The research, led by Dr. Revathe Thillaikumar, a Marie Sklodowska-Curie Actions Postdoctoral Fellow at the Max Planck Institute of Animal Behavior, together with senior author Dr. Caroline Schuppli and colleagues at Universitas Nasional in Indonesia, is the first to demonstrate that social and individual forms of learning interact over many years to build broad, survival-relevant ecological skills in a wild great ape. Until now, scientists have debated to what extent animals acquire their survival skills by watching others or by experimenting on their own, but the long developmental timelines of great apes have made it extraordinarily difficult to connect learning events to concrete outcomes. This study closes that gap with an unusually detailed dataset and a statistical approach that treats each animal as its own developmental story.

The scale of the challenge facing a young orangutan is hard to overstate. An adult orangutan’s diet consists of nearly 250 distinct food items, selected from thousands of different options scattered across the rainforest maze. Some of those options are potentially poisonous. Beyond simply knowing what to eat, an independent orangutan must master how each food should be processed, and when and where each item can be found in the forest. As Thillaikumar asks, how do infants master this complex diet curriculum during their first years of life? Humans offer a clue, because throughout our evolutionary history we too had to learn an immense set of survival skills across many years of development, drawing on a complex interplay of social and individual learning. But whether wild animals use the same combination of learning forms to build their own survival skills had remained unknown.

To answer the question, the team drew on long-term data from the Suaq Balimbing research station in Gunung Leuser National Park, Indonesia, where an international team of researchers and field assistants follows wild Sumatran orangutans across their entire lives. For this study, the researchers analyzed data from 21 immature orangutans recorded from birth until independence at around 8.5 years of age. Across 4,700 hours of observation, they tracked three key behaviors: when the youngsters closely observed their mothers and other nearby orangutans through a behavior known as peering, which serves as a behavioral indicator of social learning; when they explored different items in their habitat, indicating individual learning; and which food items they successfully ate without help from their mothers, a direct measure of ecological competence.

The analytical challenge was formidable. Because orangutans develop so slowly, there is a multi-year lag between a learning event and any measurable change in behavior, as Schuppli explains. To bridge that gap, Thillaikumar worked with theoretical statistician Professor Paul-Christian Bürkner of TU Dortmund University to analyze just under seven thousand records of social and individual learning, keeping each animal’s history separate. This individual-level modeling was, in her words, a linchpin of the study, because it finally allowed the researchers to link the two parts that had previously been unbridgeable: learning and skill development. Rather than averaging across the population, the team could trace how each animal’s own learning tendencies shaped its own eventual diet.

The first major finding is that orangutan infants have genuinely individual learning styles. Over their long development, the immatures differed substantially from one another in how frequently they engaged in social versus individual learning. Thillaikumar admits the team was astonished by how different the infants were from one another in their tendencies to learn. Yet despite this variation, a clear pattern emerged across the group: all immatures engaged in social learning more frequently than individual learning, on average as much as five times more often. The explanation, Schuppli suggests, lies in the economics of risk. Learning purely through individual exploration can be dangerous for a naive orangutan, especially for immatures who are still growing and cannot afford to miss out on feeding opportunities. The safer option may simply be to watch and learn from knowledgeable role models, such as their mothers.

Social learning, it turns out, does far more than provide a safe alternative to exploration. When an infant engaged in social learning, it triggered subsequent exploration for as long as two and a half hours afterward. Each time an infant peered at its mother or another orangutan, it produced a prolonged ripple effect on its own subsequent explorations, priming the youngster to investigate items it had just seen handled by someone else. To disentangle the contributions of the two processes, the authors focused on explorations that were independently initiated, allowing them to test how social and individual learning worked together rather than merely replacing one another.

The answer is that the two forms of learning operate in tandem across the entire developmental period. Infants that engaged in high rates of both social and individual learning ended up with the broadest diet profiles by the time they became independent. Conversely, when both forms of learning were low, individuals ended up with the narrowest diets, producing a striking three-fold difference in diet breadth between the highest and lowest learners. Perhaps most intriguingly, increased social learning could partially compensate for low individual learning, improving diet breadth even when independent exploration was infrequent. As Thillaikumar puts it, social learning stepped in to do the heavy lifting, a result that underlines just how significant it is in the lives of great apes.

For Schuppli, the findings demand a more nuanced appreciation of the mechanisms underlying great ape cultures. It is about more than just social or individual learning, she says; it is about the interplay of complex learning mechanisms that has driven the development of a broad, highly survival-relevant cultural competence in one of our closest living relatives in the wild. That interplay, she argues, suggests that the sophisticated cultural learning seen in humans may have deep evolutionary roots, predating the split between our lineages by many millions of years. In other words, the recipe for human culture, a blend of attentive observation and hands-on experimentation sustained over a long childhood, may already have been simmering in the forests where our ape relatives live today.

Questions remain. The study shows that heightened learning produces broader diets, but exactly how this advantage arises is still open. Are high-learning orangutans simply accumulating knowledge about more items, or are they actually getting better at learning itself? The team now plans to look beyond diet breadth to determine whether greater learning also improves energy intake, and ultimately whether it translates into measurable differences in survival and reproduction. As co-author Dr. Sri Suci Utami-Atmoko of Universitas Nasional notes, questions like these can only be answered by watching animals in their natural environment from birth to death, because long-term field studies provide the time and space to follow long-lived animals across their whole histories. For orangutans, she says, these studies offer a window into how culture and survival have become intertwined over evolutionary time. For the rest of us, they offer a humbling reminder that the path to competence, in the rainforest as in our own species, is neither purely taught nor purely discovered, but built patiently from both.

Subject of Research: How social and individual learning styles shape ecological skill development in wild orangutans

Article Title: Learning style predicts survival skills in young orangutans

Article References: Learning style predicts survival skills in young orangutans. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: orangutans, social learning, individual learning, animal culture, Sumatra, diet breadth, great apes, childhood development, ecological competence, field study, Science journal, Max Planck Institute

The research, conducted by Mónica F. Cisternas, an independent researcher based in Stephenville, Texas, and Ernesto Gianoli of the Department of Biological Sciences at Tarleton State University, took advantage of a rare opportunity to measure thermal biology where it actually happens: in the field, under natural sunlight, wind, and fluctuating temperatures, rather than in the controlled conditions of a laboratory. The team compared solitary and grouped caterpillars of the gregarious butterfly species, asking a deceptively simple question: how does the difference between a caterpillar’s body temperature and the surrounding air temperature change as air temperature changes? The answer, it turns out, depends strongly on whether the larva lives alone or in a group.

The core metric the researchers examined is known as the body–air temperature differential, essentially the gap between how hot or cold an animal’s body is and how hot or cold the air is. For ectotherms like caterpillars, this differential is shaped by a tug-of-war between heat gained from solar radiation, heat exchanged with the surrounding air, and heat generated or absorbed through metabolism and evaporative water loss. When the differential is positive, the animal is warmer than its environment, which can be beneficial on a cool morning but dangerous during a heat spike. When it is negative, the animal is cooler than the air, a state that may protect tissues from thermal stress. The researchers measured this differential across a natural gradient of air temperatures for both solitary larvae and members of aggregations, then analyzed how the two groups differed.

The results were striking in their asymmetry. Grouped caterpillars showed an overall relationship between their body–air temperature differential and air temperature, meaning their thermal status relative to the environment shifted systematically as conditions warmed. Solitary caterpillars, by contrast, showed no such overall association. Most notably, gregarious caterpillars registered significantly lower temperatures than the surrounding environment in the warmer regions of the temperature gradient. In other words, when the day heated up, the larvae in groups were literally cooler than the air around them, a relative cooling effect that solitary individuals did not display. The researchers note that the evidence for the opposite pattern, grouped caterpillars exceeding air temperature under cooler conditions, was comparatively weak in their dataset, hinting that the cooling benefit of aggregation may be more pronounced in the field than the warming benefit.

Digging deeper into the structure of the aggregations themselves, the team ran an analysis incorporating the number of larvae in each group, and here the story became even more interesting. The interaction between group size and air temperature was statistically significant even after accounting for population-level differences and the intensity of solar radiation at each microsite. The direction of the effect was clear: as air temperature increased, the thermal excess, the amount by which a caterpillar’s body temperature surpassed air temperature, declined more steeply in larger groups. Bigger aggregations, in other words, shed their relative warmth faster as the environment heated up. This suggests that the collective thermal properties of a group, such as the way many bodies alter airflow, shading, and evaporative surfaces, scale with the number of participants, amplifying the cooling effect precisely when it matters most.

Solar radiation at the microsites the caterpillars occupied also emerged as a significant predictor of thermal excess, a reminder that body temperature in small ectotherms is never determined by air temperature alone. A caterpillar basking in direct sun can be many degrees warmer than the air, while one sheltered in shade may be cooler. By including radiation in their models, the researchers could separate the genuine effect of grouping from the simple fact that groups might occupy sunnier or shadier spots. The persistence of the group-size effect after this adjustment strengthens the case that aggregation itself, not just microsite selection, drives the relative cooling. Still, the authors caution that the mechanistic basis of the pattern remains to be worked out, whether it stems from reduced convective heat exchange within clusters, shared shading, evaporative cooling, or some combination of these physical processes.

Perhaps the most conceptually intriguing result concerns the solitary caterpillars. The analysis showed that solitary individuals, but not grouped ones, behaved as thermoconformers, meaning their body temperatures closely tracked ambient temperature with little deviation. Thermoconformity is often considered the default state for small ectotherms lacking physiological or behavioral means of temperature control, but the gregarious larvae broke free of it. By clustering, they effectively decoupled their body temperatures from the ambient thermal environment, gaining a degree of thermal autonomy that a lone larva cannot achieve. From an adaptive standpoint, this decoupling could matter enormously, because enzyme function, growth rates, feeding behavior, and survival in insects are all tightly temperature dependent, and staying within a favorable thermal window can be the difference between thriving and wilting on a hot afternoon.

The study situates itself within a rich literature on the thermal ecology of social caterpillars. Earlier work on eastern tent caterpillars documented synchronized group foraging and tent-based thermoregulation tied to microclimate, while research on emperor moth caterpillars assessed the thermal and water-relations benefits of aggregation. Studies of forest tent caterpillars and processionary moths have explored how colony size shapes larval performance, and comparative work on nettle-feeding nymphalid butterflies contrasted the thermal ecologies of gregarious and solitary larvae. What sets the new study apart is its explicit field test of the cooling hypothesis. As the authors point out, prior evidence showed that aggregation in caterpillars may enhance heat gain under cool conditions, but whether it also facilitates cooling under warm conditions had remained unknown. Their data now supply that missing half of the picture, and they do so under authentic field conditions rather than in artificial settings.

The implications extend beyond one butterfly species. Larval gregariousness is widespread in the swallowtail family, Papilionidae, and previous work by the same team has shown that this lifestyle is more prevalent outside the tropics and influences traits such as larval melanism and defensive reactions. If grouping provides a two-way thermal buffer, warming cold bodies and cooling warm ones, it could help explain why gregarious living has evolved repeatedly across Lepidoptera and why it persists even when it carries costs, such as making clusters more conspicuous to predators. In an era of increasing climatic variability, a behavior that moderates thermal extremes could carry real fitness consequences, a possibility the authors flag as a priority for future research, alongside the need to evaluate how the observed cooling translates into caterpillar performance and survival.

For now, the study stands as a vivid reminder that even the humblest animals employ sophisticated physical strategies to manage their body temperatures, and that some of those strategies only make sense when many bodies act together. A single caterpillar sweltering on a leaf has few options beyond conforming to the heat. A cluster of them, by contrast, builds a collective thermal microenvironment, one that grows more effective at shedding excess heat as it grows larger. The next time a cluster of striped larvae pulses gently on a sunlit stem, consider that they may not be huddling for warmth at all. They may be air-conditioning themselves, together, one body at a time.

Subject of Research: Field evidence that larval aggregation provides relative cooling under warm conditions in gregarious caterpillars.

Article Title: Field evidence of relative cooling under warm conditions in grouped caterpillars

Article References: Field evidence of relative cooling under warm conditions in grouped caterpillars. (n.d.). https://doi.org/10.1007/s00114-026-02169-1

Image Credits: AI Generated

DOI: 10.1007/s00114-026-02169-1

Keywords: caterpillars, thermoregulation, aggregation, gregariousness, Lepidoptera, body temperature, ectotherms, thermal ecology, group living, swallowtail butterfly, solar radiation, field study

Researchers at the University of Liverpool, working with Richard Wall of the University of Bristol, carried out an extraordinarily intensive sampling campaign at Lyme Park in northern England. Every month from January to December 2022, the team dragged a fabric blanket across fixed transects at four-hour intervals, completing full 24-hour sampling cycles. This design allowed them, for the first time, to separate seasonal variation in tick activity from daily, or diel, variation, two dimensions of behaviour that previous studies had almost always examined in isolation. Because the sampling rounds captured ticks actively questing, that is, climbing vegetation with outstretched forelegs to ambush passing hosts, the counts represent genuine host-seeking behaviour rather than simple abundance.

The headline finding is that questing activity in I. ricinus is predominantly nocturnal. Densities of host-seeking ticks were highest during the dark hours of the sampling cycle, and statistical modelling confirmed that darkness itself was a positive predictor of the number of questing nymphs. This is a striking departure from the popular image of ticks as creatures that latch onto walkers in broad daylight, and it has immediate implications for how people, pets and wildlife encounter infected ticks in the field.

The second major moderator of activity was atmospheric moisture, captured by a single, elegant variable known as the saturation deficit. Saturation deficit combines air temperature and relative humidity into a measure of how strongly the air draws water from living tissue, and it is widely used by entomologists to describe desiccation stress in small terrestrial arthropods. Because ticks lack efficient water-conservation mechanisms and must periodically rehydrate within the humid microclimate of the soil and leaf litter, high saturation deficit effectively forces them off the vegetation and into protective refuges. In the new study, the density of questing nymphs was negatively associated with saturation deficit, meaning that hot, dry conditions suppressed host-seeking even when the season was otherwise favourable.

Crucially, the researchers showed that the strength of the nocturnal activity pattern itself varied with the seasonal moisture environment. Night-time questing was most evident in nymphs during months with high saturation deficit, when daytime conditions were too punishing for ticks to remain exposed. In cooler or wetter periods, when desiccation stress was lower, activity was distributed more evenly across the day. In other words, darkness does not simply switch ticks on; rather, harsh daytime climates push their activity into the night, and benign climates allow it to spread out. This interaction between the daily light cycle and seasonal moisture availability had not previously been demonstrated under natural field conditions for this species.

To untangle these effects, the team analysed their 24-hour, year-round dataset using Generalised Linear Mixed Modelling, a statistical framework well suited to count data with repeated measures. Mixed models allowed the investigators to account for the structure of the design, in which the same transects were sampled month after month at identical clock times, while testing the independent contributions of darkness, temperature, humidity and saturation deficit to tick density. The modelling confirmed that the negative effect of saturation deficit and the positive effect of darkness on questing nymph density were robust after controlling for the sampling structure, giving confidence that the observed rhythms reflect biology rather than artefacts of the schedule.

The seasonal dimension of the results was broadly reassuring for the field. The annual pattern of activity, with questing peaking in the warmer months and collapsing through winter, was largely consistent with previously published data on European tick phenology. Larvae, nymphs and adults each showed characteristic seasonal windows of host-seeking, reflecting the developmental timing that determines which life stages pose a threat at any given time of year. Nymphs, the stage most often implicated in transmitting Borrelia bacteria and tick-borne encephalitis virus to humans, dominated the datasets in the ways that surveillance specialists have come to expect.

What makes the study transformative is not the seasonal story but the daily one. Diel patterns in tick behaviour have been chronically understudied, largely because most tick surveillance is conducted during working hours, typically between mid-morning and late afternoon. If ticks quest mainly at night, or shift their activity into nocturnal windows during dry spells, then standard daytime dragging may systematically misestimate both true abundance and true biting risk. The authors point out that these commonly overlooked daily rhythms have important implications for estimating abundance in scientific research and surveillance programmes, and for interpreting how hazard varies across the day rather than across the year alone.

There are also ecological consequences for the transmission of pathogens among wildlife. Different host species are active at different times: birds, small mammals and deer partition the 24-hour cycle in ways that determine which hosts a nocturnal tick is most likely to encounter. If I. ricinus concentrates its host-seeking in the dark, the feeding opportunities available to it, and therefore the transmission circuits available to the pathogens it carries, may be structured by the clock as much as by the calendar. Reservoir hosts that forage at night could contribute disproportionately to infection cycles, while daytime-active animals, including humans, may benefit from the desiccation-driven suppression of tick activity during hot, dry daytime conditions. Understanding these synchronies could sharpen models of disease emergence and inform the timing of interventions, from acaricide application to public health messaging about when and where exposure risk peaks.

For the public, the practical message is nuanced rather than alarmist. Tick bites remain possible at any hour, and risk is shaped locally by habitat, vegetation and recent weather. But the study suggests that people walking in tick habitat during cool, humid evenings and overnight periods may face greater exposure than conventional advice implies, while hot, dry middays may offer comparatively lower risk, not because ticks are absent but because they are sheltering from the desiccating air. Dog walkers and other pet owners, whose animals often roam at dawn and dusk, should take particular note. As climate change alters temperature and humidity regimes across Europe, the seasonal windows and daily rhythms of tick activity are likely to shift in ways that current, daylight-biased surveillance is poorly equipped to detect. This year-round, round-the-clock field study offers a methodological template for closing that blind spot, and a timely reminder that the ecology of one of Europe’s most consequential disease vectors unfolds largely after dark.

Subject of Research: Seasonal and diel environmental drivers of host-seeking (questing) behaviour in the European tick vector Ixodes ricinus.

Article Title: Seasonal and diel environment effects on host-seeking behaviour in the European tick vector, Ixodes ricinus

Article References: Noll, M., Wall, R., Makepeace, B. L., & Rose Vineer, H. (2026). Seasonal and diel environment effects on host-seeking behaviour in the European tick vector, Ixodes ricinus. Parasites & Vectors. https://doi.org/10.1186/s13071-026-07679-5

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07679-5

Keywords: Ixodes ricinus, ticks, questing behaviour, host-seeking, saturation deficit, diel activity, seasonal activity, vector-borne disease, Lyme borreliosis, tick surveillance, Parasites & Vectors, field study