The Evolutionary Biology Of The Uncanny Valley

The obvious candidates giving rise to an evolutionary biology source for the uncanny valley effect in reality would be other archaic hominin species like Neanderthals, Denisovans, Homo erectus, and Homo floresiensis (a.k.a. "Hobbits"). And, this reaction may have evolved at the time of our pre-modern human ancestors because there were many species of the genus Homo in existence at that time, some of whom would have interacted with each other in Africa.

Less obviously, it could be something the developed to recognize when other people were suffering from diseases, physical and/or mental, or to trigger you not to trust what you see when you are under the influence of a hallucinogen.

It could also be a side effect our cognitive abilities developed for recognizing and evaluating other people, e.g., distinguishing people from another race or region, whose mechanism produces weird results when you are at the fringe of its domain of applicability.

Wikipedia notes at least nine theories to explain the psychological quirk, none of which is really dominant explanations in the academic community. They are:

Mate selection: Automatic, stimulus-driven appraisals of uncanny stimuli elicit aversion by activating an evolved cognitive mechanism for the avoidance of selecting mates with low fertility, poor hormonal health, or ineffective immune systems based on visible features of the face and body that are predictive of those traits.

Mortality salience: Viewing an "uncanny" robot elicits an innate fear of death and culturally supported defenses for coping with death's inevitability.... [P]artially disassembled androids...play on subconscious fears of reduction, replacement, and annihilation: (1) A mechanism with a human façade and a mechanical interior plays on our subconscious fear that we are all just soulless machines. (2) Androids in various states of mutilation, decapitation, or disassembly are reminiscent of a battlefield after a conflict and, as such, serve as a reminder of our mortality. (3) Since most androids are copies of actual people, they are doppelgängers and may elicit a fear of being replaced, on the job, in a relationship, and so on. (4) The jerkiness of an android's movements could be unsettling because it elicits a fear of losing bodily control.

Pathogen avoidance: Uncanny stimuli may activate a cognitive mechanism that originally evolved to motivate the avoidance of potential sources of pathogens by eliciting a disgust response. "The more human an organism looks, the stronger the aversion to its defects, because (1) defects indicate disease, (2) more human-looking organisms are more closely related to human beings genetically, and (3) the probability of contracting disease-causing bacteria, viruses, and other parasites increases with genetic similarity." The visual anomalies of androids, robots, and other animated human characters cause reactions of alarm and revulsion, similar to corpses and visibly diseased individuals.

Sorites paradoxes: Stimuli with human and nonhuman traits undermine our sense of human identity by linking qualitatively different categories, human and nonhuman, by a quantitative metric: degree of human likeness.

Violation of human norms: If an entity looks sufficiently nonhuman, its human characteristics are noticeable, generating empathy. However, if the entity looks almost human, it elicits our model of a human other and its detailed normative expectations. The nonhuman characteristics are noticeable, giving the human viewer a sense of strangeness. In other words, a robot stuck inside the uncanny valley is no longer judged by the standards of a robot doing a passable job at pretending to be human, but is instead judged by the standards of a human doing a terrible job at acting like a normal person. This has been linked to perceptual uncertainty and the theory of predictive coding.

Conflicting perceptual cues: The negative effect associated with uncanny stimuli is produced by the activation of conflicting cognitive representations. Perceptual tension occurs when an individual perceives conflicting cues to category membership, such as when a humanoid figure moves like a robot, or has other visible robot features. This cognitive conflict is experienced as psychological discomfort (i.e., "eeriness"), much like the discomfort that is experienced with cognitive dissonance. Several studies support this possibility. Mathur and Reichling found that the time subjects took to gauge a robot face's human- or mechanical-resemblance peaked for faces deepest in the uncanny valley, suggesting that perceptually classifying these faces as "human" or "robot" posed a greater cognitive challenge. However, they found that while perceptual confusion coincided with the uncanny valley, it did not mediate the effect of the uncanny valley on subjects' social and emotional reactions—suggesting that perceptual confusion may not be the mechanism behind the uncanny valley effect. Burleigh and colleagues demonstrated that faces at the midpoint between human and non-human stimuli produced a level of reported eeriness that diverged from an otherwise linear model relating human-likeness to affect. Yamada et al. found that cognitive difficulty was associated with negative affect at the midpoint of a morphed continuum (e.g., a series of stimuli morphing between a cartoon dog and a real dog). Ferrey et al. demonstrated that the midpoint between images on a continuum anchored by two stimulus categories produced a maximum of negative affect, and found this with both human and non-human entities. Schoenherr and Burleigh provide examples from history and culture that evidence an aversion to hybrid entities, such as the aversion to genetically modified organisms ("Frankenfoods"). Finally, Moore developed a Bayesian mathematical model that provides a quantitative account of perceptual conflict. There has been some debate as to the precise mechanisms that are responsible. It has been argued that the effect is driven by categorization difficulty, configural processing, perceptual mismatch, frequency-based sensitization, and inhibitory devaluation. 

Threat to humans' distinctiveness and identity: Negative reactions toward very humanlike robots can be related to the challenge that this kind of robot leads to the categorical human – non-human distinction. Kaplan stated that these new machines challenge human uniqueness, pushing for a redefinition of humanness. Ferrari, Paladino and Jetten found that the increase of anthropomorphic appearance of a robot leads to an enhancement of threat to the human distinctiveness and identity. The more a robot resembles a real person, the more it represents a challenge to our social identity as human beings.

Religious definition of human identity: The existence of artificial but humanlike entities is viewed by some as a threat to the concept of human identity. An example can be found in the theoretical framework of psychiatrist Irvin Yalom. Yalom explains that humans construct psychological defenses to avoid existential anxiety stemming from death. One of these defenses is 'specialness', the irrational belief that aging and death as central premises of life apply to all others but oneself. The experience of the very humanlike "living" robot can be so rich and compelling that it challenges humans' notions of "specialness" and existential defenses, eliciting existential anxiety. In folklore, the creation of human-like, but soulless, beings is often shown to be unwise, as with the golem in Judaism, whose absence of human empathy and spirit can lead to disaster, however good the intentions of its creator.

Uncanny valley of the mind or AI: Due to rapid advancements in the areas of artificial intelligence and affective computing, cognitive scientists have also suggested the possibility of an "uncanny valley of mind". Accordingly, people might experience strong feelings of aversion if they encounter highly advanced, emotion-sensitive technology. Among the possible explanations for this phenomenon, both a perceived loss of human uniqueness and expectations of immediate physical harm are discussed by contemporary research.

How Do People Decide Which Scientists To Believe?

Examining and resolving in my own mind disputes between scientists is pretty much the essence of what I do on a daily basis, especially, but not only, at this blog. So, this study caught my attention. I suspect that my methods are more analytical and sourced than average, and view myself as kindred to "superforecasters" in my methods.

Uncertainty that arises from disputes among scientists seems to foster public skepticism or noncompliance. Communication of potential cues to the relative performance of contending scientists might affect judgments of which position is likely more valid. We used actual scientific disputes—the nature of dark matter, sea level rise under climate change, and benefits and risks of marijuana—to assess Americans’ responses (n = 3150). 

Seven cues—replication, information quality, the majority position, degree source, experience, reference group support, and employer—were presented three cues at a time in a planned-missingness design. The most influential cues were majority vote, replication, information quality, and experience. Several potential moderators—topical engagement, prior attitudes, knowledge of science, and attitudes toward science—lacked even small effects on choice, but cues had the strongest effects for dark matter and weakest effects for marijuana, and general mistrust of scientists moderately attenuated top cues’ effects. 

Risk communicators can take these influential cues into account in understanding how laypeople respond to scientific disputes, and improving communication about such disputes.

Branden B. Johnson, Marcus Mayorga, Nathan F. Dieckmann, "How people decide who is correct when groups of scientists disagree" Risk Analysis (July 28, 2023).

Fields Without Papers

High energy biology is the subject of several science fiction treatments that I can recall. 

I'm somewhat surprised by the large number of astro-theology papers, but my own cross-check revealed 1,390 astro-theology hits on Google Scholar. 

The absence of "high-energy theology" hits is also a surprise given that the Big Bang theory was proposed by a Vatican physicist.

From here.

Even Science Is Resistant To The Scientific Method

A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die and a new generation grows up that is familiar with it. . . . An important scientific innovation rarely makes its way by gradually winning over and converting its opponents: it rarely happens that Saul becomes Paul. What does happen is that its opponents gradually die out, and that the growing generation is familiarized with the ideas from the beginning: another instance of the fact that the future lies with the youth.

— Max Planck, Scientific autobiography, at pgs. 33 and 97 (1950). Related:

Never trust an experimental result until it has been confirmed by theory.

- Astronomer Arthur Eddington who died on November 22, 1944 (discussed here noting that: "In general, Eddington’s advice is good: when an experiment contradicts theory, theory tends to win in the end." But acknowledging exceptions and discussing Hume's take on it).

A comment makes the good point, however, that ossification of views is less of a problem in fields that are new and rapidly emerging, rather than those that have settled down a bit with enough time for competing camps over unresolved issues to emerge.

But scientists are persuaded by new evidence sometimes, as documented in this paper.

The Legacy Of Herding

The Legacy Of Herding

Historical food productions practices influence culture and morality long after those food production practices are long gone.

According to the widely known ‘culture of honor’ hypothesis from social psychology, traditional herding practices are believed to have generated a value system that is conducive to revenge-taking and violence. 

We test this idea at a global scale using a combination of ethnographic records, historical folklore information, global data on contemporary conflict events, and large-scale surveys. 

The data show systematic links between traditional herding practices and a culture of honor. First, the culture of pre-industrial societies that relied on animal herding emphasizes violence, punishment, and revenge-taking. Second, contemporary ethnolinguistic groups that historically subsisted more strongly on herding have more frequent and severe conflict today. Third, the contemporary descendants of herders report being more willing to take revenge and punish unfair behavior in the globally representative Global Preferences Survey. In all, the evidence supports the idea that this form of economic subsistence generated a functional psychology that has persisted until today and plays a role in shaping conflict across the globe.

Yiming Cao, et al., "Herding, Warfare, and a Culture of Honor" NBER (September 2021).

Another paper fleshes out the concept a bit more (and has a nice literature review), although its description of the southern United States as historically a herding culture is doubtful. Appalachia was indeed settled by Scotch-Irish herders and does have a culture of honor, but, the lowlands of the American South (which also has a culture of honor), where plantation farming became predominant, was settled by lesser English gentry farmers, not by descendants of herders.

A key element of cultures of honor is that men in these cultures are prepared to protect with violence the reputation for strength and toughness. Such cultures are likely to develop where (1) a man's resources can be thieved in full by other men and (2) the governing body is weak and thus cannot prevent or punish theft. 

Todd K. Shackelford, "An Evolutionary Psychological Perspective on Cultures of Honor" Evolutionary Psychology (January 1, 2005) (open access). DOI: https://doi.org/10.1177/147470490500300126

The example of the Southern United States suggests that a weak state may be as important a factor in the development of a culture of honor as a herding economy.

The Legacy Of Plough v. Hoe Farming

Parallel hypotheses from the same disciplines associate ancestral heavy plough farming with strongly patriarchal societies with strong differentiation in gender roles, and ancestral hoe farming with less patriarchal and sometimes even matrilineal societies.

The Legacy Of Clan Based Societies

It has also become common in modern political theory to associate weak government approaching anarchy with clan based societies in which women are forced into highly subordinated roles, somewhat in the tradition of Thomas Hobbes ("nasty, brutish and short") as opposed to those who idealize an Eden-like "state of nature." See, e.g., Valerie M. Hudson, et al., "Clan Governance and State Stability: The Relationship between Female Subordination and Political Order" 109(3) American Political Science Review 535-555 (August 2015).

The Legacy Of Cousin Marriage

Also along the same lines, cousin marriage (often common in clan based societies and also among feudal aristocrats) tends to be a practice the undermines democratic government:

Image from here.

How might consanguinity affect democracy? 

Cousin marriages create extended families that are much more closely related than is the case where such marriages are not practiced. To illustrate, if a man’s daughter marries his brother’s son, the latter is then not only his nephew but also his son-in-law, and any children born of that union are more genetically similar to the two grandfathers than would be the case with non-consanguineous marriages. Following the principles of kin selection (Hamilton, 1964) and genetic similarity theory (Rushton, 1989, 2005), the high level of genetic similarity creates extended families with exceptionally close bonds. Kurtz succinctly illustrates this idea in his description of Middle Eastern educational practices:

If, for example, a child shows a special aptitude in school, his siblings might willingly sacrifice their personal chances for advancement simply to support his education. Yet once that child becomes a professional, his income will help to support his siblings, while his prestige will enhance their marriage prospects. (Kurtz, 2002, p. 37).

Such kin groupings may be extremely nepotistic and distrusting of non-family members in the larger society. In this context, non-democratic regimes emerge as a consequence of individuals turning to reliable kinship groupings for support rather than to the state or the free market. It has been found, for example, that societies having high levels of familism tend to have low levels of generalized trust and civic engagement (Realo, Allik, & Greenfield, 2008), two important correlates of democracy. Moreover, to people in closely related kin groups, individualism and the recognition of individual rights, which are part of the cultural idiom of democracy, are perceived as strange and counterintuitive ideological abstractions (Sailer, 2004).

From the body text of the following article whose abstract is also set forth below: 

This article examines the hypothesis that although the level of democracy in a society is a complex phenomenon involving many antecedents, consanguinity (marriage and subsequent mating between second cousins or closer relatives) is an important though often overlooked predictor of it. Measures of the two variables correlate substantially in a sample of 70 nations (r = −0.632, p < 0.001), and consanguinity remains a significant predictor of democracy in multiple regression and path analyses involving several additional independent variables. 

The data suggest that where consanguineous kinship networks are numerically predominant and have been made to share a common statehood, democracy is unlikely to develop. 

Possible explanations for these findings include the idea that restricted gene flow arising from consanguineous marriage facilitates a rigid collectivism that is inimical to individualism and the recognition of individual rights, which are key elements of the democratic ethos. Furthermore, high levels of within-group genetic similarity may discourage cooperation between different large-scale kin groupings sharing the same nation, inhibiting democracy. Finally, genetic similarity stemming from consanguinity may encourage resource predation by members of socially elite kinship networks as an inclusive fitness enhancing behavior.

Michael A. Woodley, Edward Bell, "Consanguinity as a Major Predictor of Levels of Democracy: A Study of 70 Nations" 44(2) Journal of Cross-Cultural Psychology (2013). 

DOI: https://doi.org/10.1177/0022022112443855

Mole Rat Mind Control

From PNAS via The Atlantic “Naked-Mole-Rat Queens Control Their Subjects by Having Them Eat Poop":

And according to a new study from Japan, naked-mole-rat queens use their hormone-rich poop to govern their subordinates. When the subordinates eat the hormone, it turns them into attentive caretakers of the queen’s own pups. It’s mind control, via poop. 

Naked mole rats had interested Kazutaka Mogi, a biologist at Azabu University, because of their unusual social structure. Like ants and bees, but unlike almost all other mammals, naked mole rats live in large colonies where the queen is the only female that reproduces. Her subordinates take care of the pups, and they never make sex hormones of their own or become sexually mature. Mogi and his team had investigated parenting in mice, and they knew that hormones play a key role in triggering parental behaviors in mammals. If the bodies of the subordinate naked mole rats aren’t making any hormones, how do they become such attentive caretakers—to pups that aren’t even their own? 

… 

The team collected fecal pellets from pregnant queens and gave them to a handful of subordinate females, which soon became much more responsive to the cries of pups. Then they repeated the experiment to make sure the hormones were really the key component of the poop. This time, they took fecal pellets from nonpregnant queens and added estradiol—a type of estrogen—to only half of the pellets. Only the naked mole rats that ate the estradiol-supplement poop became more responsive to pup cries. 

Mogi was excited. He had never seen hormones work like this before. Hormones are powerful mediators of behavior, but their effects are normally limited to the body of the animal making them. Here the queen seems to be making hormones to alter the bodies of totally separate animals. Insect colonies have sometimes been called superorganisms for the way thousands of individuals behave as one unit; in this case, hormones seem to be acting on naked-mole-rat colonies as a single superorganism.

This is pretty amazing stuff that I would not have expected in mammals.

Personalities Aren't Just For Humans

Recent studies show that animals far removed from mammals have recognizable personalities.

There are extroverted and introverted sharks in the same species.  The extroverts scare away threats by hanging out in groups.  The introverts head off alone to isolated places and rely on camouflage.

There are also aggressive and docile female communal spiders, common in the American Southeast.  Different mixes of personality are favored in different locations, with the proportion of each personality, which are hereditary, providing the first solid evidence of group selection.  The personality proportions remain the same, even in places where the radically different mix of aggressive and docile females found in local spiders of the same species would be more adaptive.

Anthropologists have demonstrated fairly convincingly that there are differences at the level of coherent ethnic, regional and national cultures in what would normally be considered to be personality traits, such as differences between cultural norms in Northern China, which was traditionally a wheat and millet farming area relative to Southern China, which was traditionally a rice farming area.  One of the ongoing debates in cultural history, anthropology and genetics is the extent to which a nation's "national character" is purely a product of cultural transmission, or instead involves (at least in part) differences in population genetic make up with group selection favoring different mixes of personalities in different environments that continue to manifest even as migration and cultural change make old the balancing selection that produced the ancestral mix of personalities of a "nation" dysfunctional in a new environment.  (The evidence concerning the wheat v. rice farming dichotomy in China tends to favor a cultural rather than a genetic source, by the way, which is the leading view, for the most part.)

While some seemingly complex phenotypes really do have complex genotypes as their source, other seemingly complex phenotypes can arise from just a single genetic locus (in the reference, butterfly wing patterns).  There are also a variety of candidate simple genes with apparent impacts on personality.  Scientists have similarly identified a very simple single locus that can be used to make fruit flies homosexual or heterosexual.

The relatively discrete personality categories observed in some species, patterns of balancing selection within groups of personality types, and the fact that, for example, the personality distribution of humans with high IQs is quite similar to the personality distribution of other humans, suggests like unlike massively polygenetic traits like IQ or stature with a quite continuous range of values and strong bias towards the fitness enhancing direction, that a fairly modest number of common genetic variants may account for personality differences.

But, large scale comprehensive searches for personality genes in humans have mostly come up empty.  Yet, there is strong evidence that personality has a strong hereditary component from sources like twin studies that strongly suggests that at least some genotype plays a major role in shaping a person's personality.  As recent studies of schizophrenia reveal, one problem with these studies may be insufficiently precise definitions of personality types to capture the link between genotype and phenotype.

* * * *

Not quite on topic, but also fascinating is a newly discovered species of parasitic ant that evolved from the species of ant for which it is a parasite (something confirmed with a genetic analysis), in the very same ant colony.  This is essentially the insect equivalent of vampires evolving as a new parasitic species of humans within a single human community.

Anatomy of A Crackpot

Razib has posted a nicely done profile of "human origins in the Americas" blogger and self-published author German Dziebel.  I've come across his posts at a number of prehistory and population genetics blogs and concur with Razib's assessment.

Menstrual Pollution Taboos Assure Paternity?

A study of people of different religious faiths among the Dogon people of Mali revealed that practitioners of indigenous religious beliefs, including the exile of women who were menstruating to special huts, found that women had children with men other than their husbands during the marriage about twice as often (2.9% v. 1.3%) if they held to indigenous religious beliefs rather than Christian or Muslim ones.  It hypothesized that:

[T]he religion uses the ideology of pollution to ensure that women honestly signal their fertility status to men in their husband's family.

"When a woman resumes going to the menstrual hut following her last birth, the husband's patrilineage is informed of the imminency of conception and cuckoldry risk. . . .Precautions include postmenstrual copulation initiated by the husband and enhanced vigilance by his family."

I can imagine a variety of other explanations, however.  For example, perhaps people who are more open to breaking with traditional norms and expectations are more likely to convert to Christianity or Islam than those who are not.  The study examined 1,706 father-son pairs and found approximately 31 cases of non-paternity.  If women who are open to extra-marital affairs are rare, and significantly favor an intrusive outside religion over the indigenous tradition one, the same effect would be observed.  Perhaps women who aren't willing to put up with spending five days a month in an uncomfortable menstrual hut are simply more independent generally.

It seems doubtful to me that public signaling is really that significant in alerting husbands to their wives's fertility, or that vigilance about something that all of the women presumably make a great effort to keep secret would really make that much of a difference between different religious faiths in the same ethnic community.

The conclusions of the study look to me like a case of anthropologists looking to exotic and flashy explanations for complex behavior patterns that may have more pedestrian causes.

Proud Men Die Young

People who most believe in a culture of honor -- who agree that "A real man doesn't let other people push him around" or that aggression is a reasonable response to being insulted -- told the researchers they were quite willing to engage in risky behaviors, such as bungee jumping or gambling away a week's wages. This willingness to take risks might well translate into an early death[.] . . .

Honor cultures are more powerful in rural areas, where the influence of personal reputation is higher than it is in cities. Although honor states had a 14% higher accidental death rate in the cities, they had a 19% higher rate of accidental death in more rural areas, compared to non-honor states. More than 7,000 deaths a year can be attributed to risk-taking associated with the culture of honor in the USA.

From here.

FWIW, it could also have something to do with the fact that "cultures of honor" also have disproportionate shares of blue collar workers whose jobs are more dangerous. But, the urban-rural comparison casts some doubt on that economic as opposed to cultural interpretation.

What Moods Are Most Attractive?

Women really are more beautiful when they smile. But women prefer body language that is emo or screams power to contentment.

["M]en and women respond very differently to displays of emotion, including smiles."

In a series of studies, more than 1,000 adult participants rated the sexual attractiveness of hundreds of images of the opposite sex engaged in universal displays of happiness (broad smiles), pride (raised heads, puffed-up chests) and shame (lowered heads, averted eyes).

The study found that women were least attracted to smiling, happy men, preferring those who looked proud and powerful or moody and ashamed. In contrast, male participants were most sexually attracted to women who looked happy, and least attracted to women who appeared proud and confident.

From here citing Jessica L. Tracy, Alec T. Beall. Happy guys finish last: The impact of emotion expressions on sexual attraction. Emotion, 2011; DOI: 10.1037/a0022902.

Perhaps this says something about the psychological bargain we are looking for, on average, when we seek a partner in the dating game. If women are selling happiness, someone who is already content is unlikely to want what they offer. If men are seeking to exchange their success for happiness from a woman, a woman who already have circumstances that make her feel proud and powerful is less likely to be interested in making that exchange.

The second place attraction of a shamed woman in this hierarchy to men also makes sense in this model. She too is looking for the success that a man can offer and if she may not be offering happiness she may at least be offering loyalty. Similarly, an emo man may be the most responsive to the happiness that a happy woman can offer, because he lacks that joy, again also fostering loyalty.

It would have been interesting to know if the results were homogeneous. Do all woman and all men have the same hierarchy of preferences? Or, are there different subtypes of people who have different priorities?

One can imagine, for example, an independently wealthy woman or one with a successful career having different priorities in men than a woman who is hoping to spend time as a dependent mother of here mate's children. Put another way, maybe cougars have different priorities than debutantes that are reflected in what they find to be attractive in terms of emotional displays.  I suppose it will take more studies to establish that.