a play signal that can turn a potentially dangerous encounter into a playful one. (B)Play bows are also often used as signals that the bowing individual wants to play, the dog in this photo is play bowing to another individual.

Ayo 2010 Ethology26 Preceding bouts of aggressive play, juvenile gorillas use a facial gesture called a ”play face”, which appears to signal that “what is about to occur is play”.

Ayo 2010 Ethology27 Role reversal (self-handicapping)  Older individuals either allow subordinate younger animals to act as it they are dominant during play or the older animals perform some act at a level clearly below that of which they are capable.  The benefits of play (Fig )  Young animals learn to cooperate during play (left) and that this might have benefits later in life, when cooperation is necessary – for example, when adult lions are hunting a wildebeest (right).  Role reversal (Fig ) squirrel monkeys

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Ayo 2010 Ethology29 In play fighting between older and younger juvenile squirrel monkeys, role reversal sometimes occurs, wherein an older, larger playmate will allow a younger, smaller playmate to act as if he is dominant and to obtain the superior position when they wrestle.

Ayo 2010 Ethology30 A general theory for the function of play  Play functions to increase the versatility of movements used to recover from sudden shocks such as loss of balance and falling over, and to enhance the ability of animals to cope emotionally with unexpected stressful situations.  Predictions:  The amount of play experienced will affect an animal ’ s ability to handle unexpected events.  Self-handicapping.  The locomotor play should be most common in species that live in the most variable environments. mice

Ayo 2010 Ethology31 Endocrinological and neurobiological bases of play  Play fighting in young male rodents  Focused on testosterone  Injected neonatal male rats with either testosterone propionate (TP) or an oil substance (as a control).  The presence of testosterone or transformation of testosterone into other substances that affected play fighting in rats.

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Ayo 2010 Ethology34 Three neurotransmitter systems  Dopamine, norepinephrine, and serotonin  Dopamine inhibitors reduce play  Siviy experiment  Rat city. This experimental apparatus served as a “ play city ” for Siviy ’ s work on rats, play, and neurotransmitters. (Fig )  Dopamine may also be involved in the increase in the “ chirping ’ sound that is often heard during rat play but not at other times.  Fig anticipating play

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Ayo 2010 Ethology36 Mean number of tunnel crossings in Siviy’s rats. Rats in the “play’ treatment were given a five-minute opportunity to play with a same age partner in a “play city” right before the test. Control animals ha no such opportunity.

Ayo 2010 Ethology37 Sexual play in young Belding’s ground squirrels  In natural populations of Belding’s ground squirrels, male initiate much more sexual play than do females. (Fig )  Females in the testosterone treatment displayed a significantly increase frequency of sexual play behavior.  Testosterone-treated females displayed sexual behavior at almost the level displayed by same-age males.  Testosterone, play, and food (Fig )

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Ayo 2010 Ethology39 In juvenile Belding’s ground squirrels, males typically display much higher levels of sexual play than do females. Females in the testosterone treatment (T-treated females) increase sexual play. For both young males and females, provisioning (supplementing the diet with a high-fat food) increased rates of sexual play.

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