Deutsches Primatenzentrum http://example.com de_DE TYPO3 News Tue, 19 Mar 2024 10:09:59 +0100 Tue, 19 Mar 2024 10:09:59 +0100 TYPO3 EXT:news news-4466 Thu, 14 Mar 2024 13:27:11 +0100 Less social with age http://www.dpz.eu/news/news/single-view/news/weniger-sozial-im-alter.html Field studies confirm social network shrinking in ageing monkeys As people get older, they increasingly focus on their more important relationships, often turning to family and close friends. This active reorientation towards a few, particularly close relationships could explain why ageing humans live in ever smaller social networks. Since human behavior not only reflects the current conditions of our modern society, but is also the result of our evolutionary past, studies on social aging in our closest relatives can shed light on the biological roots of social behavior. Scientists from the Research Group Social Evolution in Primates at the German Primate Center (DPZ) - Leibniz Institute for Primate Research and the Department for Behavioral Ecology at the University of Göttingen tested several hypotheses on the drivers of social aging in free-living Assamese macaques in Thailand. The researchers collected data on the social behavior of females for eight years and found that the size of their social networks decreases with increasing age. The females continued to interact with their close social partners, but gradually withdrew from social interactions altogether. The results contribute to the understanding of the evolutionary origins of social ageing (Proceedings of the Royal Society B).

Social bonds promote health and well-being. However, as people age, they often reduce their social contacts and focus on the people who are most important to them – family and close friends. So far, it is unclear whether this change in social engagement is motivated by the knowledge of a limited lifespan, by physical limitations of an aging body or perhaps by the social exclusion of older people in modern societies. Baptiste Sadoughi, first author of the study and former PhD student in the Social Evolution in Primates Group at the German Primate Center turned to long-term social data on female Assamese macaques collected at the DPZ field site at Phu Khieo Wildlife Sanctuary to test the drivers of social aging in non-human primate species that lack a human-like sense of mortality. The team has been studying the behavior of Assamese macaques at Phu Khieo for years amassing thousands of hours of detailed observations of their social behavior.

“For the question of social aging, we focused on females, because they remain with their mothers, sisters and daughters in their natal group all their lives, which allowed us to track changes in behavior over their life span”, Sadoughi explains.

Active social withdrawal with a constant preference for important partners
Sadoughi found that with increasing age, the females approached other females less frequently and invested less time in actively grooming them. However, less social contact does not necessarily mean that the females are alone more often. In fact, older females were not more often spatially isolated than younger ones, they just interacted less. "We assume that older females try to keep up with the group at all costs, as proximity to others is one of the best protective mechanisms against predators. However, once they have achieved this, they lack the motivation or energy to engage socially with others,” says Sadoughi.

Given the parallels between social ageing in humans and macaques, the question now arose as to whether the increasing social selectivity assumed for humans could also explain the results in macaques. “Assamese macaque females are selective. Who a female has interacted with more in the past predicts who she will interact with now. But this tendency to be selective and prefer certain partners over others doesn't get stronger with age, as we know it from humans, it stays the same. Something that is constant over age cannot explain something that decreases with age. Selectivity in partner choice is therefore not sufficient to explain the age-dependent reduction of the social network,” explains Sadoughi.

Longitudinal data are needed for aging studies

Studying age-related changes is further complicated by another phenomenon that has little to do with what we usually think of as aging. “With age comes a greater risk of death. With poor social integration and fewer partners close by comes a greater risk of death, especially under natural predation pressure. This simple fact means that changes in social integration with age are partially confounded by the greater likelihood that individuals who reach old age will be exceptionally well-connected socially, because the less well-connected have already died, a phenomenon called selective disappearance,” explains Julia Ostner, head of the Social Evolution in Primates Group and senior author of the study. Access to longitudinal data has allowed the researchers to solve this problem and distinguish between changes that are truly related to aging, and those that are due to demographic trends.

Only in the last twenty years have scientists recognized that wild animals also undergo physiological, morphological or social changes associated with the ageing process. For a long time, it was assumed that individuals in the wild do not survive long enough to show signs of ageing. “Only now are we beginning to realize the possibilities offered by long-term data on animal populations in their natural environment to study how individuals deal with the challenges of aging,” says Baptiste Sadoughi.

Original publication
Sadoughi B, Mundry R, Schülke O, Ostner J. (2024): Social network shrinking is explained by active and passive effects but not increasing selectivity with age in wild macaques. Proc. R. Soc. B 291: 20232736. https://doi.org/10.1098/rspb.2023.2736

]]>
Pressemitteilungen
news-4464 Wed, 06 Mar 2024 09:56:46 +0100 Patience pays off http://www.dpz.eu/news/news/single-view/news/geduld-lohnt-sich-1.html Researchers decode the neuronal basis of decision-making processes and can thus predict actions In a new study, neuroscientists show how decision-making processes are controlled in the primate brain during foraging. The team, including a researcher from the German Primate Center (DPZ) – Leibniz Institute for Primate Research in Göttingen, trained two rhesus monkeys to search for food in an experimental room. The animals were able to move freely and receive food pellets from two food boxes by pressing a button. In the course of the experiment, the monkeys learned that the amount of pellets dispensed from the boxes increased the longer they waited until the next button was pressed. If they were not rewarded with pellets after pressing the button, the monkeys waited longer the next time or switched to the other box. During the experiment, the researchers measured the neuronal activity in the front part of the brains of the two monkeys and decomposed it with the help of a mathematical model. By decoding monkeys’ reward expectations from the neural activity, they were able to predict how long the rhesus monkeys were willing to wait for a higher reward and when they decided to choose another option. The results advance our understanding of self-paced actions, eventually contributing to a better understanding of neurological diseases such as Parkinson's (Nature Neuroscience).

Imagine a fisherman on a boat casting fish traps into a murky lake. To be successful, he has to check the traps regularly. But when is the best time to do this? If he checks the traps too often, it is unnecessary work and he scares the fish away. If he checks too late, he has a better chance, but may be wasting time. It is also tiring to paddle from one trap to another to check them one after the other, so the fisherman has to keep deciding whether and when it is worthwhile.

For decades, neuroscientists have been trying to understand how we manage to make the best possible decisions. Due to technical limitations, researchers have so far had to rely on experiments in which monkeys perform tasks on computer screens while the activity of their brain cells is measured. The animals are trained to sit still in a chair and are therefore restricted in their natural freedom of movement. Since it is now possible to wirelessly record the activity of several individual nerve cells, decision-making in scenarios with natural movement sequences can be investigated.

For the study, a team of researchers from Germany and the USA trained two rhesus monkeys to explore an experimental room with two button-controlled food boxes. Each time the monkeys pressed a button on one of the boxes, they had the chance to receive food pellets. The two boxes were set in such a way that the time intervals between the individual food dispenses became longer and longer during an experimental run. The longer the monkeys waited until they pressed the button again, the more pellets they received.

“When we started the experiment, we expected that our monkeys would simply choose the box based on how successful they had been with that box before,” explains first author Neda Shahidi, now a junior research group leader at the Collaborative Research Center 1528 at the University of Göttingen and the German Primate Center in Göttingen. “After a while, however, they had learned to pay attention to the time since the last keystroke and also to their previous success at a box. If they had waited a while but not received any pellets, they waited even longer before pressing the next time. However, if they were not rewarded too many times in a row after pressing the button, they moved to the other box. They had apparently decided that this food box was not worth the wait and it was better to look elsewhere.”

To analyze the underlying neuronal processes, the researchers wirelessly recorded the activity of 96 neurons in the prefrontal cortex. This brain area is involved in the control of goal-directed behavior and is activated in many aspects of the foraging task, for example in the evaluation of options, the expectation of a reward, the preparation of actions, and the perception of the outcome.

“However, characterizing the activity patterns of individual neurons does not always reveal the whole story when we study complex decision-making processes,” Shahidi explains. “Complex behaviors consist of different components that are sometimes processed simultaneously in the same brain area.” To separate these components, the researchers developed a mathematical model that first identified components of neural activity, mainly consist of groups of neurons that were more strongly active when the animals waited longer before pressing a button or when the button has been more rewarding in last few presses. Since the animals cannot know in advance whether a button press will be rewarded, the researchers assume that these neurons represent the animals' subjective expectations.

The researchers also tested whether the neuronal activity could be used to predict when the animals would press the button and whether they would decide to switch between the boxes. “We were surprised at how well our model could predict what the monkeys would do in the next few seconds,” says Shahidi. “Our results show not only how the development of wireless recording technologies can improve our understanding of brain mechanisms in natural movement scenarios, but also how advances in data science are transforming neuroscience by extracting the computational components of the brain from the collective activity of neurons. We hope that in the long term, such advances will help to better understand abnormalities in cognitive processes such as self-pacing in Parkinson's or self-initiating actions in apathy” says Shahidi.

Original publication

Shahida N, Parajuli A, Franch M, Schrater P, Wright A, Pikow X, Dragoi V (2024): Population coding of strategic variables during foraging in free-moving macaques. Nature Neuroscience, https://doi.org/10.1038/s41593-024-01575-w

]]>
Pressemitteilungen Kognitive Neurowissenschaften SMG
news-4454 Mon, 04 Mar 2024 15:00:00 +0100 Money well spent on field research  http://www.dpz.eu/news/news/single-view/news/geld-fuer-feldforschung-ist-gut-angelegt.html Study shows immense importance of field stations for biodiversity and species conservation A recent study, which included data from 157 field stations in 56 countries, is the first to systematically demonstrate the value and efficiency of field stations: Not only do they make a significant contribution to biodiversity conservation by reducing deforestation rates and hunting activities, they also play a crucial role as employers and training centers. Unfortunately, more than half of the field stations complain about cuts in their financial support, in some cases due to considerable shifts in research funding. The recently published study impressively demonstrates that these cuts are highly uneconomical (Conservation Letters).

In the recently published study, the operators of 157 field stations worldwide where primate research takes place were surveyed. 80 percent of those surveyed reported an increase in the quality of habitats and reduced hunting activities in the vicinity of the stations, and almost 70 percent also reported an increase in controls by the authorities with regard to poaching and other illegal activities. Satellite images document that the loss of forest area within a radius of five kilometers around the field stations between 2000 and 2020 was significantly lower than in comparable forest areas. According to the Red List of Threatened Species (IUCN), the areas around the field stations are home to 1,045 terrestrial vertebrates that are considered threatened. At the same time, it was shown that the operating costs per square meter of area at a field station are significantly lower than the costs incurred in protected areas. "In our study, we were able to systematically demonstrate the importance of field stations for biodiversity and their good cost-benefit ratio for the first time," says Julia Fischer, scientist at the German Primate Center and head of the Simenti research station in Senegal, where she and her team have been researching Guinea baboons for almost twenty years.


Effects of the COVID-19 pandemic
From March 2020 to June 2022, almost half of all field stations were completely or partially closed. "It is only thanks to the local field assistants and station managers that research was able to take place at all during this time," says Julia Fischer. Half of the stations stated that they now have less or much less funding available than before the pandemic, with only 9% reporting an increase in funding.


Importance of long-term data
Most of the field stations surveyed are still in operation, on average for 22 years. "Only data over long periods of time can provide information on the effects of climate change and biodiversity loss and are therefore the basis for effective conservation measures," says Peter Kappeler, Head of the Behavioral Ecology and Sociobiology Unit at the German Primate Center and the Kirindy Field Station in Madagascar, which has been in operation since 1993. 


Training, nature and species conservation
93 percent of the stations employ local people and thus support the local economy, while at the same time providing important scientific results that feed into conservation policy. "From a conservation perspective, investments in field stations pay off in several ways: they promote the conservation of biodiversity, enable scientific research and contribute to the education and economic development of the local population," says Julia Ostner, head of a research station in Thailand, where the behavior of Assamese macaques has been studied since 2005. 


Field research at the German Primate Center
The German Primate Center - Leibniz Institute for Primate Research operates five field stations in Peru, Senegal, Guinea, Madagascar and Thailand, where the behavior and ecology of various primate species are studied. The oldest station has been in operation for over 30 years, the youngest for just under two years. All stations are integrated into the local communities, employ local field assistants and station managers and train students - also in the home countries of the respective stations. The researchers are also involved in local nature conservation projects and public relations work to draw attention to the loss of biodiversity and the associated consequences. The DPZ stations were also affected by the COVID-19 pandemic, but valuable long-term data series could be maintained, primarily thanks to the efforts of local employees.

Original pulication

Timothy M. Eppley et al. (2024): Tropical field stations yield high conservation return on investment. Conservation Letters. https://doi.org/10.1111/conl.13007

]]>
Primate Cognition - News Listing Primate Cognition - Slider Pressemitteilungen
news-4444 Mon, 29 Jan 2024 10:19:33 +0100 Chimärenforschung im Blickpunkt http://www.dpz.eu/news/news/single-view/news/chimaerenforschung-im-blickpunkt-1.html Stefan Schlatt und Rüdiger Behr sprechen im Interview über Chancen, Risiken und ethische Grenzen Chimäre – das Wort klingt abstrakt und geheimnisvoll zugleich. In der griechischen Mythologie ist die „Chimära“ ein feuerspeiendes Mischwesen, das vorn wie ein Löwe, in der Mitte wie eine Ziege und hinten wie eine Schlange aussieht. In der Biologie bezeichnet man als Chimäre einen Organismus, der aus Zellen besteht, die von zwei oder mehr unterschiedlichen Embryonen abstammen und trotzdem ein Individuum bilden. Chimären können natürlicherweise entstehen oder künstlich im Labor generiert werden. Bereits seit den siebziger Jahren wird daran geforscht. Von Maus-Ratte- oder Wachtel-Huhn- über Schaf-Ziege- bis hin zu Mensch-Schwein-Chimären.

Auch Primaten werden zunehmend in Chimären-Studien eingesetzt. Im Jahr 2021 erschien eine Studie, in der Forschende menschliche Stammzellen in Embryonen von Javaneraffen eingebracht hatten. Die Chimären überlebten ungewöhnlich lange in der Kulturschale. In einer Veröffentlichung eines Chinesischen Forschendenteams im November 2023 wurden jüngst intraspezifische Chimären aus zwei unterschiedlichen Javaneraffen geschaffen. Das Besondere: Den Wissenschaftler*innen gelang es, dass ein chimäres Tier geboren wurde und rund zehn Tage lebte. Vergleichbare Resultate gab es zuvor nur bei Mäusen oder Ratten.

Aber warum forschen Wissenschaftler*innen weltweit daran? Welche Erkenntnisse erhofft man sich in der Grundlagenforschung und welchen praktischen medizinischen Nutzen können wir erwarten? Stefan Schlatt, Direktor des Centrums für Reproduktionsmedizin und Andrologie am Universitätsklinikum Münster, und Rüdiger Behr, Leiter der Forschungsplattform Degenerative Erkrankungen am Deutschen Primatenzentrum in Göttingen, sind Experten auf den Forschungsgebieten Stammzellen, Reproduktionsbiologie und Embryonalentwicklung. Im Interview diskutieren sie die Chancen und Risiken der Chimärenforschung, erklären welche Rolle Studien mit Primaten dabei spielen und betrachten das Thema aus ethischer Perspektive.

Zum Interview gelangen Sie hier

]]>
Allgemeine News Stammzellbiologie Tierversuche