The sensation and expression of emotion are fundamental to the human animal’s experience. It has become increasingly clear to many researchers that emotional responses pervade human consciousness, even in thought processes that are believed to be rigidly “objective” (however that word might be defined) or purely intellectual. Emotion has been and continues to be an extraordinarily significant part of our history. It is, quite literally, a major factor in every historical event and a ubiquitous feature of daily human interaction. But defining what emotion is isn’t as straightforward as one might imagine.
Defining and Describing Emotion
It is universally agreed that emotional response is tied unalterably to a person’s perception of what is important to them at the moment in time that has caused the response. When we dig deeper and ask ourselves what emotion is, we are confronted by the fact that emotion has an ineffable element to it, and any attempt to put this ineffable element into words immediately distorts or misrepresents the emotional experience. In a sense, emotion is similar to perception or even consciousness itself. It cannot be defined by description alone. It must be felt, known, lived. Moreover, all emotions are (obviously) subjectively experienced. No one’s experience of joy, sorrow, anger, grief, or any other emotion will be exactly like that of another human. As with all aspects of human experience, we must rely for our understanding on the principle of assumed similarity, a sort of emotional general ground that most humans share, in order to proceed in our examination of human reality.
With
these caveats in mind, what are the widely accepted definitions? The temptation
here is to immediately start listing various affects and affect displays, but
this really doesn’t get to the heart of the matter. So neurologists,
psychologists, and other researchers take a more formal approach.
A
Canadian researcher contends that consciousness is a four-dimensional
experience, one that possesses quality, duration, intensity, and what he terms hedonicity,
the latter term being a metric of pleasure or displeasure. Emotion, an aspect
of consciousness, he defines as a mental experience possessing both high
intensity and a high hedonic component.1
The
neurologist Antonio Damasio has proposed that there is a distinction between feeling
and emotion:
Damasio contends that the mechanisms of emotion can arise without consciousness, even if these emotions are then consciously experienced. He goes on to give a compelling way to think of the feeling of emotion:
It is the representation of that transient change in organism state in terms of neural patterns and ensuing images. When those images are accompanied, one instant later, by a sense of self in the act of knowing, and when they are enhanced, they become conscious. They are, in the true sense, feelings of feelings.3
A pair of emotion researchers take what is called an adaptationist perspective on emotion. It is their view that natural selection produced emotions to help animals deal with dangers and to exploit opportunities for advantage. The basic emotions are therefore physiological responses that serve to help an animal adapt to the conditions in which it finds itself. They mobilize the body’s resources, coordinating changes in them to more effectively respond to a particular situation or stimulus.4
Works that offer a variety of contributions by experts in a field help us see the range of scientific opinion on a topic. One such noteworthy volume offers the following definitions of the term emotion:
Emotion may be understood as the outcome of an evaluation of the extent to which one’s goals are being met in interaction with the environment.5
I would say that emotions are specific and consistent collections of physiological responses triggered by certain brain systems when the organism represents certain objects or situations [either internal or external or retrieved from memory].6
A pair of researchers put it this way:
…an emotion is one of a large set of differentiated biologically based complex conditions that are about something.
They go on to elaborate that emotions have four components: cognitive (which evaluates the personal significance of the event or stimulus involved), motivational-behavioral (which assesses what action can be taken), somatic (in which the body’s nervous and musculoskeletal systems are mobilized for feeling the emotion involved), and subjective-experiential (in which the person feeling the emotion is aware of it, is experiencing it subjectively, and is integrating it with other feelings and knowledge). These components interact with each other, and display variable levels of duration and intensity.7
A psychologist at The University of Delaware who was noted for his contributions to emotion research laid out what he referred to as Seven Principles that explain the nature and manifestation of emotion. His main points (paraphrased) are as follows:
1. The feeling of emotion is the product of neurobiological evolution. It is the key aspect of both emotion and consciousness, and is more adaptive than maladaptive.
2. Emotions were crucial in the evolution of
consciousness. Throughout a person’s life, emotion is the chief factor that
influences the contents of their consciousness and how those contents are
focused.
3. Because they are felt and experienced, emotion feelings are central to motivation and overt behavior.
4. Fundamental emotions help to motivate and shape the response of a human to challenges to their well-being. Perception, cognition, and emotion feeling all interact in a dynamic way in these responses. These interactions can generate experiences that cause a human to have the same core feelings, but different thoughts and plans of action.
5. How emotions are used usually depends on the interaction of cognition and emotional response. The uses to which emotions are put come in part from the experience of emotion feeling and in part from learned behaviors.
6. Emotions become maladaptive, and even potentially pathological, when learning connects emotions to erroneous cognitions and harmful actions.
7. Interest is an emotion and in the normal mind, under ordinary conditions, it is present continually. It motivates humans to engage in creative or other positive activities, engagement that leads to a sense of well-being. In interaction with other emotions, it causes selective attention. This attention influences all other mental processes.8
Psychologist Lisa Feldman Barrett points to the phenomenon of interoception:
Simple pleasant and unpleasant feelings come from an ongoing process inside you called interoception. Interoception is your brain’s representation of all sensations from your internal organs and tissues, the hormones in your blood, and your immune system… This interoceptive activity produces the spectrum of basic feeling from pleasant to unpleasant, from calm to jittery, and even completely neutral…Interoception is in fact one of the core ingredients of emotion, just as flour and water are core ingredients of bread, but these feelings that come from interoception are much simpler than full-blown emotional experiences like joy and sadness.9
So, in sum, we may say that when a human perceives a particular kind of situation, one which they find either pleasing or displeasing, or when that human draws a parallel to this situation from memory, a response arises. Sometimes this response begins in the non-conscious part of the brain. This response is tied to the person’s evaluation of the immediate importance of the situation being responded to, or else the strength and/or persistence of a remembered response. The response mobilizes the body’s physiology for action and combines with the human’s cognition (especially the learned or constructed reaction to similar situations from the past) to generate what may be considered an emotion, something which is felt within the mind and expressed outside of it. And as we are about to see, the roots of this reaction are very ancient indeed.
The Evolution of Emotion in the Animal Kingdom
There is a tremendous range of behaviors in the animal kingdom, a vast spectrum ranging from completely predictable behavior to behaviors which are, to varying degrees, unpredictable. The simplest animals, several of them the direct lineal descendants of the first animal life, behave as they are genetically programmed, with no deviation. They do what they do because they can do nothing else. They lack any trace of conscious awareness. The vast majority of these simple animals do possess rudimentary nervous systems, and they do respond to certain stimuli. But they do not show anger or pleasure or surprise or approval. They simply respond. The evolution of emotional responses broadened the behavioral repertoire. Animal responses to perceived situations now became the basis of much behavior, an attempt to re-establish internal equilibrium.
It would appear that various emotions evolved at different times within Kingdom Animalia. Researchers generally believe that fear was the first emotion to emerge. Fear has utility for obvious reasons. Animals typically have predators, or else natural enemies that compete for ecological niches and resources. Fear motivates action, action which can save the animal from harm or even death, thus contributing to potential reproductive advantage.
A prominent researcher in the field contends that fear was preceded by a far older animal response to the world, a survival circuit in the brain that evolved as a way of defending animals from harm. The key to this circuit is the amygdala, a structure all vertebrates possess, and which evolved more the 400 million ybp. Based on the research he and his colleagues performed, he has concluded:
…sensory inputs to, and motor outputs from the amygdala are responsible for the behavioural and physiological expression of conditioned fear responses. And importantly, within the amygdala, a systematic pattern of synaptic connectivity from the input region (i.e. lateral nucleus) to the output region (i.e. central nucleus) was revealed. Further, while synaptic plasticity was found to occur throughout the amygdala circuitry, plasticity in the lateral amygdala seemed particularly important, based on the short latency of the neural changes and their necessity in supporting plasticity in other areas.10
In 2024 a team of researchers contended that the basic fear response emerged at least 700 million ybp, and has been conserved across enormous numbers of species. They distinguish fear from other emotions by highlighting its anticipatory nature. The fear response arises when an animal perceives that a negative or aversive outcome may occur in an unfolding situation. If the animal is unable to avoid this situation, one of two responses will occur. If the animal believes it has a chance to survive the encounter, its anger will erupt. Anger will mobilize the animal’s physiology to deal with the situation. If the animal believes it cannot avoid the bad outcome, it will respond with sorrow, which may mobilize others of its kind to help.11
In connection with this, a very widespread phenomenon in the animal kingdom is the reaction known as Fight or Flight. When an animal is confronted with a threatening situation, the sympathetic nervous system floods the body with adrenaline and noradrenaline which in turn mobilizes the body’s physiology, increasing such things as muscle strength and metabolism, among other effects. This allows the body to bring more strength and endurance to the situation at hand. After the threat has subsided, the body’s physiology returns to its normal state.12
In trying to trace the evolution of love, I thought it would be useful to offer a formal definition of the term. I’ve always liked Harry Stack Sullivan’s formulation:
When the satisfaction or the security of another person becomes as significant to one as one’s own satisfaction or security, then the state of love exists. So far as I know, under no other circumstances is a state of love present, regardless of the popular usage of the word.13
Philosophers and other scholars have identified a number of different forms and manifestations love takes. Our focus here will be more narrow. We are interested in the origins of this most common of emotions, and how the various forms love takes may have stemmed from common roots. Many researchers look to the utility of love, its usefulness in the establishment and maintenance of reproductively-advantageous relationships. To that end, important research has centered around maternal affection. And, according to some researchers, romantic love has stemmed from this.
A researcher who has done extensive work on the origins of love stresses that it is an adaptive behavior. He sees the following purposes for it:
• displaying reproductively relevant resources;
•
providing sexual access;
•
signaling sexual fidelity;
•
providing psychological and emotional resources;
•
promoting relationship exclusivity through mate guarding;
•
displaying commitment – love as a commitment device;
•
promoting actions that lead to successful reproductive outcomes; and
•
providing signals of parental investment.14
As much as it may offend the sensibilities of some of the more sentimental among us, it must be said that love evolved primarily because it facilitated the biological success of our genus. It worked. This is not to say that the growth of human intelligence simplified matters related to love. In fact, the opposite has tended to be the case. In the same fashion that humans have complicated their sexuality, the human mind has made the various aspects of love tremendously complex.
Anger, as we saw above in connection to fear, appears to have emerged in the course of animal evolution as a device for winning conflicts. Passivity often meant death. Conflict resolution in humans appears to follow a similar pattern. A trio of evolutionary psychologists has studied anger’s roots, saying that from an evolutionary standpoint anger was a logical response to certain social interactions. In the social networks in which humans evolved there were numerous occasions where conflict occurred. Selection pressures rewarded both cooperation and aggression. Evolutionary biologists note that anger and aggression are common in many other species, and humans are heirs to this tendency. Anger is a form of what the authors call social negotiation. There are times when anger produces benefits in such negotiation, particularly when one party to the negotiation believes they are not receiving a fair trade-off in whatever exchange is occurring. Anger becomes a tactic for (trying to) rectify the situation.15
Some researchers emphasize, by the way, that anger and hatred are not the same emotion, and that they serve different adaptational purposes. As one research team explains it, anger’s chief purpose is to “bargain for better treatment”. Hatred’s objective, on the other hand, is meant to neutralize a specific target that has inflicted perceived harm on the hater. The researchers identify three methods by which hatred is expressed: Distancing, which can mean simply removing one’s self from the hated person (either by removing one’s self from them or, if possible, exiling the one who is hated), stripping the hated person of power, or killing the person. Depowering and killing of course carry risks, since they invite possible retaliation or negative sanctions from the group.16
In fact, it appears that all of the major emotions emerged because they either facilitated individual survival, facilitated group solidarity, increased reproductive potential, or some combination of these factors. Happiness, for example, is useful in social bonding. Grief, which varies according to the personal significance to the grieving person of the individual or situation being mourned, appears to have diverse origins and functions. Sorrow can be a signal to other members of the group to rally to the side of the person going through it. The point is that these emotions are not arbitrary. They serve a function. They evolved in the more advanced animals and find their most complex expression in Homo sapiens sapiens. In the next volumes of this work, we will see again and again how emotions have affected every aspect of human life, have helped shape every historical event, have been at the heart of our religions, our arts, our politics, our economies, and our relationships with the natural world.
Neural Correlates of Emotion
For many years most researchers have believed the limbic system of the brain is the chief region that regulates emotional responses. A number of researchers, however, reject the idea that the term limbic system is descriptively useful. One critic of the limbic system concept arrives at the following conclusion:
Within vertebrates, the overall brain plan is highly conserved, though differences in size and complexity also exist. The forebrain differs the most between mammals and other vertebrates, though the old notion that the evolution of mammals led to radical changes such that new forebrain structures were added has not held up. Thus, the idea that mammalian evolution is characterized by the addition of a limbic system (devoted to emotion) and a neocortex (devoted to cognition) is flawed.17
There is a controversy among neurologists as to whether there are unique and distinctive brain regions that process individual emotions or whether a variety of emotions are processed in a common brain region. A group of researchers looking at how the eyes process emotion-stimulating stimuli (in this study, visual elements that provoke anger, happiness, fear, or sadness) found that there seems to be a common network that supports their processing. The researchers make it clear that there might be subnetworks within the larger network that handle individual emotional responses, or there may be other factors at work which have not yet been determined.18
A pair of researchers has amassed evidence that three interacting brain systems, functioning hierarchically, generate, perceive, and regulate emotions. These systems appraise situations, an appraisal that requires more processing for some situations than others. These appraisals effect changes to a person’s physical state. The perception of one’s emotions involves, in their words, “a multi-stage interoceptive/somatosensory process by which these body state patterns are detected and assigned conceptual emotional meaning”. Ultimately, regulation involves multiple processes, including the working memory and assessment of the situation appraisal mechanism.19
Finally, two major students of emotion, sum up their appraisal:
Why do we do anything at all, let alone in a consistent way that is recognizable to all who know us well? It is our primary-process psychobehavioral abilities, our prime movers, that arise from our subcortical brain’s primary emotional action systems that move us out of our resting state into coherent behavior patterns, which if adequately understood could be seen as our endophenotype’s [Endophenotype: an internal trait with genetic roots, such as brain function] optimal ways of trying to cope with life challenges, with further refinements being added by our learning mechanisms and thereby individual memories.20
The Nature of Emotional Attachment
When I speak of emotional attachment, I am talking about people who have a relationship with each other based on some level of affection, people who generally care about each other, and who trust each other to varying degrees. People, of course, may have emotional attachment to objects or artistic works or publicly-known individuals, but here I am speaking about what might be called mutuality of feeling. I hasten to point out that the degree of mutual feeling may be vastly different, and some parties to a relationship might feel very different levels of emotional engagement.
In a sense, a human society consists of clusters of very intense relationships (families, friendships, in-groups in general), groups in which the bonds of emotional attachment are very strong. None of these clusters has any direct knowledge of most of the others. The only relationship most of these clusters have with each other is an abstract sense of empathy. Most humans can understand, in varying degrees, what it is like to be in an emotionally-bound group.
Emotional attachment begins, for most people, in infancy. Scientists have ascertained that the principal (not necessarily only) evolutionary purpose of mother-child attachment was to ensure the safety of infants. Enlarging on this, we might say that as a general rule, the greater the maternal attention to newborns, the more likely it was that the newborns would survive. Hence maternal love and care were reproductively advantageous.
There are researchers who argue that there are additional reasons that maternal-infant attachment emerged. One of them argues that it was significant in promoting cultural evolution. He also contends that it was a significant factor in gene culture co-evolution.21 (GC co-evolution is the idea that human biological evolution brought forth human culture, and that human culture in turn affected the course of human evolution.) Another researcher, a psychiatrist, points out that attachment is only one aspect of child raising, and is not what is meant by the term “bonding”, which she sees as misleading. After presenting extensive evidence, her first conclusion is perhaps her most significant: “The quality of the infant-parent attachment is a powerful predictor of a child’s later social and emotional outcome.” Many emotional problems arise in children when their caregivers are insensitive, inconsistent, atypical, or engage in outright rejection. Levels of psychopathology in adolescents can often be traced to such negative care.22
Emotion in Everyday and Public Life
There is, I believe, a false dichotomy between the terms intellect and emotion. Supposedly, humans, in any given situation, are either guided completely by rational thought or passionate, impulsive feeling. In truth, in my view there is an emotional component to our intellect. We choose, after all, to give priority to some issues we care about over others, we choose (when adults) what to read or otherwise study by emotional preference. We often take into account what the emotional impact of our decisions will have on others. We choose careers (if we are fortunate) in fields we are emotionally drawn to. Our emotions, in turn, may have a rational basis. We may be justifiably angry at injustice. We may be saddened by that which is genuinely grievous. We may feel exhilarated by great music or a wonderful physical experience. Emotion in these instances would be a rational response. Indeed, we can legitimately say that those who are completely emotionless are suffering from a serious mental illness.
The problem, as I see it, is when emotional responses are dominant in every situation, and whenever crucial life decisions are based solely (or just predominantly) on emotion. Moreover, emotional responses can, if carried to the extreme, result in terrible violence and/or self-harm. Emotions can so overwhelm an individual that these feelings come to color and dominate every aspect of the person’s life. Grief can destroy the will to live. Chronic anger can have disastrous effects on health. A person carried away by feelings they believe to be love can make promises they have no ability to keep. Words said in momentary rage can lead to a lifetime of damage. The examples are, unfortunately, almost endless.
Even more threatening, in my view, is the way emotion is expressed and responded to in the public sphere. Demagogues routinely appeal to fear and hatred. Mobs, driven by fierce, unyielding emotion, riot and kill. Hatred and terror in war lead to horrible atrocities. False declarations of love and sympathy, uttered by those who have mastered the dark arts of emotional manipulation, lead people to follow charlatans and false prophets. Rational debate is drowned out by simplistic, childish, emotion-based “arguments”. All of these things have occurred again and again in human societies throughout the world. Yes, emotion is an intrinsic part of human beings and the human story, emotions which exist in the first place because they were useful from an evolutionary standpoint. But in the end—and this may be an unpopular opinion—thinking must take priority over feeling. Thinking and feeling are both necessary. But a society shaped primarily by emotion will ultimately lead to a dead end, one that no appeals to fear or anger or hatred can overcome.
1. https://www.researchgate.net/publication/11040893_What_is_emotion
2. Damasio,
Antonio. 1999. The Feeling of What Happens: Body and Emotion in the Making
of Consciousness. New York: Harcourt Brace, p. 42
3.
Damasio, p. 282
4. Barrett,
L. F., Niedenthal, P. M., & Winkielman, P. (Eds.). (2005). Emotion and
consciousness. The Guilford Press pp. 151-152
5. Lane,
Richard D., and Lynn Nadel, editors. Cognitive Neuroscience of Emotion.
Oxford University Press, 2000, p. 3
6. Cognitive
Neuroscience of Emotion, p. 15
7. Cognitive
Neuroscience of Emotion, pp. 24-25
8. Izard
CE. Emotion theory and research: highlights, unanswered questions, and emerging
issues. Annu Rev Psychol. 2009;60:1-25. doi:
10.1146/annurev.psych.60.110707.163539. PMID: 18729725; PMCID: PMC2723854.
9. Barrett,
Lisa Feldman. How Emotions Are Made: The Secret Life of the Brain (pp.
56-57). HarperCollins. Kindle Edition.
10. Joseph
E. LeDoux; As soon as there was life, there was danger: the deep history of
survival behaviours and the shallower history of consciousness. Philos Trans R
Soc Lond B Biol Sci 14 February 2022; 377 (1844): 20210292. https://doi.org/10.1098/rstb.2021.0292
11. O'Connell, Katherine & Rhoads, Shawn
& Marsh, Abigail. (2024). Fear: An Evolutionary Perspective on Its
Biological, Behavioral, and Communicative Features.
1093/oxfordhb/9780197544754.013.25.
12. https://www.ncbi.nlm.nih.gov/books/NBK541120/
13. Journal
of Ethics and Social Philosophy https://doi.org/10.26556/jesp.v25i1.2695
Vol. 25, No. 1 · July 2023 © 2023 Author
14. https://labs.la.utexas.edu/buss/files/2021/08/LoveinHumans.pdf
15. Sell
A, Tooby J, Cosmides L. Formidability and the logic of human anger. Proc Natl
Acad Sci U S A. 2009 Sep 1;106(35):15073-8. doi: 10.1073/pnas.0904312106. Epub
2009 Aug 3. PMID: 19666613; PMCID: PMC2736438.
16. https://www.sciencedirect.com/science/article/abs/pii/S1090513825001254
17. LeDoux JE. Evolution of human emotion: a
view through fear. Prog Brain Res. 2012;195:431-42. doi:
10.1016/B978-0-444-53860-4.00021-0. PMID: 22230640;
PMCID: PMC3600914.
18. Jastorff J, Huang YA, Giese MA,
Vandenbulcke M. Common neural correlates of emotion perception in humans. Hum
Brain Mapp. 2015 Oct;36(10):4184-201. doi: 10.1002/hbm.22910. Epub 2015 Jul 28.
PMID: 26219630; PMCID: PMC6869080.
19. https://www.sciencedirect.com/science/article/abs/pii/S0149763415002https://www.sciencedirect.com/science/article/abs/pii/S0149763415002031031
20. Davis,
Kenneth L.; Panksepp, Jaak. The Emotional Foundations of Personality: A
Neurobiological and Evolutionary Approach (p. 10). W. W. Norton &
Company. Kindle Edition.
21. Granqvist
P. Attachment, culture, and gene-culture co-evolution: expanding the
evolutionary toolbox of attachment theory. Attach Hum Dev. 2021
Feb;23(1):90-113. doi: 10.1080/14616734.2019.1709086. Epub 2020 Jan 2. PMID:
31894723.
22. Benoit
D. Infant-parent attachment: Definition, types, antecedents, measurement and
outcome. Paediatr Child Health. 2004 Oct;9(8):541-545. doi:
10.1093/pch/9.8.541. PMID: 19680481; PMCID: PMC2724160.