Chimpanzee civil war after group division sheds light on the biology of warfare

Amazing stuff! Group division and territorial disputes between new subgroups?

Oddly, the research article based on its abstract does not discuss the possibility of territorial disputes between the two subgroups of Chimpanzees.

"Chimpanzee civil war sheds light on the biology of warfare

Chimpanzees, like humans, routinely fight, and sometimes even kill each other. But unlike us, their communities rarely split into two groups and launch a civil war. By observing a chimp community in Uganda for 30 years, the researchers behind a new Science study reveal how friends turned into foes without shortages of food or cultural rifts dividing them.

More than 200 chimps in a densely forested Kibale region called Ngogo lived peacefully between 1995, when researchers first started tracking their movements and behaviors, and 2015. Although they separated into so-called Central and Western groups, the chimps frequently intermingled, with many cross-group matings.

But following the rapid death of five adult males who apparently served as peacekeepers, the Western group turned against the Central one. Over 6 years, males in the Western group killed seven adult males and 17 infants in the Central group. Even though they were larger in number, the Central group males curiously never ganged up to kill any of the Western chimps.

The civil war—only the second one ever documented in wild chimps—both clarifies motivations for human warfare and spotlights how we differ from one of our closest relatives. “You do not need ideology to generate hostilities,”  ... “The motivations for warfare are much more concerned with our biology than people would have believed a long time ago.” ...

“A hostile split among wild chimpanzees is a reminder of the danger that group divisions can present to human societies.” ...

that chimps aren’t as cooperative and prosocial as humans. “Instead of attacking our neighbors, we go out of [our] way to help them, even if they are complete strangers,” ..."

From the editor's summary and abstract:

"Editor’s summary

Group conflict among nonhuman animals from mongooses to monkeys is well known. However, lethal conflict among groups of animals that were once socially affiliated has not previously been observed outside of humans, in whom cultural ideologies can drive divisions among individuals within the same group. Sandel et al. now describe the gradual dissipation of a group of Ngogo chimpanzees over many years, ending with two socially isolated groups, one of which conducted multiple lethal raids upon the other, leading to the death of both adults and infants ... The unrelated deaths of key interconnected individuals may have contributed to the eventually violent split. ...

Abstract

Territorial conflicts in animals can inform aspects of human warfare, but civil war, with its shifting group identities, has not been previously observed. We report a rare, permanent fission in the largest-known group of wild chimpanzees (Pan troglodytes). 

Using 30 years of behavioral observations and network analyses, we describe a transition from cohesion to polarization in 2015 and the emergence of two distinct groups by 2018.

Over the next 7 years, members of one group made 24 attacks, killing at least seven mature males and 17 infants in the other group. These findings indicate that group identities can shift and escalate into lethal hostility in one of our closest living relatives in the absence of the cultural markers often thought necessary for human warfare."

ScienceAdviser

Civil war among wild chimpanzees (Perspective, open access) "A violent split in a group of chimpanzees highlights the evolutionary roots of war and peace"

Lethal conflict after group fission in wild chimpanzees (open access)

Fig. 1. Network and spatial separation precede a shift from association to violence.

Fig. 4. Territorial patrols between Western and Central chimpanzees.

In 2016, chimpanzees that would become members of the Western group (orange) began engaging in territorial patrols toward chimpanzees that would become members of the Central group (blue). In 2017, we observed the first patrols by Central chimpanzees toward Western chimpanzees. We summed the number of these within-Ngogo patrols quarterly from 2016 to 2024.

Gut bacteria influence mice social behavior through smell

Amazing stuff! Why do humans use perfume and deodorants?

When one metabolite molecule regulates aggressiveness of individuals!

"In a new study, Northwestern University neurobiologists discovered that gut bacteria and the nose work together to shape social behavior in mice, including who fights and who backs down. Using a combination of genetic and behavioral experiments, the scientists found gut microbes produce a pungent odor that other animals can smell. When detected, these scents trigger aggression and shape social hierarchies. The discovery reveals a previously unknown way the microbiome influences social interactions. ...

"Over the past 20 years, there's been a growing realization that microbes in the gut have profound influences on behavior and physiology," ... "They produce bioactive chemicals that affect the function of many organ systems, including the immune system, and can even cross the blood-brain barrier to affect behavior. These chemicals can also affect social behaviors through the sense of smell. While species use microbiome-derived chemicals for social communication, our study is the first to uncover the underlying mechanism." ...

In the new study, ... team focused on trimethylamine (TMA), a molecule produced in the gut that smells like dead, rotten fish. When gut bacteria break down choline-rich foods, such as eggs and meat, they generate TMA as a byproduct. The body's liver then converts TMA into an odorless metabolite. But in adult male mice, testosterone suppresses the liver enzyme that typically neutralizes TMA, allowing it to accumulate in urine.

"It seemed like mice use TMA as a male-specific odor," ...

To better understand why adult male mice produce this odor, ... team imaged the olfactory bulb within the brain to see which neurons respond to TMA. They specifically focused on trace amine-associated receptors (TAARs), a small family of odor detectors that are especially sensitive to strong-smelling molecules. Among the 14 TAARs in mice, the team found that TAAR5 is the most sensitive receptor to TMA and plays a central role in detecting the odor. ...

From scent to social hierarchy

When mice detect this scent, it changes how they behave. Dominant animals initiate fights, while subordinate mice adopt defensive postures—patterns that quickly establish a social hierarchy. 

But when ... team disabled TAAR5 in mice, those distinctions blurred. Mice still interacted with one another, but their behavior became more evenly matched. Without this signal, it took longer for clear dominant-subordinate relationships to emerge. ..."

From the highlights and abstract:

"Highlights

• TAAR5 deletion alters aggression and social dominance in male mice

• The effect of TAAR5 on social behavior occurs via the main olfactory pathway

• Blocking production of the TAAR5 ligand TMA by gut microbes reduces aggression

• A microbiome-derived chemical cue shapes mammalian social behavior via olfaction

Summary

Many species use microbiome-derived metabolites as chemosensory cues, yet the chemicals involved and the sensory pathways that detect and process them remain poorly understood.

Trimethylamine (TMA) is a volatile metabolite that is produced by the gut microbiome and selectively accumulated in the urine of sexually mature male mice.

Here, we show that TMA regulates inter-male aggression and social dominance by activating trace amine-associated receptor 5 (TAAR5) in the main olfactory system.

In wild-type mice, early aggressive behavior during male-male encounters strongly predicts eventual social status: dominant males initiate more attacks, whereas subordinate males display more defensive behaviors.

Deletion of TAAR5 eliminated this asymmetry, with dominant and subordinate mice showing similar levels of aggressive and defensive behaviors.

Strikingly, restoring TAAR5 expression in olfactory sensory neurons (OSNs) rescued the behavioral asymmetry, indicating that this effect is mediated by the main olfactory system and arguing against contributions from proposed TAAR5 expression in the brain.

Finally, pharmacological suppression of microbial TMA production reduced inter-male aggression, and this effect was reversed by painting treated males with TMA, showing that microbiome-derived TMA is the key volatile ligand for TAAR5 in this context.

Taken together, our findings identify TMA as a critical olfactory cue that signals the presence of sexually mature males and facilitates social hierarchy formation. More broadly, our results demonstrate that a microbiome-derived metabolite can shape mammalian social interactions through the main olfactory system and uncover a previously unrecognized role for the TAAR family in regulating social behavior."

Gut bacteria may influence social behavior through smell

A microbiome-derived olfactory signal regulates inter-male aggression and social dominance in mice (open access)

Graphical abstract

The timing of rewards plays a key role in learning, identifying a new biological principle governing learning

When scientific research confirms the obvious! Of course, besides size/value and frequency of rewards, timing of rewards matters too!

"... Researchers ... recently carried out a mouse study challenging this assumption, suggesting that the strength of reward-based learning also depends on the timing between rewards and not just on how many times a mouse is rewarded after the same stimulus. Their paper, published in Nature Neuroscience, could reshape existing models of learning, decision-making and potentially even addiction. ..."

From the abstract:

"Learning the causes of rewards is crucial for survival. Cue–reward associative learning is controlled in the brain by mesolimbic dopamine. It is widely believed that dopamine drives learning by conveying a reward prediction error. Dopamine-based learning algorithms are generally ‘trial-based’: learning progresses sequentially across individual cue–outcome experiences. A foundational assumption of these models is that the more cue–reward pairings one experiences over a fixed duration, the more one learns this association.

By identifying a new biological principle governing learning, we disprove this assumption. Specifically, across many conditions in mice, we show that behavioral and dopaminergic learning rates are proportional to the duration between rewards (or punishments). Due to this rule, the overall learning over a fixed duration is independent of the number of cue–outcome experiences. A dopamine-based model of retrospective learning explains these findings, thereby providing a unified account of the biological mechanisms of learning."

The timing of rewards plays a key role in learning, study finds

Duration between rewards controls the rate of behavioral and dopaminergic learning (open access)

Fig. 3: Learning rate scales proportionally with reward frequency across a range of trial spacing intervals.

Disclaimer:

I am currently blogging from behind the Great Firewall of China.

My Internet service in China is very spotty. Thus, I am not able to blog as usual.

Amygdala volume linked to increased social tolerance in macaques

Amazing stuff! A very interesting study!

"Researchers have found that the size of the amygdala—a region of the brain involved in processing emotions—could be linked to social tolerance in macaque monkeys. Their research ... is described by the editors as important work with a convincing methodological approach, offering new insights into the neural basis of social and emotional processing. ..."

From the editor's summary:

"This important work compares the size of two brain areas, the amygdala and the hippocampus, across 12 species belonging to the Macaca genus. The authors find, using a convincing methodological approach, that amygdala - but not hippocampal - volume varies with social tolerance grade, with high tolerance species showing larger amygdala than low tolerance species of macaques. Interestingly, their findings also suggest an inverted developmental effect, with intolerant species showing an increase in amygdala volume across the lifespan, compared to tolerant species exhibiting the opposite trend. Overall, this paper offers new insights into the neural basis of social and emotional processing."

From the abstract:

"The macaque genus includes 25 species with diverse social systems, ranging from low to high social tolerance grades. Such interspecific behavioral variability provides a unique model to tackle the evolutionary foundation of primate social brain. Yet, the neuroanatomical correlates of these social tolerance grades remain unknown.

To address this question, we expressed social tolerance grades within a novel cognitive framework and analyzed post-mortem structural scans from 12 macaque species. Our results show that amygdala volume is a subcortical predictor of macaques’ social tolerance, with high tolerance species exhibiting larger amygdala than low tolerance ones.

We further investigated the developmental trajectory of amygdala across social grades and found that intolerant species showed a gradual increase in relative amygdala volume across the lifespan. Unexpectedly, tolerant species exhibited a decrease in relative amygdala volume across the lifespan, contrasting with the age-related increase observed in intolerant species—a developmental pattern previously undescribed in primates. Taken together, these findings provide valuable insights into the cognitive, neuroanatomical, and evolutionary basis of primates’ social behaviors."

Brain structure volume linked to increased social tolerance in macaques

Toward neuroanatomical and cognitive foundations of macaque social tolerance grades

An Infected terminally ill worker Ant pupa Sends disinfect me Signal to Colony Workers, but the disinfectant also kills the pupa

Amazing stuff!

"Adult ants that have been infected with deadly pathogens often leave the colony to die so as not to infect others. But, “like infected cells in tissue, [young ants] are largely immobile and lack this option,” said ... a researcher ... who studies how social insects such as ants fight diseases collectively as superorganisms, in a statement. ..."

"Ant colonies operate as tightly coordinated “superorganisms” with individual ants working together, much like the cells of a body, to ensure colony health. Researchers ... have now discovered that terminally ill ant brood, like infected cells in a body, release an odor signaling their impending death and the risk they pose. This sophisticated early warning system facilitates rapid detection and removal of pathogenic infections. ...

Upon receiving the signal, worker ants respond swiftly by unpacking the terminally ill pupae from their cocoon, creating small openings in their body surface and applying their antimicrobial poison, formic acid, which functions as a self-produced disinfectant. While this treatment immediately kills the pathogens multiplying inside the pupa, it also results in the pupa’s own demise. ..."

From the abstract:

"Sick individuals often conceal their disease status to group members, thereby preventing social exclusion or aggression. Here we show by behavioural, chemical, immunological and infection load analyses that sick ant pupae instead actively emit a chemical signal that in itself is sufficient to trigger their own destruction by colony members.

In our experiments, this altruistic disease-signalling was performed only by worker but not queen pupae. The lack of signalling by queen pupae did not constitute cheating behaviour, but reflected their superior immune capabilities. Worker pupae suffered from extensive pathogen replication whereas queen pupae were able to restrain their infection.
Our data suggest the evolution of a finely-tuned signalling system in which it is not the induction of an individual’s immune response, but rather its failure to overcome the infection, that triggers pupal signalling for sacrifice. This demonstrates a balanced interplay between individual and social immunity that efficiently achieves whole-colony health."

Sick, Immobile Young Ants Send “Kill Me” Signal to Colony Workers | The Scientist "Cocooned ants infected with a deadly fungus call on workers to kill them to protect the colony—the first example of altruistic disease signaling in social insects."

Ants Signal Deadly Infection (original news release) "Early disease detection in the colony: Ants signal incurable sickness to save others"

Altruistic disease signalling in ant colonies (open access)

A Bumblebee's optimism is contagious to other bumblebees

Amazing stuff!

"... This phenomenon, known as affective contagion, had previously been demonstrated in a variety of social animals—but only ones with bones. Meanwhile, wee bumblebees have demonstrated remarkable cognitive complexity, including different emotional states, learning by watching, and even a penchant for play. So, researchers wondered if these bees might similarly pick up on their hive members’ vibes.

They trained bees to associate certain colored flowers with a food reward, then put some of them in a good mood by giving them an extra sugary treat. The bees that received this yummy bonus more readily landed on ambiguously colored flowers, indicating they were feeling optimistic about getting a treat. But so, too, did bees that simply observed their fellow insects excitedly rushing towards these flowers. ..."

From the editor's summary and abstract:

"Editor’s summary

Being able to adopt a knowledgeable conspecific’s perspective is highly adaptive. Likely for this reason, emotional contagion, or the spread of emotion from one individual to another, is widely distributed among vertebrates. Such an ability, however, would also be adaptive in nonvertebrates, especially those that are social. Whether insect brains are capable of such coordination has been unknown. Romero-González et al. looked at this behavior in bumble bees, whose tiny, but seemingly mighty, brains have already been shown capable of many unexpected cognitive feats. They found that a demonstrator’s positive attitude toward the potential for a reward was readily picked up by an observer. ...

Abstract

Affective contagion, a core component of empathy, has been widely characterized in social vertebrates but its existence in any invertebrate is unknown. Using a cognitive bias paradigm we demonstrate positive affective contagion in bumble bees.

After being trained on colored flowers with different reinforcements, bees that interacted with a conspecific in a positive affective state were quicker and more likely than controls to land on ambiguous colored flowers, indicating the transfer of a positive judgment bias between bees.

Additional observations and experiments showed that affect could be transmitted between bees without physical contact, i.e., through visual modality alone. Our findings suggest that affective contagion may be an evolutionarily widespread mechanism present in both social vertebrates and social insects."

ScienceAdviser

Positive affective contagion in bumble bees (no public access)

The Bee Lab At Southern Medical University, China

Mammalian mothers and their babies need the oxytocin love hormone

Amazing stuff!

Notice again the gender bias and misandry here: The researchers apparently did not bother to investigate the male mouse/father. Is the father so irrelevant here?

"... Oxytocin has been shown to play a part in forming social bonds, including for mothers during grooming and nursing. To test the hormone’s role in babies, researchers separated 15-day-old mouse pups from their mothers for 3 hours. When they were reunited, the researchers measured ultrasonic vocalizations, noises that baby mice make to signal distress and catch their mothers’ attention. The team also used invasive and noninvasive methods to simultaneously measure the activity of oxytocin-producing neurons in the mice’s brains.

Indeed, vocalizations and oxytocin production increased upon the familial reunions, declining as the mother comforted the baby. But when mouse pups were reunited with an anaesthetized mama, their vocalizations stayed high. The researchers hypothesize that synchronized oxytocin release by the mothers and babies upon reunion helps regulate their emotions and strengthen social relationships. ..."

From the abstract of the Perspective:

"Abstract

For most mammals, social bonding between mothers and infants is a fundamental, evolutionarily conserved behavior that is crucial for offspring survival, emotional regulation, and the acquisition of social skills necessary for future interactions. Early-life experiences, especially maternal care, shape developmental trajectories, profoundly influencing cognitive, emotional, and social competencies into adulthood. In rodents, the neuropeptide oxytocin has been widely recognized for its central role in maternal behaviors toward infants such as nesting, grooming, and nursing.

Yet comparatively little is known about how oxytocin regulates infant behaviors toward mothers, particularly during episodes of maternal separation and reunion. ... Zelmanoff et al. report real-time changes in the activity of oxytocin-producing neurons in mouse pups during maternal separation and reunion, offering insights into how offspring actively contribute to maternal-infant bonding."

From the editor's summary and abstract:

"Editor’s summary

The neuropeptide oxytocin has been shown to play a major role in driving parental behavior. However, its role in early life remains to be fully elucidated. Zelmanoff et al. investigated the role of oxytocin in modulating social behavior in mouse pups during separation and reunion with their mothers ... Pups separated from their mothers produced more ultrasonic vocalizations upon reunion, and the effect was modulated by the activity of oxytocin-expressing neurons. Pharmacological and optogenetic inhibition of these neurons attenuated ultrasonic vocalizations, suggesting that oxytocin plays a major role in determining social behavior during development. ...

Structured Abstract

INTRODUCTION

Oxytocin is a brain hormone that plays a critical role in regulating social behavior. Although much research has focused on how oxytocin supports adult behaviors such as pair-bonding and caregiving, far less is known about how this system functions during early life. The early postnatal period is a time of critical social interactions between infants and caregivers, and disruptions during this period may contribute to developmental disorders. Notably, expression of the oxytocin receptor peaks during infancy in both humans and mice, suggesting that this period represents a critical window of heightened sensitivity to oxytocin signaling. However, technical challenges have limited the study of the oxytocin system during this sensitive time of brain development. As a result, the role of oxytocin in shaping social behavior during infancy remains poorly understood.

RATIONALE

We set out to investigate how oxytocin influences pup behavior during a brief separation from the mother and littermates and subsequent reunion. We focused on vocal communication, as rodent pups emit ultrasonic vocalizations that signal distress but may also reflect social motivation and need. We combined detailed behavioral analysis with fiber photometry, pharmacological intervention, and a novel optogenetic strategy built on wireless silencing of oxytocin neurons in freely behaving pups—a technical advance that overcomes prior limitations in studying brain circuits during early life.

RESULTS

Pups that were acutely separated from their mother and littermates displayed a substantial increase in vocalizations upon reunion, especially when in close proximity to their mother. The rate and type of vocalizations were modulated by nipple attachment behavior. We found that hypothalamic oxytocin neurons increased their activity upon separation, and that this activity was tightly linked with the emission of vocalizations. 

Blocking the oxytocin receptor in pups during separation reduced nipple attachment and altered the pattern of vocal behavior both during separation and reunion.

For increased temporal precision, we developed a new optogenetic method using a highly light-sensitive, red-shifted inhibitory opsin (eOPN3). This allowed us to wirelessly silence oxytocin neurons in untethered pups.

We found that silencing oxytocin neurons during separation disrupted vocal—but not nonvocal—behavior during both the separation and reunion.

CONCLUSION

Our findings reveal a specific role for oxytocin in shaping maternally directed behavior during infancy. We also introduce a noninvasive optogenetic approach for studying brain circuits in developing animals, opening new opportunities to investigate the neural mechanisms underlying early life social behavior. Our work emphasizes the need to gain a more nuanced understanding of oxytocin function and provides a technical platform for studying the social brain during its most formative stages."

ScienceAdviser

Cries into ties (Perspective, no public access) "Oxytocin neurons in mouse pups regulate vocalization to maintain maternal bonds"

Oxytocin signaling regulates maternally directed behavior during early life (no public access)

Oxytocin signaling regulates maternally-directed behavior during early life (preprint, open access)

Graphical abstract

Figure 1:

Acute maternal separation increases maternally-directed behavior upon reunion.

Quitting time: Neurons that drive sociable behavior in children and teens turn off in adulthood

Amazing stuff!

"... In experiments with mice, researchers observed that Agrp neurons, a type of cell in the brain’s hypothalamus region, play a key role in controlling social behavior in young animals but not in adults. The neurons — which regulate primary survival needs like hunger and maintaining body temperature — drive social needs during youth but slowly lose this role in adulthood. ..."

From the highlights and abstract:

"Highlights

• Agrp neurons encode social need during adolescence but not in adulthood

• Inhibiting Agrp neurons blocks sociability after isolation in juvenile mice

• Social stimuli reduce Agrp neuron activity via olfaction in young mice

• Agrp neuron responsivity to social cues declines during late adolescence

Summary

Social isolation enhances sociability, suggesting that social behavior is maintained through a homeostatic mechanism. Further, mammalian social needs shift dramatically from infancy through adolescence into adulthood, raising the question of whether the neural mechanisms governing this homeostatic regulation evolve across developmental stages.

Here, we show that agouti-related peptide (Agrp) neurons in the arcuate nucleus of the hypothalamus, which are known to drive hunger in adults, are activated by social isolation from weaning through adolescence but not in adulthood. Importantly, the activity of these neurons is critical for social behavior during adolescence:

inhibiting Agrp neurons reduced isolation-induced sociability in juveniles, but not in adults, and

Agrp neuron activation promoted sociability only in young mice.

After isolation, reunion with siblings or other conspecifics, but not unfamiliar adult males or amicable rat pups, rapidly decreased neuronal activity in juveniles, an effect requiring intact olfaction. These findings identify Agrp neurons as a key component of the circuitry governing age-specific social homeostasis."

Quitting time: Neurons that drive sociable behavior in children and teens turn off in adulthood | Yale News "Researchers have mapped the neural signaling that drives social impulses critical to survival in young mammals."

Age-specific regulation of sociability by hypothalamic Agrp neurons (no public access)

Age-specific regulation of sociability by hypothalamic Agrp neurons (preprint, open access)

Graphical abstract

Female Gorillas seek out old female friends even after years apart

Amazing stuff! For some odd reason, the University of Zurich filed this research under the term of "Feministisches Netzwerk" (feminist network, see also screen print below). 

"The findings ... show how important the relationship between two individual females is in gorilla society. ...

Moving into different groups is key in shaping the animals' social structure. It's something that both males and females do - females will sometimes move several times throughout their lives.

This dispersal, as it's known, plays a role in avoiding inbreeding, spreading gene diversity and shaping social relationships. ...

Working in partnership with the Dian Fossey Gorilla Fund, at a field site that has been monitored since 1967, ... were able to track those movements.

Pouring through decades of information on the animals' lives, the scientists followed the "dispersals" of 56 female mountain gorillas - examining which new group they chose to join and why. ...

The gorillas avoided groups that had males they were likely to be related to, but the presence of females they knew also "mattered a lot" ...

The females gravitated towards their "friends", even if the animals had been apart for many years.

They would often gravitate to a group with females they had grown up with, even if that was many years ago. They also sought out individuals with whom they had made a social connection - perhaps played and interacted with - recently. ..."

From the abstract:

"Dispersal is a fundamental aspect of many animal societies, impacting gene flow, knowledge transmission, culture and individual fitness. However, little is known about the information individuals use when dispersing.

Mountain gorillas exhibit a flexible dispersal pattern with 50% of both sexes dispersing, and females often dispersing multiple times. Using two decades of data including 152 dispersals from 56 females, we examined how familiarity with individuals in other groups influenced dispersal.

We found that females avoided groups containing males from their natal group, but preferred groups containing females they had previously resided with, particularly those from their natal group.

This suggests that females prioritize the maintenance of female relationships in their dispersal decisions, while reducing inbreeding risks. Joining a new group can be costly and these pre-existing relationships may reduce dispersal costs.

These findings highlight the capacity for wider-scale societies to both shape and be shaped by dispersal decisions, with long-term inter-group relationships representing potential sources of information and support in the dispersal process. This contributes to a better understanding of not only population dynamics in this endangered ape, but also of the foundation of our own flexible society, characterized by individuals moving between social groups throughout their lifetimes."

Gorillas seek out old female friends even after years apart

Networks of Female Friends Help Gorillas Move between Groups (original news release) "New research from the University of Zurich suggests that gorillas may be using a similar strategy as humans: when moving to a new social group, female gorillas seek out groups containing females they have lived with in the past and avoid males they grew up with."

Dispersed female networks: female gorillas’ inter-group relationships influence dispersal decisions (no public access)

Credits: The Flyover

Female gorillas appear to maintain their social relationships for many years

US urban pedestrians now walk faster and linger less since the 1980s, researchers find. Really!

Amazing stuff! Is this due to global warming? Or due to the jogging and fitness craze? What about suburbia? What about crime/vagrancy or loss of amenities (e.g. shops) in downtown areas?

What is the chicken and egg here? Did urban planning and construction result in this change of behavior?

It surprises me that the study stopped analyzing videos after 2010! Why not more recent videos? Maybe the speed decreased again in the past 15 years.

This seems to be an interesting new direction of research: Using computer vision to analyze older video footage.  

Caveat: I did not read the study.

"The research ... shows that the average walking speed of pedestrians in three northeastern U.S. cities increased 15 percent from 1980 to 2010. The number of people lingering in public spaces declined by 14 percent in that time as well. ..."

From the significance and abstract:

"Significance

Urban public spaces have traditionally served as places for gathering and social connection, shaping the social fabric of cities. This study reveals important shifts in pedestrian behaviors over a 30-y period in four US public spaces.

By using AI and computer vision to analyze historical and contemporary video footage, we observe an increase in walking speed and a decrease in time spent lingering, along with fewer group encounters. 

This trend suggests a growing perception of city streets as corridors for movement rather than spaces for social interaction. These findings highlight a changing urban dynamic, where efficiency increasingly shapes public space usage, potentially impacting social connections and the community-building role of these environments.

Abstract

We analyze changes in pedestrian behavior over a 30-y period in four urban public spaces located in New York, Boston, and Philadelphia. Building on William Whyte’s observational work, which involved manual video analysis of pedestrian behaviors, we employ computer vision and deep learning techniques to examine video footage from 1979–80 and 2008–10. Our analysis measures changes in walking speed, lingering behavior, group sizes, and group formation.

We find that the average walking speed has increased by 15%, while the time spent lingering in these spaces has halved across all locations. Although the percentage of pedestrians walking alone remained relatively stable (from 67% to 68%), the frequency of group encounters declined, indicating fewer interactions in public spaces.

This shift suggests that urban residents are using streets as thoroughfares rather than as social spaces, which has important implications for the role of public spaces in fostering social engagement."

Pedestrians now walk faster and linger less, researchers find | MIT News | Massachusetts Institute of Technology "A computer vision study compares changes in pedestrian behavior since 1980, providing information for urban designers about creating public spaces."

Exploring the social life of urban spaces through AI (no public access)

Reverse engineering the sensory-motor control for schooling in zebrafish using virtual reality

Amazing stuff! This could be a breakthrough!

"... Now, using an immersive virtual reality (VR) setup, scientists have figured out the sensory-motor mechanism underlying this harmonious behavior.

While inside their 3D arena, which researchers dubbed “the Matrix,” individual zebrafish could interact with “holographic” projections of other fish. By analyzing the animals’ reactions and tweaking the movements of virtual “leader” fish, the team determined that “follower” fish used the perceived position—rather than the speed—of their neighbors to guide their own movements. “We were surprised by how little information the fish need to effectively coordinate movements within a school ,” ... Using this natural control law, the researchers programmed a variety of wheeled robots, drones, and robotic watercraft; they were able to follow targets just as well as robots programmed with an existing, state-of-the-art controller—at a fraction of the complexity. ..."

"To the point

• Innovative method: A team of biologists and robotic engineers have developed a virtual reality system for fish to decipher how they school
• Discovering nature’s algorithm: They uncovered the natural ‘control law’ that is used by zebrafish to coordinate behavior with others, a behavioral algorithm that has been tuned over millennia to facilitate effective collective motion.
• Implications for robotics: They tested the natural control law in groups of robotic cars, drones and watercraft, demonstrating its potential for the control autonomous vehicles in the future.

... Using a virtual reality (VR) setup that mimics natural schooling, researchers placed individual juvenile zebrafish into networked arenas where each fish could freely interact with ‘holographic’ virtual conspecifics. Each virtual fish was a projection of a real fish, meaning that fish could swim and interact together in the same virtual world.

The fully immersive 3D environment lets researchers precisely manipulate visual stimuli and record how the fish respond. This high level of control allowed the scientists to isolate exactly which cues the fish were using to guide their interactions with other fish. In other words, they could reverse engineer the behavior of schooling in zebrafish to understand how fish solve the complex problem of coordinating their motion.

The solution, they discovered, was a simple and robust law based only on the perceived position, not the speed, of their neighbors to regulate their following behavior. ..."

From the abstract:

"Revealing the evolved mechanisms that give rise to collective behavior is a central objective in the study of cellular and organismal systems. In addition, understanding the algorithmic basis of social interactions in a causal and quantitative way offers an important foundation for subsequently quantifying social deficits.

Here, with virtual reality technology, we used virtual robot fish to reverse engineer the sensory-motor control of social response during schooling in a vertebrate model: juvenile zebrafish (Danio rerio).

In addition to providing a highly controlled means to understand how zebrafish translate visual input into movement decisions, networking our systems allowed real fish to swim and interact together in the same virtual world. Thus, we were able to directly test models of social interactions in situ.

A key feature of social response is shown to be single- and multitarget-oriented pursuit. This is based on an egocentric representation of the positional information of conspecifics and is highly robust to incomplete sensory input.

We demonstrated, including with a Turing test and a scalability test for pursuit behavior, that all key features of this behavior are accounted for by individuals following a simple experimentally derived proportional derivative control law, which we termed “BioPD.”

Because target pursuit is key to effective control of autonomous vehicles, we evaluated—as a proof of principle—the potential use of this simple evolved control law for human-engineered systems. In doing so, we found close-to-optimal pursuit performance in autonomous vehicle (terrestrial, airborne, and watercraft) pursuit while requiring limited system-specific tuning or optimization."

ScienceAdviser

In VR school, fish teach robots (original news release) "Scientists use virtual reality for fish to teach robots how to swarm"

Reverse engineering the control law for schooling in zebrafish using virtual reality (open access)

Fig. 1. Schematic of the study of SMC of schooling behavior.

Fig. 2. Reverse engineering SMC of fish to a bioinspired proportional-derivative controller, BioPD.

Two Women can find friendship at first whiff. Really!

Wearing the same perfume/deodorant at the same place? It has the appeal of junk science.

They have used only heterosexual women for this study? In this day and age of LGBTQ mania? Just kidding!

Notice Cornell University also appears to use the ideological driven "person" instead of woman.

"... Yet two women meeting for the first time can judge within minutes whether they have potential to be friends – guided as much by smell as any other sense, according to new Cornell psychology research. ...

“... But scent, which people are registering at some level, though probably not consciously, forecasts whether you end up liking this person,” ...

In a study of heterosexual women, ... found that personal, idiosyncratic preferences based on a person’s [???] everyday scent, captured on a T-shirt, predicted how much women liked their interaction partner following four-minute chats across a table in a crowded room. These face-to-face conversations, in turn, influenced how participants later judged the T-shirt scent alone. ..."

From the abstract:

"Who we choose to befriend is highly personal, driven by idiosyncratic preferences about other individuals, including sensory cues. How does a person’s unique sensory evaluation of others’ body odor affect friendship formation? Female participants took part in a speed-friending event where they made judgments of friendship potential (FP) following a 4-minute live interaction. Prior to and following the speed-friending event, participants judged the FP of these women based solely on diplomatic odor (including daily perfume/hygiene products) presented on worn t-shirts. Participants also judged FP based on facial appearance (a 100-ms presentation of portrait photographs).

Judgments based solely on diplomatic odor predicted FP judgments following in-person interactions, beyond the predictive ability of photograph-based judgments.

Moreover, judgments based on the live interaction predicted changes in the second round of diplomatic odor judgments, suggesting that the quality of the live interaction modified olfactory perception.

Results were driven more strongly by idiosyncratic preferences than by global perceiver or target effects. Findings highlight the dynamic role of ecologically relevant social olfactory cues in informing friendship judgments, as well as the involvement of odor-based associative learning during the early stages of friendship formation."

Finding friendship at first whiff | Cornell Chronicle

The interactive role of odor associations in friendship preferences (open access)

Fig. 1 Schematic Representation of Study Procedures and Key Measures

Mice give first aid

Amazing stuff! Do mice also have first responders? 😊

"In emergency situations, humans often exhibit instinctual “first aid” behaviors toward others. Whether and how other species show prosocial behaviors toward others is unclear.

In two independent studies, ... showed that mice exhibit stereotyped behaviors toward unconscious conspecifics, escalating from sniffing and grooming to licking of the head and tongue pulling, which accelerated recovery from unconsciousness  ... 

The activation of neurons in the medial amygdala and oxytocin-expressing neurons in the hypothalamic paraventricular nucleus was required to trigger these behaviors. The results elucidate different aspects of a previously unrecognized prosocial behavior in mice and its underlying neurobiological mechanisms."

From the abstract:

"Structured Abstract

INTRODUCTION

The partial or complete loss of responsiveness, such as transient unconsciousness, presents a substantial risk to animals, increasing their vulnerability to predators or hazardous environments.

The actions of bystanders toward unresponsive individuals can be critical for enhancing survival and well-being. Humans, for instance, can readily recognize and assist unconscious individuals.

Similarly, anecdotal reports suggest that some animal species, including nonhuman primates, marine mammals (e.g., whales and dolphins), and elephants, exhibit behavioral reactions to collapsed or unresponsive conspecifics in the wild. However, it is unclear whether such behaviors occur in species beyond those few that have been documented.

Additionally, the nature, characteristics, and consequences of these behaviors have not been systematically examined in a controlled experimental setting. Moreover, the neural mechanisms underlying the perception of others’ unresponsive states and the ensuing behaviors remain elusive.

RATIONALE

Previous studies have demonstrated that rodents, including mice, can perceive and behaviorally respond to others’ negative or needy states.

For example, they can display comforting social touch through allogrooming, broadly targeted at various body parts of distressed conspecifics. In addition, they can respond to others’ local pain and injury with allolicking behavior focused on the wound site.

However, it is unclear how mice react to other animals in an unresponsive state. In this study, we examined the behaviors that mice display toward unresponsive conspecifics, their effects on the recipients, and the neural representation and regulation of these behaviors.

RESULTS

We discovered that mice preferentially approach unresponsive conspecifics over awake ones and engage in distinctive behaviors toward unresponsive conspecifics under deep sedation, characterized by intense contact and grooming directed at the sedated individuals’ head region, particularly the facial and mouth areas. These behaviors are observed in both male and female animals and are correlated with the extent of reduction in the responsiveness of the recipients.

Physical contact and grooming directed at the head region are more likely to elicit motor responses in the recipients compared with other social behaviors and can expedite the animals’ recovery from the unresponsive state.

Moreover, we uncovered an essential role of the medial amygdala (MeA) in regulating this response. MeA neural activity differentiates between awake and sedated conspecifics at both single-cell and population levels, and the neural response to sedated animals does not simply reflect a response to novelty. Optogenetic silencing of MeA γ-aminobutyric acid–producing (GABAergic) neurons suppresses head grooming behavior, whereas their activation promotes this behavior. Although mice respond to sedated, unresponsive conspecifics primarily with head-directed allogrooming and physical contact, their allogrooming response to awake conspecifics experiencing a general state of stress mainly targets other body regions.

These two different adverse states and the corresponding behavioral responses (head grooming versus body grooming) are distinguishable by neural activities in the MeA, suggesting that the MeA may be part of the neural circuitry mediating the differentiation between these states.

CONCLUSION

Our findings reveal that mice exhibit rescue-like behaviors toward unresponsive conspecifics, characterized by intense physical contact directed at the recipient’s head region. This response accelerates recovery from unresponsiveness, potentially reducing risks to unresponsive individuals and enhancing their survival. We have also uncovered that the MeA encodes the unresponsive state of others and drives head-directed grooming toward them.

Notably, the behavioral response toward unresponsive conspecifics differs from that toward awake, stressed individuals, and these responses are differentially represented in the MeA. These findings shed light on the neural mechanisms underlying prosocial responses toward unresponsive individuals, broadening our understanding of animals’ ability to detect and behaviorally react to different adverse conditions of others."

In Science Journals | Science

A neural basis for prosocial behavior toward unresponsive individuals

Reviving-like prosocial behavior in response to unconscious or dead conspecifics in rodents

Prosocial behavior toward unresponsive conspecifics.

Mouse behaviors toward an unconscious peer.

For social bats, the hippocampus is the brain’s ‘who’s who’

Amazing stuff!

Keep in mind: Wind turbines are massive killers of bats in the hundreds if not millions of bats per year! Where are the animal rights activists when you need them! Who is paying them for their silence?

"Egyptian fruit bats are remarkably social animals, often roosting in caves with dozens to thousands of other bats. These furry creatures can’t just flip through a magazine to find out the latest colony gossip, so how do they keep track of who’s who?

To find out more about how these animals navigate their complicated social environments, scientists housed groups of wild fruit bats together in laboratory “caves” for several months. Once the bats had gotten to know each other, the team outfitted some with electrodes, allowing them to monitor activity in a part of the brain known as the hippocampus. Neurons in this region are known to play a prominent role in memory and spatial navigation, thus representing an animal’s place within its physical environment, but the researchers saw them light up during social interaction too. It turns out that these same hippocampal neurons also encode distinguishing features of other bats, including their sex, their place within the colony dominance hierarchy, and whether they were perceived as friends or enemies.

“We found that the same neural network, the same neurons, represented all of these factors together,”  ... 

This isn’t the first time Egyptian fruit bats have proven themselves to be brainy: Previous studies have revealed that these communal cave dwellers learn new dialects from the colony members around them, are able to  recall past experiences and plan ahead for the future, and can even recognize the scientists performing experiments on them."

From the editor's summary and structural abstract:

"Editor’s summary

Classic work on cognitive maps has shown that neurons in the hippocampus code an organism’s environment and their place within it. However, most organisms, and especially social species, exist in complex worlds that include not just their place in their environment, but also the place and identity of other individuals relative to themselves. Ray et al. monitored fruit bats within a naturalistic environment and found that neurons in the hippocampus also coded for distinct individuals, including their sex, rank, location, and unique identity. Thus, the hippocampus creates not only an individual’s cognitive map, but also a complex map of their social environment. ...

Structured Abstract

INTRODUCTION

Social animals live in groups and interact volitionally in complex ways. To perform real-life social behaviors, the brain needs to code other individuals’ identities, represent various types of social interactions, and encode key social factors such as the sex, dominance hierarchy, and social affiliation of multiple other individuals.

However, our understanding of how the brain deals with such diverse requirements stems from constrained laboratory experiments in which an animal typically exhibits one specific behavior with one other animal in one particular task. This leaves the fundamental question unexplored: How does the brain actually represent the real world with its complex, multianimal settings?

RATIONALE

To understand natural social coding in the mammalian brain, we studied Egyptian fruit bats (Rousettus aegyptiacus), which are highly social mammals, and focused on the hippocampus, a brain area that in previous studies has been shown to be important for memories of social identities, episodic events, and spatial locations. We hypothesized that in natural scenarios, when all of these disparate aspects occur simultaneously, hippocampal neurons would bind together all of these different types of information. To create a naturalistic environment, we established a laboratory-based “cave,” housing mixed-sex groups of five to 10 wild-caught bats. The bats lived together continuously (24/7) for several months, engaging in natural social behaviors without any imposed tasks. During this time, we conducted wireless neural recordings from the dorsal hippocampus area CA1 of both male and female bats and tracked their positions, head directions, and social interactions with each other.

RESULTS

The freely behaving bats formed a stable social network and displayed three key behaviors: (i) flying between two nets located at opposite corners of the setup, (ii) engaging in social interactions, and (iii) being active on the net and observing each other. We found that hippocampal “place cells,” neurons known to represent the animal’s own position, were modulated during flight by the social context, i.e., whether the bat was flying to meet another bat or to be alone. These cells also encoded the identities of other bats. This identity coding was invariant to the bat’s flight direction. We also found that many hippocampal cells encoded social-interaction events, with different neurons typically encoding distinct types of social interactions such as affiliative grooming or aggressive boxing. During active observation on the nets, we used methods from machine learning and game theory to reveal that neurons encoded the bat’s own position and head direction, together with the positions, directions, and identities of multiple other individuals. Identity-coding neurons encoded the same specific bat across different locations and different behavioral states, both in-flight and on the net, providing another example of social invariance. The strength of identity coding was modulated by the sex, dominance hierarchy, and social affiliation of the other bats.

CONCLUSION

Our use of a naturalistic social colony allowed us to discover that the classical hippocampal cognitive map of space also integrates rich social information, forming a sociospatial cognitive map. We found neurons that encoded social interaction events, identities and sex of other individuals, dominance hierarchy, and social affiliation, along with the position and direction of both self and others. These findings combine the historically disparate views on hippocampal function, which suggested that the hippocampus is important for encoding memory, social identity, or spatial maps. Here, we have shown that all of these factors are represented together in the same neural network."

ScienceAdviser

Coding bonus: Bats’ hippocampal cells log spatial, social cues "The neurons represent not only an animal’s place in space, but also the distinguishing features of its fellow bats, including their sex and social status."

Hippocampal coding of identity, sex, hierarchy, and affiliation in a social group of wild fruit bats (no public access)

Hippocampal place cells also encode social information, forming a sociospatial cognitive map.

Marmoset monkeys may use names to call other members of their group or family members

Amazing stuff!

"It seems so, after new research appears to have discovered that small monkeys called marmosets “vocally label” their monkey friends with specific sounds.

... The team used audio recorders and pattern-recognition software to analyze the animals’ high-pitched chirps and twitters. To prove they’d cracked the monkey code—and learned the secret names—the team played recordings at the marmosets through a speaker and found they responded more often when their label, or name, was in the recording.

... Until now, only humans, dolphins, elephants, and probably parrots had been known to use specific sounds to call out to other individuals. ..."

"... The finding adds to recent revelations about marmoset communication, including that they learn to “talk” as infants by mimicking their parents, take turns while communicating, and even eavesdrop on their neighbors’ conversations. The monkeys may have evolved this sophisticated communication style to stay in touch in their dense rainforest habitat, where group members are easier heard than seen.  ..."

From the editor's summary and abstract:

"Editor’s summary

The ability to vocally label other individuals from your species and to learn these labels from others is a high-level cognitive function. Previously, this behavior has only been known to exist in humans, dolphins, and some parrot species. Oren et al. applied machine learning tools and real-time playback experiments to analyze naturally occurring “phee-call” dialogues between pairs of marmoset monkeys. Marmosets used these vocalizations to label their conspecifics. They also perceived and responded correctly to calls that were specifically directed at them. Monkeys from the same family group used similar calls to vocally label others, and they learned from other family members to vocally label other individuals. ...

Abstract

Humans, dolphins, and elephants are the only known species that vocally label their conspecifics. It remains unclear whether nonhuman primates share this ability. We recorded spontaneous “phee-call” dialogues between pairs of marmoset monkeys. We discovered that marmosets use these calls to vocally label their conspecifics. Moreover, they respond more consistently and correctly to calls that are specifically directed at them. Analysis of calls from multiple monkeys revealed that family members use similar calls and acoustic features to label others and perform vocal learning. These findings shed light on the complexities of social vocalizations among nonhuman primates and suggest that marmoset vocalizations may provide a model for understanding aspects of human language, thereby offering new insights into the evolution of social communication."

How machine learning is helping us probe the secret names of animals

Marmosets call one another by name

Vocal labeling of others by nonhuman primates (no public access)