Page 14 - Emotions through the eyes of our closest living relatives- Exploring attentional and behavioral mechanisms

Chapter 1
What are emotions? To many people, emotions are subjectively felt affective states. There is no doubt in our minds that we experience emotions, and that others do, too. Nevertheless, describing what exactly an emotion is has proved to be a major scientific challenge, and definitions are still highly contested (Adolphs et al., 2019; James, 1884; LeDoux, 2021; Russell & Barrett, 1999). For a long time, the lack of a clear definition for emotions stood in the way of understanding what role emotions play in not only our lives but the lives of other animals as well. Moreover, it made unraveling the evolution of emotions very difficult (Paul & Mendl, 2018). When Nikolaas Tinbergen published his seminal work on the four questions that scientists can ask to find proximate (“how”) and ultimate (“why”) explanations for animal behavior (Tinbergen, 1963), the topic of emotions in animals other than humans was still highly controversial. This was mainly due to the subjective nature of emotions, as animals cannot tell us what they feel or how they experience things. Since then, the interdisciplinary field that is concerned with emotions in humans and other animals has grown steadily and confidently and is now known by the name comparative affective science (Williams et al., 2020). With the rise of this new scientific field, attempts have been made to find a definition of emotion that makes it accessible to scientific inquiry. For instance, a broad definition was provided by Frans de Waal in his work What is an animal emotion?:
“Emotions [are] mental and bodily states that potentiate behavior appropriate to the environmental challenges” (De Waal, 2011).
These emotional states are adaptive; they are shaped through the process of natural selection to prepare individuals for the most appropriate and optimal response. Emotional states are caused by external, biologically relevant stimuli, bringing about a range of parallel changes in an organism (e.g., behavioral, psychophysiological, cognitive, and somatic). The kind of emotion that is triggered, is closely tied to the context an individual finds itself in (De Waal, 2011). Moreover, although we typically assign subjective experiences (“feelings”) to emotional states, these are arguably hard to probe in animals. However, even if we do not fully grasp the emotional experiences of animals, this understanding is not necessary to move forward (see for discussions e.g., Berridge, 2018; LeDoux, 2021; Mendl et al., 2010). Building from the premise that emotions are states that the body can be in, we can examine these states in more detail by looking at their cognitive and behavioral markers (Anderson & Adolphs, 2014; De Waal, 2011; Paul et al., 2005). These markers serve as proxies to the ”inner world” of animals as well as of humans, and
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