They say that all’s fair in love and war, and that certainly seems to be the case of Atlantic mollies (Poecilia mexicana). These freshwater fish are small and unassuming, but in their quest to find the best mates, they rely on and Machiavellian misdirection.
The males always prefer larger females but not if they are being watched. Under the voyeuristic gaze of a rival male, Atlantic mollies will either feign disinterest or direct their attentions toward a smaller, less attractive female.
Deception is par for the course in the animal kingdom. Plovers will try to lure predators away from nests by feigning broken wings and ravens will fool their rivals over the burial locations of food, as just two examples. But this may be the first instance of one male tricking another about which mate they fancy the most.
Imagine being able to drink ludicrous amounts of alcohol without getting drunk and without the nasty consequences in the morning. For some people, it would be a dream come true but for the pen-tailed treeshrew (Ptilocercus lowii), it’s just part of everyday life.
The treeshrew lives in the rainforests of Malaysia and its local drinking establishment is a large plant called the bertam palm. The palm develops large stems a few metres in length, each of which sprouts about a thousand flowers. These are loaded with an alcoholic nectar with a maximum alcohol concentration of 3.8% – as strong as beer and one of the most alcoholic natural foodstuffs known. And because of it, the bertam plant regularly smells a lot like a brewery.
Frank Wiens from the University of Bayreuth, Germany, put several palms under 24-hour video surveillance and found that seven species of mammals, including treeshrews, regularly visited them to drink their boozy excretions. They would move up and down the stems for hours at a time, licking nectar as they went. Many animals, from monkeys to elephants, sporadically get hammered on naturally occurring alcohol but aside from some humans, the treeshrews are one of the few species we know of that chug the demon drink on a daily basis.
Wiens calculated that the animals were frequently drinking as much alcohol for their weight as a human woman knocking back nine glasses of wine in an evening. The little binge-drinkers were imbibing these substantial amounts on an average of one night in every three.
Simon Kirby and Hannah Cornish are watching evolution take place within the confines of their laboratory. But they are studying neither bodies nor genes; their interest lies in languages, and how they change over time.
Regardless of school lessons and textbooks, most of the features of the languages we speak are learned by listening to the words of native speakers. Their sentences convey their thoughts, but they also hint at the structure of the language they are spoken in. That allows people who are learning a new language to infer something about its structure by listening to the way its sentences are put together.
In the past, computer models have shown that behaviours like these, which are passed on through repeated cycles of observation and learning, eventually evolve to become easier to learn. But these simplified models are fairly removed from realistic learning. In his book on language evolution, Derek Bickerton described these models as a “case of looking for your car-keys where the street-lamps are.” The big question is whether real languages have also evolved in this way?
What’s really needed are experiments that test the adaptations that languages pick up over time, using the brains of living people rather than the software of computers. And that’s exactly what Kirby and Cornish have done. Together with Kenny Smith at Northumbria University, they have provided the first experimental evidence that as languages are passed on, they evolve structures that make them easier to transmit effectively.
The team tracked the progress of artificial languages as they passed down a chain of volunteers. They found that in just ten iterations, the made-up tongues had become more structured and easier to learn. What’s more, these adaptive features arose without specific plans or designs on the part of the speakers. The appearance of design without the guiding will of any designer is another trait that offers compelling parallels to biological evolution.
In a (very) loose tie-in with the recent release of the Dark Knight, it’s Bat Weekend at Not Exactly Rocket Science, where I’ll be reposting a few old but relevant pieces. If you were a biologist looking for astounding innovations in nature, you could do much worse than to study bats. They are like showcases of nature’s ingenuity, possessing a massive variety of incredible adaptations that allow them to exploit the skies of the night.
They are the only mammal group capable of true flight and are one of only four groups of animals to have ever evolved the ability. As a result, they have spread across the globe and enjoyed tremendous success. Today, one in every five species of mammal is a bat. None of them beat up criminals, but some have internal compasses, others have record-breaking tongues, and others have unique spatial memories.
To a science-fiction filmmaker, the concept of being controlled by unseen forces is creative gold, but for the rest of us, it’s a fairly unsettling prospect. But like it or not, it’s clear that parasites – creatures that live off (and often control) the bodies of others – are an integral part of the world we live in and carry an influence that far exceeds their small size.
Now, a painstaking survey of the residents of river estuaries shows that parasites do indeed punch above their weight, and they aren’t slouches in that department either. Despite their tiny size, their combined mass eclipsed that of the top predators in the area and their influence extended wider still. It’s a parasite’s world and we’re just living in it.
Over five years, Armand Kuris and Ryan Hechinger from the University of California, Santa Barbara led an exhaustive census of life in three Californian estuaries. At 69 different sites, they assessed almost 200 species of free-living animals, from high-flying birds to burrowing shrimps, as well as the 138 species of parasites hitching a lifestyle on their bodies.
When I started this blog, the intention was to try and use well-written articles on cool discoveries to get people who wouldn’t normally read science blogs to be interested in science. I’ve now been writing for almost two years and while traffic has grown, it strikes me that I still don’t know a lot about my readership, or the ratio of non-scientists/scientists who come to these pages.
So with that in mind, you can help me out by taking up these two challenges:
1) Tell me about you. Who are you? Do you have a background in science? If so, what draws you here as opposed to meatier, more academic fare? And if not, what brought you here and why have you stayed? Let loose with those comments.
2) Tell someone else about this blog and in particular, try and choose someone who’s not a scientist but who you think might be interested in the type of stuff found in this blog. Ever had family members or groups of friends who’ve been giving you strange, pitying looks when you try to wax scientific on them? Send ‘em here and let’s see what they say.
Thanks folks. Game on.
A complete ban on fishing can save coral reef communities in more ways than one. A few weeks ago, I blogged about a study which found that the coral trout, a victim of severe overfishing, was bouncing back in the small regions of the Great Barrier Reef where fishing has been totally forbidden. It certainly makes sense that fish will rebound when fishing ceases, but a new study reveals that the bans have had more indirect benefits – they have protected the corals from a predatory starfish.
The crown-of-thorns starfish (Acanthaster planci) is a voracious hunter of corals and a massive problem for reef conservationists. It’s bad practice for any science writer to anthropomorphise an animal, but the crown-of-thorns really does look incredibly, well, evil. Its arms (and it can have as many as 20) are covered in sharp, venomous spines. As it crawls over the reef, it digests the underlying coral by extruding its stomach out through its underside.
From time to time, their numbers swell into plagues of thousands that leave behind the dead, white skeletons of corals in their wake. These outbreaks eventually die off as the starfish eat themselves out of food supplies, but not before seeding downstream reefs with their tiny larvae that drift along the southern currents. During their peak, they destroy far more coral than other disturbances such as bleaching events or hurricanes.
Now, Hugh Sweatman at the Australian Institute of Marine Science has found that these outbreaks are much less frequent in the “no-take marine reserves”, where fishing is absolutely forbidden. Every year between 1994 and 2004, Sweatman carried out a census of starfish numbers in up to 137 areas across the Great Barrier Reef’s massive length.
Social spiders are an arachnophobe’s nightmare. While the vast majority of spiders work alone, the odd few live communally and cooperate to hunt and feed. Their numbers, along with the massive webs that they all have a spinneret in creating, allow them to tackle prey far larger than themselves. The aftermath of a kill opens up new conflicts for the spiders that other cooperating hunters like lions or wolves don’t share. They don’t divide up the carcass to eat separately, for like all spiders, they digest their prey outside their bodies.
All the colony members spit their digestive enzymes into the corpse and suck up the liquefied remains. But producing these enzymes costs energy, and since all the spiders are using the same opaque spittoon, there’s no way for an individual to tell how much its teammates are coughing up. It’s a system that favours cheats, who take their share of the communal resources but contribute very little toward creating them. This conflict isn’t just theoretical – experiments have shown that groups of social spiders feed far less efficiently than individuals do.
In the face of this temptation to cheat, how do the spiders manage to eat anything at all? This is a perennial question faced by biologists who seek to understand the evolution of cooperation: why work together, when cheating often yields greater rewards? There are many possible answers and in the social spiders, Jutta Schneider and Trine Bilde saw a chance to test one of the most pervasive – the theory of kin selection.
In April 1998, an aggressive creature named Tyson smashed through the quarter-inch-thick glass wall of his cell. He was soon subdued by nervous attendants and moved to a more secure facility in Great Yarmouth. Unlike his heavyweight namesake, Tyson was only four inches long. But scientists have recently found that Tyson, like all his kin, can throw one of the fastest and most powerful punches in nature. He was a mantis shrimp.
Mantis shrimps are aggressive relatives of crabs and lobsters and prey upon other animals by crippling them with devastating jabs. Their secret weapons are a pair of hinged arms folded away under their head, which they can unfurl at incredible speeds.
The ‘spearer’ species have arms ending in a fiendish barbed spike that they use to impale soft-bodied prey like fish. But the larger ‘smasher’ species have arms ending in heavy clubs, and use them to deliver blows with the same force as a rifle bullet.
New Scientist’s Feedback section has a running series of items on “nominative determinism”, that strange phenomenon where a person’s bears eerie witness to their occupation, such as a neurologist called Lord Brain, or an article on urology authored by Splatt and Weedon. Well here’s another example for them – a new paper about a singing fish from a scientist called Bass.
Beyond the wall-mounted horrors of Big Mouth Billy, fish are not exactly known for their vocal stylings, but one group – the toadfishes and midshipmans – are very noisy indeed. They make a range of dull grunts and hums by vibrating their swim bladder, the same organ that keeps them afloat.
In the Trials of Life, David Attenborough tells the story of an entire bay in America whose residents were infuriated by a bizarre throbbing noise that permeated their homes and drove them up the wall. The source was eventually discovered by a marine biologist, who played recordings through an underwater microphone and attracted female toadfishes in droves. It was the amorous males that were responsible, and their sexy songs were the cause of all the ruckus.
Now, Andrew Bass at Cornell University has shown that the tunes of these aquatic loudmouths are driven by a set of neurons that are shared by all vertebrates. This ‘vocal motor nucleus’ was most likely present in the last common ancestor of the entire group and evolved more than 400 million years ago. Since then, it has driven all manner of social communication, from the beautiful songs of birds, to the duller hums of toadfishes to the even more distressing warbling of the Spice Girls.