0 comments on “Design, Naturally: Lateral lines provide a sixth sense for underwater robots”

Design, Naturally: Lateral lines provide a sixth sense for underwater robots

By Anwen Bowers

More little fish swimming in a school.
“We turning left now?” “Yeah, you do know we have a sophisticated biological mechanism for finding that out, right?” “I was just asking for a friend” | Image: Tom Thai

Have you ever seen two fish bump into each other?

The underwater world is an assault of sensory signals. Sound, for example from crashing waves, travels over twice as fast in water than it does in air. Smells, ranging from mating hormones to decaying organisms, clash against each other like instruments in an orchestra and would be overwhelming to us if we had noses sensitive enough to detect them. Light is changing constantly, with the different wavelengths becoming increasingly filtered out with depth until animals are left navigating waters so dark that they would be impossible to penetrate with human eyes.

But despite the chaos, fish are able to identify predators, prey and potential mates with lightning reflexes and take the appropriate action within milliseconds.  This is thanks to a super-human sensing mechanism called the lateral line, which gives the fish a sixth sense with which to navigate in their watery habitat.

lateralline
A subtle stripe of hair can tell fish everything they need to know about their environment | Image: Pogrebnoj Alexandroff

Sometimes visible as a dark strip running along the fish from fin to tail, the lateral line consists of minuscule bundles of hair that can be either attached to the surface of the scales or slightly submerged in channels below the skin. These hairs work similarly to whiskers on a cat, bending in response to any change in the flow of water around the fish. Cells at the base of the hairs then send messages to the brain, containing information on the scale, speed, and direction of the disturbance. This can then be interpreted to give information about the size and shape, and therefore species and likely friendliness, of anything moving in the local area. The ability to identify friend from foe by the flick of its tail is an invaluable tool of survival.

Seas and oceans are one of the least understood habitats on earth, with vast areas being simply too inaccessible to explore. As space on land is becoming rapidly exhausted, we are extending further and deeper into the oceans to source food, generate energy and hunt for new minerals and medicines. Faced with challenges such as the extreme pressure and low temperatures, increasingly we are depending on the work of underwater robots to bring us information on the chemistry, physics, and biology of the deep sea.  Engineers looking to improve the performance and capabilities of these underwater robots have found inspiration in the lateral line to improve the performance of these robots.

robofish
Bass-ta la vista, Ray-by: artificial lateral lines have inspired highly sensitive robotic fish | Image: Titus 140

Researchers in Germany and the US have independently come up with two different systems that recreate the processes that take place in the lateral line hairs. Integrated into underwater robotic technology, these systems could create a robot with much greater perceptions of their surroundings. Traditionally, operators would rely on images from video and sonar to navigate and direct the actions of the robot underwater. Both of these technologies are limited, as they can only provide information on the small area that they are pointing at Imagine only being able to view the world through a toilet roll tube ‚Äď it‚Äôs a bit like that.

Lateral lines could provide a much more detailed 3D picture of the surrounding environment, allowing more informed decisions about how the robot should proceed. The more information available about the surrounding area, including any obstacles, the greater the chance of the robot completing its mission as efficiently and safely as possible. For example, if the battery is running low, the lateral line would be able to identify nearby areas of low water movement where the robot can go to rest and conserve energy out of the current. Taking inspiration from nature, and building robots that can sense like fish, scientists can expect to soon be announcing plenty more exciting discoveries from the mysterious deep ocean.

0 comments on “Design, Naturally: Precious pearls inspire super-strong glass”

Design, Naturally: Precious pearls inspire super-strong glass

By Anwen Bowers

dukeofbuckingham
The¬†Duke of Buckingham’s frankly over-the-top bling held some fascinating material properties. | Image: Art Gallery of South Australia

Take a stroll through almost any art gallery and the cultural value of pearls as a status symbol through time is inescapable. From the intricately laced clothes in Elizabethan portraits to the long strings worn by chic youth in the early 20th century photographs, pearls have been a symbol of wealth and glamour. However, shifts in technological capabilities mean that pearls could soon have a much broader range of uses than being merely decorative.

Starting life as a humble piece of grit, pearls gain their ethereal shimmer from nacre, a biological substance secreted by oysters, which eases the discomfort once grit enters their shells. Nacre is produced by a number of different molluscs, and can also be found inside snail shells and coating mother-of-pearl. This material has long been of interest to materials scientists due to its incredible toughness.

Scanning electron microscopy has been used to reveal that the structure of nacre is similar to that of a brick wall, with ‚Äúbricks‚ÄĚ in the scale of micrometres being glued together by an organic adhesive. The bricks themselves are made of aragonite, a form of calcium carbonate with a similar structure to sea shells. ¬†These bricks overlay each other, and when pressure is applied they are able to slide against each other which prevents the material from snapping. If any cracks form in nacre then the adhesive acts as a barrier, dissipating the energy along the channels between the bricks and preventing the crack from propagating through the material.

aragonite
Layers of aragonite, held together with a natural glue, make up the intricate structure of nacre. New techniques are developing super strong glass from¬†man-made nacre, or ‘facre’ if you will | Image: Fabian Heinemann

This structure gives nacre the very desirable properties of strength and toughness combined, and a number of strategies have been proposed to create a synthetic material that mimics this brick and mortar structure. Most of the proposed methods have involved a ‚Äúground up‚ÄĚ strategy of assembling component parts, but this has only ever produced materials that have too high a proportion of adhesive and not enough solid bricks. Nacre itself is 95% aragonite, with only a tiny amount of adhesive holding everything together.

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Take it from the experts: oysters have been making better glass than us for over 100 million years. Still haven’t figured out how to make windows though. | Image: USEPA Environmental Protection Agency

A more recently proposed ‚Äútop down‚ÄĚ method involves a laser which carves into glass and fills the channels with polyurethane glue. This technique has created a material that strongly mimics the properties of nacre. It can be applied to glass or ceramic, both strong materials that are normally limited by their brittleness. By treating them with the polyurethane, scientists have created composite materials that have 700 times the toughness of the original glass!

Biology has been evolving materials for millions of years, to make structures for protection, support, buoyancy, cutting and grinding food, even building organic homes. Whereas slow evolution in the natural world means that each material has tailored properties making it the best choice for different functions, as humans we apply a relatively narrow range of materials to a very broad range of uses. As some materials become depleted, and others face environmental issues, it is vital that we explore other options, and tapping into the wisdom of nature seems like a good place to start.

0 comments on “X is for Xenophobia”

X is for Xenophobia

By Jonathan Farrow from the Thoughtful Pharaoh

A lot happened in the summer of 1954. ¬†The world’s first atomic power station opened in Russia, Alan Turing committed suicide, the CIA set up a coup in Guatemala, food rationing finally ended in the UK, and the first edition of Sports Illustrated was¬†published. ¬†Some pretty big world events, right?

You know what else happened? ¬†22 white, middle class boys boarded a bus to a Boy Scouts of America camp in Oklahoma. ¬†And I’m going to tell you why you should care that they did.

The Robber’s Cave Experiment

On one (presumably sunny) day in 1954, two busses each picked up eleven 11-year-old children who had been¬†screened to be “normal” (Remember, this was 50s America, so that meant white, protestant, middle class, two parents, above-average test¬†scores) and who didn’t know each other. ¬†The busses drove their “normal” boys to a summer camp called Robber’s Cave and deposited them on opposite sides, each group not knowing that the other existed.

For about a week, under the careful surveillance of psychologists posing as counsellors and camp staff, they participated in group bonding activities. ¬†[In some ways, ethics boards have made psychology a lot more boring. ¬†At the same time, it’s probably better that we now consider it unethical to Truman-show 22 pre-teens].

They camped out, played baseball, went swimming, and generally got to know each other.  They even came up with a name for their groups and emblazoned insignia on their t-shirts and caps.  One group killed a snake by a river and dubbed themselves the Rattlesnakes, the other group decided to be patriotic and called themselves the Eagles.

Then came the interesting part.

The experimenters introduced the groups to each other.

The Eagles and the Rattlesnakes were pitted against each other in a series of competitions Рbaseball, touch football, tug-of-war, and a treasure hunt.  The key aspect of these games was that one group always won and the other lost.  They were zero-sum games.

The result was a little bit scary. ¬†The groups started to hate each other. ¬†It started off with names like “sneak”, “cheat”, and “stinker” but soon developed into cabin raids, flag-burning, and even one Eagle telling another to brush the “dirt” of his clothes after bumping into a Rattler. ¬†There was some serious xenophobia (fear or disgust for the “other” or “alien”). ¬†The experimenters stopped the activities for fear of escalation to serious violence and started to think about how they might eliminate this extreme prejudice.

The crazy part is that these were all “normal” boys who didn’t know each other beforehand and had no reason to hate each other besides that their groups (that had also only been formed weeks ago) were in direct competition.

The experimenters tried to bring the groups together at mealtimes and for positive evening activities, but that only served to escalate the hatred.  They hurled food at each other at dinner time and jostled to be first in line.

What the experimenters tried next was pretty genius. ¬†They got the groups to try and work together to solve problems that affected everyone. ¬†One night the truck that was supposed to deliver food “broke down” so they all teamed up and pulled it out of the ditch with their tug-of-war rope. ¬†Another day, the water supply pipeline broke and they all worked together to find the leak.¬†These superordinate (larger than the group) goals brought the Rattlers and Eagles together.

Inter-group relationships built because of these events and at the end of the camp, some campers asked to mix up the busses and one group that had won $5 in a competitive contest offered to buy milkshakes on the ride home for the whole group.  How nice.  They had been reconciled as easily as they had been set against each other.

A 1997 study showed how this sort of reconciliation can be contagious. ¬†It isn’t just people who have friends in other groups who will be more likely to be empathetic. ¬†If you know someone who has friends in another group, you will be more likely to be nice to people in that group. ¬†Sounds a bit complicated, but basically if you have a friend who¬†is a clown, it’s not only you who will be more likely to not hate clowns, but also all of your friends. ¬†As soon as a few Rattlers got to thinking that maybe the Eagles weren’t so bad, the positive feelings¬†probably spread pretty quickly.

Chemical Basis for Xenophobia

But what was going on in their brains to make this happen?

Don’t worry, the kids weren’t lobotomized to find out.

A 2010 Dutch study out of the University of Amsterdam¬†showed that Oxytocin, the “cuddle chemical”, might have something to do with it.

Research subjects who had ingested some Oxytocin were more “ethnocentric” than their placebo-munching counterparts. ¬†People with a bit of extra Oxytocin in their systems were more likely to say they would sacrifice¬†the lives of many¬†outgroup members to¬†save the life of one ingrouper and associated more positive, human words with¬†ingroupers and more negative, dehumanizing words with outgroupers.

The Robber’s Cave Experiment was one of the first field experiments in¬†social psychology. ¬†It inspired Philip Zambardo’s Stanford Prison Experiment¬†and¬†Stanley Milgram’s Obedience Experiment. ¬†It pushed people to consider¬†why¬†they acted in bigoted ways and showed how easy it can be to both turn people on each other and bring them back together. ¬†When we mistreat people who belong to different racial/social/economic groups, are we really being any more¬†than rational than the Eagles and Rattlers? No, we aren’t.

To find out more about the Robber’s Cave experiment, read this summary article by the leader experimenter, Muzafer Sherif, and this webpage.

Muzafer Sherif is also famous for a series of studies using an interesting phenomenon known as the autokinetic effect.  he showed that people will create group norms and stick to them even when the group is taken away.

0 comments on “Homosexuality IS natural, (according to nature)”

Homosexuality IS natural, (according to nature)

by James Riley

One reoccurring argument constantly levelled against homosexuality is: “it’s just not natural.” Well, if you take a close look at nature, you’ll see that isn’t quite right.

(Feature Image, Original Credit: Simon Speed)

Animals partake in various same-sex sexual behaviours, ranging from frivolous romps (by the common toad) to life-long homosexual partnerships (in Chinstrap penguins).

In male fruit flies (Drosophila melanogaster) a mutation in the gene genderblind, causes a reduction in glutamate transmission, and leads males to court other males. Various other gene mutations, and social experiences, cause male-male courtships and same-sex mounting.

Bonobos, one of the closest extant relatives to humans along with the common chimpanzee, utilise sex as a method of easing social tensions. Females spend a substantial amount of time in same-sex genital stimulation. Males also engage in kissing, and somewhat intimate massages (and not just with their hands).

Numerous invertebrates also partake in homosexual behaviour, but many studies conducted on insects found this was a case of mistaken identity (must have been a rough morning). But in the animal kingdom, things are a little more romantic (if you’ll pardon my anthropomorphisation). Some male garter snakes mimic the female’s size and pheromones, leading to male-male courtships (so even drag queens are natural!). These relationships aren’t believed to be the case of mistaken identity, the courtships enable the snakes to ¬†thermoregulate better and also provides protection (there is something nice about homosexual snakes keeping each other safe and warm, even for hardline homophobes, am I right?).

In fact, homosexual behaviour is well-documented in over 450 species, but the true number is likely to be many times larger.

I can see the counter-arguments to this already forming: “Ok, so maybe nature is rife¬†with¬†gay animals, but nature isn’t always moral and it isn’t always right.”

True, nature doesn’t always exhibit the most moral of behaviours, and studying nature doesn’t always show us the right way to live our lives. But, (and this is big but… I cannot lie) the point is the argument that ‘homosexuality is immoral because it is unnatural’ is absolutely false. Observing nature shows that homosexuality is natural; it is everywhere, and it is everywhere for various reasons. So if you want to maintain that homosexuality is immoral, then please level a new argument against it rather than its supposed unnaturalness. Or, just let people live their own lives.

For more scientific information on homosexuality in animals, see:

Bailey, NW. Zuk, M (2009) Same-sex sexual behavior and evolution. Trends in. Ecology and Evolution. 24:439-446.