Chapter 6. Evolution of the Brain and Behavior
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By Drake Baer Convergent evolution is what happens when nature takes different courses from different starting points to arrive at similar results. Consider bats, birds, and butterflies developing wings; sharks and dolphins finding fins; and echidnas and porcupines sporting spines. Or, if you want to annoy a traditionalist scientist, talk about humans and octopuses — and how they may both have consciousness. This is the thrust of Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness, a new book by the scuba-diving, biology-specializing philosopher Peter Godfrey-Smith, originally of Australia and now a distinguished professor at the City University of New York’s graduate center. The book was written up by Olivia Judson in The Atlantic, and you should read the whole thing, but what I find mesmerizing is how categorically other the eight-tentacled ink-squirters are, and how their very nature challenges our conceptualizations of intelligence. “If we can make contact with cephalopods as sentient beings, it is not because of a shared history, not because of kinship, but because evolution built minds twice over,” Godfrey-Smith is quoted as saying. “This is probably the closest we will come to meeting an intelligent alien.” (He’s not the first to think so: The Hawaiian creation myth holds that octopuses are the only creatures left over from an earlier incarnation of the Earth, making them more proto-terrestrials than extraterrestrials.) © 2016, New York Media LLC.
By STEPH YIN Inuit who live in Greenland experience average temperatures below freezing for at least half of the year. For those who live in the north, subzero temperatures are normal during the coldest months. Given these frigid conditions, anthropologists have wondered for decades whether the Inuit in Greenland and other parts of the Arctic have unique biological adaptations that help them tolerate the extreme cold. A new study, published on Wednesday in Molecular Biology and Evolution, identifies gene variants in Inuit who live in Greenland, which may help them adapt to the cold by promoting heat-generating body fat. These variants possibly originated in the Denisovans, a group of archaic humans who, along with Neanderthals, diverged from modern humans about half a million years ago. “As modern humans spread around the world, they interbred with Denisovans and Neanderthals, who had already been living in these different environments for hundreds of thousands of years,” said Rasmus Nielsen, a professor of integrative biology at the University of California, Berkeley and an author of the paper. “This gene exchange may have helped some modern humans adapt to and conquer new environments.” The new study follows earlier research by Dr. Nielsen and colleagues, which found genetic mutations that might help the Inuit metabolize unsaturated fatty acids common in their diet of whales, seals and fish. In this study, Dr. Nielsen’s team focused on another distinct region in the Inuit genome, which seems to affect body fat distribution and other aspects of development. The researchers compared the genomes of nearly 200 Inuit with genomes of Neanderthals, Denisovans and modern populations around the world. © 2016 The New York Times Company
Link ID: 23011 - Posted: 12.23.2016
Ramin Skibba The high-pitched squeals of the humble bat may be as complex as the calls of dolphins and monkeys, researchers have found. A study published on 22 December in Scientific Reports1 reveals that the fruit bat is one of only a few animals known to direct its calls at specific individuals in a colony, and suggests that information in the calls of many social animals may be more detailed than was previously thought. Bats are noisy creatures, especially in their crowded caves, where they make calls to their neighbours. “If you go into a fruit-bat cave, you hear a cacophony,” says Yossi Yovel, a neuroecologist at Tel Aviv University in Israel who led the study. Until now, it has been difficult to separate this noise into distinct sounds, or to determine what prompted the individual to make a particular call. “Animals make sounds for a reason,” says Whitlow Au, a marine-bioacoustics scientist at the University of Hawaii at Manoa. “Most of the time, we don’t quite understand those reasons.” To find out what bats are talking about, Yovel and his colleagues monitored 22 captive Egyptian fruit bats (Rousettus aegyptiacus) around the clock for 75 days. They modified a voice-recognition program to analyse approximately 15,000 vocalizations collected during this time. The program was able to tie specific sounds to different social interactions captured by video, such as when two bats fought over food. © 2016 Macmillan Publishers
By Claire Asher We pride ourselves on our big brains, but when it comes to figuring out whether people or other animals with particularly big brains do better than others, the evidence has been lacking. Now, for the first time, a study in red deer is showing that bigger brained mammals tend to be more successful in the wild, and that brain size is a heritable trait that they can pass on to their offspring. Corina Logan from the University of Cambridge and her team have looked at the skulls of 1314 red deer (Cervus elaphus) from the Isle of Rum. The complete life histories of the deer are well known thanks to the Isle of Rum Red Deer Project, which has been collecting data on the island for more than 40 years, spanning seven deer generations. “This kind of study has not been conducted before because it requires long-term data from a large number of individuals,” says Logan. Heritable heads The team found that the ratio of skull volume to body size was highly heritable, explaining 63 per cent of variation between individuals. Female deer with larger skulls lived significantly longer and raised more offspring to adulthood, though it’s not clear yet why bigger brains are advantageous to females. © Copyright Reed Business Information Ltd.
Carl Zimmer Primates are unquestionably clever: Monkeys can learn how to use money, and chimpanzees have a knack for game theory. But no one has ever taught a nonhuman primate to say “hello.” Scientists have long been intrigued by the failure of primates to talk like us. Understanding the reasons may offer clues to how our own ancestors evolved full-blown speech, one of our most powerful adaptations. On Friday, a team of researchers reported that monkeys have a vocal tract capable of human speech. They argue that other primates can’t talk because they lack the right wiring in their brains. “A monkey’s vocal tract would be perfectly adequate to produce hundreds, thousands of words,” said W. Tecumseh Fitch, a cognitive scientist at the University of Vienna and a co-author of the new study. Human speech results from a complicated choreography of flowing air and contracting muscles. To make a particular sound, we have to give the vocal tract a particular shape. The vocal tracts of other primates contain the same elements as ours — from vocal cords to tongues to lips — but their geometry is different. That difference long ago set scientists to debating whether primates could make speechlike sounds. In the 1960s, Philip H. Lieberman, now a professor emeritus of Brown University, and his colleagues went so far as to pack a dead monkey’s vocal tract with plaster to get a three-dimensional rendering. © 2016 The New York Times Company
By Michael Price The famed parrot Alex had a vocabulary of more than 100 words. Kosik the elephant learned to “speak” a bit of Korean by using the tip of his trunk the way people whistle with their fingers. So it’s puzzling that our closest primate cousins are limited to hoots, coos, and grunts. For decades, monkeys’ and apes’ vocal anatomy has been blamed for their inability to reproduce human speech sounds, but a new study suggests macaque monkeys—and by extension, other primates—could indeed talk if they only possessed the brain wiring to do so. The findings might provide new clues to anthropologists and language researchers looking to pin down when humans learned to speak. “This certainly shows that the macaque vocal tract is capable of a lot more than has previously been assumed,” says John Esling, a linguist and phonetics expert at the University of Victoria in Canada, who was not involved with the work. The study’s lead author, William Tecumseh Sherman Fitch III, an evolutionary biologist and cognitive scientist at the University of Vienna, says the question of why monkeys and apes can’t speak goes back to Darwin. (Yes, Fitch is the great-great-great-grandson of U.S. Civil War General William Tecumseh Sherman.) Darwin thought nonhuman primates couldn’t talk because they didn’t have the brains, he says. But over time, anthropologists instead embraced the idea that the primates’ vocal tracts were holding them back: They simply lacked the flexibility to produce the wide range of vowels present in human speech. That remains the “textbook answer” today, Fitch says. © 2016 American Association for the Advancement of Science.
By Sam Wong Size matters. Bigger genitals mean more mating success for male mosquito fish, a relative of the guppy. But the development of longer male organs prompts females to evolve bigger brains to help them escape overeager mates. Mating among mosquito fish is far from romantic. The male makes no effort to court partners, instead sneaking up and attempting to copulate by force up to a thousand times a day. It uses a modified anal fin, the gonopodium, to deliver sperm into the female. In this sort of mating system, the relationship between males and females can resemble that between predators and prey, which commonly involve an evolutionary arms race where adaptations on one side are closely matched by changes on the other. For example, big-brained predators tend to prey on big-brained prey, as the two try to outsmart each other. Séverine Buechel and colleagues at Stockholm University in Sweden wondered if a similar arms race was going on between male and female mosquito fish. Do females evolve bigger brains to defend against sneaky males, and do males evolve bigger brains in response? To test this, the team looked at what happened to brain size when males were bred to have longer gonopodia. Male mosquito fish have long gonopodia compared with related species in which coercion is not the dominant mating strategy, and males with longer gonopodia tend to be more successful at mating. The researchers found that breeding more well-endowed males led to bigger-brained females. But there was no arms race: male brains didn’t get bigger at the same time. © Copyright Reed Business Information Ltd.
By Helen Briggs BBC News Humans may in part owe their big brains to a DNA "typo" in their genetic code, research suggests. The mutation was also present in our evolutionary "cousins" - the Neanderthals and Denisovans. However, it is not found in humans' closest living relatives, the chimpanzees. As early humans evolved, they developed larger and more complex brains, which can process and store a lot of information. Last year, scientists pinpointed a human gene that they think was behind the expansion of a key brain region known as the neocortex. They believe the gene arose about five or six million years ago, after the human line had split off from chimpanzees. Now, researchers have found a tiny DNA change - a point mutation - that appears to have changed the function of the gene, sparking the process of expansion of the neocortex. It may have paved the way for the brain's expansion by dramatically boosting the number of brain cells found in this region. Dr Wieland Huttner of the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany, led the research. "A point mutation in a human-specific gene gave it a function that allows expansion of the relevant stem cells that make a brain big," he told BBC News. "This one, as it is fixed in the human genome - so all living humans have the gene - apparently gave a tremendous selection advantage, and that's why we believe it spread in the human population." Between two and six million years ago, the ancestors of modern humans began to walk upright and use simple tools.
Carrie Arnold There was one sound that biologist Rusty Gonser always heard at Cranberry Lake — and there was one sound that he would never hear again. Every summer for more than 25 years, Gonser and his wife, Elaina Tuttle, had made the trip to this field station in the Adirondack Mountains — a 45-minute boat ride from the nearest road. Now, as he moored his boat to the shaky wooden dock, he heard a familiar and short song that sounded like 'oh-sweet-Canada'. The whistle was from a white-throated sparrow calling hopefully for a mate. What he didn't hear was the voice or laughter of his wife. For the first time, Gonser was at Cranberry Lake alone. Just a few weeks earlier, Tuttle had died of breast cancer. Her entire career, and most of Gonser's, had been devoted to understanding every aspect of the biology of the white-throated sparrow (Zonotrichia albicollis). Less than six months before she died this year at the age of 52, the couple and their team published a paper1 that was the culmination of that work. It explained how a chance genetic mutation had put the species on an extraordinary evolutionary path. The mutation had flipped a large section of chromosome 2, leaving it unable to pair up with a partner and exchange genetic information. The more than 1,100 genes in the inversion were inherited together as part of a massive 'supergene' and eventually drove the evolution of two different 'morphs' — subtypes of the bird that are coloured differently, behave differently and mate only with the opposite morph. Tuttle and Gonser's leap was to show that this process is nearly identical to the early evolution of certain sex chromosomes, including the human X and Y. The researchers realized that they were effectively watching the bird evolve two sex chromosomes, on top of the two it already had. © 2016 Macmillan Publishers Limited,
By Ann Gibbons On a promontory high above the sweeping grasslands of the Georgian steppe, a medieval church marks the spot where humans have come and gone along Silk Road trade routes for thousands of years. But 1.77 million years ago, this place was a crossroads for a different set of migrants. Among them were saber-toothed cats, Etruscan wolves, hyenas the size of lions—and early members of the human family. Here, primitive hominins poked their tiny heads into animal dens to scavenge abandoned kills, fileting meat from the bones of mammoths and wolves with crude stone tools and eating it raw. They stalked deer as the animals drank from an ancient lake and gathered hackberries and nuts from chestnut and walnut trees lining nearby rivers. Sometimes the hominins themselves became the prey, as gnaw marks from big cats or hyenas on their fossilized limb bones now testify. "Someone rang the dinner bell in gully one," says geologist Reid Ferring of the University of North Texas in Denton, part of an international team analyzing the site. "Humans and carnivores were eating each other." This is the famous site of Dmanisi, Georgia, which offers an unparalleled glimpse into a harsh early chapter in human evolution, when primitive members of our genus Homo struggled to survive in a new land far north of their ancestors' African home, braving winters without clothes or fire and competing with fierce carnivores for meat. The 4-hectare site has yielded closely packed, beautifully preserved fossils that are the oldest hominins known outside of Africa, including five skulls, about 50 skeletal bones, and an as-yet-unpublished pelvis unearthed 2 years ago. "There's no other place like it," says archaeologist Nick Toth of Indiana University in Bloomington. "It's just this mother lode for one moment in time." © 2016 American Association for the Advancement of Science.
Link ID: 22899 - Posted: 11.23.2016
James Gorman The Goffin’s cockatoo is a smart bird, so smart it has been compared to a 3-year-old human. But even for this species, a bird named Figaro stands out for his creativity with tools. Hand-raised at the Veterinary University of Vienna, the male bird was trying to play with a pebble that fell outside his aviary onto a wooden beam about four years ago. First he used a piece of bamboo to try to rake the stone back in. Impressed, scientists in the university Goffin’s lab, which specializes in testing the thinking abilities of the birds, put a cashew nut where the pebble had been. Figaro extended his beak through the wire mesh to bite a splinter off the wooden beam. He used the splinter to fish the cashew in, a fairly difficult process because he had to work the splinter through the mesh and position it at the right angle. In later trials, Figaro made his tools much more quickly, and also picked a bamboo twig from the bottom of the aviary and trimmed it to make a similar tool. Cockatoos don’t do anything like this in nature, as far as anyone knows. They don’t use tools. They don’t even build nests, so they are not used to manipulating sticks. And they have curved bills, unlike the straight beaks of crows and jays that make manipulating tools a bit easier. Blue jays have been observed creating tools from newspaper to pull food pellets to them. Alice M.I. Auersperg, a researcher at the Veterinary University of Vienna who studies cognition in animals, and her colleagues reported those first accomplishments by Figaro in 2012. Since then, they have continued to test Figaro and other birds in the lab that were able to learn tool use or tool making, sometimes both, by watching Figaro. © 2016 The New York Times Company
By STEPH YIN Neanderthals and modern humans diverged from a common ancestor about half a million years ago. Living in colder climes in Eurasia, Neanderthals evolved barrel chests, large skulls and strong hands. In Africa, modern humans acquired shorter faces, a prominent chin and slender limbs. Then, roughly 50,000 years ago, the two species encountered one another and interbred, as modern humans spread out of Africa. The legacy of this interbreeding has been the subject of much scientific inquiry in the past few years. Today, up to 4 percent of the genes of non-Africans are Neanderthal in origin.. These may have influenced a diverse range of traits, including keratin production, disease risk and the propensity to sneeze after eating dark chocolate. Where did all the other Neanderthal DNA go? Why did a Neanderthal-human hybrid not prevail? Two recent studies converge on an explanation. They suggest the answer comes down to different population sizes between Neanderthals and modern humans, and this principle of population genetics: In small populations, natural selection is less effective. “Neanderthals have this small population over hundreds of thousands of years, presumably because they’re living in very rough conditions,” said Graham Coop, a genetics professor at the University of California, Davis, and an author of one of the studies, published Tuesday in PLOS Genetics. As a result, Neanderthals were more inbred than modern humans and accumulated more mutations that have a slightly adverse effect, such as increasing one’s risk of disease, but do not prevent one from reproducing (and thus, passing such mutations along). © 2016 The New York Times Company
By Felicity Muth Kirsty Graham is a PhD student at the University of St Andrews, Scotland, who works on gestural communication of chimpanzees and bonobos in Uganda and DRCongo. I recently asked her some questions about the work that she does and some exciting recent findings of hers about how these animals communicate. How did you become interested in communication, and specifically gestures? Languages are fascinating – the diversity, the culture, the learning – and during undergrad, I became interested in the origins of our language ability. I went to Quest University Canada (a small liberal arts university) and learned that I could combine my love of languages and animals and being outdoors! Other great apes don’t have language in the way that humans do, but studying different aspects of communication, such as gestures, may reveal how language evolved. Although my interest really started from an interest in languages, once you get so deep into studying other species you become excited about their behaviour for its own sake. In the long run, it would be nice to piece together how language evolved, but for now I’m starting with a very small piece of the puzzle – bonobo gestures. How do you study gestures in non-human primates? There are a few different approaches to studying gestures: in the wild or in captivity; through observation or with experiments; studying one gesture in detail or looking at the whole repertoire. I chose to observe wild bonobos and look at their whole repertoire. Since not much is known about bonobo gestural communication, this seemed like a good starting point. During my PhD, I spent 12 months at Wamba (Kyoto University’s research site) in the DRCongo. I filmed the bonobos, anticipating the beginning of social interactions so that I could record the gestures that they use. Then I spent a long time watching the videos, finding gestures, and coding information about the gestures. © 2016 Scientific American
By Solomon Israel, A May-December romance brings benefits for young female gray jays mated to older males, according to new Canadian research. The paper, published this month in the journal Animal Behaviour, used almost four decades of data on a marked population of gray jays in Ontario's Algonquin Park to study how the birds adjust their reproductive habits in response to changes in temperature and other conditions. Gray jays, also known as Canada jays or whisky jacks, don't migrate south in the winter, instead living year-round in boreal forests across Canada and the northern U.S. They manage this feat of survival by caching food all over their large, permanent habitats, then retrieving it during the winter months. The small, fluffy birds take advantage of those winter supplies to nest much earlier than most other birds, laying eggs between late February and March. Gray jays don't migrate during the winter, instead relying on hidden caches of food to feed themselves and their offspring. (Dan Strickland) The researchers found that female gray jays that laid their eggs earlier in the season had the most reproductive success, with a higher survival rate for offspring. ©2016 CBC/Radio-Canada
By Virginia Morell Human hunters may be making birds smarter by inadvertently shooting those with smaller brains. That’s the conclusion of a new study, which finds that hunting may be exerting a powerful evolutionary force on bird populations in Denmark, and likely wherever birds are hunted. But the work also raises a red flag for some researchers who question whether the evolution of brain size can ever be tied to a single factor. The new work “broadens an emerging view that smarts really do matter in the natural, and increasingly human-dominated, world,” says John Marzluff, a wildlife biologist and expert on crow cognition at the University of Washington in Seattle who was not involved with the work. Hunting and fishing are known to affect many animal populations. For instance, the pike-perch in the Finnish Archipelago Sea has become smaller over time thanks to fishing, which typically removes the largest individuals from a population. This pressure also causes fish to reach sexual maturity earlier. On land, natural predators like arctic foxes and polar bears can also drive their prey species to become smarter because predators are most likely to catch those with smaller brains. For instance, a recent study showed that common eiders (maritime ducks) that raise the most chicks also have the largest heads and are better at forming protective neighborhood alliances than ducks with smaller heads—and presumably, brains. © 2016 American Association for the Advancement of Science
By Brian Owens Cooperation makes it happen. Sailfish that work together in groups to hunt sardines can catch more fish than if they hunt alone, even without a real coordinated strategy. To catch their sardine dinner, a group of sailfish circle a school of sardines – known as a baitball – and break off a small section, driving it to the surface. They then take turns attacking these sardines, slashing at them with their long sword-like bills, which account for a quarter of their total length of up to 3.5 metres. Knocking their prey off-balance makes them easier to grab. These attacks only result in a catch about 25 per cent of the time, but they almost always injure several sardines. As the number of injured fish increases, it becomes ever easier for everyone to snag a meal. “There’s no coordination, no strict turn-taking or specific hunting roles, it’s opportunistic,” says James Herbert-Read, from Uppsala University in Sweden. But Herbert-Reads computer models now show that even this rudimentary form of cooperation is better than going it alone. Sailfish that work in groups capture more sardines than a lone fish would get in the same amount of time. © Copyright Reed Business Information Ltd
Erin Wayman SALT LAKE CITY — The earliest primate was a tiny, solitary tree dweller that liked the night life. Those are just some conclusions from new reconstructions of the primate common ancestor, presented October 27 at the annual meeting of the Society of Vertebrate Paleontology. Eva Hoffman, now a graduate student at the University of Texas at Austin, and colleagues at Yale University looked at behavioral and ecological data from 178 modern primate species. Examining patterns of traits across the primate family tree, the researchers inferred the most likely characteristics of ancestors at different branching points in the tree — all the way back to the common ancestor. This ancient primate, which may have lived some 80 million to 70 million years ago, was probably no bigger than a guinea pig, lived alone and gave birth to one offspring at a time, the researchers suggest. Living in trees and active at night, the critter probably ventured out to the ends of tree branches to eat fruits, leaves and insects. But this mix of traits probably didn’t arise in primates, Hoffman says. After adding tree shrews and colugos — primates’ closest living relatives — to the analysis, the researchers concluded these same attributes were also present in the three groups’ common ancestor. So explanations of early primate evolution that rely on these features need to be reconsidered, Hoffman says. |© Society for Science & the Public 2000 - 2016.
Link ID: 22808 - Posted: 10.31.2016
Nicola Davis A brown, pebble-sized object found in a rock pool on a beach near Bexhill, Sussex bears the first evidence of fossilised dinosaur brain tissue, scientists say. Found in 2004 by an amateur fossil collector, the object is the cast of a dinosaur’s brain cavity, and appears to show a thin veneer of mineralised tissues on its surface. Scientists say the find is most likely from a relative of the Iguanodon, which lived around 125 million years ago. Large, hefty herbivores, Iguanodons reached up around eight metres in length, could walk on either two legs or all fours and boasted sharp spikes on their thumbs - a feature initially thought to be a horn on the nose and immortalised as such in the Victorian dinosaur sculptures of Crystal Palace Park. While casts of the inside of dinosaur brain cases have been found before, it is the first time fossilised brain soft tissue has been discovered for any land-living vertebrate. “The most striking thing is that something as delicate as brain tissue, and which you wouldn’t expect to ever see, has been preserved,” said Alex Liu, co-author of the research from the University of Cambridge. “It just speaks volumes [about] the spectacular preservational quality that can be obtained in the fossil record even 130 million years after this dinosaur is alive.” Writing in a special publication from the Geological Society of London to commemorate the work of the late co-author Martin Brasier, an international team of researchers describe how the cast was discovered near other dinosaur remains, including ribs and leg bones. “We can’t say it is from the same organism, but it is from a fairly large dinosaur,” said Liu. © 2016 Guardian News and Media Limited
Link ID: 22799 - Posted: 10.28.2016
By Brian Owens Chimpanzees and their relatives bonobos are closer than we thought. Bonobos seem to have donated genes to chimps at least twice in the roughly two million years since they last shared an ancestor. The two closely related apes have occasionally interbred in captivity, and bonobos are renowned for their free and easy sex life. But the finding that they interbred in the wild was unexpected. The two species split sometime between 1.5 and 2.1 million years ago, around the same time that the Congo River system formed. Wild bonobo populations are entirely contained in that river system, separated from two nearby subspecies of chimps, the eastern and central subspecies. Scientists assumed the river was an impenetrable barrier, says Christina Hvilsom from Copenhagen Zoo in Denmark, one of the researchers who worked on the genetic project. But it turns out that it must have been breached more than once – although it’s not clear how that happened. Hvilsom and her colleagues weren’t actually looking for genetic evidence of ancient interspecies erotica. They were mapping genetic markers that could be used to determine where illegally traded chimps came from so they could be returned to their homes in the wild. © Copyright Reed Business Information Ltd.
Link ID: 22798 - Posted: 10.28.2016
By Agata Blaszczak-Boxe Some rodents have a sweet tooth. And sometimes, you need to get crafty to reach your sugar fix. Rats have been filmed for the first time using hooked tools to get chocolate cereal – a manifestation of their critter intelligence. Akane Nagano and Kenjiro Aoyama, of Doshisha University in Kyotanabe, Japan, placed eight brown rats in a transparent box and trained them to pull small hooked tools to obtain the cereal that was otherwise beyond their reach. In one experiment they gave them two similar hooked tools, one of which worked well for the food retrieval task, and the other did not. The rats quickly learned to choose the correct tool for the job, selecting it 95 per cent of the time. The experiments showed that the rats understood the spatial arrangement between the food and the tool. The team’s study is the first to demonstrate that rats are able to use tools, says Nagano. The rats did get a little confused in the final experiment. When the team gave them a rake that looked the part but with a bottom was too soft and flimsy to move the cereal, they still tried to use it as much as the working tool that was also available. But, says Nagano, it is possible their eyesight was simply not good enough for them to tell that the flimsy tool wasn’t up to the task. The rodents’ crafty feat places them in the ever-growing club of known tool-using animals such as chimps, bearded capuchin monkeys, New Caledonian crows, alligators and even some fish. © Copyright Reed Business Information Ltd.