The relevance of animal play for animal welfare

动物为什么玩耍是行为生物学中最经久不衰的谜题之一。玩耍似乎并没有以任何明显的方式帮助动物生存或繁殖。那么它为什么会进化呢？到目前为止，这个问题还没有被广泛接受的答案。另一个相关的问题是，玩耍是否可以用来更好地了解农场动物的福利。动物通常只有在食物和安全等基本需求得到满足时才会玩耍，但这条规则也有例外。例如，减少小牛和小猫的奶量会让它们感到痛苦，也会让小牛比以前玩得少。令人惊讶的是，它让小猫花更多的时间玩东西。我们需要了解这些例外情况，才能知道玩耍何时真正意味着良好的福利，也因为它们可能为玩耍进化的原因提供线索。我对这样一种假设特别感兴趣，即玩耍的动作看起来如此尴尬、夸张或鲁莽，因为玩耍是动物让自己陷入麻烦的一种安全方式，只是为了让它们学会如何摆脱麻烦。这将帮助他们发展应对危险挑战所需的身体技能，以及在这些可怕的情况下避免恐慌的情绪弹性。我的研究计划旨在回答以下一系列相关问题：为什么游戏会进化，它能告诉我们关于动物福利的什么，以及游戏对动物福利的影响是什么？仔猪是测试这些假设的理想物种。它们有丰富多样的游戏行为，科学界比其他养殖物种更了解猪的游戏行为，而且猪在玩耍的年龄是成群饲养的。第一个实验将测试环境因素是否预示着动物在未来可能遇到危险的情况，从而导致它们增加玩耍——如果玩耍是一种准备的方式，它们就应该这样做——以及这是否解释了为什么当福利变得更差时，玩耍有时会增加。随后的实验将测试花更多时间玩耍的动物在面对危险情况时是否会变得更有技巧和情绪弹性。最后，我们将使用源自人类临床研究的认知测试来评估单个仔猪的整体情绪，以测试情绪的变化是否与游戏的变化有关。这项研究将对所有对我们为什么玩耍感兴趣的人，以及寻求更好地了解动物福利的科学家和农民都很重要。如果玩耍可以帮助小动物成为有能力和勇敢的成年人，那么找到鼓励玩耍的方法也会带来更好的福利，因为动物将更好地面对压力事件，如被处理或运输。在社会对人道对待农场动物的需求日益增加的背景下，这将有重要的应用。这项研究还可能带来更广泛的长期积极的社会成果，因为提高动物福利也可以以各种方式与农民和消费者的福祉联系在一起。

Why animals play is one of the most enduring puzzles in behavioural biology. Playing does not seem to help animals survive or reproduce in any obvious way. So why did it evolve? There is as yet no widely accepted answer to this question. Another connected question is whether play can be used to better understand the welfare of farm animals. Animals usually play only if essential needs like food and safety are met, but there are exceptions to this rule. For instance, cutting the milk rations of calves and kittens makes them distressed, and makes calves play less than before. Surprisingly, it makes kittens spend more time playing with objects. We need to understand such exceptions to know when play truly indicates good welfare, and also because they might provide clues as to why play evolved. I am particularly interested in the hypothesis that play movements can look so awkward, exaggerated, or reckless because playing is a safe way for animals to get themselves into trouble, just so that they can learn how to get out of trouble. This would help them develop the physical skills they will need to cope with dangerous challenges, and the emotional resilience to avoid panicking in these frightening situations. My research program aims to answer the following set of related questions: why did play evolve, what can it tell us about animal welfare, and what are the effects of play on animal welfare? Piglets are an ideal species in which to test these hypotheses. They have a rich, varied repertoire of play behaviour, the scientific community understands more about play in pigs than in other farmed species, and pigs are housed in groups at playful ages. A first experiment will test whether environmental factors that signal that an animal risks encountering dangerous situations in the future lead to increase play - as they should if play is a way of preparing - and whether this explains why play sometimes increases as welfare gets worse. Subsequent experiments will test whether animals who spend more time playing do become more skilled and emotionally resilient when facing dangerous situations. Finally, we will evaluate the overall mood of individual piglets using cognitive tests derived from human clinical research, to test whether changes in mood are associated with changes in play. This research will be important for all interested in why we play, and for scientists and farmers seeking to better understand animal welfare. If playing can help young animals become competent and brave adults, then finding ways to encourage play will also lead to better welfare, as animals will be better equipped to face stressful events like being handled or transported. This will have important applications in the context of increased societal demands for humane treatment of farm animals. The research may also lead to broader long-term positive social outcomes, as enhanced animal welfare can also be tied in various ways to the well-being of farmers and consumers.