Researchers Create 15-Million-Year Model Of Great Ape History

Using the study of genetic variation in a large panel of humans, chimpanzees, gorillas and orangutans, researchers from the Universitat Pompeu Fabra in Barcelona, Spain, and Washington University in Seattle have created a model of great ape history over the past 15 million years.

This is the most comprehensive catalog of great ape genetic diversity. The catalog elucidates the evolution and population histories of great apes from Africa and Indonesia. The research team hopes the catalog will also help current and future conservation efforts that strive to preserve natural genetic diversity in populations.

An international group of more than 75 scientists and wildlife conservationists worked on the genetic analysis of 79 wild and captive-born great apes. The group of great apes represents all six great ape species: chimpanzee, bonobo, Sumatran orangutan, Bornean orangutan, eastern gorilla and western lowland gorilla; as well as seven subspecies. The study, published in Nature, also included nine human genomes.

“The research provided us the deepest survey to date of great ape genetic diversity with evolutionary insights into the divergence and emergence of great-ape species,” noted Evan Eichler, a UW professor of genome sciences and a Howard Hughes Medical Institute Investigator.

Due to the difficulty in obtaining genetic specimens from wild apes, genetic variation among great apes had been largely uncharted prior to this study. The research team credits the many conservationists in various countries, many of them in dangerous or isolated locations, with the success of the project.

Peter H. Sudmant, a UW graduate student in genome sciences, said, “Gathering this data is critical to understanding differences between great ape species, and separating aspects of the genetic code that distinguish humans from other primates.”

Factors that shaped primate evolution, including natural selection, population growth and collapse, geographic isolation and migration, climate and geological changes are likely to be revealed by the analysis of great ape genetic diversity.

Understanding more about great ape genetic diversity, according to Sudmant, also contributes to knowledge about disease susceptibility among various primate species. This knowledge is important to both conservation efforts and to human health. For example, the ebola virus is responsible for thousands of chimp and gorilla deaths in Africa. Also, the origin of the HIV in humans comes from simian immunodeficiency virus (SIV), which is found in non-human primates.

“Because the way we think, communicate and act is what makes us distinctively human,” Sudmant, who works in a lab that studies both primate evolutionary biology and neuropsychiatric diseases such as autism, schizophrenia, developmental delay, and cognitive and behavioral disorders, said, “we are specifically looking for the genetic differences between humans and other great apes that might confer these traits.”

The differences between species may direct scientists to portions of the human genome associated with cognition, speech or behavior. This could provide clues to which mutations might underlie neurological disease.

The research team published a companion paper in Genome Research, in which they found the first genetic evidence of a disorder in chimpanzees that resembles Smith-Magenis syndrome. Smith-Magenis is a disabling physical, mental and behavioral condition in humans. The veterinary records of Suzie-A, the chimpanzee exhibiting the disorder, match human symptoms of Smith-Magenis almost exactly. Suzie-A was overweight, rage-prone, had a curved-spine and died from kidney failure.

The discovery of Suzie-A’s syndrome came about while the scientists were exploring and comparing the accumulation of copy number variants during great ape evolution, which are differences between individuals, populations or species in the number of times specific segments of DNA appear. The genomes of humans and great apes have been restructured by the duplication and deletion of DNA segments, which are also behind many genetic diseases.

The new catalog of genetic diversity will help address the challenging plight of great ape species on the brink of extinction, in addition to offering a view of the origins of humans and their disorders. It will also provide an important tool to allow biologists to identify the origin of great apes poached for their body parts or hunted for bush meat. The study also explains why current zoo breeding programs that have tried to increase the genetic diversity of their captive great ape populations have resulted in populations that are genetically dissimilar to their wild counterparts.

“By avoiding inbreeding to produce a diverse population, zoos and conservation groups may be entirely eroding genetic signals specific to certain populations in specific geographic locations in the wild,” Sudmant said.

Donald, one of the captive-bred apes studied by the team, had a genetic makeup of two distinct chimpanzee subspecies which are located around 1,250 miles away from each other in the wild.

The variety of changes that occurred along each of the ape lineages, as they separated from each other through migration, geological change and climate events, are delineated in the study findings. Natural disturbances such as the formation of rivers and the partition of islands from the mainland have all served to isolate groups of apes. These isolated populations are exposed to a unique set of environmental pressures that result in population fluctuations and adaptations, depending on the circumstances.

The ancestors of some present day apes were present at the same time as early human-like species. The researchers found, however, the evolutionary history of the ancestral great ape populations had far more complexity than that of humans. Human history appears “almost boring,” according to Sudmant and Eicher, when compared to our closest relatives, the chimpanzees. For example, the last few million years of chimp evolution are full of population explosions followed by implosions. These rapid fluctuations in chimpanzee populations demonstrate remarkable plasticity. Scientists still don’t understand the reasons for the fluctuations in chimpanzee population size long before our own population explosion.

Sudmant’s interest in studying and preserving the great apes stems from the similarities of the great apes to humans.

“If you look at a chimpanzee or a gorilla, those guys will look right back at you,” he said. “They act just like us. We need to find ways to protect these precious species from extinction.”

Why do we gesticulate?

If you rely on hand gestures to get your point across, you can thank fish for that! Scientists have found that the evolution of the control of speech and hand movements can be traced back to the same place in the brain, which could explain why we use hand gestures when we are speaking.

Professor Andrew Bass (Cornell University), who will be presenting his work at the meeting of the Society for Experimental Biology on the 3rd July, said: “We have traced the evolutionary origins of the behavioural coupling between speech and hand movement back to a developmental compartment in the brain of fishes.”

"Pectoral appendages (fins and forelimbs) are mainly used for locomotion. However, pectoral appendages also function in social communication for the purposes of making sounds that we simply refer to as non-vocal sonic signals, and for gestural signalling."

Studies of early development in fishes show that neural networks in the brain controlling the more complex vocal and pectoral mechanisms of social signalling among birds and mammals have their ancestral origins in a single compartment of the hindbrain in fishes. This begins to explain the ancestral origins of the neural basis for the close coupling between vocal and pectoral/gestural signalling that is observed among many vertebrate groups, including humans.

Professor Bass said: “Coupling of vocal and pectoral-gestural circuitry starts to get at the evolutionary origins of the coupling between vocalization (speech) and gestural signalling (hand movements). This is all part of the perhaps even larger story of language evolution.”

Gestures of Human and Ape Infants Are More Similar Than You Might Expect

Thirteen years after the release of On the Origin of Species, Charles Darwin published another report on the evolution of mankind. In the 1872 book The Expression of the Emotions in Man and Animals, the naturalist argued that people from different cultures exhibit any given emotion through the same facial expression. This hypothesis didn’t quite pan out—last year, researchers poked a hole in the idea by showing that the expression of emotions such as anger, happiness and fear wasn’t universal (PDF). Nonetheless, certain basic things—such as the urge to cry out in pain, an increase in blood pressure when feeling anger, even shrugging when we don’t understand something—cross cultures.

A new study, published today in the journal Frontiers in Psychology, compares such involuntary responses, but with an added twist: Some observable behaviors aren’t only universal to the human species, but to our closest relatives too—chimpanzees and bonobos.

Using video analysis, a team of UCLA researchers found that human, chimpanzee and bonobo babies make similar gestures when interacting with caregivers. Members of all three species reach with their arms and hands for objects or people, and point with their fingers or heads. They also raise their arms up, a motion indicating that they want to be picked up, in the same manner. Such gestures, which seemed to be innate in all three species, precede and eventually lead to the development of language in humans, the researchers say.

To pick up on these behaviors, the team studied three babies of differing species through videos taken over a number of months. The child stars of these videos included a chimpanzee named Panpanzee, a bonobo called Panbanisha and a human girl, identified as GN. The apes were raised together at the Georgia State University Language Research Center in Atlanta, where researchers study language and cognitive processes in chimps, monkeys and humans. There, Panpanzee and Panbanisha were taught to communicate with their human caregivers using gestures, noises and lexigrams, abstract symbols that represent words. The human child grew up in her family’s home, where her parents facilitated her learning.

Researchers filmed the child’s development for seven months, starting when she was 11 months old, while the apes were taped from 12 months of age to 26 months. In the early stages of the study, the observed gestures were of a communicative nature: all three infants engaged in the behavior with the intention of conveying how their emotions and needs. They made eye contact with their caregivers, added non-verbal vocalizations to their movements or exerted physical effort to elicit a response.

By the second half of the experiment, the production of communicative symbols—visual ones for the apes, vocal ones for the human—increased. As she grew older, the human child began using more spoken words, while the chimpanzee and bonobo learned and used more lexigrams. Eventually, the child began speaking to convey what she felt, rather than only gesturing. The apes, on the other hand, continued to rely on gestures. The study calls this divergence in behavior “the first indication of a distinctive human pathway to language.”

The researchers speculate that the matching behaviors can be traced to the last shared ancestor of humans, chimps and bobonos, who lived between four and seven million years ago. That ancestor probably exhibited the same early gestures, which all three species then inherited. When the species diverged, humans managed to build on this communicative capacity by eventually graduating to speech.

Hints of this can be seen in how the human child paired her gestures with non-speech vocalizations, the precursors to words, far more than the apes did. It’s this successful combinationof gestures and words that may have led to the birth of human language.

What The Human Face Might Look Like 100,000 Years From Now

The human face might look very different in the future.

Artist and researcher Nickolay Lamm from U.K. discount site MyVoucherCodes.co.uk collaborated with a genomics expert to create pictures that show the evolution of the human face 20,000, 60,000, and 100,000 years from now.

In one possible future scenario, humans will have full control of human genome engineering. That is, they will be able to eliminate hereditary genetic disorders, or select desirable genetic traits like straight teeth and natural blonde hair.

Natural human evolution is still at work — the head will get bigger to make room for a larger brain — but most facial features will be molded to reflect what the majority of us perceive as attractive: big eyes, a straight nose, and facial symmetry.

Is the Brain No Different From a Light Switch? The Uncomfortable Ideas of the Philosopher Daniel Dennett

To a philosopher, is the human brain no different from a nonliving gizmo like a computer or a light switch? Is consciousness largely an illusion? Jonathan Weiner on the uncomfortable ideas of the thinker Daniel Dennett.

For Daniel Dennett, philosophers are like blacksmiths: they make their own tools as they go along. Unlike carpenters, who have to buy their drills and saws at Sears, blacksmiths can use their own hammers, tongs, and anvils to pound out more hammers, tongs, and anvils. Dennett, whose famous white beard gives him the look of both a blacksmith and a philosopher, has been particularly industrious at the anvil. He has been working as a philosopher for 50 years, and in his new book, Intuition Pumps and Other Tools for Thinking, he shares a few tricks to make the hard work easier. He is a master at inventing tools for thought—metaphysical jokes, fables, parables, puzzles, and zany Monty-Python-like sketches that can help thinkers feel their way forward. Dennett calls them hand tools and power tools for the mind, and he’s built dozens and dozens of them over the years.

“Thinking is hard,” he writes. “Thinking about some problems is so hard that it can make your head ache just thinking about thinking about them.” Thinking tools help philosophers work on the really deep, hard questions about life, the universe, and everything. They facilitate what another philosopher has called Jootsing, which stands for Jumping Out Of the System—the goal is to pop out of the goldfish bowl of commonplace ideas without drowning in thin air. Think of Plato’s Cave, for instance. That little story has helped philosophers puzzle about the nature of reality for more than 23 centuries and counting.

Dennett’s own inventions include “Swampman Meets a Cow-Shark,” “Zombies and Zimboes,” and many other thought experiments that illuminate great questions in philosophy. He focuses on problems of free will, evolution, and consciousness. His ideas about consciousness are rather shocking; he can make you feel that the human brain itself is just a collection of tongs, hammers, and intuition pumps. (More about that in a moment.) Dennett has written more than a dozen books about those deep topics. His best known are Darwin’s Dangerous Idea, and Consciousness Explained. He writes very well, in a colorful, lively, clear style, and he is a popular professor at Tufts University, to which he dedicates his new book. And every book and lecture is packed with intuition pumps for juicy, jootsy epiphanies.

In a way, we all use thinking tools, all the time, without thinking twice about them. Everyday speech is full of what Dennett calls “small hand tools,” familiar words and phrases like “wild goose chase” or “feedback” or “slam dunk.” The English language is a tool chest with a million metaphors that serve as a kind of verbal mathematics. They’re informal formulas for describing the way things go. Newton’s equations describe the behavior of a cannonball; “loose cannon” describes the behavior of a certain kind of cannoneer we’ve all had the misfortune to know.

Then there are simple, familiar intuition pumps like Aesop’s “The Boy Who Cried Wolf,” “The Ant and the Grasshopper,” and “The Fox and the Grapes.” We’ve all used those thinking tools too. “Look how much you can say about what somebody has just said by asking, simply, ‘Sour grapes?’” writes Dennett. You can get someone to rethink her position, to consider her situation from a completely different perspective. You can also insult her. (As Dennett observes, “Tools can be used as weapons too.”)

The intuition pumps that he’s created are really philosophical arguments in disguise. Dennett has designed them to push us to see the world his way, and that’s what he’s trying to do by recapitulating them here. “I will not just describe them,” he writes; “I intend to use them to move your mind gently through uncomfortable territory all the way to a quite radical vision of meaning, mind, and free will.”

And his ideas are uncomfortable. His essential claim is that there is no great gulf between nonliving, unconscious gizmos like computers and light switches, on the one hand, and the human brain, on the other. Our strong feeling that there’s something special and inexplicable about consciousness is largely an illusion. It will fade as science advances, like the illusion that the Earth is the center of the universe and everything revolves around us. Biologists used to believe that living things are made of some special material, some elan vital that sets us apart from the stuff of rocks and minerals. Now that we know about DNA, we no longer need an elan vital. Someday we won’t need consciousness either. There’s no metaphysical difference between your body and your mind, or between your laptop and your necktop, so to speak.

That’s a controversial position, obviously. It still feels counterintuitive to most of us, and to most philosophers too, in spite of all of Dennett’s intuition pumps. Does Consciousness Explained explain consciousness, or just explain it away? Check out Dennett’s story “The Sad Case of Mr. Clapgras” and see what you intuit. Mr. Clapgras wakes up one morning and finds that everything he sees is suddenly disgusting. His vision is still normal, but his associations with every color have somehow gone awry overnight. He now hates his old favorite color, red, and prefers his former least favorite, blue. Everything looks the same but nothing feels right. His food looks revolting—he has to eat in the dark. Dennett exploits the tale of poor Mr. Clapgras to raise difficult questions about the nature of perception, and thought, and to disrupt our faith in consciousness itself.

Even if you don’t love logic puzzles, brainteasers, and code-writing, all of which delight Dennett, you may still find this book an entertaining introduction to Dennett’s tenets. As you stretch your mind on his mind-twisters, you begin to feel your way to glimpses of his view of life. At the same time, it’s also something like torture to twist your thoughts into the pretzel-shaped path that Dennett wants you to follow—to walk the Mobius-shaped ribbon of highway on which, no matter how you hurry and scurry ahead, you can never arrive at a place where there is something special about the human mind.

Read this book carefully and you’ll find yourself Jumping Out of the System in all directions. Dennett will lift off the top of your head, and tie your forehead into knots. Is this really where the philosophy of mind is headed? There’s no question that as neuroscience hurtles ahead, our current system of thought is beginning to feel creaky and rusty in the extreme. Some bright new ideas probably are going to have to take its place. It may be that Dennett and his friends are the philosophers who are building them—Dennett most cheerfully of all, in his Santa’s workshop of intuition pumps.

Monkey Math: Baboons Show Brain’s Ability To Understand Numbers

Opposing thumbs, expressive faces, complex social systems: it’s hard to miss the similarities between apes and humans. Now a new study with a troop of zoo baboons and lots of peanuts shows that a less obvious trait—the ability to understand numbers—also is shared by man and his primate cousins.

“The human capacity for complex symbolic math is clearly unique to our species,” says co-author Jessica Cantlon, assistant professor of brain and cognitive sciences at the University of Rochester. “But where did this numeric prowess come from? In this study we’ve shown that non-human primates also possess basic quantitative abilities. In fact, non-human primates can be as accurate at discriminating between different quantities as a human child.”

“This tells us that non-human primates have in common with humans a fundamental ability to make approximate quantity judgments,” says Cantlon. “Humans build on this talent by learning number words and developing a linguistic system of numbers, but in the absence of language and counting, complex math abilities do still exist.”

Cantlon, her research assistant Allison Barnard, postdoctoral fellow Kelly Hughes, and other colleagues at the University of Rochester and the Seneca Park Zoo in Rochester, N.Y., reported their findings online May 2 in the open-access journal Frontiers in Psychology.

The study tracked eight olive baboons, ages 4 to 14, in 54 separate trials of guess-which-cup-has-the-most-treats. Researchers placed one to eight peanuts into each of two cups, varying the numbers in each container. The baboons received all the peanuts in the cup they chose, whether it was the cup with the most goodies or not. The baboons guessed the larger quantity roughly 75 percent of the time on easy pairs when the relative difference between the quantities was large, for example two versus seven. But when the ratios were more difficult to discriminate, say six versus seven, their accuracy fell to 55 percent.

That pattern, argue the authors, helps to resolve a standing question about how animals understand quantity. Scientists have speculated that animals may use two different systems for evaluating numbers: one based on keeping track of discrete objects—a skill known to be limited to about three items at a time—and a second approach based on comparing the approximate differences between counts.

The baboons’ choices, conclude the authors, clearly relied on this latter “more than” or “less than” cognitive approach, known as the analog system. The baboons were able to consistently discriminate pairs with numbers larger than three as long as the relative difference between the peanuts in each cup was large. Research has shown that children who have not yet learned to count also depend on such comparisons to discriminate between number groups, as do human adults when they are required to quickly estimate quantity.

Studies with other animals, including birds, lemurs, chimpanzees, and even fish, have also revealed a similar ability to estimate relative quantity, but scientists have been wary of the findings because much of this research is limited to animals trained extensively in experimental procedures. The concern is that the results could reflect more about the experimenters than about the innate ability of the animals.

“We want to make sure we are not creating a ‘Clever Hans effect,’” cautions Cantlon, referring to the horse whose alleged aptitude for math was shown to rest instead on the ability to read the unintentional body language of his human trainer. To rule out such influence, the study relied on zoo baboons with no prior exposure to experimental procedures. Additionally, a control condition tested for human bias by using two experimenters—each blind to the contents of the other cup—and found that the choice patterns remained unchanged.

A final experiment tested two baboons over 130 more trials. The monkeys showed little improvement in their choice rate, indicating that learning did not play a significant role in understanding quantity.

“What’s surprising is that without any prior training, these animals have the ability to solve numerical problems,” says Cantlon. The results indicate that baboons not only use comparisons to understand numbers, but that these abilities occur naturally and in the wild, the authors conclude.

Finding a functioning baboon troop for cognitive research was serendipitous, explains study co-author Jenna Bovee, the elephant handler at the Seneca Park Zoo who is also the primary keeper for the baboons. The African monkeys are hierarchical, with an alpha male at the top of the social ladder and lots of jockeying for status among the other members of the group. Many zoos have to separate baboons that don’t get along, leaving only a handful of zoos with functioning troops, Bovee explained.

Involvement in this study and ongoing research has been enriching for the 12-member troop, she said, noting that several baboons participate in research tasks about three days a week. “They enjoy it,” she says. “We never have to force them to participate. If they don’t want to do it that day, no big deal.

“It stimulates our animals in a new way that we hadn’t thought of before,” Bovee adds. “It kind of breaks up their routine during the day, gets them thinking. It gives them time by themselves to get the attention focused on them for once. And it reduces fighting among the troop. So it’s good for everybody.”

The zoo has actually adapted some of the research techniques, like a matching game with a touch-screen computer that dispenses treats, and taken it to the orangutans. “They’re using an iPad,” she says.

She also enjoys documenting the intelligence of her charges. “A lot of people don’t realize how smart these animals are. Baboons can show you that five is more than two. That’s as accurate as a typical three year old, so you have to give them that credit.”

Cantlon extends those insights to young children: “In the same way that we underestimate the cognitive abilities of non-human animals, we sometimes underestimate the cognitive abilities of preverbal children. There are quantitative abilities that exist in children prior to formal schooling or even being able to use language.”

Pathway Competition Affects Early Differentiation of Higher Brain Structures

Sand-dwelling and rock-dwelling cichlids living in East Africa’s Lake Malawi share a nearly identical genome, but have very different personalities. The territorial rock-dwellers live in communities where social interactions are important, while the sand-dwellers are itinerant and less aggressive.

Those behavioral differences likely arise from a complex region of the brain known as the telencephalon, which governs communication, emotion, movement and memory in vertebrates – including humans, where a major portion of the telencephalon is known as the cerebral cortex. A study published this week in the journal Nature Communications shows how the strength and timing of competing molecular signals during brain development has generated natural and presumably adaptive differences in the telencephalon much earlier than scientists had previously believed.

In the study, researchers first identified key differences in gene expression between rock- and sand-dweller brains during development, and then used small molecules to manipulate developmental pathways to mimic natural diversity.

“We have shown that the evolutionary changes in the brains of these fishes occur really early in development,” said Todd Streelman, an associate professor in the School of Biology and the Petit Institute for Bioengineering and Biosciences at the Georgia Institute of Technology. “It’s generally been thought that early development of the brain must be strongly buffered against change. Our data suggest that rock-dweller brains differ from sand-dweller brains – before there is a brain.”

For humans, the research could lead scientists to look for subtle changes in brain structures earlier in the development process. This could provide a better understanding of how disorders such as autism and schizophrenia could arise during very early brain development.

The research was supported by the National Science Foundation and published online April 23 by the journal.

“We want to understand how the telencephalon evolves by looking at genetics and developmental pathways in closely-related species from natural populations,” said Jonathan Sylvester, a postdoctoral researcher in the Georgia Tech School of Biology and lead author of the paper. “Adult cichlids have a tremendous amount of variation within the telencephalon, and we investigated the timing and cause of these differences. Unlike many previous studies in laboratory model organisms that focus on large, qualitative effects from knocking out single genes, we demonstrated that brain diversity evolves through quantitative tuning of multiple pathways.”

In examining the fish from embryos to adulthood, the researchers found that the mbuna, or rock-dwellers, tended to exhibit a larger ventral portion of the telencephalon, called the subpallium – while the sand-dwellers tended to have a larger version of the dorsal structure known as the pallium. These structures seem to have evolved differently over time to meet the behavioral and ecological needs of the fishes. The team showed that early variation in the activity of developmental signals expressed as complementary dorsal-ventral gradients, known technically as “Wingless” and “Hedgehog,” are involved in creating those differences during the neural plate stage, as a single sheet of neural tissue folds to form the neural tube.

To specifically manipulate those two pathways, Sylvester removed clutches of between 20 and 40 eggs from brooding female cichlids, which normally incubate fertilized eggs in their mouths. At about 36 to 48 hours after fertilization, groups of eggs were exposed to small-molecule chemicals that either strengthened or weakened the Hedgehog signal, or strengthened or weakened the Wingless signal. The chemical treatment came while the structures that would become the brain were little more than a sheet of cells. After treatment, water containing the chemicals was replaced with fresh water, and the embryos were allowed to continue their development.

“We were able to artificially manipulate these pathways in a way that we think evolution might have worked to shift the process of rock-dweller telencephalon development to sand-dweller development, and vice-versa. Treatment with small molecules allows us incredible temporal and dose precision in manipulating natural development,” Sylvester explained. “We then followed the development of the embryos until we were able to measure the anatomical structures – the size of the pallium and subpallium – to see that we had transformed one to the other.”

The two different brain regions, the dorsal pallium and ventral subpallium, give rise to excitatory and inhibitory neurons in the forebrain. Altering the relative sizes of these regions might change the balance between these neuronal types, ultimately producing behavioral changes in the adult fish.

“Evolution has fine-tuned some of these developmental mechanisms to produce diversity,” Streelman said. “In this study, we have figured out which ones.”

The researchers studied six different species of East African cichlids, and also worked with collaborators at King’s College in London to apply similar techniques in the zebrafish.

As a next step, the researchers would like to follow the embryos through to adulthood to see if the changes seen in embryonic and juvenile brain structures actually do change behavior of adults. It’s possible, said Streelman, that later developmental events could compensate for the early differences.

The results could be of interest to scientists investigating human neurological disorders that result from an imbalance between excitatory and inhibitory neurons. Those disorders include autism and schizophrenia. “We think it is particularly interesting that there may be some adaptive variation in the natural proportions of excitatory versus inhibitory neurons in the species we study, correlated with their natural behavioral differences,” said Streelman.

The Shrinking of the Hobbit’s Brain

Where do Hobbits come from? No, not the little humanoids in the J. R. R. Tolkien books, but Homo floresiensis, the 1-meter-tall human with the chimp-sized brain that lived on the Indonesian island of Flores between 90,000 and 13,000 years ago. There are two main hypotheses: either the creature downsized from H. erectus, a human ancestor that lived in Africa and Asia and that is known to have made it to Flores about 800,000 years ago and may have shrunk when it got there—a case of so-called “insular dwarfism” often seen in other animals that get small when they take up residence on islands. Or it evolved from an even earlier, smaller-brained ancestor, such as the early human H. habilis or an australopithecine like Lucy, that somehow made it to Flores from Africa. The insular dwarfism hypothesis had fallen out of favor recently, however, because many researchers thought that the Hobbit’s brain, often estimated at 400 cubic centimeters in volume, was too small to have evolved from the larger H. erectus brain, which was at least twice as big. But a new study, published online today in the Proceedings of the Royal Society B, finds from CT scans of the Hobbit’s brain that it was actually about 426 cubic centimeters in volume. The team calculates that this is big enough to make the island dwarfism hypothesis considerably more plausible once the body size differences between the Hobbit and H. erectus—which was nearly twice as tall—are adjusted for.