Beyond the sleep-amyloid interactions in Alzheimer's disease pathogenesis
Shen Ning, Mehdi Jorfi
Alzheimer's research has largely focused on the presence of two proteins -- amyloid beta and tau -- in the brain. Amyloid beta is thought to be involved with learning and the ability of the brain to change and adapt, and tau helps regulate normal signaling between neuronal cells. People with Alzheimer's disease have been found to have both hallmarks: a buildup of amyloid beta and tau tangles in the brain.
Previous studies in healthy animals and humans have reported higher levels of amyloid beta after a single night of sleep deprivation. This is consistent with normal fluctuation patterns of the protein that occur before sleeping and upon waking. These findings suggest that sleep helps the body eliminate excess amyloid beta before too much accumulates in the brain. Research has also shown that disruption of slow-wave sleep -- a deep sleep phase -- causes amyloid beta levels to rise as much as 30 percent. "This evidence demonstrates the significance of sleep in clearing metabolic waste and sleep disruption as a significant mediator in the development of [Alzheimer's disease]," Shen Ning and Mehdi Jorfi, PhD, the authors of the article, wrote.
The presence of tau -- the protein that is found tangled in the brain of people with Alzheimer's disease -- in the fluid that surrounds the brain and spinal cord (cerebrospinal fluid) is a marker of injury to the nerve cells, the authors explained. Sleep deprivation for as little as one night has been found to increase tau levels by as much as 50 percent in cerebrospinal fluid.
The research suggests that increased production of amyloid beta and tau and reduced elimination of these proteins is the primary contributing factor to Alzheimer's disease. While quality sleep seems to be able to help the body clear excess proteins, "the question remains whether sleep disruption aggravates [Alzheimer's disease] symptoms and augments disease progression, or if sleep disruption actually initiates the cascade of [Alzheimer's disease] development," the researchers wrote.
Continuing study of the relationship between sleep and Alzheimer's disease "holds great promise in bridging the molecular and cellular biology of sleep in context of the development of [Alzheimer's disease]. It may even provide helpful therapeutic benefits in preventing not only [Alzheimer's disease], but also in improving diagnosis and treatments for psychiatric and metabolic diseases," the researchers wrote.
Cognitive impairment in older adults is associated with sleep and circadian rhythm disturbances. Numerous studies have linked disrupted sleep and circadian rhythms with amyloid-β (A&β), a key pathological hallmark in Alzheimer's disease (AD). While previous evidence suggests that Aβ initiates AD pathogenesis, tau, another major hallmark of AD, seems to drive neurodegeneration. Recent studies imply that sleep-wake cycles affect brain tau more significantly than Aβ levels, leading to accelerated AD progression and cognitive decline. The study of sleep disturbances in AD is shedding light on our understanding of the mechanism underlying sleep disturbances in AD and dementia.
Social genes are selection hotspots in kin groups of a soil microbe
Sébastien Wielgoss
The microbe Myxococcus xanthus is particularly cooperative. Found in soils all over the world, it has been used by scientists as a model organism to study microbial development and cooperation. The cells of this predatory bacterium form cooperative groups that swarm together and hunt other microorganisms within the soil. In order to move as a group, they secrete lubricating substances and cast out appendages that attach to the surrounding surface and other cells, moving them forward as they retract these appendages. When food becomes scarce, thousands of these bacteria aggregate into a fruiting body and form resting spores, allowing them to withstand hunger and drought.
Closely related, yet very different
Researchers previously had theoretical reasons to expect that cooperative groups of microbes in nature might generally be socially homogeneous, as this would prevent conflict between cells from undermining cooperation. Genetically distinct individuals from different groups have been shown to often avoid, obstruct, and even combat each other. "Our knowledge about the genetic composition within cooperative groups of these social bacteria in nature used to be very limited," says Sébastien Wielgoss, a lecturer in the research group of Professor Gregory Velicer, Institute for Integrative Biology, ETH Zurich.
With their colleagues, Wielgoss and Velicer have more closely examined the genetic relationships between members of the same M. xanthus fruiting body group in the soil. They used one of the largest collections of M. xanthus strains worldwide, kept by Velicer in his laboratory freezers.
In a study recently published in Science, the researchers used genetic analyses to show that while cooperative groups of the soil bacterium M. xanthus do consist of closely related cells, the number of genetic types and varieties of social behaviour found within individual fruiting-body groups are unexpectedly high. The researchers inferred that these collections of diversified cell lines can remain intact for hundreds of generations.
Selection on social genes
For their study, the researchers investigated groups of cells that descended recently from a common ancestor. Mutation formed various socially different, but closely related, cell lines within these groups, with lines differing in how fast they swarm or how many spores they produce within a fruiting body.
Some forms of diversity pose a threat to group productivity. For example, individual bacteria can exhibit "cheating" behaviour: they contribute little to the group while exploiting its other members and lowering group function. "However, behavioural studies with these same groups have not found such socially disruptive cheating," Wielgoss said. In contrast, while the majority of groups are highly genetically and socially diverse, the observed diversity does not appear to undermine cooperative functions at the group level.
The researchers attribute this high diversity of behavioural patterns to evolutionary selection that focuses on a small number of "social" genes that control the social habits of the bacteria. Mutations in these "selection hotspots" favoured by natural selection cause a variety of behavioural changes, yielding a diverse society of cells with varying levels of spore production and swarming speed. The researchers speculate that distinct lines in the same group likely also differ in their cooperative hunting abilities, although this was not tested in this study.
Wielgoss explained that natural selection may favour some combinations of diversified cell lines over other combinations or even over homogeneous groups: "Cell groups with a large behavioural repertoire may respond to environmental changes more effectively. They may often be more evolutionarily successful than homogeneous groups of cells that all behave in the same way. 'Cultural diversity' appears to be rather frequent among bacterial social groups."
Understanding cell cooperation
Microorganisms are omnipresent. They fulfil important functions in our everyday lives: as helpers in our intestinal flora, as pathogens or as agents in food production. Many combine into cooperative groups of cells in nature, too. The researchers believe that these new insights into the genetic and behavioural properties of cooperative soil bacteria may help us to understand cooperation within other types of bacteria as well, including the important pathogen Pseudomonas aeruginosa that infects immuno-compromised patients and causes serious long-term infections.
The composition of cooperative systems, including animal societies, organismal bodies, and microbial groups, reflects their past and shapes their future evolution. However, genomic diversity within many multiunit systems remains uncharacterized, limiting our ability to understand and compare their evolutionary character. We have analyzed genomic and social-phenotype variation among 120 natural isolates of the cooperative bacterium Myxococcus xanthus derived from six multicellular fruiting bodies. Each fruiting body was composed of multiple lineages radiating from a unique recent ancestor. Genomic evolution was concentrated in selection hotspots associated with evolutionary change in social phenotypes. Synonymous mutations indicated that kin lineages within the same fruiting body often first diverged from a common ancestor more than 100 generations ago. Thus, selection appears to promote endemic diversification of kin lineages that remain together over long histories of local interaction, thereby potentiating social coevolution.
Foliar-feeding insects acquire microbiomes from the soil rather than the host plant
S. Emilia Hannula
Earlier NIOO research had found that belowground and aboveground insects can communicate with each other using plants as a kind of 'green telephone'. Messages can even be left in the soil to be retrieved later, like voicemail. This new research by a team of four ecologists shows that surprisingly, aboveground insects such as caterpillars can retrieve these voicemails from the soil without any mediation from plants.
Emilia Hannula, Feng Zhu, Robin Heinen and Martijn Bezemer conducted experiments that focused on the 'microbiome': a community of micro-organisms that you'll find in almost any place. Lining grains of sand and roots for example, but also on leaves, on teeth and in intestines.
Microbial ecologist Emilia Hannula explains: "the composition of the microbiome in the intestines of the caterpillars we studied was astonishingly similar to that of the soil itself. There was a 75% overlap." That is indeed surprising, as expectations were that the species of bacteria and fungi found in herbivorous insects would be most similar to those on the plant.
First evidence
There's more: the soil the researchers used was from a field experiment in the Veluwe natural area, with various combinations of herbs and grasses. The differences between these plants in growth form and rate also prompted differences in the composition of the soil bacteria and soil fungi, which were still traceable in the insects in the greenhouse experiment.
According to the researchers, it's the first evidence that these legacy effects in the soil can have such a strong impact on the microbiome of insects. Heinen observed that if caterpillars had the option, they would "move actively from the plant to the ground. They regularly spend time on the soil."
Caterpillars that were put on an exclusive diet of cut leaves from the same plant (dandelion) instead, without being able to move to the ground, had a much simpler intestinal flora, which was three times less varied: much more in line with that of the micro-organisms on the leaves.
Self-medicating
This knowledge could be useful not just for explaining certain scientific effects, but also to farmers and growers. "The history of the soil is visible not just in plants but also in insects. So in order to control pests, for example, you'll have to take into account the soil in which you work," says Martijn Bezemer. Healthy and biodiverse soil life can contribute greatly to pest control, and provide food for healthy crops and a species-rich nature."
So do caterpillars really play doctor? The researchers confirm that they may be actively searching the soil for beneficial substances and micro-organisms: "you could think of it as self-medicating." Among the things they observed during their experiments was an abundance of soil bacteria that are known to have a symbiotic relationship with the intestines of insects and even humans.
Some of these produce antibiotics: great against pathogens, which are also present in the soil of course. "It's one of the reasons why we're pursuing this research further."
Extensive Recovery of Embryonic Enhancer and Gene Memory Stored in Hypomethylated Enhancer DNA
Unmesh Jadhav
"We discovered that adult cells maintain a catalog of all of the genes in use early in development -- a record of the stage in which organs and tissues are formed within the embryo," says the senior author of the new study, Ramesh Shivdasani, MD, PhD, of Dana-Farber, Brigham and Women's Hospital, Harvard Medical School, and the Harvard Stem Cell Institute. "Beyond the sheer existence of this archive, we were surprised to find that it doesn't remain permanently locked away but can be accessed by cells under certain conditions. The implications of this discovery for how we think about cells' capabilities, and for the future treatment of degenerative and other diseases, are potentially profound."
The "embryonic memory" discovered by Shivdasani and his colleagues takes the form of molecules called methyl groups that bind to and detach from the DNA within cells. The placement of these methyl groups -- which portion of DNA they bind to, and in what numbers -- determines which genes are active and which are not. The arrangement of methyl groups in a given section of DNA is known as its methylation pattern.
In the new study, researchers focused on the methylation pattern of regions of DNA known as enhancers. Enhancers can be thought of as keys for switching genes on and off. To activate a gene, DNA forms a loop that brings an enhancer close to the coding portion of the gene -- the section that contains the blueprint for making a protein. Then, along with other regions of DNA and specialized proteins, the genetic code embedded in DNA is converted into RNA.
Over the course of embryonic and fetal development, as cells evolve to take on the specific characteristics of the hundreds of types of adult tissues, cells "are constantly making choices about what kind of cell they will become," Shivdasani explains. "This process, known as cell differentiation, involves cells flipping different genes on and off using different enhancers." At each stage of development, particular sets of enhancers become active, much as individual sections of an orchestra play during different portions of a symphony.
By the time a child is fully formed, the set of active enhancers remains largely unchanged for the remainder of life (although the liver, for example, becomes larger as a child grows, its identity as a liver is consistent). For the most part, enhancers that were used early in development but are now idle "look like they've been shut down," Shivdasani says. "They don't seem to have the features of activity."
One of the distinguishing features of enhancers is that certain sections of them -- where the C molecule of the genetic code is followed by the G molecule -- are largely shorn of methyl groups, a state known as hypomethylation. This is true even of enhancers that have been shut down after their role in embryonic development ended. Scientists didn't know, however, how extensively cells preserve this memory of their earliest incarnations, and whether these memories can be accessed.
The results of the new study were illuminating on both counts. In intestinal cells from adult mice, Shivdasani and his colleagues found a nearly complete archive of enhancers that were active in the formative stages of intestinal development. Moreover, they found that in the absence of a protein called Polycomb Repressive Complex 2 (PRC2), most of these mothballed enhancers returned to activity within two weeks' time. (PRC2 is one of the major proteins used by cells to turn off specific genes.)
"We showed that adult cells not only retain a memory of the embryonic and fetal period but also that, under certain circumstances, this memory can be recovered," Shivdasani remarks. "The archive is stored safely and can be recalled with remarkable specificity and accuracy."
At this point, researchers can only speculate about why adult cells preserve these molecular memories. One possibility is that they're simply relics of an earlier stage of cells' lineage -- fossils of their course of development. Another is that cells may need to summon these memories -- to bring them to life, in effect -- in order to generate fresh tissue to repair damage. "If the body needs to regenerate tissue that is damaged, it may be necessary for cells within that tissue to replay what happened in the embryo," Shivdasani states.
The findings may open a new chapter in regenerative medicine, as scientists explore whether cell memory can be harnessed to generate replacement tissue for organs that are damaged or diseased, the study authors say. Since such tissue would be derived from patients' own cells, there would be no risk of rejection by the immune system.
The discovery may also hold promise for cancer treatment. It's thought that one of the ways cancer cells gain the ability to leave the original tumor and metastasize is by switching on genes that were active during fetal development but later became dormant. Knowing that cells keep a record of their once-active enhancers may suggest new targets for therapies aimed at halting or preventing metastasis in patients.
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Hypomethylated DNA preserves nearly complete catalogs of developmental enhancers
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Adult H3K4me1+H3K27ac− enhancers are not poised but remnants of fetal gene activity
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TFs relieved of PRC2 repression selectively reactivate hypomethylated enhancers
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Recommissioned enhancers drive tissue-specific fetal and embryonic gene activity
Summary
Developing and adult tissues use different cis-regulatory elements. Although DNA at some decommissioned embryonic enhancers is hypomethylated in adult cells, it is unknown whether this putative epigenetic memory is complete and recoverable. We find that, in adult mouse cells, hypomethylated CpG dinucleotides preserve a nearly complete archive of tissue-specific developmental enhancers. Sites that carry the active histone mark H3K4me1, and are therefore considered “primed,” are mainly cis elements that act late in organogenesis. In contrast, sites decommissioned early in development retain hypomethylated DNA as a singular property. In adult intestinal and blood cells, sustained absence of polycomb repressive complex 2 indirectly reactivates most—and only—hypomethylated developmental enhancers. Embryonic and fetal transcriptional programs re-emerge as a result, in reverse chronology to cis element inactivation during development. Thus, hypomethylated DNA in adult cells preserves a “fossil record” of tissue-specific developmental enhancers, stably marking decommissioned sites and enabling recovery of this epigenetic memory.
Prenatal Allergen Exposure Perturbs Sexual Differentiation and Programs Lifelong Changes in Adult Social and Sexual Behavior
Kathryn M. Lenz
Female rats born to mothers exposed to an allergen during pregnancy acted more characteristically "male" -- mounting other female rodents, for instance -- and had brains and nervous systems that looked more like those seen in typical male animals.
The male offspring also showed a tendency toward more female characteristics and behaviors, though the changes were not as significant.
"The study shows for the first time that an allergic reaction in a mother could alter the sexual development of its offspring," said Kathryn Lenz, the study's lead author and an assistant professor of psychology at The Ohio State University. The research appears online in the journal Scientific Reports.
"This allergic response is enough to make the female brain look like a male's brain, and that's something that endures throughout its entire life."
Previous research has shown that insults to the immune system, including stress, infection and malnutrition, can change brain development. This new research highlights the important role allergies could play, Lenz said.
She compared the allergic reaction in the study to an asthma attack -- something that prompts a more-robust immune response than low-grade seasonal allergies but less severe than an allergic attack that would require a person to use an EpiPen or go to the emergency department.
Sexual development occurs on a spectrum and, in and of themselves, these shifts in sexual behavior after allergy exposure are not particularly troubling, Lenz said. They do help researchers understand the interplay between allergens and brain development, however, and highlight that early life immune activation could be a source of normal variations in female behavior, which haven't been as well-studied.
And these types of brain changes as a response to an allergen could mean changes in other areas of concern, such as cognitive development.
"It's possible these changes could also contribute to things like impaired decision-making, attention and hyperactivity," she said.
The study builds on Lenz's previous work, which found changes in immune cells called microglia and mast cells in an area of the brain called the preoptic area, a region of the hypothalamus involved in sexual behavior.
"We wanted to see if an allergic exposure that activated these cells would also change typical development," said Lenz.
Mother animals in the study were either exposed once to an allergen derived from eggs or unexposed.
Then, the research team studied their pups into adulthood. Females born to mothers that had an allergic reaction during pregnancy exhibited higher levels of behavior normally attributed to males. They mounted other females more often and were as quick to mount another female as typical male rats. They also were drawn to bedding that smelled like other females.
Furthermore, they had increases in brain cells called mast cells and microglia and evidence of more synapses in the brain -- changes that looked more like what the researchers would expect in a male rat.
Males born to the allergy-exposed mothers behaved less like typical male rats. They had less interest in mounting and less interest in female bedding. The researchers also saw less activation of microglia and fewer synapses -- both of which point to a change in the rats as a result of the allergen exposure that made them more like females, Lenz said.
"Most of the scientific literature on immune activation during pregnancy and outcomes in offspring has focused on autism and schizophrenia. This is the first time we're seeing this kind of connection with altered sexual development," Lenz said.
"Interestingly, there's some research out there to show an increase in gender variance and gender-identity differences in people with autism. It suggests that something about sexual development is different in people with autism."
Lenz said she was especially interested in the profound changes seen in female brain development, because that's an area that hasn't been as well-studied in neuroscience.
"Oftentimes, we are focused on male animals because they appear to be more sensitive to environment changes and also have a higher incidence of conditions such as ADHD and autism. We often frame what we understand about the female brain and female behavior in relation to males. We need to move past that," Lenz said.
"Study of female sexual development has just really been neglected. Even though we know there's wide variety in girls' and women's behavior, we don't really understand what contributes to those variations."
Sexual differentiation is the early life process by which the brain is prepared for male or female typical behaviors, and is directed by sex chromosomes, hormones and early life experiences. We have recently found that innate immune cells residing in the brain, including microglia and mast cells, are more numerous in the male than female rat brain. Neuroimmune cells are also key participants in the sexual differentiation process, specifically organizing the synaptic development of the preoptic area and leading to male-typical sexual behavior in adulthood. Mast cells are known for their roles in allergic responses, thus in this study we sought to determine if exposure to an allergic response of the pregnant female in utero would alter the sexual differentiation of the preoptic area of offspring and resulting sociosexual behavior in later life. Pregnant rats were sensitized to ovalbumin (OVA), bred, and challenged intranasally with OVA on gestational day 15, which produced robust allergic inflammation, as measured by elevated immunoglobulin E. Offspring of these challenged mother rats were assessed relative to control rats in the early neonatal period for mast cell and microglia activation within their brains, downstream dendritic spine patterning on POA neurons, or grown to adulthood to assess behavior and dendritic spines. In utero exposure to allergic inflammation increased mast cell and microglia activation in the neonatal brain, and led to masculinization of dendritic spine density in the female POA. In adulthood, OVA-exposed females showed an increase in male-typical mounting behavior relative to control females. In contrast, OVA-exposed males showed evidence of dysmasculinization, including reduced microglia activation, reduced neonatal dendritic spine density, decreased male-typical copulatory behavior, and decreased olfactory preference for female-typical cues. Together these studies show that early life allergic events may contribute to natural variations in both male and female sexual behavior, potentially via underlying effects on brain-resident mast cells.
NILM Dashboard: A Power System Monitor for Electromechanical Equipment Diagnostics
Andre Aboulian
a sensor that simply is attached to the outside of an electrical wire at a single point, without requiring any cutting or splicing of wires. From that single point, it can sense the flow of current in the adjacent wire, and detect the distinctive "signatures" of each motor, pump, or piece of equipment in the circuit by analyzing tiny, unique fluctuations in the voltage and current whenever a device switches on or off. The system can also be used to monitor energy usage, to identify possible efficiency improvements and determine when and where devices are in use or sitting idle.
The technology is especially well-suited for relatively small, contained electrical systems such as those serving a small ship, building, or factory with a limited number of devices to monitor. In a series of tests on a Coast Guard cutter based in Boston, the system provided a dramatic demonstration last year.
About 20 different motors and devices were being tracked by a single dashboard, connected to two different sensors, on the cutter USCGC Spencer. The sensors, which in this case had a hard-wired connection, showed that an anomalous amount of power was being drawn by a component of the ship's main diesel engines called a jacket water heater. At that point, Leeb says, crewmembers were skeptical about the reading but went to check it anyway. The heaters are hidden under protective metal covers, but as soon as the cover was removed from the suspect device, smoke came pouring out, and severe corrosion and broken insulation were clearly revealed.
"The ship is complicated," Leeb says. "It's magnificently run and maintained, but nobody is going to be able to spot everything."
Lt. Col. Nicholas Galanti, engineer officer on the cutter, says "the advance warning from NILM enabled Spencer to procure and replace these heaters during our in-port maintenance period, and deploy with a fully mission-capable jacket water system. Furthermore, NILM detected a serious shock hazard and may have prevented a class Charlie [electrical] fire in our engine room."
The system is designed to be easy to use with little training. The computer dashboard features dials for each device being monitored, with needles that will stay in the green zone when things are normal, but swing into the yellow or red zone when a problem is spotted.
Detecting anomalies before they become serious hazards is the dashboard's primary task, but Leeb points out that it can also perform other useful functions. By constantly monitoring which devices are being used at what times, it could enable energy audits to find devices that were turned on unnecessarily when nobody was using them, or spot less-efficient motors that are drawing more current than their similar counterparts. It could also help ensure that proper maintenance and inspection procedures are being followed, by showing whether or not a device has been activated as scheduled for a given test.
"It's a three-legged stool," Leeb says. The system allows for "energy scorekeeping, activity tracking, and condition-based monitoring." But it's that last capability that could be crucial, "especially for people with mission-critical systems," he says. In addition to the Coast Guard and the Navy, he says, that includes companies such as oil producers or chemical manufacturers, who need to monitor factories and field sites that include flammable and hazardous materials and thus require wide safety margins in their operation.
One important characteristic of the system that is attractive for both military and industrial applications, Leeb says, is that all of its computation and analysis can be done locally, within the system itself, and does not require an internet connection at all, so the system can be physically and electronically isolated and thus highly resistant to any outside tampering or data theft.
Although for testing purposes the team has installed both hard-wired and noncontact versions of the monitoring system -- both types were installed in different parts of the Coast Guard cutter -- the tests have shown that the noncontact version could likely produce sufficient information, making the installation process much simpler. While the anomaly they found on that cutter came from the wired version, Leeb says, "if the noncontact version was installed" in that part of the ship, "we would see almost the same thing."
Nonintrusive load monitoring (NILM) uses electrical measurements taken at a centralized point in a network to monitor many loads downstream. This paper introduces NILM dashboard, a machine intelligence, and graphical platform that uses NILM data for real-time electromechanical system diagnostics. The operation of individual loads is disaggregated using signal processing and presented as time-based load activity and statistical indicators. The software allows multiple NILM devices to be networked together to provide information about loads residing on different electrical branches at the same time. A graphical user interface provides analysis tools for energy scorekeeping, detecting fault conditions, and determining operating state. The NILM dashboard is demonstrated on the power system data from two United States Coast Guard cutters.
The complexity of understanding others as the evolutionary origin of empathy and emotional contagion
Fabrizio Mafessoni, Michael Lachmann
standard theoretical models of the origins of empathy tend to focus on scenarios in which coordination or cooperation are favored.
Mafessoni, and his co-author Michael Lachmann, a theoretical biologist and Professor at the Santa Fe Institute, explored the possibility that the cognitive processes underlying a broad range of empathetic responses -- including emotional contagion, contagious yawning, and pathologies like echopraxia (compulsive repetition of others' movements) and echolalia (compulsive repetition of others' speech) -- could evolve in the absence of kin selection or any other mechanism directly favoring cooperation or coordination.
Mafessoni and Lachmann posited that animals, including humans, can engage in the act of simulating the minds of others. We cannot read other minds -- they are like black boxes to us. But, as Lachmann explains, all agents share almost identical "black boxes" with members of their species, and "they are constantly running simulations of what other minds might be doing." This ongoing as-actor simulation is not necessarily geared toward cooperation: it's just something humans and animals do spontaneously.
An example of this process is represented by mirror neurons: it has been known for some time that the same neurons engaged in planning a hand movement are also used when observing the hand movement of others. Mafessoni and Lachmann wondered what the consequences would be if they were to extend that process of understanding to any social interaction.
When they modeled outcomes rooted in cognitive simulation, they found that actors engaged in as-actor simulation produce a variety of systems typically explained in terms of cooperation or kin-selection. They also found that an observer can occasionally coordinate with an actor even when this outcome is not advantageous. Their model suggests that empathetic systems do not evolve solely because agents are disposed to cooperation and kin-selection. They also evolve because animals simulate others to envision their actions. According to Mafessoni, "the very origin of empathy may lie in the need to understand other individuals."
For Lachmann, their findings "completely change how we think about humans and animals." Their model is grounded in a single, cognitive mechanism that unifies a broad set of phenomena under one explanation. It therefore has theoretical import for a wide range of fields, including cognitive psychology, anthropology, neuroscience, complex systems, and evolutionary biology. Its power stems from both its unifying clarity and its theoretical interest in the limits of cooperation as an explanatory frame.
Contagious yawning, emotional contagion and empathy are characterized by the activation of similar neurophysiological states or responses in an observed individual and an observer. For example, it is hard to keep one’s mouth closed when imagining someone yawning, or not feeling distressed while observing other individuals perceiving pain. The evolutionary origin of these widespread phenomena is unclear, since a direct benefit is not always apparent. We explore a game theoretical model for the evolution of mind-reading strategies, used to predict and respond to others’ behavior. In particular we explore the evolutionary scenarios favoring simulative strategies, which recruit overlapping neural circuits when performing as well as when observing a specific behavior. We show that these mechanisms are advantageous in complex environments, by allowing an observer to use information about its own behavior to interpret that of others. However, without inhibition of the recruited neural circuits, the observer would perform the corresponding downstream action, rather than produce the appropriate social response. We identify evolutionary trade-offs that could hinder this inhibition, leading to emotional contagion as a by-product of mind-reading. The interaction of this model with kinship is complex. We show that empathy likely evolved in a scenario where kin- and other indirect benefits co-opt strategies originally evolved for mind-reading, and that this model explains observed patterns of emotional contagion with kin or group members.
Embodied fortitude: An introduction to the Finnish construct of sisu
Lahti, E.
'Sisu is a Finnish word that goes back hundreds of years and a quality that Finns hold dear but the phenomenon itself is universal,' says Emilia Lahti, a doctoral student at Aalto University and author of the study. 'Taking a close look at the concept reminds us that, as humans, not only are we all vulnerable in the face of adversity but we share unexplored inner strength that can be accessed in adverse times.'
In her study, Lahti analysed more than 1000 responses from Finns and others knowledgeable about sisu on what the concept means -- as well as whether it is inherently a good thing. One of the most prominent aspects apparent in the data: extraordinary perseverance, in other words, an individual's ability to surpass preconceived limitations, either mentally or physically, by accessing stored-up energy reserves.
Lahti also found the concept to be marked in the responses by a consistent courageous approach to taking action against slim odds, in some cases appearing to the respondents almost as a 'magic' source of power that can help pull through tremendous challenges, whether self-selected like an ultra-run or something unexpected like a health struggle.
It is hard to exhaustively describe sisu but, according to the study, it denotes an internal, latent force that moves you forward when you think you have reached your limit. It is almost like a spare tank of gas, Lahti explains; its benefits are thanks to adversity, not in spite of it. Sisu is not always, however, for the better.
'Sisu will help us take the next step -- or the first one -- but the outcome of that action will depend on how we use it. In that sense, sisu can be constructive or it can be destructive.'
It was apparent from the data that too much sisu can result in burnout, exhaustion, disconnection and even create an attitude of mercilessness as the individual imposes his or her own harsh standards on others. It seems that sisu is neither good nor bad, but a tool you must learn to master.
While the public discourse at large glorifies mental strength and perpetuates a 'faster, higher and stronger' mentality, the answers in the data displayed an alternative view. '[Too much sisu leads to] denying the realities of life, as well as the limits of human strength, therefore denying the very core of our humanity in ourselves and others,' one respondent wrote.
As an action researcher, Lahti sees the study results as an opportunity to engage in a broader societal conversation on how we might improve the quality of human life through greater self-understanding that includes the sisu construct.
'Finland is an interesting case,' she says. 'We've again been named world's happiest country and in global terms we have an excellent social welfare system, but at the same time we are a country that, also, struggles with things like suicide, depression and domestic violence.' With global conversations on burnout and the tolls of modern life, understanding the extent and limits of human strength through new cultural contexts, like Finland, can contribute to a roadmap toward a more harmonious way of living.
'We need sisu, but we also need things like benevolence, compassion and honesty with ourselves, Lahti says. 'The study is basically an invitation to talk about balance.'