Thursday, 29 September 2011

'Once in a lifetime' rare white whale calf spotted off Australia

The (Sept. 29, 2011) - An extremely rare white humpback whale calf has been spotted near Australia's Great Barrier Reef in an event witnesses described Thursday as a "once in a lifetime experience".

Believed to be just a few weeks old, the baby humpback was seen at Cid Harbour in the famous reef's Whitsunday Islands area by local man Wayne Fewings, who was with his family in a boat when he spotted a whale pod.

"We were just drifting when I noticed the smaller whale in the pod was white. I couldn't believe my eyes, and I just grabbed my camera," Fewings said.

"Then the white calf approached my boat, seeming to want to check us out. I was just so amazed at seeing this animal, it made me think how truly astounding the Great Barrier Reef is," he added of the sighting on Saturday.

"I feel very lucky to have witnessed this, it's a once in a lifetime experience."

Reef official Mark Read said white whales were highly unusual, with only 10-15 believed to exist among the 10,000-15,000 humpbacks living along Australia's east coast, and purely white ones – like the calf spotted on Saturday – rarer still.

Its parents could both have been dark humpbacks carrying the recessive white whale gene, but Read said one or either may also have been white themselves, raising speculation it was the offspring of famous white humpback Migaloo.

Migaloo – the name is an Aboriginal word meaning "whitefella" – is the world's best-known all-white humpback and has built up a loyal following in Australia since first being sighted in 1991.

Humpback whales are currently on their southern migration and Mr Read said the baby white would be feeding heavily from its mother as it laid down fat stores for the "cold Antarctic waters."

Its sex was unknown and Read said there were no plans to bestow the young mammal with a name of its own.

"We'd be pretty comfortable for him or her just to simply remain anonymous and just live out its life in relative peace and harmony," Read said.

Australia's east coast humpback population has been brought back from the brink of extinction following the halting of whaling in the early 1960s, he added, describing it as a "conservation success story."

Australian koalas' loud noises 'made by human-style voice boxes'

The (Sept. 29, 2011) - Male koalas in Australia bellow so loud during mating season because their voice boxes are akin to those found in humans, scientists have discovered.

Despite the tree-dwelling mammal having a cute and furry appearance, a 15 pound koala is as loud as a cow weighing more than a tonne, a study found.

Researchers discovered the marsupial emitted a louder sound as a way of attracting sexual partners during mating season.

The team of Australian and Austrian scientists, writing in The Journal of Experimental Biology, also found their cries were a way of boasting about their body size and intimidate rival lovers.

Using complex medical imaging they discovered the sounds were louder because their larynx had “descended” and sat deeper in their throat and chest than other species.

This was similar to human development because as a person grows up, their larynx also becomes lower, and deeper, as they learn more complex language and speech.

"A lot of times people in the bush might hear a Koala calling… you have this cute fluffy animal but on the other hand (hear) this booming voice which jolts them a bit,” said Dr Bill Ellis, a co-author of the study.

"There are some interesting parallels in the structure of the actual vocal tract. This descendant of larynx koalas have is similar to that in some of the big cats but also in humans.”

“In adult humans we have really complex speech we should expect that similarly in koalas - it might be complex as well.”

Dr Ellis, the director of the Koala Ecology Group at the University of Queensland, added: "To our ear, we can't actually hear much difference between a large and not so large koala, but it seems koalas can tell.”

During their research, the scientists recorded 140 of the animals at the Lone Pine Koala Sanctuary in Queensland and measured their heads and body lengths.

They also carried out a medical scan on one male koala, which disclosed the marsupial's strange vocal anatomy.

An analysis of the recordings found the difference was not in the pitch but in “vocal tract resonance”. The bellows gave the impression their vocal tract was nearly 20 inches long or almost entire length of their body.

Dr Ben Charlton, from the University of Vienna, Austria, who led the study, said: “A permanently descended larynx hasn't been documented in marsupials before.

"It was believed that only humans had (this)… and that it was an essential adaptation for the creation of vowel sounds."

Dr Ellis said their noises were a way of “making themselves sound a lot bigger than they are".

They also found that as a female searched for a mating partner, they identified who issued the loudest bellows and calculated how big they were.

Previous studies using GPS tracking, specialists listening devices and DNA technology found larger males had better breeding success than their smaller rivals.

“It's quite apparent that there are some attributes that are closely correlated between the size and that one male can tell how big another male is,” Dr Ellis said.

"There are a number of strategies that koalas use for breeding and ... it isn't like an arms race to be the biggest koala.”

Earlier this year the Australian government warned koalas were facing serious risk of extinction, thanks to predators, climate change and rampant human development.


Wednesday, 28 September 2011

Sexy snacks: Study finds female mate searching evolves when mating gifts are important (Sept. 28, 2011) - In the animal world, males typically search for their female partners. The mystery is that in some species, you get a reversal -- the females search for males.

A new study of katydids in the latest issue of the journal Proceedings of the Royal Society B -- co-authored by U of T Mississauga professor Darryl Gwynne -- supports a theory that females will search if males offer a lot more than just sperm.

"In this beast [in this study], it's a big cheesy, gooey substance that the male ejects when he copulates," says Gwynne. "It's attached to his sperm packet, so while she's being inseminated, she can reach back and grab this mating gift and eat it."

Gwynne met the lead author of the study, Jay McCartney, while on sabbatical at Massey University in New Zealand. Since part of his own research expertise covered the mating behaviours of these types of insects, Gwynne was asked to act as a co-supervisor of the project and suggested that the data could provide clues into the diversity in nature of how animals search for mates.

"Males mostly do the searching, because the Darwinian sexual selection process is typical stronger in males; they're competitive," says Gwynne." As a consequence of their eagerness to get to the females, the females just hang out waiting for the males to come to them."

In the insects that Gwynne works with, some males sing to advertise that they have a safe burrow to offer the females, while in other species, they offer the females a nutritional perk. In the katydids, where a female searched for a male, she stood to gain the largest nutritional gift.

And from the male's perspective, a large food gift not only potentially benefits his offspring, but distracts the female long enough to ensure that he has time for a full insemination. Otherwise, says Gwynne, "she's hungry…if he didn't give her this gift, she'd just pull off the sperm packet and snack on that like a little hors d'oeuvre." Gwynne says that female searching behaviour exists elsewhere in the animal kingdom -- for example, in singing animals like frogs -- and deserves further study.

Monday, 26 September 2011

Monkeys at typewriters 'close to reproducing Shakespeare'

The Telegraph (Sept. 26, 2011) - Millions of virtual monkeys have almost typed out the entire works of Shakespeare by bashing random keys on simulated typewriters.

The virtual monkeys, created by an American programmer, have already typed up the whole of the poem A Lover's Complaint and are 99.99 per cent of the way through the Bard's complete works.

The experiment attempts to prove the theory that an infinite number of monkeys sitting at an infinite number of typewriters would eventually reproduce the works of Shakespeare by chance.

Jesse Anderson, the programmer behind the project, said he was inspired by an episode of The Simpsons which spoofs the famous problem.

Mr Anderson set up millions of small computer programmes, or virtual monkeys, using Amazon's SC2 cloud computing system, and programmed them to churn out random sequences of nine characters.

If the nine-letter sequence appears anywhere in one of Shakespeare's writings, it is matched against the relevant passage in a copy of the Bard's complete works, and is checked off the list.

The monkeys, which started typing on August 21, have already completed more than five trillion of the 5.5 trillion possible nine-letter combinations, but have so far only finished one whole work.

But the experiment is an imperfect reproduction of the infinite monkey theorem because it saves correct sections of text while discarding future wrong guesses, experts said.

Dr Ian Steward, emeritus professor of mathematics at Warwick University, said that for the monkeys to type up the complete works in the correct order without mistakes would take much longer than the age of the universe.

He told the BBC: "Along the way there would be untold numbers of attempts with one character wrong; even more with two wrong, and so on.

"Almost all other books, being shorter, would appear (countless times) before Shakespeare did."

Writing on his blog, Mr Anderson said: "This is the largest work ever randomly reproduced. It is one small step for a monkey, one giant leap for virtual primates everywhere.

"I understand the definition of infinite and infinite monkey theorem and I realise that this project does not have infinite resources.

"No monkeys were harmed during the making of this code. This project is my attempt to find a creative way to attain an answer without infinite resources."

In 2003 the Arts Council for England paid £2,000 for a real-life test of the theorem involving six Sulawesi crested macaques, but the trial was abandoned after a month.

The monkeys produced five pages of text, mainly composed of the letter S, but failed to type anything close to a word of English, broke the computer and used the keyboard as a lavatory.

New study says birds learn how to build nests

BBC News (Sept. 26, 2011) New study has found birds learn the art of nest-building, rather than it being just an instinctive skill.

Researchers from Edinburgh, Glasgow and St Andrews Universities studied film of southern masked weavers recorded by scientists in Botswana.

This colourful species was chosen because individual birds build many complex nests in a season.

Dr Patrick Walsh of Edinburgh University said the study revealed "a clear role for experience".

The research has been published in the Behavioural Processes journal.

Individual birds varied their technique from one nest to the next and there were instances of birds building nests from left to right as well as from right to left.

Even for birds, practise makes perfect”Dr Patrick WalshUniversity of Edinburgh

As birds gained more experience, they dropped blades of grass less often.

"If birds built their nests according to a genetic template, you would expect all birds to build their nests the same way each time. However this was not the case," added Dr Walsh.

"Southern Masked Weaver birds displayed strong variations in their approach, revealing a clear role for experience.

"Even for birds, practise makes perfect."

Saturday, 24 September 2011

Painting Pachyderm

Oli Scarff/Getty Images (Sept. 20, 2011) - DUNSTABLE, UK.  Karishma, a 13 year old female Asian elephant, paints at an easel in her enclosure at ZSL Whipsnade Zoo on September 20, 2011 in Dunstable, England. A selection of Karishma’s artwork will go on display at the Zoo this weekend to celebrate Elephant Appreciation Day.

Thursday, 22 September 2011

Unlike Humans, Chimpanzees Don’t Enjoy Collaborating

Wired Science (Sept. 22, 2011) - When it benefits them, chimpanzees willingly work together. Otherwise, they can’t be bothered.

For humans, collaboration is rewarding for its own sake, a behavioral split that may underlie key differences between human and chimpanzee societies.

Primate researchers, working with semi-free ranging chimpanzees at a sanctuary in Uganda, found chimpanzees recruit a helping partner only if it gets them more food than they’d get alone. The study, described in Animal Behavior, Sept. 7, is part of a current trend in primatology to unpick how motivation and mental state affects an animal’s interactions.

“It looks like motivation plays a very important role in how we behave,” said Anke Bullinger, primary author. “And it gives a hint that even though species might be cognitively capable of doing certain things, they might not show the behavior, because they just don’t want to.”

The extent of human cooperation is unique, but not cooperation itself. Chimpanzees, bonobos, elephants and many birds work together for joint rewards.

“The interesting thing is that there isn’t much research on the motivational aspects of this,” Bullinger said. “I suspect that motivation plays a role in many aspects of cognition, not just in cooperative behavior, but also in social learning, in communication.”

For the study, Bullinger and her colleagues set food boards out of the chimpanzee’s direct reach. To bring the banana bearing platforms close, the chimps pulled on a rope resting on the ground. Chimpanzees had two options. One board they could pull close solo. On another board, loose rope threaded between loops. To get these boards, both ends had to be pulled, so the chimpanzee had to go get their partner, waiting in an adjoining room.

When Bullinger placed two banana pieces on the single board, and four pieces on the partner board, amounting to the same payoff for each chimpanzee, the animals chose to work alone the vast majority of the time. If another banana piece for each was added to the partner board, the chimpanzees overwhelmingly choose to collaborate.

“We were a bit surprised that just one more piece made such a difference,” Bullinger said.

The study implies that chimpanzees view others as social tools, as a means of maximizing their own rewards.

Continue reading: "Unlike Humans, Chimpanzees Don’t Enjoy Collaborating"

Wednesday, 21 September 2011

Former Trainer Says Killer Whale Captivity Causes Attacks

Wired Science (Sept. 20, 2011) - On Sept. 19, a federal hearings began on the safety of keeping killer whales in captivity. Convened by the Occupational Health and Safety Administration in the aftermath of two fatal attacks on trainers, the hearings won’t consider the safety of killer whales — but according to former SeaWorld trainer Jeff Ventre, the two issues are inseparable.

An animal-loving Florida kid who majored in biology and rose to trainer stardom in Shamu Stadium before being fired, Ventre says the attacks that killed Dawn Brancheau at SeaWorld and Alexis Martinez at Loro Parque are manifestations of stress, even madness, in animals forced into miserable, unnatural conditions.

“Killer whales don’t attack humans in the wild,” said Ventre. “What we’ve seen in these injuries to people is a direct byproduct of the stress associated with captivity.”

Ventre was fired in 1995. SeaWorld says it was for being careless; Ventre says it’s because he’d become critical of the industry. Wired recently talked to Ventre, who has since become a medical doctor and cetacean advocate, about his work.

Wired: When did your feelings about keeping killer whales in captivity begin to change?

Jeff Ventre: When I started, I was just happy to have the job. It was amazing to see dolphins and sea lions and killer whales, despite the fact that they were in captivity. I thought there was going to be a lot of science, too. I’d grown up with Jacques Cousteau programming. Over time I found out there wasn’t much science going on. It was just a different version of the circus. Over time, that wears on you.

I did two different tours of duty at Shamu Stadium. The first time I was there, I was an apprentice. I did a lot of bucket-scrubbing, blue-collar type work, and had only a little water experience. Then I went around to the other stadiums, where they had dolphins, belugas and false killer whales, and honed my waterwork abilities. Then I was brought back to Shamu Stadium in 1994, where I spent my last two years. It was that second tour of duty that was somewhat enlightening.

By that time I’d learned enough about killer whales that I began to realize that what we were telling students coming in for education shows was at odds with what was true.

Wired: Give me an example.

Ventre: We were telling people that the animals lived to maybe 20 years old. But in reality, I knew that females lived to be 50, and males to be 30. That was a red flag. I also began to realize that all the killer whales in captivity had broken teeth. That seemed odd to me, because we were feeding them dead fish.

It’s because, when you put on a live public performance, or do a training session, you have to separate the killer whales with steel gates. These have horizontal bars on them. If you’ve ever seen two dogs on the opposite side of a fence barking, this is two orcas on the opposite side of a gate. Sometimes they charge the gate and bite down on the bars.

This knocks off the enamel and exposes the pulp of the tooth. This fleshy pulp is then drilled out by a veterinarian. What you have is a hollow tooth, creating a corridor down into the jaw itself. So for the rest of that animal’s life, they need to get their teeth flushed two or three times a day. In humans, it’s known that poor dentition leads to heart disease, kidney disease and stroke. These orcas are essentially left with a diseased mouth.

Wired: What are other ways in which killer whales are poorly suited for captivity?

Tuesday, 20 September 2011

How Far Will Dolphins Go to Relate to Humans?

New York Times Science (Sept. 19, 2011) - OFF THE BAHAMAS — In a remote patch of turquoise sea, Denise L. Herzing splashes into the water with a pod of 15 Atlantic spotted dolphins. For the next 45 minutes, she engages the curious creatures in a game of keep-away, using a piece of Sargassum seaweed like a dog’s chew toy.

Dr. Herzing is no tourist cavorting with marine mammals. As the world’s leading authority on the species, she has been studying the dolphins for 25 years as part of the Wild Dolphin Project, the longest-running underwater study of its kind.

“I’m kind of an old-school naturalist,” she said. “I really believe in immersing yourself in the environment of the animal.”

Immerse herself she has. Based in Jupiter, Fla., she has tracked three generations of dolphins in this area. She knows every animal by name, along with individual personalities and life histories. She has captured much of their lives on video, which she is using to build a growing database.

And next year Dr. Herzing plans to begin a new phase of her research, something she says has been a lifetime goal: real-time two-way communication, in which dolphins take the initiative to interact with humans.

Up to now, dolphins have shown themselves to be adept at responding to human prompts, with food as a reward for performing a task. “It’s rare that we ask dolphins to seek something from us,” Dr. Herzing said.

But if she is right, the dolphins will seek to communicate with humans, and the reward will be social interaction itself, with dolphins and humans perhaps developing a crude vocabulary for objects and actions.

Other scientists are excited by the project. “ ‘Mind-blowing’ doesn’t do justice to the possibilities out there,” said Adam Pack, a cetacean researcher at the University of Hawaii at Hilo and an occasional collaborator with Dr. Herzing. “You’ve got crystal-clear warm water, no land in sight and an interest by this community of dolphins of engaging with humans.”

How far will dolphins go to engage?

“The key is going to be coming up with a system in which the dolphins want to communicate,” said Stan Kuczaj, director of the Marine Mammal Behavior and Cognition Laboratory at the University of Southern Mississippi. “If they don’t care, it won’t work.”

Dr. Kuczaj developed an early two-way communication system while working at a captive lab in Orlando in the late 1980s. The system relied on visual symbols, not sound, and used a large stationary keyboard that proved to be too cumbersome.

But he says that the effort gave him confidence that such a system could work and that Dr. Herzing is “definitely the closest to getting there.”

“If it works,” he said, “it’ll be a huge step forward.”

Continue reading: "How Far Will Dolphins Go to Relate to Humans?" >>

Exposing the Impact of Our Choices on Nonhuman Animals

Care2 by Zoe Weil (Sept. 19, 2011)

In 1985, I was fascinated by what I’d read about Sarah, a chimpanzee who could use a symbolic language to communicate, so I contacted Dr. David Premack, the principal researcher working with Sarah and other chimps at the University of Pennsylvania primate research lab, to volunteer. I’ll never forget meeting Sarah. When I was brought to her cage, I was warned to stay away from the bars because Sarah was strong enough, and often aggressive enough, to grab me and cause severe injury.

Sarah lived alone in her cage. The four other chimps at the lab were only three years old, and I was told that Sarah might harm them, so this social animal was confined permanently in solitude. She had long since refused to continue with her language training, so her life consisted largely of watching soap operas on a TV on the other side of her cage or sitting in her small outdoor enclosure. It was the new young chimps, who were the subjects in the ongoing language acquisition studies who lived together and had a huge outdoor space in which to play.

Sarah threw what was described as a temper tantrum when introduced to new people, and I was no exception. She screamed and bounded from wall to wall, but I felt determined to have a positive relationship with her. Every time I volunteered I made a point of visiting Sarah. One day I said to her, “Sarah, turn around and I’ll scratch your back.” I rotated my right index finger in the air as I said “turn around” in case she didn’t understand my words. Sure enough, Sarah turned around, sank down to sit on the floor and pressed her back against the bars of the cage. I was unafraid as I went up to her and scratched her back.

I didn’t volunteer for very long. One of the young chimps bit my hand when I was paying too much attention to another who had climbed onto my shoulders. Even a three-year-old chimp can administer quite a bite, and it came just a week before my father died, and I needed to be gone for some time. I realized I didn’t really want to go back. Once I’d seen behind the scenes of something that had initially seemed so benign – teaching chimpanzees language – I realized just how much suffering was being inflicted on these cousins of ours.

For years I felt haunted by Sarah. Was she to live out her days in isolation and misery? All I could do was tell her story and, as a humane educator, teach, so that we might make different societal choices in relationship to others, whether people or nonhuman animals. Fifteen years later, I learned that Sarah had found a final home at Chimp Haven, a chimpanzee sanctuary that houses chimps formerly used in medical research, entertainment and as pets. My eyes filled with tears of relief at this good news.

Continue reading: "Exposing the Impact of Our Choices on Nonhuman Animals" >>

Crows Use Mirrors To Find Food

BBC Nature (Sept. 20, 2011) Clever New Caledonian crows can use mirrors to find food, according to scientists.

Researchers from the University of Auckland, New Zealand, tested wild-caught crows' reactions to mirrors.

The crows did not recognise themselves but found cached food items by studying their reflections.  The results put the birds in an elite group of species - which includes primates and elephants - known to be able to process mirror information.

New Caledonian crows (Corvus moneduloides) are known for their intelligent and innovative use of tools, such as twigs, which they use to fish nutritious insects out of holes and crevices.

Mirror experiments with other members of the same family of birds, the corvids, have found that magpies recognise their reflections but jungle crows do not.

In this study, published in the journal Animal Behaviour, psychologists examined the recognition skills of the notoriously clever New Caledonian crows.

Scientists captured 10 wild birds and placed them in large cages in order to record their behaviour in response to mirrors.

All the crows reacted to seeing their reflections as if they were encountering another crow; the birds made rapid head movements, raised their tails and even attacked the reflection.

Lead researcher Felipe S Medina Rodriguez said the crows' antagonistic reaction to their mirror image "was not surprising". He explained that an animal usually had extensive exposure to mirrors before it began to display an understanding that the image it was seeing was itself.

When the crows moved away from the mirror and lost sight of their reflection, they frequently searched behind the mirror to locate the "other" bird.

The researchers think that the behaviour was probably caused by the birds' lack of experience of mirrors; similar reactions have been recorded in primate infants and two-year-old children.

The second part of the experiment, though, revealed some surprising findings.

The scientists devised a task to test whether the crows could use mirrors to locate cubes of meat that were hidden from direct view.

All of the crows tested appeared to understand how the meat's reflection correlated to its location.

Escaped Pet Birds Are Teaching Wild Birds to Speak English

Treehugger (Sept. 15, 2011) Across parts of Australia, reports have been pouring in of strange voices chattering high in the treetops -- mysterious, non-sensical conversations in English. But while this phenomenon is certainly quite odd, its explanation isn't paranormal. It turns out that escaped pet birds, namely parrots and cockatoos, have begun teaching their wild bird counterparts a bit of the language they picked up from their time in captivity -- and, according to witnesses, that includes more than a few expletives.

Jaynia Sladek, an ornithologist from the Australian Museum, says that some birds are just natural mimickers, able to acquire new sounds based on things they hear around them. For birds kept as pets, these sounds tend to mirror human language -- but that influence doesn't cease even after said birds escape or are released back into the wild.

Once back in their natural environments, these chatty ex-pets eventually join with wild birds who, in turn, start picking up the new words and sounds. The remnants of that language also eventually gets passed along to the escaped birds' offspring, much like it does for humans.

"There's no reason why, if one comes into the flock with words, [then] another member of the flock wouldn't pick it up as well," Sladek said in an interview with Australian Geographic.

According to the report, 'Hello cockie' is one of the most commonly heard phrases feral birds are teaching in the wild, along with a host of expletives -- perhaps the last words those escapees heard after their frantic owners realized they were making a break for freedom.

Monday, 19 September 2011

Zoo Death Stirs Debate About Keeping Dolphins in Captivity

Wired Science (Sept. 14, 2011) - The death of a young bottlenose dolphin at a Chicago zoo was accidental, but some biologists say it shows why dolphins shouldn’t be kept in captivity for entertainment.

The dolphin, a 4-year-old named Nea, died on the afternoon of Sept. 5 at the Brookfield Zoo. According to a zoo press release, trainers heard “a loud pop” from the pool, apparently the sound of two dolphins colliding. Nobody reported seeing the collision, but it’s thought to have happened in the air as the animals jumped. Nea died minutes later from a fractured skull.

Zoo officials described it as a “freak incident,” ascribing it to typical roughhousing gone awry. But crowding dolphins into small, unnatural environments makes accidents more likely, said Wild Dolphin Project biologist Denise Herzing.

“Dolphins whack each other in the wild. That’s part of their aggressiveness. But in captivity, there’s less room,” said Herzing. “This isn’t the first time dolphins have had an accident in the air. Certainly there have been dolphins jumping out of tanks. The restricted lives of dolphins jumping in a pool can impact their ability to do what they normally do.”

Continue Reading “Zoo Death Stirs Debate About Keeping Dolphins in Captivity” »

Sunday, 18 September 2011

Mother Tongue Comes from Your Prehistoric Father

ScienceDaily (Sep. 17, 2011) Language change among our prehistoric ancestors came about via the arrival of immigrant men -- rather than women -- into new settlements, according to new research.

The claim is made by two University of Cambridge academics, Peter Forster and Colin Renfrew, in a report to be published in Science on September 9.

They studied the instances of genetic markers (the male Y chromosome and female mtDNA) from several thousand individuals in communities around the world that seem to show the emergence globally of sex-specific transmission of language.

From Scandinavian Vikings who ferried kidnapped British women to Iceland -- to African, Indian and Polynesian tribes, a pattern has emerged which appears to show that the arrival of men to particular geographic locations -- through either agricultural dispersal or the arrival of military forces -- can have a significant impact on what language is spoken there.

Professor Renfrew said: "It may be that during colonisation episodes by emigrating agriculturalists, men generally outnumber women in the pioneering groups and take wives from the local community.

"When the parents have different linguistic backgrounds, it may often be the language of the father which is dominant within the family group."

Dr Forster, of Murray Edwards College, also pointed to the fact that men have a greater variance in offspring than women -- they are more likely to father children with different mothers than vice versa. This has been recorded both in prehistoric tribes such as the 19th and 20th century Polar Eskimos from Greenland and in historic figures like Genghis Khan, who is believed to have fathered hundreds of children.

Indeed, his Y chromosome is carried by 0.5 per cent of the world's male population today.

Perhaps the most striking example of sex-biased language change however comes from a genetic study on the prehistoric encounter of expanding Polynesians with resident Melanesians in New Guinea and the neighbouring Admiralty Islands. The New Guinean coast contains pockets of Polynesian-speaking areas separated by Melanesian areas. The Polynesian mtDNA level (40-50%) is similar in these areas regardless of language, whereas the Y chromosome correlates strongly with the presence of Polynesian languages.

Past studies have shown similar findings in the Indian subcontinent among the speakers of Tibeto-Burman and among the immigrant Indo-European languages as opposed to indigenous Dravidian languages.

In the Americas, too, language replacement in the course of postulated farming dispersal has also been found to correlate for the Uto-Aztecan language family.

Added Forster: "Whether in European, Indian, Chinese or other languages, the expression 'mother tongue' and its concept is firmly embedded in popular imagination -- perhaps this is the reason why for so many years the role of fathers, or more likely, specific groups of successful males, in determining prehistoric language switches has not been recognised by geneticists."

"Prehistoric women may have more readily adopted the language of immigrant males, particularly if these newcomers brought with them military prowess or a perceived higher status associated with farming or metalworking."

Journal Reference:
P. Forster, C. Renfrew. Mother Tongue and Y Chromosomes. Science, 2011; 333 (6048): 1390 DOI:10.1126/science.1205331