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current biology
According to a new study published in the Current Biology, wild kangaroos tend to use their left hands during common tasks like grooming and feeding.
The researchers say this is the first demonstration of population-level “handedness” in a species other than humans, who are mostly right-handed.
They say evidence comes from hours spent observing multiple species in the wild.
Two species of roo and one wallaby all showed the left-handed trend; some other marsupials, which walk on all fours, did not show the same bias.
The research was conducted by Russian scientists from St Petersburg State University, who travelled to Australia to do the fieldwork. There they collaborated with Janeane Ingram, a wildlife ecologist and PhD student at the University of Tasmania.
Senior author Dr. Yegor Malashichev said there had been a “widespread notion” that handedness was a uniquely human phenomenon, until research in the last 10-20 years showed that asymmetry in behavior and brain structure was surprisingly widespread.
Examples of left- or right-handedness tended to be specific to particular behaviors, and were not consistent across a population.
“As one of our reviewers pointed out, laterality is also obvious in how parrots hold their food or how your dog shakes hands,” Janeane Ingram said.
“But these examples of lateralization have not been proven at the population level.”
The new study found a consistent left-handed bias across eastern grey kangaroos, red kangaroos, and red-necked wallabies – no matter whether the animals were grooming, feeding, or propping themselves up.
In terms of handedness, Dr. Yegor Malashichev said this confirmed for the first time that “we are not alone in the Universe; we are two – humans and kangaroos”.
Dr. Yegor Malashichev and his colleagues suggest that their discovery is an example of “parallel evolution”. This is because handedness seems to have appeared in primates, which belong in the group of placental mammals, as well as the marsupials in the new study, but not in related animals across these two branches of the evolutionary tree.
The researchers also argue that posture is an important factor. The left-handed trend was only seen in species that stand upright on their hind legs, using their forelimbs more regularly for tasks other than walking.
Similarly, they suggest, the transition to an upright posture may have been key to primates developing handedness.
It remains to be seen if there are particular aspects of the brain in these marsupials that have allowed handedness to develop – and whether they can explain why kangaroos, in contrast to predominantly right-handed humans, tend to be southpaws.
A new research sheds light on how turtles’ hard shells were formed.
Scientists say the ancient fossil skeleton of extinct South African reptile Eunotosaurus has helped bridge a 30 to 55-million-year gap.
Eunotosaurus, the ancestor of the modern turtle, is thought to be around 260 million years old.
It had significant differences to a recently found fossil relative.
Eunotosaurus was discovered over a century ago but new research in the journal Current Biology has only now analyzed its differences to other turtle fossils.
A turtle’s shell is unique in that it is made up of around 50 bones, with ribs, shoulder bones and vertebrae fused together to form a hard external shell.
How it forms today can be observed in a developing turtle embryo. Ribs broaden first followed by the broadening of vertebrae. The final state is the development of an outer layer of skin on the perimeter of the shell.
“The turtle shell is a complex structure whose initial transformations started over 260 million years ago in the Permian period,” said lead author of the study, Dr. Tyler Lyson from the Smithsonian Institution and Yale University.
Ancient fossil skeleton of extinct South African reptile Eunotosaurus has revealed how turtle’s shell was developed
“The shell evolved over millions of years and was gradually modified into its present-day shape.”
A turtle fossil 210 million years old had a fully developed shell similar to those today, but 10 million years earlier, a fossil discovered in China, named Odontochelys semitestac, had an incomplete top shell, called a carapace.
This fossil has now helped Dr. Tyler Lyson and colleagues compare the modern turtle with its ancestor Eunotosaurus.
Like turtles today, Eunotosaurus had nine pairs of T-shaped ribs. This ancient creature however did not have broad spines on its vertebrae, which both Odontochelys and modern-day turtles do have.
It also lacked intercostal muscles, which are the group of muscles that run between the ribs, and did not have osteoderms – bony scales.
“Eunotosaurus is a good transitional fossil which bridges the morphological gap between turtles and other reptiles,” said Dr. Tyler Lyson.
The evidence between fossil and developmental data shows that first the ribs broadened, then the neural spines of the vertebrae broadened, and finally osteoderms on the outer side of the shell formed. These all sutured together to form the modern-day turtle shell, he added.
“One of the direct consequences of forming a protective shell by broadening and locking their ribs is that turtles cannot use their ribs to breathe.
“Instead turtles have developed a unique abdominal muscular sling that wraps around their lungs and organs to help them breathe.”
Judith Cebra-Thomas, assistant professor from the department of biology at Millersville University in Pennsylvania, who was not involved with the study, said the research was very important in terms of understanding the turtle shell’s evolution.
“The turtle shell is considered an evolutionary novelty, which means that there are no closely analogous structures in related animals.
“That leads to the notion that such things cannot occur through normal evolutionary processes. But, when you examine it in detail, you can see the series of steps, each of them explainable through small changes that gradually add up to the novel structure.”
Turtle’s shell:
- The shell’s main function is protection but it can also help a turtle live underwater for longer than any other vertebrate
- This is because it stores potassium and magnesium which can help protect it from a buildup of lactic acid
- Other animals such as armadillos or various lizards, all form a shell via the acquisition of more and more osteoderms (ossified scales)
US researchers have found that people with higher IQs are slow to detect large background movements because their brains filter out non-essential information.
Instead, they are good at detecting small moving objects.
The findings come in a study of 53 people given a simple, visual test in Current Biology.
The results could help scientists understand what makes a brain more efficient and more intelligent.
In the study, individuals watched short video clips of black and white bars moving across a computer screen. Some clips were small and filled only the centre of the screen, while others filled the whole screen.
The participants’ sole task was to identify in which direction the bars were drifting – to the right or to the left.
Participants also took a standardized intelligence test.
The results showed that people with higher IQ scores were faster at noticing the movement of the bars when observing the smallest image – but they were slower at detecting movement in the larger images.
People with higher IQs are slow to detect large background movements because their brains filter out non-essential information
Michael Melnick of the University of Rochester, who was part of the research team said the results were very clear.
“From previous research, we expected that all participants would be worse at detecting the movement of large images, but high IQ individuals were much, much worse.”
The authors explain that in most scenarios, background movement is less important than small moving objects in the foreground, for example driving a car, walking down a hall or moving your eyes across the room.
As a person’s IQ increases, so too does his or her ability to filter out distracting background motion and concentrate on the foreground.
In an initial study on 12 people, there was a 64% correlation between motion suppression and IQ scores. In this larger study on 53 people, a 71% correlation was found.
In contrast, previous research on the link between intelligence and reaction times, color discrimination and sensitivity to pitch found only a 20-40% correlation.
But the ability to ignore background movements is not the only indicator of intelligence.
“Because intelligence is such a broad construct, you can’t really track it back to one part of the brain,” says Duje Tadin, who also worked on the study.
“But since this task is so simple and so closely linked to IQ, it may give us clues about what makes a brain more efficient, and, consequently, more intelligent.
“We know from prior research which parts of the brain are involved in visual suppression of background motion.
“This new link to intelligence provides a good target for looking at what is different about the neural processing, what’s different about the neurochemistry, what’s different about the neurotransmitters of people with different IQs.”
Asian elephant Koshik has astounded scientists with his Korean language skills.
Researchers report that the mammal has learnt to imitate human speech and can say five words in Korean: “hello”, “no”, “sit down”, “lie down” and “good”.
The zoo animal places the tip of his trunk into his mouth to transform his natural low rumble into a convincing impression of a human voice.
The study is published in the journal Current Biology.
Koshik’s vocal abilities mean that elephants now join a growing list of animals that are able to mimic man, from parrots and mynah birds to more unusual animals such as sea lions or the recently reported case of a human-sounding beluga whale.
The study’s lead author Dr. Angela Stoeger, from the University of Vienna in Austria, said she first came across Koshik after videos of the elephant, who belongs to Everland Zoo in South Korea, were posted on YouTube.
After making contact with the zoo, she went to South Korea to record the animal so she could study its unusual vocal talent.
Dr. Angela Stoeger said: “We asked native Korean speakers, who had never experienced the elephant before, to write down what they understood when we played back recordings from Koshik.
“We found a high agreement of the overall meaning.”
Asian elephant Koshik has astounded scientists with his Korean language skills
Dr. Angela Stoeger and her colleagues found that Koshik’s calls correlated to five Korean words: “annyeong” (hello); “anja” (sit down); “aniya” (no); “nuwo” (lie down) and “choah” (good).
“Human speech has two important aspects, one is pitch (how high or low a sound is) and one is timbre (the musical quality of a voice), and Koshik is matching both of these aspects,” said Dr. Angela Stoeger.
Usually, elephants produce much deeper sounds, sometimes of such a low frequency that they are outside the range of human hearing, and these calls can boom many miles away.
While Koshik was capable of producing these more typical elephant noises, he needed the help of his trunk to morph these into something far more human. The researchers said this was behavior they had not seen before.
“He always puts his trunk tip into his mouth and then modulates the oral chamber,” explained Dr. Angela Stoeger.
“We don’t have X-rays, so we don’t really know what is going on inside his mouth, but he’s invented a new way of sound production to match his vocalizations with his human companions.”
She added: “If you consider the huge size of the elephant and the long vocal tract and other anatomic difference – for example he has a trunk instead of lips… and a huge larynx – and he is really matching the voice pitch of his trainers, this is really remarkable.”
But while Koshik sounds convincing, the researchers do not believe that he has any comprehension of the words that he is saying.
Instead, they think that the elephant took up talking as a way to bond with his human companions.
Between the ages of five and 12, Koshik was the only elephant at Everland Zoo, and the researchers said that this was a crucial period for elephant development.
Dr. Angela Stoeger explained: “Humans were his only social contact – and we believe Koshik is using these vocalizations as a function to strengthen the socials bonds with his companions, which are humans in this case.”
Professor Klaus Zuberbuehler from the school of psychology and neuroscience at the University of St Andrews said that the findings were “enlightening”.
He said: “What’s needed now, in my view, is field research with free-ranging animals to see if vocal imitation plays any role in the natural lives of elephants or if it’s just a byproduct of human enculturation and socially abnormal upbringing.”
Scientists say that understanding how and why some animals make sounds could help us to understand how speech evolved.
A limited but diverse number of species are capable of hearing a sound, copying it and then reproducing it. Understanding these vocal imitations could help to provide clues about the building blocks of language.
Prof. Klaus Zuberbuehler added: “Vocal imitation… may be driven largely by specific social forces, such as the desire to bond with a specific other individual.
“It also makes me think that the evolution of vocal imitation may be more successfully investigated by comparing how different animal species use vocal behavior to strengthen their social bonds, rather than by studying the anatomy and neurophysiology of vocal tracts.”
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US researchers have discovered that beluga whale vocalizations were remarkably close to human speech.
While dolphins have been taught to mimic the pattern and durations of sounds in human speech, no animal has spontaneously tried such mimicry.
But researchers heard a nine-year-old whale named NOC make sounds octaves below normal, in clipped bursts.
The researchers outline in Current Biology just how NOC did it.
But the first mystery was figuring out where the sound was coming from. The whales are known as “canaries of the sea” for their high-pitched chirps, and while a number of anecdotal reports of whales making human-like speech, none had ever been recorded.
When a diver at the National Marine Mammal Foundation in California surfaced saying: “Who told me to get out?” the researchers there knew they had another example on their hands.
Once they identified NOC as the culprit, they made the first-ever recordings of the behavior.
Researchers have discovered that beluga whale vocalizations were remarkably close to human speech
They found that vocal bursts averaged about three per second, with pauses reminiscent of human speech. Analysis of the recordings showed that the frequencies within them were spread out into “harmonics” in a way very unlike whales’ normal vocalizations and more like those of humans.
They then rewarded NOC for the speech-like sounds to teach him to make them on command and fitted him with a pressure transducer within his nasal cavity, where sounds are produced, to monitor just what was going on.
They found that he was able to rapidly change the pressure within his nasal cavity to produce the sounds.
To amplify the comparatively low-frequency parts of the vocalizations, he over-inflated what is known at the vestibular sac in his blowhole – which normally acts to stop water entering the lungs.
In short, the mimicry was no easy task for NOC.
“Our observations suggest that the whale had to modify its vocal mechanics in order to make the speech-like sounds,” said Sam Ridgway, president of the National Marine Mammal Foundation and lead author on the paper.
“The sounds we heard were clearly an example of vocal learning by the white whale.”
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An analysis of hundreds of years of eunuch “family” records showed that castration had a huge effect on the lifespans of Korean men.
They lived up to 19 years longer than uncastrated men from the same social class and even outlived members of the royal family.
The researchers believe the findings show male hormones shorten life expectancy.
The study is published in the journal Current Biology.
Castration before puberty prevents the shift from boy to man. One of the scientists involved in the study, Dr. Cheol-Koo Lee from Korea University, said: “The records said that eunuchs had some women-like appearances such as no moustache hair, large breasts, big hips and thin high-pitched voice.”
An analysis of hundreds of years of eunuch "family" records showed that castration had a huge effect on the lifespans of Korean men
Eunuchs had important roles in many cultures from protecting harems to castrati superstar singing sensations. The imperial court of the Korean Chosun dynasty used eunuchs to guard the gates and manage food. They were the only men outside the royal family allowed to spend the night in the palace.
They could not have children of their own, so they adopted girls or castrated boys.
Researchers in South Korea analyzed the genealogical record of these “eunuch families”.
They worked out the lifespans of 81 eunuchs born between 1556 and 1861. The average age was 70 years, including three centenarians – the oldest reached 109.
By comparison, men in other families in the noble classes lived into their early 50s. Males in the royal family lasted until they were just 45 on average.
There are no records for women at the time for comparison.
Dr. Kyung-Jin Min, from Inha University, said: “We also thought that different living circumstances or lifestyles of eunuchs can be attributed to the lifespan difference.
“However, except for a few eunuchs, most lived outside the palace and spent time inside the palace only when they were on duty.”
Instead he thinks the data “provides compelling evidence that male sex hormone reduces male lifespan”.
Women tend to outlive men across human societies. However, theories are hard to test in experiments and the exact reason for the difference is uncertain.
One thought is that male sex hormones such as testosterone, which are largely produced in the testes, could be damaging. The researchers said the hormones could weaken the immune system or damage the heart. Castration would prevent most of the hormone from being produced, protecting the body from any damaging effect and prolonging lifespan.
Dr. Kyung-Jin Min said: “It is quite possible that testosterone reduction therapy extends male lifespan, however, we may need to consider the side effects of it, mainly reduction of sex drive in males.”
A group of scientists believe they have discovered a clue to why women tend to live longer than men by studying fruit flies.
Published in Current Biology, the study focuses on mutations in mitochondrial DNA – the power source of cells.
Mitochondria are inherited only from mothers, never from fathers, so there is no way to weed out mutations that damage a male’s prospects.
But one ageing expert said there were many factors that explained the gender difference in life expectancy.
And females outlive males in many other species.
Scientists believe they have discovered a clue to why women tend to live longer than men by studying fruit flies
In the research, experts from Australia’s Monash University and the UK’s Lancaster University analyzed the mitochondria of 13 different groups of male and female fruit flies.
Mitochondria, which exist in almost all animal cells, convert food into the energy that powers the body.
Dr. Damian Dowling, of Monash University who was one of the researchers, said the results point to numerous mutations within mitochondrial DNA that affect how long males live, and the speed at which they age.
“Intriguingly, these same mutations have no effects on patterns of ageing in females,” he said.
“All animals possess mitochondria, and the tendency for females to outlive males is common to many different species.
“Our results therefore suggest that the mitochondrial mutations we have uncovered will generally cause faster male ageing across the animal kingdom.”
They suggest this is because there is no evolutionary reason for the faults that affect males to be picked up – because mitochondria are passed down by females.
Dr. Damian Dowling added: “If a mitochondrial mutation occurs that harms fathers, but has no effect on mothers, this mutation will slip through the gaze of natural selection, unnoticed.
“Over thousands of generations, many such mutations have accumulated that harm only males, while leaving females unscathed.”
