While our brains are pretty good at picking up (and on) even very subtle accents, we struggle to transfer that insight to our own speech. Why is that? Scientists say it may come down to the first few months of our lives, before we’ve spoken our first word.
For over two decades, researchers at the University of Washington have been figuring out how our brains learn language. Many of their experiments have involved measuring how babies from different parts of the world respond to sounds over time. In one study, they played a reel of sounds common in both Japanese and English to children from each culture. At around 6 months, all of the babies responded equally to sounds from both languages. But by the time they reached 10 months, babies failed to notice sounds that don’t exist in their mother’s tongue. For instance, at 10 months, the Japanese babies were ignoring the “r” and “l” sounds that are nonexistent in Japanese, but common in English.
Another study from a different group of researchers suggests that this ability to learn languages doesn’t end abruptly, but tapers off as we age towards puberty. After surveying a broad sample of studies, the authors found that the strength of a person’s accent in their second language directly correlated with the age at which they learned the language.
“You start learning language by picking up sounds, trying to imitate your parents,” explained Eric Baković, a linguist who studies sound patterns in language at UC San Diego. “Then, your brain gets busy doing other things and assumes you have learned all the sounds you need to learn to communicate with the people around you.” This library of sounds enables us to communicate fluently and stay abreast of the language as it evolves, but makes us effectively deaf to sounds that fall outside it, says Baković.
“When you hear a totally different accent or language, you start mapping the sounds onto the language you already know,” he said. Rather than pronouncing the sounds of a new language, you piece together a rough approximation with the sounds your brain already knows.
But pesky foreign accents, rooted as they are in our brains’ incomplete library of sounds, can be trained away. Joel Goldes is an accent coach based in Hollywood. He works with everyone from actors trying to sound right for a part to foreign business people who want to be free of their linguistic liability. He says his experience fits with the scientific research. “Our brains really block us from hearing what we’re hearing. Until someone is taught to form the new sounds, they don’t hear them. That’s why a person can be in a country 30 to 40 years without losing their accent,” he said.
The number of wild animals on Earth has halved in the past 40 years, according to a new analysis. Creatures across land, rivers and the seas are being decimated as humans kill them for food in unsustainable numbers, while polluting or destroying their habitats, the research by scientists at WWF and the Zoological Society of London found.
A second index in the new Living Planet report calculates humanity’s “ecological footprint”, ie the scale at which it is using up natural resources. Currently, the global population is cutting down trees faster than they regrow, catching fish faster than the oceans can restock, pumping water from rivers and aquifers faster than rainfall can replenish them and emitting more climate-warming carbon dioxide than oceans and forests can absorb.
The report concludes that today’s average global rate of consumption would need 1.5 planet Earths to sustain it. But four planets would be required to sustain US levels of consumption, or 2.5 Earths to match UK consumption levels.
The fastest decline among the animal populations were found in freshwater ecosystems, where numbers have plummeted by 75% since 1970.
The number of animals living on the land has fallen by 40% since 1970. From forest elephants in central Africa, where poaching rates now exceed birth rates, to the Hoolock gibbon in Bangladesh and European snakes like the meadow and asp vipers, destruction of habitat has seen populations tumble. But again intensive conservation effort can turn declines around, as has happened with tigers in Nepal.
Marine animal populations have also fallen by 40% overall, with turtles suffering in particular. Hunting, the destruction of nesting grounds and getting drowned in fishing nets have seen turtle numbers fall by 80%. Some birds have been heavily affected too. The number of grey partridges in the UK sank by 50% since 1970 due to the intensification of farming, while curlew sandpipers in Australia lost 80% of their number in the 20 years to 2005.
The biggest declines in animal numbers have been seen in low-income, developing nations, while conservation efforts in rich nations have seen small improvements overall. But the big declines in wildlife in rich nations had already occurred long before the new report’s baseline year of 1970 – the last wolf in the UK was shot in 1680.
Also, by importing food and other goods produced via habitat destruction in developing nations, rich nations are “outsourcing” wildlife decline to those countries, said Norris. For example, a third of all the products of deforestation such as timber, beef and soya were exported to the EU between 1990 and 2008.
Add dolphins to the list of magnetosensitive animals, French researchers say. Dolphins are indeed sensitive to magnetic stimuli, as they behave differently when swimming near magnetized objects. So says Dorothee Kremers and her colleagues at Ethos unit of the Université de Rennes in France, in a study in Springer’s journal Naturwissenschaften — The Science of Nature. Their research, conducted in the delphinarium of Planète Sauvage in France, provides experimental behavioral proof that these marine animals are magnetoreceptive. Magnetoreception implies the ability to perceive a magnetic field. It is supposed to play an important role in how some land and aquatic species orientate and navigate themselves. Some observations of the migration routes of free-ranging cetaceans, such as whales, dolphins and porpoises, and their stranding sites suggested that they may also be sensitive to geomagnetic fields.
"Dolphins are able to discriminate between objects based on their magnetic properties, which is a prerequisite for magnetoreception-based navigation," says Kremers. "Our results provide new, experimentally obtained evidence that cetaceans have a magenetic sense, and should therefore be added to the list of magnetosensitive species."
How the brain ages is still largely an open question – in part because this organ is mostly insulated from direct contact with other systems in the body, including the blood and immune systems. In research that was recently published in Science, Weizmann Institute researchers Prof. Michal Schwartz of the Neurobiology Department and Dr. Ido Amit of Immunology Department found evidence of a unique “signature” that may be the “missing link” between cognitive decline and aging. The scientists believe that this discovery may lead, in the future, to treatments that can slow or reverse cognitive decline in older people. Until a decade ago, scientific dogma held that the blood-brain barrier prevents the blood-borne immune cells from attacking and destroying brain tissue. Yet in a long series of studies, Schwartz’s group had shown that the immune system actually plays an important role both in healing the brain after injury and in maintaining the brain’s normal functioning. They have found that this brain-immune interaction occurs across a barrier that is actually a unique interface within the brain’s territory. This interface, known as the choroid plexus, is found in each of the brain’s four ventricles, and it separates the blood from the cerebrospinal fluid. Schwartz: “The choroid plexus acts as a ‘remote control’ for the immune system to affect brain activity. Biochemical ‘danger’ signals released from the brain are sensed through this interface; in turn, blood-borne immune cells assist by communicating with the choroid plexus. This cross-talk is important for preserving cognitive abilities and promoting the generation of new brain cells.” This finding led Schwartz and her group to suggest that cognitive decline over the years may be connected not only to one’s “chronological age” but also to one’s “immunological age,” that is, changes in immune function over time might contribute to changes in brain function – not necessarily in step with the count of one’s years. To test this theory, Schwartz and research students Kuti Baruch and Aleksandra Deczkowska teamed up with Amit and his research group in the Immunology Department. The researchers used next-generation sequencing technology to map changes in gene expression in 11 different organs, including the choroid plexus, in both young and aged mice, to identify and compare pathways involved in the aging process. That is how they identified a strikingly unique “signature of aging” that exists solely in the choroid plexus – not in the other organs. They discovered that one of the main elements of this signature was interferon beta – a protein that the body normally produces to fight viral infection. This protein appears to have a negative effect on the brain: When the researchers injected an antibody that blocks interferon beta activity into the cerebrospinal fluid of the older mice, their cognitive abilities were restored, as was their ability to form new brain cells. The scientists were also able to identify this unique signature in elderly human brains. The scientists hope that this finding may, in the future, help prevent or reverse cognitive decline in old age, by finding ways to rejuvenate the “immunological age” of the brain.
Professor Simon Baron-Cohen of Cambridge University argues that, broadly speaking, there are two different “brain types”. There are empathisers, who are good at identifying how other people are thinking or feeling, and there are systemisers, people who are more interested in trying to take apart and analyse systems i.e. people who are a bit nerdy. We are all a mix of the two, but most of us are more one than the other. Men tend to sit more along the systemising end of the spectrum, women at the empathising end, though there are plenty of exceptions. But is this simply the product of social conditioning? Professor Baron-Cohen thinks not, that exposure to different levels of hormones in the womb can influence the brain and subsequent behavour. Some of his most intriguing findings have come from on-going research into a large group of children who have been followed from before they were born. At around 16 weeks gestation, the children’s mothers had an amniocentesis test, which involves collecting samples of the fluid that bathes the womb. The researchers measured levels of testosterone in the fluid and have since discovered intriguing links between those levels and behaviour. “The higher the child’s pre-natal testosterone” Professor Baron-Cohen told me, “the slower they were to develop socially. They showed, for example, less eye contact at their first birthday”. They also had a smaller vocabulary when they were toddlers and showed less empathy when they were primary school age. On the other hand he found that being exposed to higher levels of testosterone in the womb seems to enhance some spatial abilities. “Children with higher levels of pre-natal testosterone were faster to find specific shapes hidden within an overall design.”
According to one of the researchers, Professor Ruben Gurr, men showed stronger connections between the front and back of their brain, suggesting that, “they are better able to connect what they see with what they do, which is what you need to be able to do if you are a hunter. You see something, you need to respond right away.”
Women, on the other hand, had more wiring between the left and right hemispheres of the brain. According to another of the researchers involved in this study, Dr Ragini Verman, “the fact that you can connect from different regions of the brain means you ought to be good at multi-tasking and you may be better at emotional tasks”.
As Alice was quick to point out, this particular study has its critics and even if it is true that our brains are wired differently this doesn’t prove it is innate. The human brain is extremely malleable, particularly during adolescence, and any differences you see could simply be the product of stereotyping and social pressure.
The programme contains lots of fascinating studies which can be used to support either camp, but what surprised us both is how little progress there has been in research looking at gender differences in areas like pain.
We know that women experience more chronic pain than men, but are less likely to get treatment. We also know that men respond better to some pain killers (paracetamol), while women respond better to some opioids.
Professor Jeff Mogil of McGill University in Montreal, Canada, thinks this is because men and women process pain differently, something which we should take into account when designing new drugs.