Carbon dioxide in the ocean acts like alcohol on fish, leaving them less able to judge risks and prone to losing their senses.

New Scientists reports

Around 2.3 billion tonnes of human-caused CO2 emissions dissolve into the world’s oceans every year, turning the water more acidic.

Philip Munday and colleagues at James Cook University in Townsville, Queensland, Australia, previously found that if you put reef fish into water with more CO2 than normal in it – similar to the levels expected in oceans by the end of the century – they become bolder and attracted to odours they would normally avoid, including those of predators and unfavourable habitats.

Munday and his colleague Göran Nilsson at the University of Oslo, Norway, have now discovered that CO2 leads to riskier behaviour by interfering with a neurotransmitter receptor called GABA-A.

The pair reared clownfish (Amphiprion percula) larvae in seawater with normal (450 microatmospheres) and elevated (900 microatmospheres) CO2 levels. When they reached adulthood, the fish were given a choice between a water stream containing the odour of common predators such as the rock cod (Cephalopholis cyanostigma) or a stream lacking predatory odours. Those reared in high levels of CO2 swam towards rock cod’s scent around 90 per cent of the time, whereas those that had enjoyed normal levels of CO2 avoided the predator’s scent more than 90 per cent of the time.

Treating the clownfish bred under CO2-rich conditions with gabazine, a chemical that blocks the GABA-A receptor, helped them to regain their senses, though: fish treated this way swam towards the predatory smell only 12 per cent of the time.

Journal reference: Nature Climate Change, DOI: 10.1038/nclimate1352

The sins of the father are indeed passed onto the children. High fat diets cause tiny changes in sperm that may lead to metabolic disorders in pups. The discovery brings us closer to understanding how lifestyle choices affect the health of future generations.

New Scientist reports

Maria Ohlsson Teague and Michelle Lane at the University of Adelaide, Australia, have shown that mice brought up on a bad diet have offspring that are prone to insulin resistance.

To investigate, the team screened mouse sperm for tiny bits of genetic material that switch off protein production. They identified 21 of these microRNAs that were expressed differently in the sperm of mice fed on a high fat diet compared with those on a healthy diet.

The pair used a database of known microRNAs to predict the effect of the altered markers. The top biological networks likely to be affected were associated with embryo and sperm development, and metabolic disorders.

The large amounts of fat around the testes of obese mice, “could alter the environment and encourage epigenetic changes”, says Teague, who presented the results at the 14th World Congress on Human Reproduction in Melbourne, Australia, this month.

In the future, it may be possible to screen sperm during IVF or block unwanted epigenetic changes with drug therapy, says Teague. “We prefer to encourage healthy lifestyles,” she adds.

The rat race isn’t too harsh after all. Turns out the distress shown by a trapped rat will encourage another rat to spring the trap and free the rodent. New Scientist Magazine reports

Inbal Ben-Ami Bartal and Peggy Mason at the University of Chicago housed 60 rats in pairs. Two weeks later, one of each pair was placed in a plastic trap that could be opened if the other nudged the door with its snout.

The free rats showed signs of distress at their cage-mates’ predicament, says Bartal. After 12 days of practice, 77 per cent of them learned how to open the door and liberate the trapped rat. The experiments suggest not only that rats can share in the distress of another, but that they dampen their natural anxiety in the face of that distress enough to offer assistance.

To see how far they could push this empathy, the researchers gave the free rats a tempting alternative. “We pitted chocolate against liberating a trapped rat,” says Bartal. The free rat was confronted with a trap restraining their cage-mate and another harbouring a tasty chocolate treat. Which would they open first?

On average, the free rats were as quick to free their cage-mate as to liberate the chocolate. Most surprisingly, says Bartal, although the liberator could choose to eat all the chocolate before freeing their cage-mate, they were more likely to share. “They were very generous. It is really impressive for rats,” says Bartal. “It would be impressive for people too.”

We are impressed when chimps use tools to hunt, crack nuts and forage for honey. Or when an octopus cracks coconuts with his tentacles .

But, a new study suggests that tool use is not related to cognitive ability. Using tools seems to be mentally demanding because it involves several skills, for example grabbing food with a stick involves learning the spatial relationship between two objects. Plus, a strong correlation has been found between tool use and brain size in birds and primates.

These studies don’t demonstrate that an animal is clever though. So Sabine Tebbich at the University of Vienna and colleagues compared the smarts of two species of Darwin’s finches: the woodpecker finch and its close relative, the small tree finch.

Both species live in the Galápagos archipelago, but small tree finches do not use tools, while woodpeckers can use twigs to poke arthropods out of tree holes. Tebbich also compared younger woodpecker finches that had not developed tool-use skills yet. Tebbich captured woodpecker and small tree finches and subjected them to four tasks, each testing different cognitive abilities.

First, food was balanced in the center of a seesaw, with a hole on one arm. The birds couldn’t get the food directly as it was covered by a plastic box. Instead they had to jump on a lever to let the food roll down so they could eat it. If the finches jumped on wrong lever, the tasty morsel would roll into the hole and be lost.

Five of the six small tree finches tested solved the task, while only two of the six tool-using woodpecker finches worked it out. None of the young woodpecker finches completed the task.

In a harder test, two canes were rested on a table with food placed within one. The bird had to pull one cane to get a reward, but they were connected with a string so pulling the wrong one caused the food to move out of reach. Successful birds spotted where location of the food, and knew to pull the cane that brought the food close to them. Eight of 12 woodpecker finches – three non tool-users and five tool users – and all six small tree finches successfully completed the task.

Testing the bird’s ability to unlearn, the animals were next shown two lids of different colours – orange and blue – with food always hidden under the same coloured lid. Once the birds knew where the food was, the researchers reversed the lids. Again, the small tree finches outperformed the woodpeckers by learning the new rule faster.

The only test where the tool using woodpeckers surpassed small tree finches was a box-opening task. Woodpeckers opened a box with an opaque lid using their beaks, while small tree finches hopelessly pecked the top of box to get the goodies inside.

“Everybody, for god knows how long, has been making a blind assumption that if you use a tool you are intelligent,” says Calum Brown an ecologist at Macquarie University in Sydney, who was not involved in the work. “It’s such an overwhelming idea in this field, but this shows it’s not the case.”

Alex Kacelnik a behavioural ecologist at Oxford University, UK agrees. “While it is valid to use flimsy arguments and intuition to form a hypothesis, it takes systematic reasoning and experimentation to prove it. Tebbich has been a pioneer.”

According to Brown, some animals maybe use tools through trial and error, which doesn’t mean they’re smart. “You need to really show that there is some kind of higher order cognitive process going on,” says Brown. For example an animal might be aware that if they push something, another action will happen. One way to prove this, says Brown, would be to show animals a task and give them one chance to solve it.

Russell Gray at the University of Auckland, New Zealand points out that making tools is a lot more cognitively demanding than using them. So, there are still good reasons for thinking animals making tools makes us smart.

Journal Reference: Animal Behaviour doi:10.1016/j.anbehav.2011.07.032

Image credit: Erica Cartmill

Penguins drenched in oil from New Zealand’s Oil Spill have something to look forward to – a slick new wardrobe.

Over a thousand oil-soaked birds, including 22 little blue penguins, have died since the 236 metre cargo vessel ran aground on the 5th of October dumping at least 350 tonnes of fuel into the Bay of Plenty in New Zealand.

According to Maritime New Zealand, a further 58 oiled penguins have been taken into the Wildlife Response Centre for rehabilitation.

To help the languishing birds, Skeinz a small yarn store in Napier, New Zealand posted a request on their website last week asking crafty-types around the world to knit penguin jumpers (aka sweaters). Marree Buscke of Skeinz told New Scientist they have since received hundreds of woolies, and she expects over a thousand to arrive in the next week. “We just wanted to get some knitters together, but it went a little viral,” she says.

It’s not a joke, but a rather ingenious idea. The notion of penguin jumpers was concocted a decade ago by the Tasmanian Conservation Trust (TCT) as part of a preventative strategy to protect little penguins (Eudyptula minor) in southern Australia that are regularly threatened by oil slicks from passing cargo ships.

According to TCT, oil clogs penguin feathers, reducing their ability to insulate and waterproof the birds. Worse still, the penguins ingest toxic oil when they attempt to clean themselves by preening. Jumpers solve both problems by keeping the birds warm, and creating a barrier to stop them consuming oil.

Before grabbing your needles and yarn, facility manager Brett Gartrell at the Wildlife Response Centre told Maritime New Zealand they have now received enough jumpers and for no more are needed.

Producing an annoying sound may seem like an unlikely way to attract a mate. But male and female mosquitoes buzz at each other to signal their interest, which sometimes leads to a harmonic duet (Click here to see them action).

As New Scientist reports – to investigate why mosquitoes would bother harmonising Lauren Cator and Laura Harrington at Cornell University in Ithaca, USA tethered female mosquitoes to strands of human hair and released three male suitors close to each one. Following the styles of Kim K and Paris, they captured the mating insects on video and took sound recordings of the encounters.

Harmonising males were much more likely to get lucky and to produce offspring. The males that couldn’t sing in tune were often rejected, with females kicking them, holding them away with their legs, or even tilting their abdomens to prevent genital contact, as shown in the video.

But some non-harmonising fellows were successful, so harmonising isn’t necessarily required for males and females to mate. To explore the benefits of the duet, the team mated five sons of both harmonising and non-harmonising males with an unrelated female.

They found that harmonising pairs was more likely to produce sons that could harmonise, suggesting that there is a genetic component to their musical ability. “By singing in synch, males might signal to females that they carry genes that create sexy sons”, says Cator.

The findings could improve current programs attempting to eradicate mosquito-borne diseases by releasing genetically modified or sterile males into the wild. For example, releasing harmonising GM males might outcompete wild mosquitoes faster than non-harmonisers.

New Scientist reports

The world’s first high-rise factory will be built in Nanjing, China.

The 24-storey industrial and commercial building, to be completed in 2024, will dwarf today’s tallest factories. According to the project architect Robert Caulfield of CK Designworks, based in Melbourne, Australia, existing factories don’t rise above eight storeys.

The high-rise’s footprint is 18,400 square metres, but the building has a total floor area of 111,700 square metres.

Caulfield estimates it will use less than half the energy of conventional factories producing similar goods.

The energy savings come from efficiently trapping heat in the stacked factory floors to keep the building warm when necessary, with solar power supplementing it. Treated waste water will be used for cooling in warm weather, before being fed into a lake nearby.

The building’s ground floor is designed to house amenities and the top 12 floors will be offices. But sandwiched between these levels are 12 industrial floors with 6-metre high ceilings, reinforced floor slabs and heavy-duty lifts that can hold forklifts.

Small cranes and conveyor systems will be installed on each floor, creating the possibility for 200-metre-long production lines that move between floors. It’s not yet decided what will be manufactured in the building, but it can accommodate the production a wide range of goods, such as mass-produced electronics or refrigerators, says Caulfield.

New Scientist reports

What can evolution tell us about domestic violence? Two researchers in the US suggest such violence has ancient origins and that establishing evolution’s role could help to better identify those at risk. Others argue that the research makes simplistic assumptions, and warn that some people will interpret the research as an excuse for violence.

Each year more than 500,000 women in the US alone report to the police violent attacks by current or former male partners. There is a reason why domestic violence is so widespread, says David Buss, an evolutionary biologist at the University of Texas in Austin: it carries a selective advantage, tied with reproductive success. In other words, men who are violent are trying to make sure that their partner has his child and not another man’s. “There are very predictable circumstances in which violence occurs,” says Buss. “For instance, with the threat of sexual infidelity or the threat of relationship termination.”

For instance, in a study of 8000 women some 14 per cent of those with a history of domestic violence agreed that their partner “is jealous and doesn’t want you to talk to other men” – less than 1 per cent of women who experienced no violence agreed with the statement.

Buss predicts that domestic violence will be more likely when a man has a female partner of higher “mate value” – a woman who earns more, is more intelligent or is considered more physically attractive than him. He says men in such circumstances may resort to violence to deter the woman from straying, or else to reduce her own perception of her value by lowering her self-esteem.

“Buss’s hypotheses are certainly plausible,” says biologist Barbara Tschirren at the University of Zurich in Switzerland. “We know from studies in animals that conflicts among family members are ubiquitous.”

“For many people, saying something might have been adaptive in the past is difficult to separate out from saying it is good or right or natural,” says Robert Brooks, an evolutionary biologist at the University of New South Wales in Sydney, Australia. “But we are the product of the traits that made our ancestors good at reproducing, including many quite abhorrent traits.”