Chimps can psych out humans

Interesting work from Eckert et al. shows that chimps can use mental state information revealed by experimenters' biases in selecting food items.

Great apes have been shown to be intuitive statisticians: they can use proportional information within a population to make intuitive probability judgments about randomly drawn samples [unpublished data]. Humans, from early infancy onward, functionally integrate intuitive statistics with other cognitive domains to judge the randomness of an event. To date, nothing is known about such cross-domain integration in any nonhuman animal, leaving uncertainty about the origins of human statistical abilities. We investigated whether chimpanzees take into account information about psychological states of experimenters (their biases and visual access) when drawing statistical inferences. We tested 21 sanctuary-living chimpanzees in a previously established paradigm that required subjects to infer which of two mixed populations of preferred and non-preferred food items was more likely to lead to a desired outcome for the subject. In a series of three experiments, we found that chimpanzees chose based on proportional information alone when they had no information about experimenters’ preferences and (to a lesser extent) when experimenters had biases for certain food types but drew blindly. By contrast, when biased experimenters had visual access, subjects ignored statistical information and instead chose based on experimenters’ biases. Lastly, chimpanzees intuitively used a violation of statistical likelihoods as indication for biased sampling. Our results suggest that chimpanzees have a random sampling assumption that can be overridden under the appropriate circumstances and that they are able to use mental state information to judge whether this is necessary. This provides further evidence for a shared statistical inference mechanism in apes and humans.

Crows make mental templates.

Weintraub points to further studies from the University of Aukland School of Psychology on the extraordinary New Caledonian crows that have been shown to learn tool use. They also appear to use “mental template matching” - forming an image in their heads of tools they have seen used by others, and then copying them.

 

Deep origins of consciousness

I want to recommend an engaging book by Peter Godfrey-Smith that I have read recently, "Other Minds: The Octopus, theSea, and the Deep Origins of Consciousness." Below are a few clips pointing to some of his core points:

Sentience is brought into being somehow from the evolution of sensing and acting; it involves being a living system with a point of view on the world around it. If we take that approach, though, a perplexity we run into immediately is the fact that those capacities are so widespread— they are found far outside the organisms that are usually thought to have experience of some kind. Even bacteria sense the world and act... A case can be made that responses to stimuli, and the controlled flow of chemicals across boundaries, are an elementary part of life itself. Unless we conclude that all living things have a modicum of subjective experience— a view I don’t regard as insane, but surely one that would need a lot of defense— there must be something about the way animals deal with the world that makes a crucial difference.

The senses can do their basic work, and actions can be produced, with all this happening “in silence” as far as the organism’s experience is concerned. Then, at some stage in evolution, extra capacities appear that do give rise to subjective experience: the sensory streams are brought together, an “internal model” of the world arises, and there’s a recognition of time and self.

What we’ve learned over the last thirty years or so is that there’s a particular style of processing— one that we use to deal especially with time, sequences, and novelty— that brings with it conscious awareness, while a lot of other quite complex activities do not.

Baars suggested that we are conscious of the information that has been brought into a centralized “workspace” in the brain. Dehaene adopted and developed this view. A related family of theories claim that we are conscious of whatever information is being fed into working memory,These views don’t hold that the lights went on in a sudden flash, but they do hold that the “waking up” came late in the history of life and was due to features that are clearly seen only in animals like us.

...certainly there’s an alternative to consider. I’ll call this the transformation view. It holds that a form of subjective experience preceded late-arising things like working memory, workspaces, the integration of the senses, and so on. These complexities, when they came along, transformed what it feels like to be an animal. Experience has been reshaped by these features, but it was not brought into being by them. The best argument I can offer for this alternative view is based on the role in our lives of what seem like old forms of subjective experience that appear as intrusions into more organized and complex mental processes. Consider the intrusion of sudden pain, or of what the physiologist Derek Denton calls the primordial emotions— feelings which register important bodily states and deficiencies, such as thirst or the feeling of not having enough air. As Denton says, these feelings have an “imperious” role when they are present: they press themselves into experience and can’t easily be ignored. Do you think that those things (pain, shortness of breath, etc.) only feel like something because of sophisticated cognitive processing in mammals that has arisen late in evolution? I doubt it. Instead, it seems plausible that an animal might feel pain or thirst without having an “inner model” of the world, or sophisticated forms of memory.

Subjective experience does not arise from the mere running of the system, but from the modulation of its state, from registering things that matter. These need not be external events; they might arise internally. But they are tracked because they matter and require a response. Sentience has some point to it. It’s not just a bathing in living activity.

By the Cambrian, the vertebrates were already on their own path (or their own collection of paths), while arthropods and mollusks were on others. Suppose it’s right that crabs, octopuses, and cats all have subjective experience of some kind. Then there were at least three separate origins for this trait, and perhaps many more than three. Later, as the machinery described by Dehaene, Baars, Milner, and Goodale comes on line, an integrated perspective on the world arises and a more definite sense of self. We then reach something closer to consciousness. I don’t see that as a single definite step. Instead, I see “consciousness” as a mixed-up and overused but useful term for forms of subjective experience that are unified and coherent in various ways. Here, too, it is likely that experience of this kind arose several times on different evolutionary paths: from white noise, through old and simple forms of experience, to consciousness.

Evolutionary cognition - bees demonstrate an understanding of zero

Howard et al. demonstrate an astounding evolutionary convergence by showing that insects have developed the concept of zero, a capability once thought to be a unique major intellectual advance in humans. The last common ancestor of humans and the honeybees used in the experiments lived more than 600 million years ago. Their abstract:

Some vertebrates demonstrate complex numerosity concepts—including addition, sequential ordering of numbers, or even the concept of zero—but whether an insect can develop an understanding for such concepts remains unknown. We trained individual honey bees to the numerical concepts of “greater than” or “less than” using stimuli containing one to six elemental features. Bees could subsequently extrapolate the concept of less than to order zero numerosity at the lower end of the numerical continuum. Bees demonstrated an understanding that parallels animals such as the African grey parrot, nonhuman primates, and even preschool children.

...and a description of their experiment from a review by Nieder:

...the authors lured free-flying honey bees from maintained hives to their testing apparatus (see the figure) and marked the insects with color for identification. They rewarded the bees for discriminating displays on a screen that showed different numbers (numerosities) of items. The researchers controlled for systematic changes in the appearance of the numerosity displays that occur when the number of items is changed. They thus ensured that the bees were discriminating between different numbers, rather than responding to low-level visual cues.

First, the researchers trained the bees to rank two numerosity displays at a time. Over the course of training, they changed the numbers presented to encourage rule learning. Bees from one group were rewarded with a sugar solution whenever they flew to the display showing more items, thereby following a greater-than rule. The other group of bees was trained on the less-than rule and rewarded for landing at the display that presented fewer items. The bees learned to master this task with displays consisting of one to four items; they were able to do so not only for familiar numerosity displays but also for new displays.

Next, the researchers occasionally inserted displays containing no item. Would the bees understand that empty displays could be ranked with countable numerosities? Indeed, the bees obeying the less-than rule spontaneously landed on displays showing no item, that is, an empty set (see the figure). In doing so, bees understood that the empty set was numerically smaller than sets of one, two, or more items. Further experiments confirmed that this behavior was related to quantity estimation and not a product of the learning history.

Wealth inequality as a law of nature.

Here is the abstract from Scheffer et al.,  a bit of work that casts an interesting light on the current Republican tax legislation that significantly accelerates the unequal distribution of wealth in this country, as described nicely by David Leonhardt:

Significance

Inequality is one of the main drivers of social tension. We show striking similarities between patterns of inequality between species abundances in nature and wealth in society. We demonstrate that in the absence of equalizing forces, such large inequality will arise from chance alone. While natural enemies have an equalizing effect in nature, inequality in societies can be suppressed by wealth-equalizing institutions. However, over the past millennium, such institutions have been weakened during periods of societal upscaling. Our analysis suggests that due to the very same mathematical principle that rules natural communities (indeed, a “law of nature”) extreme wealth inequality is inevitable in a globalizing world unless effective wealth-equalizing institutions are installed on a global scale.

Abstract

Most societies are economically dominated by a small elite, and similarly, natural communities are typically dominated by a small fraction of the species. Here we reveal a strong similarity between patterns of inequality in nature and society, hinting at fundamental unifying mechanisms. We show that chance alone will drive 1% or less of the community to dominate 50% of all resources in situations where gains and losses are multiplicative, as in returns on assets or growth rates of populations. Key mechanisms that counteract such hyperdominance include natural enemies in nature and wealth-equalizing institutions in society. However, historical research of European developments over the past millennium suggests that such institutions become ineffective in times of societal upscaling. A corollary is that in a globalizing world, wealth will inevitably be appropriated by a very small fraction of the population unless effective wealth-equalizing institutions emerge at the global level.

Figure - Inequality in society (Left) and nature (Right). The Upper panels illustrate the similarity between the wealth distribution of the world’s 1,800 billionaires (A) (8) and the abundance distribution among the most common trees in the Amazon forest (B) (3). The Lower panels illustrate inequality in nature and society more systematically, comparing the Gini index of wealth in countries (C) and the Gini index of abundance in a large set of natural communities (D). (The Gini index is an indicator of inequality that ranges from 0 for entirely equal distributions to 1 for the most unequal situation. It is a more integrative indicator of inequality than the fraction that represents 50%, but the two are closely related in practice. Surprisingly, Gini indices for our natural communities are quite similar to the Gini indices for wealth distributions of 181 countries.)

Dogs can smell our happiness and fear.

From D'Aniello et al:

We report a study examining interspecies emotion transfer via body odors (chemosignals). Do human body odors (chemosignals) produced under emotional conditions of happiness and fear provide information that is detectable by pet dogs (Labrador and Golden retrievers)? The odor samples were collected from the axilla of male donors not involved in the main experiment. The experimental setup involved the co-presence of the dog's owner, a stranger and the odor dispenser in a space where the dogs could move freely. There were three odor conditions [fear, happiness, and control (no sweat)] to which the dogs were assigned randomly. The dependent variables were the relevant behaviors of the dogs (e.g., approaching, interacting and gazing) directed to the three targets (owner, stranger, sweat dispenser) aside from the dogs' stress and heart rate indicators. The results indicated with high accuracy that the dogs manifested the predicted behaviors in the three conditions. There were fewer and shorter owner directed behaviors and more stranger directed behaviors when they were in the "happy odor condition" compared to the fear odor and control conditions. In the fear odor condition, they displayed more stressful behaviors. The heart rate data in the control and happy conditions were significantly lower than in the fear condition. Our findings suggest that interspecies emotional communication is facilitated by chemosignals.

Like apes and small children, ravens plan ahead.

The notion that animal cognition outside of the primate lineage is locked into the present has to be tossed. It appears that cognitive evolution of the ability to plan ahead proceeded independently in the (Corvid) lineage that lead to modern Ravens. Kabadayi and Osvath now show that ravens anticipate the nature, time, and location of a future event based on previous experiences. The ravens' behavior is not merely prospective, anticipating future states; rather, they flexibly apply future planning in behaviors not typically seen in the wild. From the summary by Boeckle and Clayton:

Kabadayi and Osvath test ravens' abilities to plan for future tool use and trading, rather than for food caching (a behavior that might be considered as an adaptive specialization to gather food in order to eat it at a future date)...The authors presented five ravens with a choice of objects. Only one of these objects was a functional tool, which could be used to retrieve food from a puzzle box. The ravens chose correctly not only when they were offered the box but also when they had to store the tool and plan for the next day. In another experiment, the ravens were trained to exchange tokens for food. When the ravens knew that trading would only happen on the next day, they chose and stored these tokens as soon as they were offered to them. By manipulating tool choice, time, and trading opportunities, the authors controlled the value of the items at choice in relation to current as well as future interactions.

The results from the two experiments show that ravens take temporal distance between item choice and reward into account, exercise self-control, and make decisions for predicted futures rather than arbitrary ones. Thus, the birds opt for a more distant but higher gratification rather than an immediate but lower gratification and do so flexibly across behaviors.

Mammalian empathy: neural basis and behavioral manifestations

I want to point to an interesting review by de Waal and Preston in Nature Reviews Neuroscience. Here are the Abstract and a few excerpts from the article:

Recent research on empathy in humans and other mammals seeks to dissociate emotional and cognitive empathy. These forms, however, remain interconnected in evolution, across species and at the level of neural mechanisms. New data have facilitated the development of empathy models such as the perception–action model (PAM) and mirror-neuron theories. According to the PAM, the emotional states of others are understood through personal, embodied representations that allow empathy and accuracy to increase based on the observer's past experiences. In this Review, we discuss the latest evidence from studies carried out across a wide range of species, including studies on yawn contagion, consolation, aid-giving and contagious physiological affect, and we summarize neuroscientific data on representations related to another's state.

Key points:

Observational and experimental studies dating back to the 1950s demonstrate that mammals spontaneously help distressed conspecifics. Research emphasizes the untrained, unrewarded nature of this behaviour, which is also biased towards familiar individuals, thus arguing against explanations that are exclusively based on associative learning or conditioning.

The perception–action model extends an existing motor theory on overlapping representations to emotional phenomena; it states that observers who attend to a target's state understand and 'feel into' it through personal distributed representations of the target, the state and the situation. Easily observed manifestations of this mechanism are emotional contagion and motor mimicry, which have been demonstrated in many animals. In cognitive forms of empathy, the same representations are accessed from the top-down.

Experiments on two common mammalian expressions of empathy — the consolation of distressed individuals and spontaneous assistance to those in need — support the crucial role of caught distress and arousal because these behaviours are suppressed by anti-anxiety medication and engage the same neuropeptide system that supports social attachment.

The Russian-doll model seeks to arrange forms of empathy into layers that are built on top of each other — with the layers ranging from emotional contagion to more cognitive forms of empathy — in a functionally integrated whole based on perception–action processes. Perspective-taking is well developed in some non-human species, as manifested by theory-of-mind and targeted helping.

One can segregate emotional and cognitive empathy (as well as felt and observed states) in the brains of observers, but all forms require some initial access to the observer's distributed, shared, personal representations of the target's state. At least in the initial phase of processing, this access helps to decode the target's state and provide subsequent processing with content and meaning, even if the shared state is not experienced, or is incomplete or inaccurate.

Empathic pain does not usually include the peripheral sensation of the target's injury, but it can include sensory information when the stimuli and task instructions emphasize the specific nature of the feeling at the location of the injury.

The Russian Doll Model of the Evolution of Empathy

Dogs can know what you know.

Catela et al. offer evidence in dogs for theory of mind ability (recognizing that others have a different perspective, shown for humans, apes, and corvids). They show that dogs prefer to follow the pointing of a human who witnessed a food hiding event over a human who did not, and can distinguish two individuals who are showing identical looking behaviors, only one of which had the opportunity to see where the food was hidden by a third person. This perspective taking ability may occur more widely in the animal kingdom than previously supposed.

Currently, there is still no consensus about whether animals can ascribe mental states (Theory of Mind) to themselves and others. Showing animals can respond to cues that indicate whether another has visual access to a target or not, and that they are able to use this information as a basis for whom to rely on as an informant, is an important step forward in this direction. Domestic dogs (Canis familiaris) with human informants are an ideal model, because they show high sensitivity towards human eye contact, they have proven able to assess the attentional state of humans in food-stealing or food-begging contexts, and they follow human gaze behind a barrier when searching for food. With 16 dogs, we not only replicated the main results of Maginnity and Grace (Anim Cogn 17(6):1375–1392, 2014) who recently found that dogs preferred to follow the pointing of a human who witnessed a food hiding event over a human who did not (the Guesser–Knower task), but also extended this finding with a further, critical control for behaviour-reading: two informants showed identical looking behaviour, but due to their different position in the room, only one had the opportunity to see where the food was hidden by a third person. Preference for the Knower in this critical test provides solid evidence for geometrical gaze following and perspective taking in dogs.

Some outstanding books on the biology of our behaviors.

If you are wanting to find a humorous, fascinating, engaging, authoritative account of why we humans behave the way we do, you should immediately buy a copy of Robert Sapolsky's new book, "Behave - The Biology of Humans at Our Best and Worst." I've been a fan of Sapolsky ever since reading his "Why Zebras don't get Ulcers," whose 3rd edition dates to 2004. His writing has a flexibility, lightness and sense of humor that I wish I could even begin to emulate. I'm only up to the third chapter (of 17), and wish I could suspend all my other activities and read this book. I'm familiar with virtually all of the material he presents, but I could never present it with his clarity and lucid organization.

Another book I want to make a positive comment about is Richard Haier's "The Neuroscience of Intelligence," part of the Cambridge Fundamentals of Neuroscience in Psychology series. It is a bit more academic and weighty, beginning by dispelling popular misinformation on intelligence and then describing how it is defined and measured for scientific research. The book reviews evidence for the importance of genetics and epigenetics, and has chapters that do a nice synthesis of neuroimaging and other new technologies. The final two chapters focus on approaches to enhancing intelligence, and also how intelligence research may inform education policies.

Finally, I want to mention a book by Ken Richardson, "Genes, Brains, and Human Potential," that discusses how the ideology of human intelligence has infiltrated genetics,  brain science, and psychology, so that (from the dust jacket) "ideology, more than pure science, has come to dominate our institutions, especially education, encouraging fatalism about the development of human intelligence among individuals and societies. Build on work being done in molecular biology, epigenetics, dynamical systems, evolution theory, and complexity theory, Richardson maps a fresh understanding of intelligence and the development of human potential informed by a more complete and nuanced understanding of both ideology and science."

Our spatial memory is driven by perceived animacy of simple shapes.

Chin points to work of van Buren and Scholl who use “wolfpack” animations of dart shapes whose points track the movement of a disc (the prey) to show that these are more readily remembered than identical animations in which the dart points are oriented away from or perpendicular to the prey. Perceiving such moving shapes as animate reinforces visual memory and has possibly been important in human evolution. The abstract of the article:

Even simple geometric shapes are seen as animate and goal-directed when they move in certain ways. Previous research has revealed a great deal about the cues that elicit such percepts, but much less about the consequences for other aspects of perception and cognition. Here we explored whether simple shapes that are perceived as animate and goal-directed are prioritized in memory. We investigated this by asking whether subjects better remember the locations of displays that are seen as animate vs. inanimate, controlling for lower-level factors. We exploited the ‘Wolfpack effect’: moving darts (or discs with ‘eyes’) that stay oriented toward a particular target are seen to be actively pursuing that target, even when they actually move randomly. (In contrast, shapes that stay oriented perpendicular to a target are correctly perceived to be drifting randomly.) Subjects played a ‘matching game’ – clicking on pairs of panels to reveal animations with moving shapes. Across four experiments, the locations of Wolfpack animations (compared to control animations equated on lower-level visual factors) were better remembered, in terms of more efficient matching. Thus perceiving animacy influences subsequent visual memory, perhaps due to the adaptive significance of such stimuli.

From learning to instinct

I pass on a few chunks from the Science Perspective article by Robinson and Barron:

An animal mind is not born as an empty canvas: Bottlenose dolphins know how to swim and honey bees know how to dance without ever having learned these skills. Little is known about how animals acquire the instincts that enable such innate behavior. Instincts are widely held to be ancestral to learned behavior. Some have been elegantly analyzed at the cellular and molecular levels, but general principles do not exist. Based on recent research, we argue instead that instincts evolve from learning and are therefore served by the same general principles that explain learning.

Tierney first proposed in 1986 that instincts can evolve from behavioral plasticity, but the hypothesis was not widely accepted, perhaps because there was no known mechanism. Now there is a mechanism, namely epigenetics. DNA methylation, histone modifications, and noncoding RNAs all exert profound effects on gene expression without changing DNA sequence. These mechanisms are critical for orchestrating nervous system development and enabling learning-related neural plasticity.

For example, when a mouse has experienced fear of something, changes in DNA methylation and chromatin structure in neurons of the hippocampus help stabilize long-term changes in neural circuits. These changes help the mouse to remember what has been learned and support the establishment of new behavioral responses. Epigenetic mechanisms that support instinct by operating on developmental time scales also support learning by operating on physiological time scales. Evolutionary changes in epigenetic mechanisms may sculpt a learned behavior into an instinct by decreasing its dependence on external stimuli in favor of an internally regulated program of neural development (see the figure).

There is evidence for such epigenetically driven evolutionary changes in behavior. For example, differences in innate aggression levels between races of honey bees can be attributed to evolutionary changes in brain gene expression that also control the onset of aggressive behavior when threatened. These kinds of changes can also explain more contemporary developments, including new innate aspects of mating and foraging behavior in house finches associated with their North American invasion 75 years ago, and new innate changes in the frequency and structure of song communication in populations of several bird species now living in urban environments. We propose that these new instincts have emerged through evolutionary genetic changes that acted on initially plastic behavioral responses.

Are human-specific plastic cortical synaptic connections what makes us human?

I want to pass on an excellent primer (open source) on the plasticity of a specific synapse between pyramidal neurons and fast-spiking interneurons of the human neocortex observed only in our human brains.

One outstanding difference between Homo sapiens and other mammals is the ability to perform highly complex cognitive tasks and behaviors, such as language, abstract thinking, and cultural diversity. How is this accomplished? According to one prominent theory, cognitive complexity is proportional to the repetition of specific computational modules over a large surface expansion of the cerebral cortex (neocortex). However, the human neocortex was shown to also possess unique features at the cellular and synaptic levels, raising the possibility that expanding the computational module is not the only mechanism underlying complex thinking. In a study published in PLOS Biology, Szegedi and colleagues analyzed a specific cortical circuit from live postoperative human tissue, showing that human-specific, very powerful excitatory connections between principal pyramidal neurons and inhibitory neurons are highly plastic. This suggests that exclusive plasticity of specific microcircuits might be considered among the mechanisms endowing the human neocortex with the ability to perform highly complex cognitive tasks.

Knowing how confidently we know

Here is a fascinating piece of work from Miyamoto et al. showing that parallel stream of information in the brain regulate the confidence that a memory is correct, apart from the memory itself. From the journal's description of the work:

Self-monitoring and evaluation of our own memory is a mental process called metamemory. For metamemory, we need access to information about the strength of our own memory traces. The brain structures and neural mechanisms involved in metamemory are completely unknown. Miyamoto et al. devised a test paradigm for metamemory in macaques, in which the monkeys judged their own confidence in remembering past experiences. The authors combined this approach with functional brain imaging to reveal the neural substrates of metamemory for retrospection. A specific region in the prefrontal brain was essential for meta mnemonic decision-making. Inactivation of this region caused selective impairment of metamemory, but not of memory itself.

and, the abstract from Miyamoto et al.:

We know how confidently we know: Metacognitive self-monitoring of memory states, so-called “metamemory,” enables strategic and efficient information collection based on past experiences. However, it is unknown how metamemory is implemented in the brain. We explored causal neural mechanism of metamemory in macaque monkeys performing metacognitive confidence judgments on memory. By whole-brain searches via functional magnetic resonance imaging, we discovered a neural correlate of metamemory for temporally remote events in prefrontal area 9 (or 9/46d), along with that for recent events within area 6. Reversible inactivation of each of these identified loci induced doubly dissociated selective impairments in metacognitive judgment performance on remote or recent memory, without impairing recognition performance itself. The findings reveal that parallel metamemory streams supervise recognition networks for remote and recent memory, without contributing to recognition itself.

Our Arthropod housemates.

Now I know more about what is in the haze of particles I see illuminated by the horizontal rays of the rising sun flowing through my Fort Lauderdale condo in early morning.  I pass on, under the "random curious stuff" MindBlog category,  an accounting by Madden et al. that shows the ubiquity of insects detected in settled dust samples collected from inside homes. They used a DNA-based method for investigating the arthropod diversity in homes via high-throughput marker gene sequencing of home dust. Settled dust samples were collected by citizen scientists from both inside and outside more than 700 homes across the United States, yielding the first continental-scale estimates of arthropod diversity associated with our residences. Here is a graphic (click to enlarge), in which (A) shows the Genera detected, (B) shows orders detected in at least 5% of homes. The Y-axes indicate the percentage of homes (of 651 homes with arthropods detected) where those arthropods were detected.

Why does time fly when you’re having fun? Dopamine neurons…

Soares et al. find by observing timing behavior in mice that dopaminergic neurons control temporal judgments on a time scale of seconds.

Our sense of time is far from constant. For instance, time flies when we are having fun, and it slows to a trickle when we are bored. Midbrain dopamine neurons have been implicated in variable time estimation. However, a direct link between signals carried by dopamine neurons and temporal judgments is lacking. We measured and manipulated the activity of dopamine neurons as mice judged the duration of time intervals. We found that pharmacogenetic suppression of dopamine neurons decreased behavioral sensitivity to time and that dopamine neurons encoded information about trial-to-trial variability in time estimates. Last, we found that transient activation or inhibition of dopamine neurons was sufficient to slow down or speed up time estimation, respectively. Dopamine neuron activity thus reflects and can directly control the judgment of time.

Sex differences in brain regulation of aggression

Interesting work from Terranova et al., done with hamsters, and almost certainly applicable to us humans. Here is their summary of the significance of the study, and the abstract with more technical stuff:

Significance

There are profound sex differences in the expression of social behavior and in the incidence of many psychiatric disorders, and yet little is known about how the brain mechanisms underlying these phenomena differ in females and males. Here, we report that serotonin (5-HT) and arginine–vasopressin (AVP) act in opposite ways within the hypothalamus to regulate dominance and aggression in females and males. Dominance and aggression are promoted by 5-HT in females and by AVP in males. Because dominance and aggressiveness have been linked to the resistance to stress-related psychiatric disorders, these disorders may be more effectively treated with 5-HT–targeted drugs in females and AVP-targeted drugs in males.

Abstract

There are profound sex differences in the incidence of many psychiatric disorders. Although these disorders are frequently linked to social stress and to deficits in social engagement, little is known about sex differences in the neural mechanisms that underlie these phenomena. Phenotypes characterized by dominance, competitive aggression, and active coping strategies appear to be more resilient to psychiatric disorders such as posttraumatic stress disorder (PTSD) compared with those characterized by subordinate status and the lack of aggressiveness. Here, we report that serotonin (5-HT) and arginine–vasopressin (AVP) act in opposite ways in the hypothalamus to regulate dominance and aggression in females and males. Hypothalamic injection of a 5-HT1a agonist stimulated aggression in female hamsters and inhibited aggression in males, whereas injection of AVP inhibited aggression in females and stimulated aggression in males. Striking sex differences were also identified in the neural mechanisms regulating dominance. Acquisition of dominance was associated with activation of 5-HT neurons within the dorsal raphe in females and activation of hypothalamic AVP neurons in males. These data strongly indicate that there are fundamental sex differences in the neural regulation of dominance and aggression. Further, because systemically administered fluoxetine increased aggression in females and substantially reduced aggression in males, there may be substantial gender differences in the clinical efficacy of commonly prescribed 5-HT–active drugs such as selective 5-HT reuptake inhibitors. These data suggest that the treatment of psychiatric disorders such as PTSD may be more effective with the use of 5-HT–targeted drugs in females and AVP-targeted drugs in males.

Turn-taking skills unique to humans?

In yet another "humans are unique with respect to...." type article Melis, Tomasello and collaborators do experiments showing that humans differ in their ability to carry out long-term collaborative relationships that involve taking turns. I've been reading de Waal's recent book "Are we smart enough to know how smart animals are?" (which I highly recommend), which suggests that the "unique to humans" implicit in the title of the article of the article may not be appropriate, for the article demonstrates a more 'advanced' behavior in humans only in a specific paradyme involving just the two species. Potential turn taking behavior in other social animals, invertebrates as well as vertebrates, is still a possibility. The experiments:

...gave pairs of 3- and 5-year-old children and chimpanzees a collaboration task in which equal rewards could be obtained only if the members of a pair worked together first to reward one and then to reward the other. Neither species had previously been tested in a paradigm in which partners can distribute collaboratively produced rewards in “fair” ways only by taking turns being the sole beneficiary.

Here is their abstract:

Long-term collaborative relationships require that any jointly produced resources be shared in mutually satisfactory ways. Prototypically, this sharing involves partners dividing up simultaneously available resources, but sometimes the collaboration makes a resource available to only one individual, and any sharing of resources must take place across repeated instances over time. Here, we show that beginning at 5 years of age, human children stabilize cooperation in such cases by taking turns across instances of obtaining a resource. In contrast, chimpanzees do not take turns in this way, and so their collaboration tends to disintegrate over time. Alternating turns in obtaining a collaboratively produced resource does not necessarily require a prosocial concern for the other, but rather requires only a strategic judgment that partners need incentives to continue collaborating. These results suggest that human beings are adapted for thinking strategically in ways that sustain long-term cooperative relationships and that are absent in their nearest primate relatives.

Abstract thinking in newborn ducklings!

Martinho and Kacelnik have shown that duckings imprint on the relational concept of "same or different." From Wasserman's perspective on the work:

Adhering to the adage that “actions speak more loudly than words,” scientists are deploying powerful behavioral tests that provide animals with nonverbal ways to reveal their intelligence to us. Although animals may not be able to speak, studying their behavior may be a suitable substitute for assaying their thoughts, and this in turn may allow us to jettison the stale canard that thought without language is impossible. Following this behavioral approach and using the familiar social learning phenomenon of imprinting, Martinho and Kacelnik report that mallard ducklings preferentially followed a novel pair of objects that conformed to the learned relation between a familiar pair of objects. Ducklings that had earlier been exposed to a pair of identical objects preferred a pair of identical objects to a pair of nonidentical objects; other ducklings that had been exposed to a pair of nonidentical objects preferred a pair of nonidentical objects to a pair of identical objects. Because the testing objects were decidedly unlike the training objects, Martinho and Kacelnik concluded that the ducklings had effectively understood the abstract concepts of “same” and “different.”

A duckling in the testing arena approaches a stimulus pair composed of “different” shapes.

This study is important for at least three reasons. First, it indicates that animals not generally believed to be especially intelligent are capable of abstract thought. Second, even very young animals may be able to display behavioral signs of abstract thinking. And, third, reliable behavioral signs of abstract relational thinking can be obtained without deploying explicit reward-and-punishment procedures.

Are we smart enough to know how smart animals are?

I want to pass on some clips from Silk's recent review of Frans de Waal's recent book whose title is the title of this post:

Natural selection, he argues, shapes cognitive abilities in the same way as it shapes traits such as wing length. As animals' challenges and habitats differ, so do their cognitive abilities. This idea, which he calls evolutionary cognition, has gained traction in psychology and biology in the past few decades.

For de Waal, evolutionary cognition has two key consequences. First, it is inconsistent with the concept of a 'great chain of being' in which organisms can be ordered from primitive to advanced, simple to complex, stupid to smart. Name a 'unique' human trait, and biologists will find another organism with a similar one. Humans make and use tools; so do wild New Caledonian crows (Corvus moneduloides). Humans develop cultures; so do humpback whales (Megaptera novaeangliae), which socially transmit foraging techniques. We can mentally 'time travel', remembering past events and planning for the future; so can western scrub jays (Aphelocoma californica), which can recall what they had for breakfast on one day, anticipate whether they will be given breakfast the next and selectively cache food when breakfast won't be delivered.

Furthermore, humans do not necessarily outdo other animals in all cognitive domains. Black-capped chickadees (Poecile atricapillus) store seeds in hundreds of locations each day, and can remember what they stored and where, as well as whether items in each location have been eaten, or stolen. Natural selection has favoured those prodigious feats of memory because they spell the difference between surviving winter and starving before spring. Human memory doesn't need to be as good: primates evolved in the tropics. “In the utilitarian view of biology,” de Waal argues, “animals have the brains they need — nothing more, nothing less.”

The second consequence of de Waal's view is that there is continuity across taxa. One source of continuity is based on evolutionary history: natural selection modifies traits to create new ones, producing commonalities among species with a common history. He points out that tool use is found not just in humans and chimpanzees, but also in other apes and monkeys, implying that relevant cognitive building blocks are shared across all primates. Continuity is also generated by convergent evolution, which produces similar traits in distantly related organisms such as New Caledonian crows and capuchin monkeys. De Waal opines that continuity “ought to be the default position for at least all mammals, and perhaps also birds and other vertebrates”.

...researchers are eager to understand what is distinctly human; some are driven by curiosity about how humans came to dominate the planet..Our success presumably has something to do with the emergence of a unique suite of cognitive traits...De Waal recognizes only one such trait: our rich and flexible system of symbolic communication, and our ability to exchange information about past and future. His commitment to the principle of continuity forces him to discount the importance of language for human cognition because of evidence of thinking by non-linguistic creatures. And he ignores compelling findings from linguists and developmental psychologists such as Elizabeth Spelke on the formative role of language in cognition.

A more satisfying book would leave readers with a clearer understanding of why, a few million years after our lineage diverged from the lineage of chimpanzees, we are the ones reading this book, and not them.