Posts tagged primates
Articles and news from the latest research reports.
Neural interaction in periods of silence
While in deep dreamless sleep, our hippocampus sends messages to our cortex and changes its plasticity, possibly transferring recently acquired knowledge to long-term memory. But how exactly is this done? Scientists from the Max Planck Institute for Biological Cybernetics have now developed a novel multimodal methodology called “neural event-triggered functional magnetic resonance imaging” (NET-fMRI) and presented the very first results obtained using it in experiments with both anesthetized and awake, behaving monkeys. The new methodology uses multiple-contact electrodes in combination with functional magnetic resonance imaging (fMRI) of the entire brain to map widespread networks of neurons that are activated by local, structure-specific neural events.
Primate Behavior May Reveal Clues to Evolution of Favor Exchange in Humans
When your neighbor asks to borrow a cup of sugar and you readily comply, is your positive response a function of the give and take that characterize your longstanding relationship? Or does it represent payment –– or prepayment –– for the cup of sugar you borrowed last week, or may need to borrow a month from now?
Adrian Jaeggi, a postdoctoral researcher in anthropology at UC Santa Barbara, and a junior research fellow at the campus’s SAGE Center for the Study of the Mind, is studying this question of reciprocity, using chimpanzees and bonobos as his test subjects. His findings appear in the current online issue of the journal Evolution & Human Behavior.
"The article focuses on the question of whether individuals do favors because they expect them to be reciprocated at some other time, and, more specifically, whether such exchanges have to happen immediately, or can take place over longer time spans," Jaeggi explained. "We studied the question in chimpanzees and bonobos –– our two closest living relatives –– and looked at the exchanges of grooming and food sharing, which are two common types of favors among these apes."
According to Jaeggi, while results of his research provide some evidence for immediate exchanges, they more strongly support the notion that favors are exchanged over long periods of time. Calculated exchanges, in which individuals keep a detailed score of past interactions, are much less common than the more loosely balanced exchanges that take place in stable relationships.
Great apes go through mid-life crisis
They may not take up surfing or start second careers as cupcake-makers, but chimpanzees and orangutans seem to go through a ‘mid-life crisis’, just like humans.
A study of 508 great apes in captivity shows that the animals’ sense of well-being bottoms out in their late 20s to mid-30s, the ape equivalent of middle age, before rebounding in old age.
The finding that mid-life crises may not be uniquely human suggests that the events might have a biological, rather than a sociological, cause.
Men and women worldwide, regardless of their wealth or status, experience a dip in happiness at middle-age, generally defined as from the mid-30s to late 50s. Despite this universality, social scientists have struggled to identify the underlying cause of the dissatisfaction. Social and economic factors, such as financial hardship and the failure to realize unrealistic ambitions, are possible causes.
Alexander Weiss, a psychologist at the University of Edinburgh, UK, and his team set out to see if there might be a biological factor involved in the crises. They sought to assess the well-being of captive chimpanzees and orangutans as judged by their keepers or those who knew them well.
The apes covered all age ranges, and their ‘happiness’ was rated through a survey answered by their keepers. The survey covered four criteria: the animals’ overall mood; how much pleasure they got out of socializing; their success in achieving goals such as obtaining food and objects they desire; and how happy the keeper would be if he or she were that animal for a week.
The survey is admittedly anthropomorphic, says Weiss, but he adds that it is easy for someone who spends a lot of time with an ape to gauge its mood. Moreover, his previous work shows that the measure of well-being is consistent when measured by different caretakers, and is based, in part, on inherited genetic factors.
Among three different groups of chimps and orangutans surveyed, the happiest tended to be the oldest and youngest, and the most dissatisfied tended to be in their 30s. The study, however, is a snapshot — it didn’t follow any of the apes over time — which means there could be confounding factors such as the early death of unhappy apes. Nonetheless, Weiss believes the results offer a true picture.
Bonobos Catch Yawns from Friends
For bonobos, yawning is contagious, but only between friends.
Yawns spread more easily between family and close friends, and from high-status monkeys to those lower on the totem pole, according to a study published online in the journal PLoS ONE. This pattern of social yawning mimics one found in humans and suggests infectious yawning is a byproduct of empathy, which coordinates emotions in a group.
"It underlines that the mechanism of yawn contagion in the two species is the same," said study co-author Elisabetta Palagi, a primate researcher at the University of Pisa in Italy. "One of the possible functions of yawn contagion is to synchronize individuals of a social group. In humans, yawn contagion is extremely important but just between people who share strong bonds."
Photographer Volker Gutgessell has spent the last four years visiting Frankfurt Zoo capturing these sensitive images of bonobos, gorillas and orangutans. Standing for several hours a day, the 58-year-old has documented the behaviours and expressions of his subjects - despite suffering chronic back pain caused by a severe slipped disc. Volker also developed tinnitus as a result of his injury, causing a constant ringing in his ears. But despite his condition, he has found a way of communicating through his pictures and picks up on the body language of his ape “models” while shooting them.
(Source: telegraph.co.uk)
Humans, Chimpanzees and Monkeys Share DNA but Not Gene Regulatory Mechanisms
Humans share over 90% of their DNA with their primate cousins. The expression or activity patterns of genes differ across species in ways that help explain each species’ distinct biology and behavior.
DNA factors that contribute to the differences were described on Nov. 6 at the American Society of Human Genetics 2012 meeting in a presentation by Yoav Gilad, Ph.D., associate professor of human genetics at the University of Chicago.
Dr. Gilad reported that up to 40% of the differences in the expression or activity patterns of genes between humans, chimpanzees and rhesus monkeys can be explained by regulatory mechanisms that determine whether and how a gene’s recipe for a protein is transcribed to the RNA molecule that carries the recipe instructions to the sites in cells where proteins are manufactured.
In addition to improving scientific understanding of the uniqueness of humans, studies such as the investigation conducted by Dr. Gilad and colleagues could have relevance to human health and disease.
"Through inter-species’ comparisons at the DNA sequence and expression levels, we hope to identify the genetic basis of human specific traits and in particular the genetic variations underlying the higher susceptibility to certain diseases such as malaria and cancer in humans than in non-human primates," said Dr. Gilad.
Dr. Gilad and his colleagues studied gene expression in lymphoblastoid cell lines, laboratory cultures of immortalized white blood cells, from eight humans, eight chimpanzees and eight rhesus monkeys.
They found that the distinct gene expression patterns of the three species can be explained by corresponding changes in genetic and epigenetic regulatory mechanisms that determine when and how a gene’s DNA code is transcribed to a messenger RNA (mRNA) molecule.
Dr. Gilad also determined that the epigenetics process known as histone modification also differs in the three species. The presence of histone marks during gene transcription indicates that the process is being prevented or modified.
"These data allowed us to identify both conserved and species-specific enhancer and repressor regulatory elements, as well as characterize similarities and differences across species in transcription factor binding to these regulatory elements," Dr. Gilad said.
Among the similarities among the three species were the promoter regions of DNA that initiated transcription of a particular gene.
In all three species, Dr. Gilad’s lab found that transcription factor binding and histone modifications were identical in over 67% of regulatory elements in DNA segments that are regarded as promoter regions.
The researchers presentation is titled, “Genome-wide comparison of genetic and epigenetic regulatory mechanisms in primates.”
(Source: sciencedaily.com)
Primates teach us about society
A Swiss primatologist who arrived at The University of Western Australia in April to work in the School of Anatomy, Physiology and Human Biology probably won’t mind too much if his students start ‘monkeying around’ occasionally in class.
Assistant Professor Cyril Grueter is used to it, having spent almost two years in Yunnan - a remote mountainous region of China - studying a group of 400 black and white snub-nosed monkeys.
The monkeys - never seen outside China - live in similar social groups to humans and Assistant Professor Grueter observed them in their wild state to investigate the evolutionary pathways that lead to our multilevel societies. His study was recently published in the International Journal of Primatology.
For early man, walking beat talking
A new fossil discovery shows we did not climb out of the trees until much later than once thought.
Animals, including dogs, dolphins, monkeys and man, follow gaze. What mediates this bias towards the eyes? One hypothesis is that primates possess a distinct neural module that is uniquely tuned for the eyes of others. An alternative explanation is that configural face processing drives fixations to the middle of peoples’ faces, which is where the eyes happen to be located. We distinguish between these two accounts. Observers were presented with images of people, non-human creatures with eyes in the middle of their faces (`humanoids’) or creatures with eyes positioned elsewhere (`monsters’). There was a profound and significant bias towards looking early and often at the eyes of humans and humanoids and also, critically, at the eyes of monsters. These findings demonstrate that the eyes, and not the middle of the head, are being targeted by the oculomotor system.
Primates’ brains make visual maps using triangular grids
Primates’ brains see the world through triangular grids, according to a new study published online Sunday in the journal Nature.
Scientists at Yerkes National Primate Research Center, Emory University, have identified grid cells, neurons that fire in repeating triangular patterns as the eyes explore visual scenes, in the brains of rhesus monkeys.
The finding has implications for understanding how humans form and remember mental maps of the world, as well as how neurodegenerative diseases such as Alzheimer’s erode those abilities. This is the first time grid cells have been detected directly in primates. Grid cells were identified in rats in 2005, and their existence in humans has been indirectly inferred through magnetic resonance imaging.
Grid cells’ electrical activities were recorded by introducing electrodes into monkeys’ entorhinal cortex, a region of the brain in the medial temporal lobe. At the same time, the monkeys viewed a variety of images on a computer screen and explored those images with their eyes. Infrared eye-tracking allowed the scientists to follow which part of the image the monkey’s eyes were focusing on. A single grid cell fires when the eyes focus on multiple discrete locations forming a grid pattern.
"The entorhinal cortex is one of the first brain regions to degenerate in Alzheimer’s disease, so our results may help to explain why disorientation is one of the first behavioral signs of Alzheimer’s," says senior author Elizabeth Buffalo, PhD, associate professor of neurology at Emory University School of Medicine and Yerkes National Primate Research Center. "We think these neurons help provide a context or structure for visual experiences to be stored in memory."
"Our discovery of grid cells in primates is a big step toward understanding how our brains form memories of visual information," says first author Nathan Killian, a graduate student in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University. "This is an exciting way of thinking about memory that may lead to novel treatments for neurodegenerative diseases."
(Image credit: Mark Snelson)