Links for Keyword: Evolution
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By Elise Cutts In March 2019, on a train headed southwest from Munich, the neuroscientist Maximilian Bothe adjusted his careful grip on the cooler in his lap. It didn’t contain his lunch. Inside was tissue from half a dozen rattlesnake spinal cords packed in ice — a special delivery for his new research adviser Boris Chagnaud, a behavioral neuroscientist based on the other side of the Alps. In his lab at the University of Graz in Austria, Chagnaud maintains a menagerie of aquatic animals that move in unusual ways — from piranhas and catfish that drum air bladders to produce sound to mudskippers that hop around on land on two fins. Chagnaud studies and compares these creatures’ neuronal circuits to understand how new ways of moving might evolve, and Bothe was bringing his rattlesnake spines to join the endeavor. The ways that animals move are just about as myriad as the animal kingdom itself. They walk, run, swim, crawl, fly and slither — and within each of those categories lies a tremendous number of subtly different movement types. A seagull and a hummingbird both have wings, but otherwise their flight techniques and abilities are poles apart. Orcas and piranhas both have tails, but they accomplish very different types of swimming. Even a human walking or running is moving their body in fundamentally different ways. The tempo and type of movements a given animal can perform are set by biological hardware: nerves, muscle and bone whose functions are bound by neurological constraints. For example, vertebrates’ walking tempos are set by circuits in their spines that fire without any conscious input from the brain. The pace of that movement is dictated by the properties of the neuronal circuits that control them. For an animal to evolve a novel way of moving, something in its neurological circuitry has to change. Chagnaud wants to describe exactly how that happens. “In evolution, you don’t just invent the wheel. You take pieces that were already there, and you modify them,” he said. “How do you modify those components that are shared across many different species to make new behaviors?” © 2024 Simons Foundation.
Related chapters from BN: Chapter 11: Motor Control and Plasticity; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 29194 - Posted: 03.16.2024
By Erin Garcia de Jesús A genetic parasite may have robbed humans and other apes of their tails. Around 25 million years ago, this parasite, a small stretch of repetitive DNA called an Alu element, ended up in a gene important for tail development, researchers report in the Feb. 29 Nature. The single insertion altered the gene Tbxt in a way that seems to have sparked one of the defining differences between monkeys and apes: Monkeys have tails, apes don’t. “It was like lightning struck once,” says Jef Boeke, a geneticist at New York University Langone Health, and ape behinds ultimately became bare. The genetic tweak may also give insight into why some babies are born with spinal cord defects such as spina bifida, when the tube that holds the cord doesn’t close all the way (SN: 12/6/16). Alu elements are part of a group of genetic parasites known as transposons or jumping genes that can hop across genetic instruction books, inserting themselves into their hosts’ DNA (SN: 5/16/17). Sometimes, when the gene slips itself into a piece of DNA that is passed down to offspring, these insertions become permanent parts of our genetic code. Transposons, including more than 1 million Alu elements, are found throughout our genome, says geneticist and systems biologist Bo Xia of the Broad Institute in Cambridge, Mass. Researchers once thought of transposons as genetic garbage, but some have central roles in evolution. Without transposons, the placenta, immune system and insulation around nerve fibers may not exist (SN: 2/16/24). And humans might still have tails. To find out how apes lost their tails, Xia, then at NYU Langone Health, Boeke and colleagues analyzed 140 genes involved in vertebrate tail development. © Society for Science & the Public 2000–2024.
Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 29170 - Posted: 02.29.2024
By Annie Melchor When the first known flying dinosaurs took to the skies some 150 million years ago, the evolutionary leap relied on adaptations to their nervous system. The changes remained a mystery, though, because of the paucity of fossilized neural tissue. Now fresh clues have emerged from a study that started with the long-gone dinosaurs’ living kin: the common pigeon, Columba livia. Flight taps neural pathways involving the pigeon’s cerebellum, the new works shows, which prompted study investigator Amy Balanoff and her team to look specifically at that structure in digital brain “endocasts,” created by CT scanning fossilized dinosaur skulls. “The birds can help us look for certain things within these extinct animals,” says Balanoff, assistant professor of evolutionary biology at Johns Hopkins University. “Then these extinct animals can tell us about the evolutionary history leading up to living birds.” An analysis of the endocasts — from 10 dinosaur specimens dating to between 90 and 150 million years ago — revealed that the volume of the cerebellum expanded in birds’ closest relatives, but not in more distant ones. And at some point, the cerebellum began folding — instead of growing — to accommodate more neurons within a fixed cranial space, Balanoff says. The results suggest that the cerebellum was “flight-ready before flying,” says Crístian Gutiérrez-Ibáñez, an evolutionary biology research associate at the University of Alberta who was not involved in the study. “So the question is, why did dinosaurs get such a big cerebellum?” © 2024 Simons Foundation
Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 29162 - Posted: 02.25.2024
By Cara Giovanetti The human brain's billions of neurons represent a menagerie of cells that are among both the most highly specialized and variable ones in our bodies. Neurons convert electrical signals to chemical signals, and in humans, their lengths can be so tiny as to span just the tip of a sharpened pencil or, in some cases, even stretch the width of a doorway. Their flexible control of movement and decision-making explains why they are so key to survival in the animal kingdom. Most animals depend on their allotment of neurons for survival. It might stand to reason, then, that the common ancestor of all of these animals also moved about the Earth millions of years ago under the guidance of electrochemical signals transmitted and received by networks of neurons. The idea that these pivotal cells evolved multiple times seems implausible because neurons are highly complex cells, and they are also quite similar among animal lineages. But a series of recent evolutionary biology studies are straining the assumption that all animal neurons have a single origin. These findings are the culmination of several years’ worth of research on and debate about early evolutionary animal lineages and the cells and systems present in those species. The first such finding came from studying relationships among early animals, with a focus on two particular types of organisms: sponges (including sea sponges and freshwater varieties) and ctenophores, invertebrates often known as comb jellies, though they are unrelated to jellyfish. For roughly 15 years, evolutionary biologists have been divided over whether ctenophores or sponges were the first animals to branch from all other animals in the evolutionary tree. Hundreds of millions of years ago the common ancestor to all living animals branched into two species. On one side was the common ancestor of all groups of animals except for one. On the other side was that “one”—the “sister group” that was the first to diverge from all other animals. A persistent question has been whether the sister group was the sponges or ctenophores. A compelling paper published last year lends strong support to the hypothesis that ctenophores are, in fact, the long-sought sister group. Ctenophores, the researchers found, branched off before sponges and are therefore the group most distantly related to all other animals. Yet despite the new evidence, what exactly happened in evolutionary history is still unsettled because of the puzzle it poses in explaining the evolution of neurons. © 2023 SCIENTIFIC AMERICAN,
Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 29081 - Posted: 01.06.2024
By Joseph Howlett Garter snakes have something in common with elephants, orcas, and naked mole rats: They form social groups that center around females. The snakes have clear “communities” composed of individuals they prefer hanging out with, and females act as leaders that tie the groups together and guide their members’ movements, according to the most extensive field study of snake sociality ever carried out. “This is an important first step in understanding how a community of snakes is organized in the wild,” says Gordon Burghardt, an ecologist at the University of Tennessee, Knoxville, who was not involved in the research. Other experts agree: “This is a big deal,” says integrative biologist Robert Mason of Oregon State University. “It’s a whole new avenue of research that I don’t think people have really given any thought to.” Ecologists had long assumed snakes are antisocial loners that hang out together only for core functions such as mating and hibernation. However, in 2020, Morgan Skinner, a behavioral ecologist at Wilfrid Laurier University, and collaborators showed in laboratory experiments that captive garter snakes have “friends”—specific snakes whose company they prefer over others. Still, studies of wild snakes were lacking “because they’re so secretive and difficult to find,” Skinner says. Then he learned that the Ontario Ministry of Transportation had funded an unprecedented long-term study of a huge population of Butler’s garter snakes (Thamnophis butleri) in Windsor, Canada. Ecologists began to monitor the flute-size slitherers in 2009 to keep them safe from nearby road construction. They regularly captured snakes in the 250-hectare study area, using identifying markings to track more than 3000 individuals over a 12-year span—about the lifetime of a garter snake. “We were mainly monitoring the population after they were relocated, to make sure they were thriving,” says Megan Hazell, a biologist with the consulting firm WSP, who led the field research as a graduate student at Queen’s University.
Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 29050 - Posted: 12.16.2023
By Carl Zimmer Sign up for Science Times Get stories that capture the wonders of nature, the cosmos and the human body. Get it sent to your inbox. If a troop of baboons encounters another troop on the savanna, they may keep a respectful distance or they may get into a fight. But human groups often do something else: They cooperate. Tribes of hunter-gatherers regularly come together for communal hunts or to form large-scale alliances. Villages and towns give rise to nations. Networks of trade span the planet. Human cooperation is so striking that anthropologists have long considered it a hallmark of our species. They have speculated that it emerged thanks to the evolution of our powerful brains, which enable us to use language, establish cultural traditions and perform other complex behaviors. But a new study, published in Science on Thursday, throws that uniqueness into doubt. It turns out that two groups of apes in Africa have regularly mingled and cooperated with each other for years. “To have extended, friendly, cooperative relationships between members of other groups who have no kinship ties is really quite extraordinary,” said Joan Silk, a primatologist at Arizona State University who was not involved in the study. The new research comes from long-term observations of bonobos, an ape species that lives in the forests of the Democratic Republic of Congo. A century ago, primatologists thought bonobos were a slender subspecies of chimpanzee. But the two species are genetically distinct and behave in some remarkably different ways. Among chimpanzees, males hold a dominant place in society. They can be extremely violent, even killing babies. In bonobo groups, however, females dominate, and males have never been observed to commit infanticide. Bonobos often defuse conflict with sex, a strategy that primatologists have not observed among chimpanzees. Scientists made most of their early observations of bonobos in zoos. But in recent years they’ve conducted long-term studies of the apes in the wild. © 2023 The New York Times Company
Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 29011 - Posted: 11.18.2023
COMIC: When, why and how did neurons first evolve? Scientists are piecing together the ancient story. By Tim Vernimmen Illustrated by Maki Naro 09.14.2023 © 2023 Annual Reviews
Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28920 - Posted: 09.21.2023
By Kenneth S. Kosik Before our evolutionary ancestors had a brain—before they had any organs—18 different cell types got together to make a sea sponge. Remarkably, some of these cells had many of the genes needed to make a brain, even though the sponge has neither neurons nor a brain. In my neuroscience lab at the University of California, Santa Barbara, my colleagues and collaborators discovered this large repository of brain genes in the sponge. Ever since, we have asked ourselves why this ancient, porous blob of cells would contain a set of neural genes in the absence of a nervous system? What was evolution up to? The sea sponge first shows up in the fossil record about 600 million years ago. They live at the bottom of the ocean and are immobile, passive feeders. In fact, early biologists thought they were plants. Often encased by a hard exterior, a row of cells borders a watery center. Each cell has a tiny cilium that gently circulates a rich flow of microorganisms on which they feed. This seemingly simple organization belies a giant step in evolution. For the previous 3 billion years, single-celled creatures inhabited the planet. In one of evolution’s most creative acts, independent cells joined together, first into a colony and later into a truly inseparable multicellular organism. Colonies of single cells offered the first inkling that not every cell in the colony had to be identical. Cells in the interior might differ subtly from those on the periphery that are subject to the whims of the environment. Colonies offered the advantages of cooperation among many nearly identical cells. The next evolutionary innovation, multicellularity, broke radically from the past. © 2023 NautilusNext Inc.,
Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 28913 - Posted: 09.16.2023
by Adam Kirsch Giraffes will eat courgettes if they have to, but they really prefer carrots. A team of researchers from Spain and Germany recently took advantage of this preference to investigate whether the animals are capable of statistical reasoning. In the experiment, a giraffe was shown two transparent containers holding a mixture of carrot and courgette slices. One container held mostly carrots, the other mostly courgettes. A researcher then took one slice from each container and offered them to the giraffe with closed hands, so it couldn’t see which vegetable had been selected. In repeated trials, the four test giraffes reliably chose the hand that had reached into the container with more carrots, showing they understood that the more carrots were in the container, the more likely it was that a carrot had been picked. Monkeys have passed similar tests, and human babies can do it at 12 months old. But giraffes’ brains are much smaller than primates’ relative to body size, so it was notable to see how well they grasped the concept. Such discoveries are becoming less surprising every year, however, as a flood of new research overturns longstanding assumptions about what animal minds are and aren’t capable of. A recent wave of popular books on animal cognition argue that skills long assumed to be humanity’s prerogative, from planning for the future to a sense of fairness, actually exist throughout the animal kingdom – and not just in primates or other mammals, but in birds, octopuses and beyond. In 2018, for instance, a team at the University of Buenos Aires found evidence that zebra finches, whose brains weigh half a gram, have dreams. Monitors attached to the birds’ throats found that when they were asleep, their muscles sometimes moved in exactly the same pattern as when they were singing out loud; in other words, they seemed to be dreaming about singing. © 2023 Guardian News & Media Limited
Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28808 - Posted: 05.31.2023
By Carl Zimmer One of the greatest transformations in the history of life occurred more than 600 million years ago, when a single-celled organism gave rise to the first animals. With their multicellular bodies, animals evolved into a staggering range of forms, like whales that weigh 200 tons, birds that soar six miles into the sky and sidewinders that slither across desert dunes. Scientists have long wondered what the first animals were like, including questions about their anatomy and how they found food. In a study published on Wednesday, scientists found tantalizing answers in a little-known group of gelatinous creatures called comb jellies. While the first animals remain a mystery, scientists found that comb jellies belong to the deepest branch on the animal family tree. The debate over the origin of animals has endured for decades. At first, researchers relied largely on the fossil record for clues. The oldest definitive animal fossils date back about 580 million years, although some researchers have claimed to find even older ones. In 2021, for example, Elizabeth Turner, a Canadian paleontologist, reported finding 890-million-year-old fossils of possible sponges. Sponges would make sense as the oldest animal. They are simple creatures, with no muscles or nervous system. They anchor themselves to the ocean floor, where they filter water through a maze of pores, trapping bits of food. Sponges are so simple, in fact, that it can come as a surprise that they are animals at all, but their molecular makeup reveals their kinship. They make certain proteins, such as collagen, that are produced only by animals. What’s more, their DNA shows they are more closely related to animals than to other forms of life. Starting in the 1990s, as scientists gathered DNA from more animal species, they tried to draw the animal family tree. In some studies, the sponges ended up on the deepest branch of the tree. In this scenario, animals evolved a nervous system only after the sponges branched off. © 2023 The New York Times Company
Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 28793 - Posted: 05.23.2023
By Jake Buehler Shimmering, gelatinous comb jellies wouldn’t appear to have much to hide. But their mostly see-through bodies cloak a nervous system unlike that of any other known animal, researchers report in the April 21 Science. In the nervous systems of everything from anemones to aardvarks, electrical impulses pass between nerve cells, allowing for signals to move from one cell to the next. But the ctenophores’ cobweb of neurons, called a nerve net, is missing these distinct connection spots, or synapses. Instead, the nerve net is fused together, with long, stringy neurons sharing a cell membrane, a new 3-D map of its structure shows. While the nerve net has been described before, no one had generated a high-resolution, detailed picture of it. It’s possible the bizarre tissue represents a second, independent evolutionary origin of a nervous system, say Pawel Burkhardt, a comparative neurobiologist at the University of Bergen in Norway, and colleagues. Superficially similar to jellyfish, ctenophores are often called comb jellies because they swim using rows of beating, hairlike combs. The enigmatic phylum is considered one of the earliest to branch off the animal tree of life. So ctenophores’ possession of a simple nervous system has been of particular interest to scientists interested in how such systems evolved. Previous genetics research had hinted at the strangeness of the ctenophore nervous system. For instance, a 2018 study couldn’t find a cell type in ctenophores with a genetic signature that corresponded to recognizable neurons, Burkhardt says. Burkhardt, along with neurobiologist Maike Kittelmann of Oxford Brookes University in England and colleagues, examined young sea walnuts (Mnemiopsis leidyi) using electron microscopes, compiling many images to reconstruct the entire net structure. Their 3-D map of a 1-day-old sea walnut revealed the funky synapse-free fusion between the five sprawling neurons that made up the tiny ctenophore’s net. © Society for Science & the Public 2000–2023.
Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 28745 - Posted: 04.22.2023
By Elizabeth Preston Several years ago, Christian Rutz started to wonder whether he was giving his crows enough credit. Rutz, a biologist at the University of St. Andrews in Scotland, and his team were capturing wild New Caledonian crows and challenging them with puzzles made from natural materials before releasing them again. In one test, birds faced a log drilled with holes that contained hidden food, and could get the food out by bending a plant stem into a hook. If a bird didn’t try within 90 minutes, the researchers removed it from the dataset. But, Rutz says, he soon began to realize he was not, in fact, studying the skills of New Caledonian crows. He was studying the skills of only a subset of New Caledonian crows that quickly approached a weird log they’d never seen before—maybe because they were especially brave, or reckless. The team changed their protocol. They began giving the more hesitant birds an extra day or two to get used to their surroundings, then trying the puzzle again. “It turns out that many of these retested birds suddenly start engaging,” Rutz says. “They just needed a little bit of extra time.” Scientists are increasingly realizing that animals, like people, are individuals. They have distinct tendencies, habits, and life experiences that may affect how they perform in an experiment. That means, some researchers argue, that much published research on animal behavior may be biased. Studies claiming to show something about a species as a whole—that green sea turtles migrate a certain distance, say, or how chaffinches respond to the song of a rival—may say more about individual animals that were captured or housed in a certain way, or that share certain genetic features. That’s a problem for researchers who seek to understand how animals sense their environments, gain new knowledge, and live their lives. © 2023 NautilusNext Inc.,
Related chapters from BN: Chapter 17: Learning and Memory; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28724 - Posted: 04.01.2023
By Bruce Bower Monkeys in southern Thailand use rocks to pound open oil palm nuts, inadvertently shattering stone pieces off their makeshift nutcrackers. These flakes resemble some sharp-edged stone tools presumed to have been created on purpose by ancient hominids, researchers say. Thailand’s long-tailed macaques (Macaca fascicularis) produce shards that could easily be mistaken for stone flakes previously found at 17 East African hominid sites dating from about 3.3 million to 1.56 million years ago, say archaeologist Tomos Proffitt and colleagues. The finding suggests that ancient hominids may sometimes have created the stone flakes by accident while using rocks to smash nuts, bones or other objects, the scientists report March 10 in Science Advances. Previous research has already shown that rock-wielding capuchin monkeys in Brazil unwittingly produce hominid-like stone flakes (SN: 10/19/16). Observations of rock bashing by these two monkey species undermine a long-standing assumption that hominids must have intentionally made certain ancient stone flakes, including some of the earliest known examples of tools, Proffitt says (SN: 6/3/19). It’s time to reevaluate how such determinations are made, he contends. Proffitt’s group identified 219 complete and fragmented stone flakes at 40 macaque nut-cracking sites on the island where the monkeys live. The team also found rocks showing damage consistent with having been used either as pounding implements or pounding platforms. Some differences do exist between macaque and hominid stone flakes, says Proffitt, of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. For instance, many macaque flakes display battering damage on only one side, versus frequent two-sided damage on hominid artifacts. © Society for Science & the Public 2000–2023.
Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28699 - Posted: 03.11.2023
By Rodrigo Pérez Ortega Was Tyrannosaurus rex as smart as a baboon? Scientists don’t like to compare intelligence between species (everyone has their own talents, after all), but a controversial new study suggests some dino brains were as densely packed with neurons as those of modern primates. If so, that would mean they were very smart—more than researchers previously thought—and could have achieved feats only humans and other very intelligent animals have, such as using tools. The findings, reported last week in the Journal of Comparative Neurology, are making waves among paleontologists on social media and beyond. Some are applauding the paper as a good first step toward better understanding dinosaur smarts, whereas others argue the neuron estimates are flawed, undercutting the study’s conclusions. Measuring dinosaur intelligence has never been easy. Historically, researchers have used something called the encephalization quotient (EQ), which measures an animal’s relative brain size, related to its body size. A T. rex, for example, had an EQ of about 2.4, compared with 3.1 for a German shepherd dog and 7.8 for a human—leading some to assume it was at least somewhat smart. EQ is hardly foolproof, however. In many animals, body size evolves independently from brain size, says Ashley Morhardt, a paleoneurologist at Washington University School of Medicine in St. Louis who wasn’t involved in the study. “EQ is a fraught metric, especially when studying extinct species.” Looking for a more trustworthy alternative, Suzana Herculano-Houzel, a neuroanatomist at Vanderbilt University, turned to a different measure: the density of neurons in the cortex, the wrinkly outer brain area critical to most intelligence-related tasks. She had previously estimated the number of neurons in many animal species, including humans, by making “brain soup”—dissolving brains in a detergent solution—and counting the neurons in different parts of the brain. © 2023 American Association for the Advancement of Science.
Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28627 - Posted: 01.12.2023
By Bruce Bower An ancient hominid dubbed Homo naledi may have lit controlled fires in the pitch-dark chambers of an underground cave system, new discoveries hint. Researchers have found remnants of small fireplaces and sooty wall and ceiling smudges in passages and chambers throughout South Africa’s Rising Star cave complex, paleoanthropologist Lee Berger announced in a December 1 lecture hosted by the Carnegie Institution of Science in Washington, D.C. “Signs of fire use are everywhere in this cave system,” said Berger, of the University of the Witwatersrand, Johannesburg. H. naledi presumably lit the blazes in the caves since remains of no other hominids have turned up there, the team says. But the researchers have yet to date the age of the fire remains. And researchers outside Berger’s group have yet to evaluate the new finds. H. naledi fossils date to between 335,000 and 236,000 years ago (SN: 5/9/17), around the time Homo sapiens originated (SN: 6/7/17). Many researchers suspect that regular use of fire by hominids for light, warmth and cooking began roughly 400,000 years ago (SN: 4/2/12). Such behavior has not been attributed to H. naledi before, largely because of its small brain. But it’s now clear that a brain roughly one-third the size of human brains today still enabled H. naledi to achieve control of fire, Berger contends. Last August, Berger climbed down a narrow shaft and examined two underground chambers where H. naledi fossils had been found. He noticed stalactites and thin rock sheets that had partly grown over older ceiling surfaces. Those surfaces displayed blackened, burned areas and were also dotted by what appeared to be soot particles, Berger said. © Society for Science & the Public 2000–2022.
Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 28582 - Posted: 12.06.2022
Cephalopods like octopuses, squids and cuttlefish are highly intelligent animals with complex nervous systems. In “Science Advances”, a team led by Nikolaus Rajewsky of the Max Delbrück Center has now shown that their evolution is linked to a dramatic expansion of their microRNA repertoire. If we go far enough back in evolutionary history, we encounter the last known common ancestor of humans and cephalopods: a primitive wormlike animal with minimal intelligence and simple eyespots. Later, the animal kingdom can be divided into two groups of organisms – those with backbones and those without. While vertebrates, particularly primates and other mammals, went on to develop large and complex brains with diverse cognitive abilities, invertebrates did not. With one exception: the cephalopods. Scientists have long wondered why such a complex nervous system was only able to develop in these mollusks. Now, an international team led by researchers from the Max Delbrück Center and Dartmouth College in the United States has put forth a possible reason. In a paper published in “Science Advances”, they explain that octopuses possess a massively expanded repertoire of microRNAs (miRNAs) in their neural tissue – reflecting similar developments that occurred in vertebrates. “So, this is what connects us to the octopus!” says Professor Nikolaus Rajewsky, Scientific Director of the Berlin Institute for Medical Systems Biology of the Max Delbrück Center (MDC-BIMSB), head of the Systems Biology of Gene Regulatory Elements Lab, and the paper’s last author. He explains that this finding probably means miRNAs play a fundamental role in the development of complex brains.
Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28571 - Posted: 11.30.2022
By Diana Kwon Crows are some of the smartest creatures in the animal kingdom. They are capable of making rule-guided decisions and of creating and using tools. They also appear to show an innate sense of what numbers are. Researchers now report that these clever birds are able to understand recursion—the process of embedding structures in other, similar structures—which was long thought to be a uniquely human ability. Recursion is a key feature of language. It enables us to build elaborate sentences from simple ones. Take the sentence “The mouse the cat chased ran.” Here the clause “the cat chased” is enclosed within the clause “the mouse ran.” For decades, psychologists thought that recursion was a trait of humans alone. Some considered it the key feature that set human language apart from other forms of communication between animals. But questions about that assumption persisted. “There’s always been interest in whether or not nonhuman animals can also grasp recursive sequences,” says Diana Liao, a postdoctoral researcher at the lab of Andreas Nieder, a professor of animal physiology at the University of Tübingen in Germany. In a study of monkeys and human adults and children published in 2020, a group of researchers reported that the ability to produce recursive sequences may not actually be unique to our species after all. Both humans and monkeys were shown a display with two pairs of bracket symbols that appeared in a random order. The subjects were trained to touch them in the order of a “center-embedded” recursive sequence such as { ( ) } or ( { } ). After giving the right answer, humans received verbal feedback, and monkeys were given a small amount of food or juice as a reward. Afterward the researchers presented their subjects with a completely new set of brackets and observed how often they arranged them in a recursive manner. Two of the three monkeys in the experiment generated recursive sequences more often than nonrecursive sequences such as { ( } ), although they needed an additional training session to do so. One of the animals generated recursive sequences in around half of the trials. Three- to four-year-old children, by comparison, formed recursive sequences in approximately 40 percent of the trials. © 2022 Scientific American,
Related chapters from BN: Chapter 17: Learning and Memory; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28563 - Posted: 11.23.2022
Emma Marris For the first time, octopuses have been spotted throwing things — at each other1. Octopuses are known for their solitary nature, but in Jervis Bay, Australia, the gloomy octopus (Octopus tetricus) lives at very high densities. A team of cephalopod researchers decided to film the creatures with underwater cameras to see whether — and how — they interact. Once the researchers pulled the cameras out of the water, they sat down to watch more than 20 hours of footage. “I call it octopus TV,” laughs co-author David Scheel, a behavioural ecologist at Alaska Pacific University in Anchorage. One behaviour stood out: instances in which the eight-limbed creatures gathered shells, silt or algae with their arms — and then hurled them away, propelling them with water jetted from their siphon. And although some of the time it seemed that they were just throwing away debris or food leftovers, it did sometimes appear that they were throwing things at each other. The team found clues that the octopuses were deliberately targeting one another. Throws that made contact with another octopus were relatively strong and often occurred when the thrower was displaying a uniform dark or medium body colour. Another clue: sometimes the octopuses on the receiving end ducked. Throws that made octo-contact were also more likely to be accomplished with a specific set of arms, and the projectile was more likely to be silt. “We weren’t able to try and assess what the reasons might be,” Scheel cautions. But throwing, he says, “might help these animals deal with the fact that there are so many octopuses around”. In other words, it is probably social. © 2022 Springer Nature Limited
Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28549 - Posted: 11.13.2022
Laurel Wamsley Perhaps the real law of the jungle is that it's good to have friends — especially those who know where to find the the free food. Case in point: It turns out chimpanzees and gorillas can be pals, evidently with advantages for all. That finding is from a new paper in the journal iScience that analyzes social interactions between the primate species over two decades at the Nouabalé-Ndoki Park in the Republic of Congo. Over that 20-year period, researchers saw gorillas follow the sound of chimps to a canopy full of ripe figs, and then co-feed at the same tree. They witnessed young individuals of both species playing and wrestling with each other – interactions that can foster their development. And when bands of the two species encountered each other, researchers saw gorillas and chimps scan the others and then approach the ones they knew. They even saw chimpanzees beating their chests – a behavior associated with gorillas. Researchers had theorized that associations between the species could perhaps be to avoid predators such as leopards or snakes. But the apes' behavior didn't show that to be a major factor in their interactions. "Predation is certainly a threat in this region, as we have cases in which chimpanzees have been killed by leopards," Washington University primatologist Crickette Sanz, who led the research, said in a news release. "However, the number of chimpanzees in daily subgroups remains relatively small, and gorillas within groups venture far from the silverback who is thought to be a protector from predation." Instead, better foraging seemed to be a key upside for both species – sometimes eating at the same tree, sometimes dining nearby on different foods. Not every interaction was warm and friendly. "Interspecific aggression was bidirectional and most frequently consisted of threats," the study notes – but it never rose to the level of lethal aggression that has occurred between chimps and gorillas in Gabon. © 2022 npr
Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28548 - Posted: 11.13.2022
By Jack Tamisiea An elephant’s trunk has 40,000 muscles and weighs more than a Burmese python. The appendage is strong enough to uproot a tree, yet sensitive enough to suction up fragile tortilla chips. But how does an elephant’s brain help accomplish these feats of dexterity? That has been difficult to study, according to Michael Brecht, a neuroscientist at the Humboldt University of Berlin. Weighing in excess of 10 pounds, the elephant’s brain degrades quickly after death and is a hassle to store. “I tend to think that the big animals are a bit neglected because we don’t do enough work on big brains,” Dr. Brecht said. Dr. Brecht and his colleagues were fortunate enough to gain access to a trove of elephant brains from animals that had died of natural causes or were euthanized for health reasons and ended up either frozen or in a fixative substance at the Leibniz Institute for Zoo and Wildlife Research in Berlin. In a study published Wednesday in the journal Science Advances, Dr. Brecht and his colleagues reported that elephants had more facial neurons than any other land mammal, which might contribute to trunk dexterity and other anatomical abilities. The study also helped to pinpoint major differences between the neural wirings of African savanna elephants and Asian elephants. Using the brains of four Asian elephants and four African savanna elephants, the researchers homed in on the facial nucleus, a bundle of neurons concentrated in the brainstem and hooked up to facial nerves. In mammals, these neurons serve as the control center for facial muscles. They’re in command whenever you wrinkle your nose, purse your lips or raise your eyebrows. They also help elephants employ their trunks. The researchers divided the facial nucleus into regions of neurons that controlled the elephant’s ears, lips and trunk. African elephants sported 63,000 facial neurons, while their Asian cousins had 54,000. The only mammals with more are dolphins, which pack nearly 90,000 facial neurons into their sensitive snouts. While his team expected both African savanna and Asian elephants to possess massive stores of facial neurons, Dr. Brecht said the discrepancy between the two species was noteworthy. © 2022 The New York Times Company
Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 28533 - Posted: 10.28.2022