Weird Science: Looking stressed keeps the peace

Scratching is a sign of stress in many primates including ourselves. Photo / Steve Shattuck

Keep the peace

When we're threatened with aggression from others, we scratch ourselves to take down the heat.

That's been suggested by a UK study that says scratching - a sign of stress in many primates including ourselves - might have evolved as a communication tool to help social cohesion.

"Showing others you are stressed could benefit both the scratcher and those watching, because both parties can then avoid conflict," said the study's lead author, Jamie Whitehouse, of the University of Portsmouth.

Over eight months, Whitehouse and his colleagues tracked the social interactions of 45 monkeys from a group of 200, on the 35-acre island of Cayo Santiago, Puerto Rico.

The researchers found that scratching in the monkeys was more likely to occur in times of heightened stress, such as being close to high-ranking individuals or to non-friends.

Stress scratching significantly lowered the likelihood of a scratching monkey being attacked.

The likelihood of aggression when a high ranking monkey approached a lower ranking monkey was 75 per cent if no scratching took place, and only 50 per cent when the lower ranking monkey scratched.

Scratching also reduced the chance of aggression between individuals who did not have a strong social bond.

"As scratching can be a sign of social stress, potential attackers might be avoiding attacking obviously stressed individuals because such individuals could behave unpredictably or be weakened by their stress, meaning an attack could be either risky or unnecessary," Whitehouse said.

The researchers expect the findings will lead to a better understanding of stress and the evolution of stress in humans as well as how we manage stress in captive animals.

Insects' jaws act like gin traps

Myrmoteras ants live in the tropics of Southeast Asia. Photo / Steve Shattuck

Few potential victims stand a chance against the formidable mandibles of a trap-jaw ant - and now scientists have found spiders in New Zealand which also have these lightning-fast, spring-loaded systems.

In conflicts between predators and prey, speed is a decided advantage, and evolution has given these insects an edge with spring-loaded jaws that snap shut - often on their next meal - with astonishing speed.

Scientists at the Smithsonian's National Museum of Natural History have just provided the first mechanical description of the jaws of a little-known group of trap-jaw ants called Myrmoteras.

While at least four different groups of ants have independently evolved systems involving a latch, spring and trigger to power their fast-moving mandibles, the researchers have discovered that Myrmoteras ants' jaws work differently than those of any other known ant.

"It's a very interesting example of convergent evolution," said Fredrick Larabee, a postdoctoral researcher at the museum who led the research.

"Different trap-jaw ants have very fast jaws to accomplish similar tasks, but this group has evolved them in a completely independent way."

Myrmoteras ants live in the tropics of Southeast Asia, where they feed primarily on springtails - tiny arthropods that launch themselves into the air like fleas when they detect a threat.

Until they encounter their prey, the ants hold their long, slender jaws at the ready, opened to a 280-degree angle.

Latched into this position, the jaws store elastic energy.

When they are released, they snap shut in a fraction of a second.

No one knew previously just how fast Myrmoteras jaws move, but according to the new study, the ant's predatory strike takes only about half a millisecond.

That's 700 times faster than the blink of an eye.

Last year, Smithsonian scientists discovered a trap-jaw system in an unusual group of spiders that live in South America and here in New Zealand.

Spring-loaded systems are also responsible for the lightning-fast hops and leaps of grasshoppers, crickets and fleas.

These systems are diverse and have evolved through a variety of structural adaptations - highlighting just how advantageous high-speed movements can be.

Ancient Greeks chose quake zones for sacred sites

The Temple of Apollo at Delphi, Greece. Photo / File

While we've made our building codes quake-safe, it seems the Ancient Greeks took the extreme opposite approach, deliberately choosing land previously affected by earthquakes for their sacred or treasured sites.

A leading UK geologist now believes fault lines created by seismic activity in the Aegean region may have caused areas to be afforded special cultural status and, as such, led to them becoming sites of much-celebrated temples and great cities.

Scientists have previously suggested Delphi, a mountainside complex once home to a legendary oracle, gained its position in Classical Greek society largely as a result of a sacred spring and intoxicating gases which emanated from a fault line caused by an earthquake.

But Professor Iain Stewart, of the University of Plymouth, believes Delphi may not be alone in this regard, and that other cities including Mycenae, Ephesus, Cnidus and Hierapolis may have been constructed specifically because of the presence of fault lines.

"Earthquake faulting is endemic to the Aegean world, and for more than 30 years, I have been fascinated by the role earthquakes played in shaping its landscape," Stewart said.

"But I have always thought it more than a coincidence that many important sites are located directly on top of fault lines created by seismic activity.

"The Ancient Greeks placed great value on hot springs unlocked by earthquakes, but perhaps the building of temples and cities close to these sites was more systematic than has previously been thought."

In a new study, Stewart said a correspondence of active faults and ancient cities in parts of Greece and western Turkey might not seem unduly surprising given the Aegean region is riddled with seismic faults and littered with ruined settlements.

But, he added, many seismic fault traces in the region do not simply disrupt the fabric of buildings and streets, but run straight through the heart of the ancient settlements' most sacred structures.

There were prominent examples to support the theory, such as in Delphi itself, where a sanctuary was destroyed by an earthquake in 373BC only for its temple to be rebuilt directly on the same fault line.

"I am not saying that every sacred site in ancient Greece was built on a fault line," Stewart said.

"But while our association with earthquakes nowadays is that they are all negative, we have always known that in the long run, they give more than they take away.

"The ancient Greeks were incredibly intelligent people and I believe they would have recognised this significance and wanted their citizens to benefit from the properties they created."