The Evolution of Altruism And Its Relationship to Personality

Altruism, put simply, is helping others or cooperating with others, even if it is costly to self. Of course, something like that cannot evolve, unless there are benefits too, associated with such acts of apparent selflessness.

Evolutionary theory mandates that there be some genetic payoffs in terms of either inclusive fitness or future benefits to self (reciprocity) for any kind of altruism/ cooperation to evolve.

I recommend reading Wikipedia articles on reciprocity, kin selection, and evolution of cooperation if they are not familiar to you or you need a refresher.

Cooperation, to start with, can evolve based on three forms of reciprocity: direct, indirect and network. All are based on the fact that there re repeated interactions between group of people- dyads, triads or many more. Reciprocity can typically be measured in the lab using the repeated Dictator/ Trust game.

Direct reciprocity was proposed by Robert Trivers as a mechanism for the evolution of cooperation. If there are repeated encounters between the same two players in an evolutionary game in which each of them can choose either to “cooperate” or “defect”, then a strategy of mutual cooperation may be favoured even if it pays each player, in the short term, to defect when the other cooperates.

Here, in direct reciprocity A trusts/helps B and hopes that when time comes B will reciprocate/help A. The top-of-the-mind factor is whether or not to trust somebody and whether or not to reciprocate someone’s trust. Trust and exploitation may be relevant issues here. In the Dictator/ Trust game this trust/exploitation manifests as the amount that is split and given to the other person vs kept with oneself.

In the standard framework of indirect reciprocity, there are randomly chosen pairwise encounters between members of a population; the same two individuals need not meet again. One individual acts as donor, the other as recipient. The donor can decide whether or not to cooperate. The interaction is observed by a subset of the population who might inform others. Reputation allows evolution of cooperation by indirect reciprocity.

This is partially correct that reputation for being trustworthy helps in indirect reciprocity; however that is only true for the downstream version; for the upstream version feelings of gratitude/happiness/awe/elevation in persons receiving the help/ witnessing the act also lead to more pro-social behavior by those receiving help/ witnessing. Thus feelings of gratitude/ awe/elevation mediate this kind of upstream indirect reciprocity. See below for upstream and downstream variants.

Individual acts of indirect reciprocity may be classified as “upstream” or “downstream”:

  • Upstream reciprocity occurs when an act of altruism causes the recipient to perform a later act of altruism in the benefit of a third party. In other words: A helps B, which then motivates B to help C.

  • Downstream reciprocity occurs when the performer of an act of altruism is more likely to be the recipient of a later act of altruism. In other words: A helps B, making it more likely that C will later help A.

Before touching upon network reciprocity, I will take a quick detour about kin selection. I believe kin selection or inclusive fitness is also a type of reciprocity (that between related individuals sharing genes) and may be rechristened genetic reciprocity. After all if A is likely to help B because they share x % of genes, the reverse is equally true and applicable. And of course this is mediated by emotional attachment to the kid/kin.

As per one definition of kin selection:

A biological theory stating that a gene that causes an organism to exhibit behavior detrimental to its survival will increase in frequency in a population if that behavior benefits the organism’s relatives, which will pass the gene on to subsequent generations.

If I slightly change words form above definition, I can now define a neighbor selection process as a cultural theory stating that a meme that causes an organism to exhibit behavior detrimental to its survival will increase in frequency in a population if that behavior benefits the organism’s neighbors, which will pass the meme on to subsequent neighbors.

We are now ready to look at network reciprocity:

Real populations are not well mixed, but have spatial structures or social networks which imply that some individuals interact more often than others. One approach of capturing this effect is evolutionary graph theory, in which individuals occupy the vertices of a graph. The edges determine who interacts with whom. If a cooperator pays a cost, c, for each neighbor to receive a benefit, b, and defectors have no costs, and their neighbors receive no benefits, network reciprocity can favor cooperation.

Basically, what I understand from the above is that if you help your neighbors sometimes such that the cost is not too high but benefits to neighbors are high and if  cost to benefit compares favorably with average number of neighbors/ neighborly interactions you have, then in the long run you will benefit and this form of cooperation can evolve.  To me the effects are mediated by the number of neighbors or sociability of a person.

Of course, even if you have all these mechanisms in place, cooperation may not evolve, as you may have free-riders. One important mechanism that has evolved to keep the free-riders in check is that of punishment. And once punishment is part of the picture you don’t even need repeated interactions, one-off games may be sufficient. I call this phenomenon Direct Punishment. One way it has been measured is with the Ultimatum game.

In the Ultimatum game, the second player can inflict costly punishment on first player by refusing to accept the division; this costly punishment is dyadic in nature and the aggression/hostility/vengefulness of the second player ensures that cooperation in even one-off encounters happens.

Basically instead of trusting and helping B, A starts by exploiting B and B retaliates by punishing A at cost to oneself.

Of course one can then surmise that there can be a phenomena of indirect punishment. This again may happen in two ways:

  1. Indirect punishment upstream: A is exploitative in nature; A exploits B; B punishes A, who then feels guilt/ gets reformed and stops exploiting C or even starts helping C.
  2. Indirect punishment downstream: A is exploitative in nature: A exploits B, B punishes A; B gets a reputation for being tough/competent and stops getting exploited by others say C or C may now even help B.

The Indirect reciprocity effects can be seen in Public goods/ trust game.

I will now take a detour and introduce the HEXACO model of personality which set me thinking about this in the first place.

HEXACO is an alternate personality model that is based on the same principles as the Big Five/FFM; i.e. it uses factor analysis of lexical terms in various languages to arrive at major personality traits.

The six factors are generally named Honesty-Humility (H), Emotionality (E), Extraversion (X), Agreeableness (A), Conscientiousness (C), and Openness to Experience (O). The personality-descriptive adjectives that typically belong to these six groups are as follows:

  • Honesty-Humility (H): sincere, honest, faithful, loyal, modest/unassuming versus sly, deceitful, greedy, pretentious, hypocritical, boastful, pompous

  • Emotionality (E): emotional, oversensitive, sentimental, fearful, anxious, vulnerable versus brave, tough, independent, self-assured, stable

  • Extraversion (X): outgoing, lively, extraverted, sociable, talkative, cheerful, active versus shy, passive, withdrawn, introverted, quiet, reserved

  • Agreeableness (A): patient, tolerant, peaceful, mild, agreeable, lenient, gentle versus ill-tempered, quarrelsome, stubborn, choleric

  • Conscientiousness (C): organized, disciplined, diligent, careful, thorough, precise versus sloppy, negligent, reckless, lazy, irresponsible, absent-minded

  • Openness to Experience (O): intellectual, creative, unconventional, innovative, ironic versus shallow, unimaginative, conventional

The factor H is a new factor not present in Big Five/FFM. The E though looking similar to N of big Five, is conceptually different; it no longer contains anger/hostility which are instead present in HEXACO A. similalrly there are important differences between HEXACO A and Big Five A. the other 3, C, O and X (extarversion) are similarly conceptualized and defined in both systems and have same loadings when tested together.

Ashton and Lee, the proponents of the HEXACO model, have themselves related evolution of altruism to these traits [pdf] and I am building on their work.

Basically as per them,

To begin, we have proposed that the Honesty- Humility and Agreeableness factors represent two complementary aspects of the construct of reciprocal altruism (Trivers, 1971). Honesty-Humility represents the tendency to be fair and genuine in dealing with others, in the sense of cooperating with others even when one might exploit them without suffering retaliation. Agreeableness represents the tendency to be forgiving and tolerant of others, in the sense of cooperating with others even when one might be suffering exploitation by them. (For a discussion of two broadly similar, although not identical, constructs, see Perugini, Gallucci, Presaghi, & Ercolani, 2003.) Presumably, high levels of Honesty- Humility are associated with decreased opportunities for personal gains from the exploitation of others but also with decreased risks of losses from withdrawal of cooperation by others. In a similar manner, high levels of Agreeableness are associated with increased opportunities for personal gains from long-run reciprocal cooperation with others, as well as with increased risks of losses from exploitation by others. (Note that we use the term altruism in terms of a dimension of altruistic versus antagonistic tendency, which involves both a willingness to help or provide benefits to others and an unwillingness to harm or impose costs on others.)
In addition, we have proposed that Emotionality represents tendencies relevant to the construct of kin altruism (Hamilton, 1964), including not only empathic concern and emotional attachment toward close others (who tend to be one’s kin) but also the harm-avoidant and help-seeking behaviors that are associated with investment in kin (see also Lee & Ashton, 2004). Presumably, high levels of Emotionality are associated with increased likelihood of personal and kin survival, as well as with decreased opportunities for gains that are often associated with risks to personal and kin survival.
To me, this looks like equating direct reciprocity with H and direct punishment with A.  With this in mind I now list the personality trait (HEXACO)/ evolution of altruism linkages.
1. Kin Selection/ Genetic Reciprocity : mediated by emotional attachments etc and related to Emotioanlity.
2. Neighbor Selection / Network Reciprocity: mediated by sociability and related to sociability aspects of Extrarversion.
3. Direct Reciprocity : mediated by trusting others and being honest and related to Honesty-humility.
4. Direct Punishment:  mediated by punishing others and being aggressive/ hostile when needed and related to Agreeablness.
5. Indirect Reciprocity upstream:  mediated by feelings of gratitude/ awe/ elevation and possibly related to Openness to Experience
6. Indirect Punishment upstream: mediated by feelings of guilt/responsibility and related to Conscientiousness.
 7. Indirect Reciprocity downstream: mediated by signaling and being trustworthy; need a new personality dimension for this.
8. Indirect Punishment downstream: mediated by signaling and being competent/ tough and possibly related to Surgency dimension of Extarversion.
I am more and more convinced, looking at the above model that we evolved to be cooperative/ altruistic rather than otherwise.

The four mechanisms of evolution

Darwin's finches or Galapagos finches. Darwin,...

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Regular readers of the blog will know of my enthusiasm for evolutionary and developmental theories especially the eight stage evo-devo theory.

I have also advocated the four primary problems faced by all creatures undergoing evolution, as delineated by Theodore Millon– the problems of Existence; Adaptation; Replication and Abstraction which lead to polarities of pain/pleasure;  active/passive; self/other and broad/narrow at each of the stages/domains/ solutions.

However, when we pause to look at what the mechanism of evolution actually is, we clearly note that there are a few prerequisites for evolution to take place and unless all the four mechanisms/ preconditions are present it is unlikely that the creatures will evolve.   I have been having this in the back of my mind for quite some time especially as I  have been ruminating on the BVSR (blind variation and selective retention)  theory of Donald Campbell as applied to creativity.

I was recently reading ‘Driven’ and in that book too a lot of emphasis is placed on the V-S-R (Variation, Selection, Retention) mechanism of evolution. I think this popular portrayal of evolution misses another important ingredient required for evolution that of Struggle due to limited resources and excess fecundity. If the problem of limited resources and excess fecundity was not there, probably there would be no pressure to evolve.


Thus I would like to frame the four evolutionary prerequisites/ mechanisms as Struggle-Retention- Variation-Selection or S_R_V_S.  To elaborate:

1. Struggle: This is driven by the fact of limited resources and overproduction due to excess fecundity. Here two strategies, leading to 2 polarities,  work; one can either compete for resources or one can cooperate and exist symbiotically.  Also, one can either have a r-strategy (low investment in many) of reproduction or A K-strategy (high investment in few). In the eight stage model, the organisms at first 2 levels would be primarily constrained by this evolutionary mechanisms.

2. Retention:  There must exist some mechanism by which the traits that confer survival/reproductive or selection advantage can be retained over time in the same individual and over generations in the same species. Again the mechanism of stable trait over time as well as  over generations may be in conflict with each other and may lead to a polarity. Creatures at stage 3 and 4 of 8 stage evo-devo theory would likely face issues regarding stability and retention of traits; retaining in individual the same trait is an active process; while retaining in generations is more passively driven.

3. Variation. There must exist some  mechanism that causes minor changes in the stable traits such that variation may lead to deleterious or beneficial effect over the individual having that variation. This is classically implemented using mutations and sexual-recombinations. While mutations confer (dis)advantages at an individual level; recombinations take that to the next level by affecting offsprings variability. The creatures at stages 5 and 6 of evo-devo stages are grappling with these problems of adequate variation in self and other.

4. Selection: There must exist some selection criteria based on which the struggling creatures having stable but slightly varying traits can be selected for or against.  While Natural selection (stage 7) employs the three methods of directional, stabilizing and disruptive selection; the stage 8 deploys a qualitatively different method of sexual selection where the criteria for selection may be  arbitrarily driven by choices of the other gender conspesifics.  While the Natural selection criteria is broad, the sexual selection criteria can be said to be narrow. Another way to look at this is that the selection crteria is either to survive (natural selction) or to reproduce (sexual slection) and those who are sucessful can very well move from one level/species to another (speciation due to sexual selection).

To me this is further  corrobrating evidence of the eight stage evo-devo theory and ABCD model being on the right track.


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universal human mate preference: four dimensions or eight factors?


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In  my last post I had mentioned how Seligman and Peterson have tried to correlate their structure of human virtues/character strengths with work of other researchers like the universal dimensions of human mate preferences discovered by Buss et al.  Today I wish to discuss in detail the universal dimensions of human mate preferences discovered by Buss  et al.

Buss et al looked at data , using an 18 item preference ratings archival database, of about ten thousand people, from various cultures across the globe, and used the analysis strategy outlined by Bond to take care of different sample size from different cultures. they then applied the Principal component analysis to the refined data so obtained to determine the underlying structure of the mate preferences.

Their PCA analysis led to discovery of four dimensions all of which could be quantified as bipolar dimensions with one pole representing a different construct and another representing a sort-of-but-not-really opposed construct. For eg.,the first factor included loadings from ‘‘good financial prospects’’ (-0.65), ‘‘favorable social status or ratings’’ (-0.62), and ‘‘ambition and industriousness’’ (-0.41), each of which loaded negatively. The component also included ‘‘mutual attraction—love’’ (0.49), which loaded positively. They thus labeled this component ‘‘Love vs. Status/Resources.’

Similarly the 3 other components were labeled “Dependable/Stable vs. Good Looks/Health”; “Education/Intelligence vs. Desire for Home/Children”; and “Sociability vs. Similar Religion”.

To my naive mind all of these bipolar dimensions seem to be separate constructs in themselves and I cannot fathom why dependable/stable should be taken as opposed to good looks/health. to me they seem sort of independent constructs. I would rather view the findings as eight separate poles than 4 bipolar dimensions with each dimension conflating two constructs/factors.

The paper immediately drew to my mind this paper, by Haslam et al, that while finding the underlying structure of positive characteristics, found three consistent bipolar dimensions using multi dimensional scaling. However, when the same data was subjected to cluster analysis, 6 factors were or clusters were apparent , each cluster being the pole of a single bipolar dimension. These 6 factors were “self-control,” “love,” “wisdom,” “drive,” “vivacity,” and “collaboration” which to my mind seems to map onto the virtues of self-restraint/temperance strengths, interpersonal or humanity strengths, intellectual or wisdom strengths, courage or emotional strengths , activity or vitality strengths and justice or civic strengths. Of course I think their MDS missed a fourth dimension which would have led to 8 clusters , the 2 remaining being religious and transcendence strengths.

Returning back to our current paper on universal mate preferences, I would like to break up the 4 dimensions into 8 factors and present them in a staged developmental order. It would be worthwhile to note that the two opposed dimensions are usually two adjacent stages following each other and may indeed reflect some conflict in mind of people as to which stage of mate preference to prefer based on their evolved natures . Here goes:

  1. first stage: Physical/biological : good looks/health
  2. second stage: will, restraint and control: dependable/stable.
  3. third stage: dominance/hierarchy, friends and foes: status/ resources.
  4. fourth stage: interpersonal: Love
  5. fifth stage: cognitive: education/ intelligence
  6. sixth stage: intimacy: desire for home/children.
  7. seventh stage: communicative/ generative:  sociability
  8. eights stage: integrity, ingroup/outgroup: similar vs dissimilar religion.

Of course this is not the first time I have tried to put Buss’s findings in a 8 stage model; earlier I had tried to put his views on personality in a  eight fold structure- whereby the last three stages of reproduction/evolution may be now characterized as biological, linguistic and cultural evolution. Anyway getting back to universal mate preferences, I can see that eight fold structure is found in the mate preferences too depending on which stage of preferences you have evolved/developed.

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SHACKELFORD, T., SCHMITT, D., & BUSS, D. (2005). Universal dimensions of human mate preferences Personality and Individual Differences, 39 (2), 447-458 DOI: 10.1016/j.paid.2005.01.023
Haslam, N., Bain, P., & Neal, D. (2004). The Implicit Structure of Positive Characteristics Personality and Social Psychology Bulletin, 30 (4), 529-541 DOI: 10.1177/0146167203261893

Major conscious and unconcoscious processes in the brain

Today I plan to touch upon the topic of consciousness (from which many bloggers shy) and more broadly try to delineate what I believe are the important different conscious and unconscious processes in the brain. I will be heavily using my evolutionary stages model for this.

To clarify myself at the very start , I do not believe in a purely reactive nature of organisms; I believe that apart from reacting to stimuli/world; they also act , on their own, and are thus agents. To elaborate, I believe that neuronal groups and circuits may fire on their own and thus lead to behavior/ action. I do not claim that this firing is under voluntary/ volitional control- it may be random- the important point to note is that there is spontaneous motion.

  1. Sensory system: So to start with I propose that the first function/process the brain needs to develop is to sense its surroundings. This is to avoid predators/ harm in general. this sensory function of brain/sense organs may be unconscious and need not become conscious- as long as an animal can sense danger, even though it may not be aware of the danger, it can take appropriate action – a simple ‘action’ being changing its color to merge with background. 
  2. Motor system:The second function/ process that the brain needs to develop is to have a system that enables motion/movement. This is primarily to explore its environment for food /nutrients. Preys are not going to walk in to your mouth; you have to move around and locate them. Again , this movement need not be volitional/conscious – as long as the animal moves randomly and sporadically to explore new environments, it can ‘see’ new things and eat a few. Again this ‘seeing’ may be as simple as sensing the chemical gradient in a new environmental.
  3. Learning system: The third function/process that the brain needs to develop is to have a system that enables learning. It is not enough to sense the environmental here-and-now. One needs to learn the contingencies in the world and remember that both in space and time. I am inclined to believe that this is primarily pavlovaion conditioning and associative learning, though I don’t rule out operant learning. Again this learning need not be conscious- one need not explicitly refer to a memory to utilize it- unconscious learning and memory of events can suffice and can drive interactions. I also believe that need for this function is primarily driven by the fact that one interacts with similar environments/con specifics/ predators/ preys and it helps to remember which environmental conditions/operant actions lead to what outcomes. This learning could be as simple as stimuli A predict stimuli B and/or that action C predicts reward D .
  4. Affective/ Action tendencies system .The fourth function I propose that the brain needs to develop is a system to control its motor system/ behavior by making it more in sync with its internal state. This I propose is done by a group of neurons monitoring the activity of other neurons/visceral organs and thus becoming aware (in a non-conscious sense)of the global state of the organism and of the probability that a particular neuronal group will fire in future and by thus becoming aware of the global state of the organism , by their outputs they may be able to enable one group to fire while inhibiting other groups from firing. To clarify by way of example, some neuronal groups may be responsible for movement. Another neuronal group may be receiving inputs from these as well as say input from gut that says that no movement has happened for a time and that the organism has also not eaten for a time and thus is in a ‘hungry’ state. This may prompt these neurons to fire in such a way that they send excitatory outputs to the movement related neurons and thus biasing them towards firing and thus increasing the probability that a motion will take place and perhaps the organism by indulging in exploratory behavior may be able to satisfy hunger. Of course they will inhibit other neuronal groups from firing and will themselves stop firing when appropriate motion takes place/ a prey is eaten. Again nothing of this has to be conscious- the state of the organism (like hunger) can be discerned unconsciously and the action-tendencies biasing foraging behavior also activated unconsciously- as long as the organism prefers certain behaviors over others depending on its internal state , everything works perfectly. I propose that (unconscious) affective (emotional) state and systems have emerged to fulfill exactly this need of being able to differentially activate different action-tendencies suited to the needs of the organism. I also stick my neck out and claim that the activation of a particular emotion/affective system biases our sensing also. If the organism is hungry, the food tastes (is unconsciously more vivid) better and vice versa. thus affects not only are action-tendencies , but are also, to an extent, sensing-tendencies.
  5. Decisional/evaluative system: the last function (for now- remember I adhere to eight stage theories- and we have just seen five brain processes in increasing hierarchy) that the brain needs to have is a system to decide / evaluate. Learning lets us predict our world as well as the consequences of our actions. Affective systems provide us some control over our behavior and over our environment- but are automatically activated by the state we are in. Something needs to make these come together such that the competition between actions triggered due to the state we are in (affective action-tendencies) and the actions that may be beneficial given the learning associated with the current stimuli/ state of the world are resolved satisfactorily. One has to balance the action and reaction ratio and the subjective versus objective interpretation/ sensation of environment. The decisional/evaluative system , I propose, does this by associating values with different external event outcomes and different internal state outcomes and by resolving the trade off between the two. This again need not be conscious- given a stimuli predicting a predator in vicinity, and the internal state of the organism as hungry, the organism may have attached more value to ‘avoid being eaten’ than to ‘finding prey’ and thus may not move, but camouflage. On the other hand , if the organisms value system is such that it prefers a hero’s death on battlefield , rather than starvation, it may move (in search of food) – again this could exist in the simplest of unicellular organisms.

Of course all of these brain processes could (and in humans indeed do) have their conscious counterparts like Perception, Volition,episodic Memory, Feelings and Deliberation/thought. That is a different story for a new blog post!

And of course one can also conceive the above in pure reductionist form as a chain below:

sense–>recognize & learn–>evaluate options and decide–>emote and activate action tendencies->execute and move.

and then one can also say that movement leads to new sensation and the above is not a chain , but a part of cycle; all that is valid, but I would sincerely request my readers to consider the possibility of spontaneous and self-driven behavior as separate from reactive motor behavior. 

On Reading Darwin

12 th of February was Darwin day, and I decided to study an original text of Darwin to honor the occasion. I chose the ‘Expression of emotions in Man and animals’ as my first text as I am familiar with the work of Paul Ekman and have had a deep fascination with the subject and wanted to find out how much Darwin had anticipated and got right in his times.I have only read the introduction and the first chapter till now, but am surprised at the level of modernity visible in Darwin’s analysis.

Of course Darwin takes an evolutionary view on the subject and is also cognizant of the subtleness of the entire field.

He who admits on general grounds that the structure and habits of all animals have been gradually evolved, will look at the whole subject of Expression in a new and interesting light.

The study of Expression is difficult, owing to the movements being often extremely slight, and of a fleeting nature. A difference may be clearly perceived, and yet it may be impossible, at least I have found it so, to state in what the difference consists. When we witness any deep emotion, our sympathy is so strongly excited, that close observation is forgotten or rendered almost impossible; of which fact I have had many curious proofs. Our imagination is another and still more serious source of error; for if from the nature of the circumstances we expect to see any expression, we readily imagine its presence. Notwithstanding Dr. Duchenne’s great experience, he for a long time fancied, as he states, that several muscles contracted under certain emotions, whereas he ultimately convinced himself that the movement was confined to a single muscle.

He then lists the various ways he plans to get to universal features of emotional expressions. These involve using questionnaires given to various anthropologists to discover if the emotions are expressed in a similar fashion all over the world ;and the study of infants and insane as they may have unadulterated / extreme emotional expressions respectively. He also briefly touches upon the usefulness of studying emotional expressions as depicted by Masters in painting in sculpture but finds the method wanting. Lats , but not the least, he studied emotional expression in other animals and treated emotional expression as a continuum.

Sixthly, and lastly, I have attended. as closely as I could, to the expression of the several passions in some of the commoner animals; and this I believe to be of paramount importance, not of course for deciding how far in man certain expressions are characteristic of certain states of mind, but as affording the safest basis for generalisation on the causes, or origin, of the various movements of Expression. In observing animals, we are not so likely to be biassed by our imagination; and we may feel safe that their expressions are not conventional.

He then lists the three basic principles of emotional expressions. I list them verbatim.

I. _The principle of serviceable associated Habits_.–Certain complex actions are of direct or indirect service under certain states of the mind, in order to relieve or gratify certain sensations, desires, &c.; and whenever the same state of mind is induced, however feebly, there is a tendency through the force of habit and association for the same movements to be performed, though they may not then be of the least use. Some actions ordinarily associated through habit with certain states of the mind may be partially repressed through the will, and in such cases the muscles which are least under the separate control of the will are the most liable still to act, causing movements which we recognize as expressive. In certain other cases the checking of one habitual movement requires other slight movements; and these are likewise expressive.

II. _The principle of Antithesis_.–Certain states of the mind lead to certain habitual actions, which are of service, as under our first principle. Now when a directly opposite state of mind is induced, there is a strong and involuntary tendency to the performance of movements of a directly opposite nature, though these are of no use; and such movements are in some cases highly expressive.

III. _The principle of actions due to the constitution of the Nervous System, independently from the first of the Will, and independently to a certain extent of Habit_.— When the sensorium is strongly excited, nerve-force is generated in excess, and is transmitted in certain definite directions, depending on the connection of the nerve-cells, and partly on habit: or the supply of nerve-force may, as it appears, be interrupted. Effects are thus produced which we recognize as expressive. This third principle may, for the sake of brevity, be called that of the direct action of the nervous system


The first principal is easy to understand. It basically states that facial expression etc are associated with mental emotional states and do so by way of habit formation or association. Now, this should not exclude instinctual emotional expressions like smiling as they become fixed by the action of evolution.

The second principle has had only some relatively moderate success. I remember a recent study claiming that Fear and Disgust had opposite effects on facial muscle movements such that Fear led to movements (like broadening of eyes/ dilation of pupils)that allowed more information/material to be ingested; while disgust led to constriction of nose, eye, mouth etc. although Fear and disgust are not antithetical, one may discern similar patterns in other movements.

The third again, I believe has mixed success. It can be ralete to Jams-lange theory of emtoions, where nervous arousal happens first, and emotional feeling or expressions accompanying them follow next.

I am only thus far in my reading of Darwin, but surely will keep doing follow up posts.

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