Ubiquity of same-sex couplings in nature.

A student has pointed out to me an interesting article in Science American Mind on unorthodox sex in the animal kingdom:

As many as 1,500 species of wild and captive animals have been observed engaging in homosexual activity. Speculations seeking an evolutionary rationale are that animals may engage in same-sex couplings to diffuse social tensions, to better protect their young or to maintain fecundity when opposite-sex partners are unavailable—or simply because it is fun. Bisexuality is a natural state among animals, perhaps Homo sapiens included, despite the sexual-orientation boundaries most people take for granted. In humans the categories of gay and straight are socially constructed.

...homosexuality among some species, including penguins, appears to be far more common in captivity than in the wild. Captivity, scientists say, may bring out gay behaviors in part because of a scarcity of opposite-sex mates. In addition, an enclosed environment boosts an animal’s stress levels, leading to a greater urge to relieve the stress. Some of the same influences may encourage what some researchers call “situational homosexuality” in humans in same-sex settings such as prisons or sports teams.

Driscoll's article continues to describe a number of studies of same-sex partners in wild and captive animals.

Discontinuity between human and nonhuman minds?

In a recent issue of Brain and Behavioral Science (BBS) Penn, Holyoak and Povinelli argue for a profound difference in kind, not degree, between human and animal minds. Their suggestions elicit mainly vigorous opposition as well as some support from an array of commentators. Several of the commentators point out evidence for flexible relational capabilities within a physical symbol system exhibited by dolphins and birds. As I read through the debate and its mind-numbing detail I give up on trying to convey a succinct summary, but here is their abstract. (You might compare this with the work of Hauser et al, that I mentioned in a previous post.):

Over the last quarter century, the dominant tendency in comparative cognitive psychology has been to emphasize the similarities between human and nonhuman minds and to downplay the differences as “one of degree and not of kind” (Darwin 1871). In the present target article, we argue that Darwin was mistaken: the profound biological continuity between human and nonhuman animals masks an equally profound discontinuity between human and nonhuman minds. To wit, there is a significant discontinuity in the degree to which human and nonhuman animals are able to approximate the higher-order, systematic, relational capabilities of a physical symbol system (PSS) (Newell 1980). We show that this symbolic-relational discontinuity pervades nearly every domain of cognition and runs much deeper than even the spectacular scaffolding provided by language or culture alone can explain. We propose a representational-level specification as to where human and nonhuman animals' abilities to approximate a PSS are similar and where they differ. We conclude by suggesting that recent symbolic-connectionist models of cognition shed new light on the mechanisms that underlie the gap between human and nonhuman minds.

Can 'emergence' put spirituality back into nature?

The anti-reductionist view of emergence undergoes cycles of popularity as a philosophical topic. Valerie Hardcastle gives a rather critical review (in Jour. Consciousness Studies, Vol. 14, No. 11, pp.119-122) of a recent collection "The Re-Emergence of Emergence - The Emergentist Hypothesis from Science to Religion" edited by Clayton and Davies (Oxford Univ. Press, 2006). This emergentism is 'feel good' stuff. I think most of us get a bit frightened and a bit dried and shriveled up at the implications of strong reductionism in which all the explanatory arrows point down. Reversing the reductionist’s causal arrow with a comprehensive theory of emergence and self-organization that breaks no laws of physics and yet cannot be explained by them is a laudable project, but as Hardcastle wryly notes, one that continues to fail the "where's the beef" test.

Michael Shermer offers a very appealing gloss in his "Skeptic" column in the Scientific American, with the title: Sacred Science - Can emergence break the spell of reductionism and put spirituality back into nature? He specifically reviews a new book by Stuart Kauffman, Reinventing the Sacred (Basic Books, 2008). Denis Noble also reviews Kauffman's book in Science Magazine. Here are some clips from Shermer's column:
Kaufman:

...reverses the reductionist’s causal arrow with a comprehensive theory of emergence and self-organization that Kaufman says “breaks no laws of physics” and yet cannot be explained by them. God “is our chosen name for the ceaseless creativity in the natural universe, biosphere and human cultures.” In Kauffman’s emergent universe, reductionism is not wrong so much as incomplete. It has done much of the heavy lifting in the history of science, but reductionism cannot explain a host of as yet unsolved mysteries, such as the origin of life, the biosphere, consciousness, evolution, ethics and economics... How would a reductionist explain the biosphere, for example? “One approach would be, following Newton, to write down the equations for the evolution of the biosphere and solve them. This cannot be done,” Kauffman avers. “We cannot say ahead of time what novel functionalities will arise in the biosphere. Thus we do not know what variables—lungs, wings, etc.—to put into our equations. The Newtonian scientific framework where we can prestate the variables, the laws among the variables, and the initial and boundary conditions, and then compute the forward behavior of the system, cannot help us predict future states of the biosphere.”... This problem is not merely an epistemological matter of computing power, Kauffman cautions; it is an ontological problem of different causes at different levels. Something wholly new emerges at these higher levels of complexity.

Similar ontological differences exist in the self-organized emergence of consciousness, morality and the economy...economics and evolution are complex adaptive systems that learn and grow as they evolve from simple to complex...they are autocatalytic, containing self-driving feedback loops...such phenomena “cannot be deduced from physics, have causal powers of their own, and therefore are emergent real entities in the universe.” This creative process of emergence, Kauffman contends, “is so stunning, so overwhelming, so worthy of awe, gratitude and respect, that it is God enough for many of us. God, a fully natural God, is the very creativity in the universe.”

Shermer ends noting that Kaufman's:

God 2.0 is a deity worthy of worship. But I am skeptical that it will displace God 1.0, Yahweh, whose Bronze Age program has been running for 6,000 years on the software of our brains and culture.

Increasing complexity of nerve synapses during evolution

Nicholas Wade points to the work of Grant and colleagues on how the complexity of nerve interconnections (synapses) has increased during evolution as the variety of their protein components has increased from a few to several hundred. Vertebrate synapses have about 1,000 different proteins, assembled into 13 molecular machines, one of which is built from 183 different proteins. The human brain has about 100 billion neurons, interconnected at 100 trillion synapses. Grant provides an analogy:

If the synapses are thought of as the chips in a computer, then brainpower is shaped by the sophistication of each chip, as well as by their numbers...From the evolutionary perspective, the big brains of vertebrates not only have more synapses and neurons, but each of these synapses is more powerful — vertebrates have big Internets with big computers and invertebrates have small Internets with small computers.

The top part of the figure (click to enlarge) shows the phylogenetic relationships of the species studied. The number of varieties of two signaling complexes, NMDA receptor (NRC or MASC) / postsynaptic density (PSD) are in parentheses. The lower half shows the occurrences of PSD and MASC homologs found in each of the 19 species as a percentage of those found in human.

Evolutionary Psychology as Maladapted Psychology

Bolhuis reviews a book with the title of this post by philosopher Robert Richardson. (I have read a longer excellent book, "Adapting Minds", by philosopher David Buller. Here are some clips from the review:

Evolutionary psychology aims to apply evolutionary theory to the human mind. Specifically, it proposes that the mind consists of cognitive modules that evolved in response to selection pressures faced by our Stone Age ancestors. The approach has a wide popular appeal, perhaps because it often addresses such exciting topics as human desire, sex, and passion....Richardson readily acknowledges that our psychological capacities are evolved traits subject to natural selection. But at the same time, he maintains that there is very little we can find out about the evolution of the mind and that the evolutionary psychology interpretation is wrong from the perspective of evolutionary biology...he criticizes mainly the methods used by evolutionary psychologists, weighing the approach's theoretical framework using criteria from evolutionary biology...The main problem with evolutionary psychology is that it usually does not consider alternative explanations but takes the assumption of adaptation through natural selection as given.

Richardson rightly suggests that paleontologists are unlikely to unearth the evidence that can inform us about the social structure of our ancestral communities. I think one can go a step further. Even if we would be able to muster the evidence needed for an evolutionary psychological analysis of human cognition, it would not tell us anything about our cognitive mechanisms. The study of evolution is concerned with a historical reconstruction of traits. It does not, and cannot, address the mechanisms that are involved in the human brain. Those fall within the domains of neuroscience and cognitive psychology. In that sense, evolutionary psychology will never succeed, because it attempts to explain mechanisms by appealing to the history of these mechanisms. To use the author's words, "We might as well explain the structure of orchids in terms of their beauty." In this excellent book, Richardson shows very clearly that attempts at reconstruction of our cognitive history amount to little more than "speculation disguised as results." The book's title implies that the field is itself subject to selection pressure. Richardson is certainly piling it on.

Only a theory!

Rodent trained to be Las Vegas croupier

Atshushi Iriki's group in Tokyo has trained degus (intelligent rodents native to the highlands of Chile) to provide the first example (published in PLOS ONE) of rodents wielding tools for a task. (see my 5/7/2007 post for an example with Ravens. Monkeys and Chimps also use tools - Hihara et al. have found extension of corticocortical afferents into the anterior bank of the intraparietal sulcus after tool-use training in adult monkeys.) It will be interesting to see whether tool-use training in degus also results in extended representations in parietotemporal areas and newly formed connections between brain areas, including the prefrontal cortex, similar to those observed in the macaque brain. Work of this sort begins to define brain structures used in the development of tool use.

Our innate number sense.

Jim Holt has written an excellent article in the New Yorker focusing on the work of Stanislas Dehaene, who argues that humans (and higher animals) have an inbuilt “number sense” capable of some basic calculations and estimates. Evidence from cognitive deficits in brain-damaged patients has shown that we have a sense of number that is independent of language, memory, and reasoning in general.
When we see numerals or hear number words, our brains appear to automatically map them onto a number line that grows increasingly fuzzy above 3 or 4. A few chunks from Holt's article:

... it is generally agreed that infants come equipped with a rudimentary ability to perceive and represent number. (The same appears to be true for many kinds of animals, including salamanders, pigeons, raccoons, dolphins, parrots, and monkeys.) And if evolution has equipped us with one way of representing number, embodied in the primitive number sense, culture furnishes two more: numerals and number words. These three modes of thinking about number, Dehaene believes, correspond to distinct areas of the brain. The number sense is lodged in the parietal lobe, the part of the brain that relates to space and location; numerals are dealt with by the visual areas; and number words are processed by the language areas.

Dehaene has been able to bring together the experimental and the theoretical sides of his quest, and, on at least one occasion, he has even theorized the existence of a neurological feature whose presence was later confirmed by other researchers. In the early nineteen-nineties, working with Jean-Pierre Changeux, he set out to create a computer model to simulate the way humans and some animals estimate at a glance the number of objects in their environment. In the case of very small numbers, this estimate can be made with almost perfect accuracy, an ability known as “subitizing” (from the Latin word subitus, meaning “sudden”). Some psychologists think that subitizing is merely rapid, unconscious counting, but others, Dehaene included, believe that our minds perceive up to three or four objects all at once, without having to mentally “spotlight” them one by one. Getting the computer model to subitize the way humans and animals did was possible, he found, only if he built in “number neurons” tuned to fire with maximum intensity in response to a specific number of objects. His model had, for example, a special four neuron that got particularly excited when the computer was presented with four objects. The model’s number neurons were pure theory, but almost a decade later two teams of researchers discovered what seemed to be the real item, in the brains of macaque monkeys that had been trained to do number tasks. The number neurons fired precisely the way Dehaene’s model predicted—a vindication of theoretical psychology. “Basically, we can derive the behavioral properties of these neurons from first principles,” he told me. “Psychology has become a little more like physics.”

Moral Neuropolitics

Gary Olson, who is Chair of the Dept. of Political Science of Maravian College in Bethlehm, PA., sent me a latest draft of his article "From Mirror Neuron to Moral Neuropolitics." It does a nice job with the literature on mirror neurons and its implications, as well as political and cultural factors that enhance and inhibit moral behaviors. Gary is willing to pass on the draft article to blog readers for further comment (web version here; PDF download here).

My main comment was that the article might - in addition to covering cultural and political factors that work against moral behaviors between groups of distant people - add more data from evolutionary and developmental biology studies that also offer some evidence for factors working against morality and compassion. There is evidence for xenophobia and aggression between groups of animals (intra-group morality and cooperation, but also inter-group aggression and warfare), well documented in Chimps (cf. Feb. 19 Killer Instincts post), and other social animals (cf. March 8 post on Hyenas). Also, experiments show that that groups of children spontaneously invent not only language, but also in-groups and out-groups (cf. July 31 post) that can become competitive.

A voice region in the monkey brain

Both human and monkey brains have visual regions that are activated most strongly by the faces of conspecifics. Our brains also have have a region that is specialized for processing human voices that is located anteriorly on the temporal lobe, on the upper bank of the superior-temporal sulcus. Logothetis and his colleagues have now found a corresponding region in monkey brains. Their abstract and a portion of one of the figures:

For vocal animals, recognizing species-specific vocalizations is important for survival and social interactions. In humans, a voice region has been identified that is sensitive to human voices and vocalizations. As this region also strongly responds to speech, it is unclear whether it is tightly associated with linguistic processing and is thus unique to humans. Using functional magnetic resonance imaging of macaque monkeys (Old World primates, Macaca mulatta) we discovered a high-level auditory region that prefers species-specific vocalizations over other vocalizations and sounds. This region not only showed sensitivity to the 'voice' of the species, but also to the vocal identify of conspecific individuals. The monkey voice region is located on the superior-temporal plane and belongs to an anterior auditory 'what' pathway. These results establish functional relationships with the human voice region and support the notion that, for different primate species, the anterior temporal regions of the brain are adapted for recognizing communication signals from conspecifics.

Figure - The color code from orange to red indicates voxels with a clear and significant preference for macaque vocalizations. The cyan-to-blue color code identifies voxels with no preference for MVocs. The slice orientation and position are shown in the lower inset

The social brains of Hyenas

There is a correlation between brain size, particularly the newer frontal lobes, and the size of the social group an animal lives in. This rule works for our primate lineage and, it turns out, also for hyenas: those with the simplest social systems have the tiniest frontal cortices. The spotted hyena, which lives in the most complex societies, has far and away the largest frontal cortex. The brown and striped hyenas, with intermediate social systems, have intermediate brains. It appears that primates are not unique in the complexity of their social lives. An article by Zimmer describes the work of Holekamp and colleagues, who have found an array of complex social behaviors in spotted hyenas that are as complex as those of baboons. The groups are comprised of 60 to 80 individuals who all know each other individually. There are alliances, rivalries, and social hierarchies headed by an alpha female. Cubs undergo an education period. Hyena clans patrol their territory borders together against neighboring clans, kills near these borders can provoke clan conflicts. These behaviors are accomplished by brains with frontal lobes that are as easily distinguished as those of social primates (see figure.)

Need something to worry about? Climate tipping points...

This graphic is from an open access article in PNAS by Lenton et al. on tipping elements in the earth's climate system. You probably need to click on the graphic to make it larger; the color indicating the population densities is hard to see. In the same issue of PNAS, there is an article on how when it get warm (as in the Paleocene – Eocene Thermal Maximum caused by a carbon dioxide increase about 55 million years ago), the insects chow down on the plants.

Legend for graphic - Map of potential policy-relevant tipping elements in the climate system, overlain on global population density. Subsystems indicated could exhibit threshold-type behavior in response to anthropogenic climate forcing, where a small perturbation at a critical point qualitatively alters the future fate of the system. They could be triggered this century and would undergo a qualitative change within this millennium. We exclude from the map systems in which any threshold appears inaccessible this century (e.g., East Antarctic Ice Sheet) or the qualitative change would appear beyond this millennium (e.g., marine methane hydrates). Question marks indicate systems whose status as tipping elements is particularly uncertain.

Why men are at the top.

Helena Cronin presents an interesting idea about why men walk off with most of the top positions and prizes that sidesteps the usual assumption of average differences between men and women in innate talents, tastes and temperaments. She notes that there not only more Nobels, but also more dumbbells among men, and suggests that it is a fourth "T" that most decisively shapes the distinctive structure of male — female differences. Some clips from her essay:

That T is Tails — the tails of these statistical distributions. Females are much of a muchness, clustering round the mean. But, among males, the variance — the difference between the most and the least, the best and the worst — can be vast. So males are almost bound to be over-represented both at the bottom and at the top...Consider the mathematics sections in the USA's National Academy of Sciences: 95% male. Which contributes most to this predominance — higher means or larger variance? One calculation yields the following answer. If the sex difference between the means was obliterated but the variance was left intact, male membership would drop modestly to 91%. But if the means were left intact but the difference in the variance was obliterated, male membership would plummet to 64%. The overwhelming male predominance stems largely from greater variance...Similarly, consider the most intellectually gifted of the USA population, an elite 1%. The difference between their bottom and top quartiles is so wide that it encompasses one-third of the entire ability range in the American population, from IQs above 137 to IQs beyond 200. And who's overwhelmingly in the top quartile? Males. Look, for instance, at the boy:girl ratios among adolescents for scores in mathematical-reasoning tests: scores of at least 500, 2:1; scores of at least 600, 4:1; scores of at least 700, 13.1.

The legacy of natural selection is twofold: mean differences in the 3 Ts and males generally being more variable; these two features hold for most sex differences in our species and, as Darwin noted, greater male variance is ubiquitous across the entire animal kingdom...The upshot? When we're dealing with evolved sex differences, we should expect that the further out we go along the right curve, the more we will find men predominating. So there we are: whether or not there are more male dumbbells, there will certainly be — both figuratively and actually — more male Nobels.

Unfortunately, however, this is not the prevailing perspective in current debates, particularly where policy is concerned. On the contrary, discussions standardly zoom in on the means and blithely ignore the tails. So sex differences are judged to be small. And thus it seems that there's a gaping discrepancy: if women are as good on average as men, why are men overwhelmingly at the top? The answer must be systematic unfairness — bias and barriers. Therefore, so the argument runs, it is to bias and barriers that policy should be directed. And so the results of straightforward facts of statistical distribution get treated as political problems

Creationists launch 'science' journal

Oh my gawd........ a new Creationist 'scientific' journal. This from the Jan. 23 online Nature News:

Papers will be peer reviewed by those who “support the positions taken by the journal”, according to editor-in-chief Andrew Snelling, a geologist based in Brisbane, Australia.

The Answers Research Journal makes life simple. You start with the result you want, and work from there. Much more efficient than conventional science.

Newborn humans: predisposition for biological motion

This work demonstrates that when we are born, we have an innate bias towards attending to motions characteristic of other living things. Newborn chickens do this also. The abstract, a figure, and a video from Simion et al. :

An inborn predisposition to attend to biological motion has long been theorized, but had so far been demonstrated only in one animal species (the domestic chicken). In particular, no preference for biological motion was reported for human infants of less than 3 months of age. We tested 2-day-old babies' discrimination after familiarization and their spontaneous preferences for biological vs. nonbiological point-light animations. Newborns were shown to be able to discriminate between two different patterns of motion (Exp. 1) and, when first exposed to them, selectively preferred to look at the biological motion display (Exp. 2). This preference was also orientation-dependent: newborns looked longer at upright displays than upside-down displays (Exp. 3). These data support the hypothesis that detection of biological motion is an intrinsic capacity of the visual system, which is presumably part of an evolutionarily ancient and nonspecies-specific system predisposing animals to preferentially attend to other animals.

Figure: Three sample frames taken from the animation sequences used in the study: the biological motion stimulus (i.e., the walking hen) (Top), the nonbiological motion stimulus (random motion) (Middle), and the inverted biological motion display (upside-down walking hen) (Bottom). Squares indicate the point-lights.

Coevolution of choosiness and cooperation

An interesting modeling article by McNamara et al. suggests a novel evolutionary mechanism based on a positive coevolutionary feedback between cooperativeness and choosiness. If individuals vary in their degree of cooperativeness, and if they can decide whether or not to continue interacting with each other on the basis of their respective levels of cooperativeness, then cooperation can gradually evolve from an uncooperative state. When an individual's cooperativeness is used by other individuals as a choice criterion, there can be competition to be more generous than others (competetive altruism). The evolution of cooperation between non-relatives can then be driven by a positive feedback between increasing levels of cooperativeness and choosiness. In this model, individual behavioural differences are the key to the evolution of cooperation. Because the model does not invoke complex mechanisms such as negotiation behaviour, it can be applied to a wide range of species.

The model calculations use an infinite population where, in each of a discrete series of time steps (rounds), pairs of individuals engage in a game that can be described as a social dilemma. Each individual is characterized by two traits: a cooperativeness trait x, which specifies the amount of effort that the individual devotes to generating benefits available (at least in part) to its co-player; and a choosiness trait y, which specifies the minimum degree of cooperativeness that the focal individual is prepared to accept from its co-player. The traits x and y are genetically determined and are not adjusted in response to the co-player's behaviour. Thus, unlike in many models in which flexible effort adjustment is a key ingredient1, individuals in their model are consistent in their degree of cooperativeness.

Planned Obsolescence? The Four-Year Itch

Helen Fisher, author of "Why We Love" and an anthropology professor at Rutgers, has written a brief essay with the title of this post. She did a cross cultural survey of when divorces occur and found that divorces regularly peaked during and around the fourth year after wedding (no evidence for the commonly assumed seven year itch indicated in the graphic). Divorces peaked among couples in their late twenties. And the more children a couple had, the less likely they were to divorce: some 39% of worldwide divorces occurred among couples with no dependent children; 26% occurred among those with one child; 19% occurred among couples with two children; and 7% of divorces occurred among couples with three young. In trying to figure out so many men and women divorce during and around the 4-year mark; at the height of their reproductive years; and often with a single child, she had an "a ha" moment:

Women in hunting and gathering societies breastfeed around the clock, eat a low-fat diet and get a lot of exercise — habits that tend to inhibit ovulation. As a result, they regularly space their children about four years apart. Thus, the modern duration of many marriages—about four years—conforms to the traditional period of human birth spacing, four years.

Perhaps human parental bonds originally evolved to last only long enough to raise a single child through infancy, about four years, unless a second infant was conceived. By age five, a youngster could be reared by mother and a host of relatives. Equally important, both parents could choose a new partner and bear more varied young.

Her theory fits with data on other species:

Only about three percent of mammals form a pairbond to rear their young. Take foxes. The vixen's milk is low in fat and protein; she must feed her kits constantly; and she will starve unless the dog fox brings her food. So foxes pair in February and rear their young together. But when the kits leave the den in mid summer, the pairbond breaks up. Among foxes, the partnership lasts only through the breeding season. This pattern is common in birds. Among the more than 8,000 avian species, some 90% form a pairbond to rear their young. But most do not pair for life. A male and female robin, for example, form a bond in the early spring and rear one or more broods together. But when the last of the fledgling fly away, the pairbond breaks up... Like pair-bonding in many other creatures, humans have probably inherited a tendency to love and love again—to create more genetic variety in our young.

Monkeys and college students: similar in non-verbal math

This work from Cantlon and Brannon suggests that humans and nonhuman primates share a cognitive system for nonverbal arithmetic, suggesting an evolutionary link in their cognitive abilities., full text in PLoS Biology, here is the abstract:

Adult humans possess mathematical abilities that are unmatched by any other member of the animal kingdom. Yet, there is increasing evidence that the ability to enumerate sets of objects nonverbally is a capacity that humans share with other animal species. That is, like humans, nonhuman animals possess the ability to estimate and compare numerical values nonverbally. We asked whether humans and nonhuman animals also share a capacity for nonverbal arithmetic. We tested monkeys and college students on a nonverbal arithmetic task in which they had to add the numerical values of two sets of dots together and choose a stimulus from two options that reflected the arithmetic sum of the two sets. Our results indicate that monkeys perform approximate mental addition in a manner that is remarkably similar to the performance of the college students. These findings support the argument that humans and nonhuman primates share a cognitive system for nonverbal arithmetic, which likely reflects an evolutionary link in their cognitive abilities.

Monkeys judge inequity like humans

DeWaal and collaborators expand on previous observations to show that capuchin monkeys get really pissed off if they worked harder for a reward than another monkey, and then see that monkey get a greater reward! This suggests that our human resentment of inequity in rewards my have a very ancient origin in primate behavior. Here is their abstract:

Without joint benefits, joint actions could never have evolved. Cooperative animals need to monitor closely how large a share they receive relative to their investment toward collective goals. This work documents the sensitivity to reward division in brown, or tufted, capuchin monkeys (Cebus apella). In addition to confirming previous results with a larger subject pool, this work rules out several alternative explanations and adds data on effort sensitivity. Thirteen adult monkeys exchanged tokens for rewards, showing negative reactions to receiving a less-favored reward than their partner. Because their negative reaction could not be attributed to the mere visibility of better rewards (greed hypothesis) nor to having received such rewards in the immediate past (frustration hypothesis), it must have been caused by seeing their partner obtain the better reward. Effort had a major effect in that by far the lowest level of performance in the entire study occurred in subjects required to expend a large effort while at the same time seeing their partner receive a better reward. It is unclear whether this effort–effect was based on comparisons with the partner, but it added significantly to the intensity of the inequity response. These effects are as expected if the inequity response evolved in the context of cooperative survival strategies.

Kewl Bio-inspired Robotics...

The Nov. 16 issue of Science has a special section on Robotics. I thought this graphic from the article by Pfeifer et al. - "Self-Organization, Embodiment, and Biologically Inspired Robotics" - was fascinating. It describes several biologically inspired robots.


Figure: Self-organization, dynamics, and materials in bio-inspired robotics. (A) Smooth transition between swimming and walking. This amphibious salamanderlike robot (~80 cm long) embeds a spinal cord model that explains the ability of salamanders to switch between swimming and walking. The locomotion model is built by extending a primitive neural circuit for swimming by phylogenetically more recent limb oscillatory centers. (B) Rich sensory stimulation through proper sensor morphology. This robot (~7 cm in diameter) owes its sophisticated sensory capacities to the specific arrangement, shape, and material characteristics of its whiskers. Natural whiskers from rodents (such as the ones used on this robot) are far superior to whiskers built from other materials in terms of richness of the signals relayed to the neural system. (C) Self-stabilizing rapid hexapod locomotion. This robot (~15 cm long) moves with a bouncing gait, achieving rapid (over 4 body lengths per second) locomotion. Its legs are built with compliant pneumatic actuators, which yield self-stabilization through mechanical feedback. (D) Passive dynamics–based walking. Designed to work on a slope as a dynamic walker, this robot (~45 cm tall) exploits dynamics and morphology (in particular, the shape and length of the body and feet) to achieve stable walking. The robot's natural dynamics serves as the target dynamics for a reinforcement learning mechanism, enabling the robot to quickly learn to walk on flat ground. (E) Self-stabilizing vertical takeoff through materials and morphology. Inspired by flies, this ultralight (60 mg, 3-cm wingspan) ornithopter (a device that flies by flapping its wings) generates sufficient lift to take off vertically (power is supplied externally). A large part of the control is delegated to the morphological and material properties of the robot. Compliant structures are driven into resonance to produce a large wing stroke, and flexible material is used in the wing hinges to allow for passive rotations of the wings. (F) Agile wall-climbing through materials. The bio-inspiration for this palm-sized robot is provided by the gecko and its uncanny climbing talents. The robot's tri-foot (three-footed wheel) is equipped with a polymer dry adhesive material, which to some extent has contact properties comparable to those of its biological analog. The robot can flexibly navigate on smooth vertical and even inverted surfaces. (G) Morphing through localized self-reconfiguration. This self-reconfigurable robot is composed of active (actuated, black) and passive (nonactuated, white) cubic modules (~400 g, ~60 to 65 mm side length). The modules connect to each other through hooks, which enables the robot to change its morphology in a large number of ways. The picture shows the metamorphosis from a four-legged (quadruped) structure to a linear (snakelike) structure. (H) Global movement through local interaction dynamics. The individual wheel-like modules (~10 cm in diameter) constituting this robot are equipped with spokelike parts driven by linear actuators. The wheels lie horizontally on the ground and attach to neighboring modules by Velcro. Although no module can move on its own, by using neural oscillators as drivers for the actuators and through the physical coupling between the units, a coordinated global wave of activation can be induced in clusters of more than 30 modules, which leads to forward movement, even though there is no global control.