Not Exactly Rocket Science

Clock gene and moonlight help corals to co-ordinate a mass annual orgy

Sat, 03 Oct 2009 10:01:53 -0500

This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.

Every month, at the full moon, tourists and students gather on the beach at Koh Phangan, Thailand for a night of booze, dancing, and debauchery. But the moon-themed antics of these party-goers look positively tepid when compared to those of the Great Barrier Reef's corals. With the help of two genes and a spot of moonlight, the corals synchronise one of the greatest spectacles of the natural world - a mass annual orgy.

When it comes to sex, corals play a numbers game. Encased in their rocky shells, direct contact is out of the question so they reproduce by releasing millions of eggs and sperm directly into the surrounding water.

This strategy only makes sense if all the corals release their sex cells en masse and sure enough, every individual within a third of a million square kilometres of reef does so during the days after the October full moon.

The corals' co-ordination would put even the most organised flash-mobs to shame and until now, scientists had no idea how they did it, especially with neither eyes nor brains. Aside from the obvious contribution of moonlight, the only other available clue was that corals seem to be especially sensitive to blue light.

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Leopards and elephants and rhinos, oh my

Sat, 03 Oct 2009 10:00:11 -0500

I'm back! For anyone wondering why I've been reposting old pieces for the last few weeks, it's because my wife and I were enjoying a much-deserved holiday in South Africa. I'll stick a link to some photos shortly, but for the moment, here's some post-holiday geekery for you.

The trip was a wildlife extravaganza. We spent four days in the Sabi Sands Game Reserve (just south of Kruger), as well as whale-watching, various walks through national parks and four fabulous hours tracking wild meerkats. I'll be sticking up details and photos over the coming weeks/months, but for now, here's a full list of the species we saw.

I've restricted it to only those animals that we saw in the wild, and then only those that I could identify down to the species level (which explains why the bird list isn't longer and why they're all vertebrates). Asterisks denote species that I have photos of.

Mammals

Southern right whale, Eubalaena australis *
Leopard, Panthera pardus *
Spotted hyena, Crocuta crocuta *
Meerkat, Suricata suricatta *
Slender mongoose, Galerella sanguinea
White-tailed mongoose, Ichneumia albicauda
Dwarf mongoose, Helogale parvula *
Cape fur seal, Arctocephalus pusillus
Rock hyrax, Procavia capensis *
African bush elephant, Loxodonta africana *
Chacma baboon, Papio cynocephalus *
Lesser bushbaby, Galago moholi
Hippopotamus, Hippopotamus amphibius *
White rhinoceros, Ceratotherium simum *
Plain's zebra, Equus burchelli *
Warthog, Phacochoerus aethiopicus *
Giraffe, Giraffa camelopardalis *
Cape buffalo, Syncerus caffer *
Nyala, Tragelaphus angasi *
Kudu Tragelaphus strepsiceros*
Bushbuck, Tragelaphus scriptus *
Eland, Taurotragus oryx *
Springbok, Antidorcas marsupalis
Common duiker, Sylvicapra grimmia
Steenbok Raphicerus campestris
Waterbuck, Kobus ellipsiprymnus
Impala, Aepyceros melampus *
Blue wildebeest, Connochaetes taurinus *
Bontebok, Damaliscus pygargus pygargus*
Striped mouse, Rhabdomys pumilio
Smith's bush squirrel, Paraxerus cepapi*
Scrubhare, Lepus saxatilis

Birds

Ostrich, Struthio camelus *
African penguin, Spheniscus demersus *
White-breasted cormorant, Phalacrocorax lucidus *
Cape cormorant, Phalacrocorax capensis *
Grey heron, Ardea cinerea *
Cattle egret, Bubulcus ibis
Hadada ibis, Bostrychia hagedash *
Sacred ibis, Threskiornis aethiopicus
Egyptian goose, Alopochen aegyptiacus *
Yellow-billed kite, Milvus aegyptius *
African Fish eagle, Haliaeetus vocifer *
White-backed vulture, Gyps africanus *
Bateleur, Terathopius ecaudatus *
Gymnogene (African harrier-hawk), Polyboroides typus
Wahlberg's eagle, Aquila wahlbergi *
Martial eagle, Polemaetus bellicosus *
Shelley's francolin, Francolinus shelleyi
Helmeted guineafowl, Numida meleagris *
Blue crane, Grus paradisea *
Red-knobbed coot, Fulica cristata
Red-crested korhaan, Lophotis ruficrista
Blacksmith plover, Vanellus armatus *
Three-banded plover, Charadrius tricollaris *
Kelp gull, Larus dominicanus *
Hartlaub's gull, Chroicocephalus hartlaubii
Spotted eagle-owl, Bubo africanus
European roller, Coracias garrulus
Southern Yellow-billed hornbill, Tockus leucomelas *
Black-collared barbet, Lybius torquatus *
Crested barbet, Trachyphonus vaillantii *
Cardinal woodpecker, Dendropicos fuscescens *
Yellow wagtail, Motacilla flava *
Malachite sunbird, Nectarinia famosa
Greater double-collared sunbird, Cinnyris afer *
Lesser double-collared sunbird, Cinnyris chalybeus
Eurasian golden oriole, Oriolus oriolus
Fiscal shrike, Lanius collaris
Magpie shrike, Corvinella melanoleuca *
Fork-tailed drongo, Dicrurus adsimilis
Cape crow, Corvus capensis *
Pied crow, Corvus albus
Red-winged starling, Onychognathus morio *
Cape glossy starling, Lamprotornis nitens
Yellow-billed oxpecker, Buphagus africanus *
Red bishop, Euplectes orix *
Cape weaver, Ploceus capensis *
Blue swallow, Hirundo atrocaerulea
Cape white-eye, Zosterops pallidus,
Lemon dove, Columba larvata

Reptiles and amphibians

Black girdled lizard, Cordylus niger *
Southern rock agama Agama atra *
Foamy nest frog, Chiromantis rufescens *
Leopard Tortoise, Geochelone pardalis

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The neuroscience of optimism - how the brain creates a rosy outlook

Fri, 02 Oct 2009 10:01:55 -0500

This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.

In 1979, a crucified Eric Idle advised movie-goers to always look on the bright side of life. It seems that he needn't have bothered. Psychological experiments have consistently shown that as a species, our minds are awash with a pervasive optimism.

We expect our future successes to overpower our past ones. Compared to an imaginary Joe Bloggs, we deem ourselves likely to live longer, more likely to have a successful career and less likely to suffer divorce or ill health. Even the most cynical of minds had a tendency for making similar, overconfident predictions.

Now, Tali Sharot and colleagues form New York University have pinpointed a neural circuit in the brain that generates this glass-half-full outlook.

Sharot asked 18 recruits to remember past events or imagine future ones based on on-screen cues (such as "the end of a relationship" or "winning an award"). She then asked them to describe their imaginings along several different lines, like how positive, vivid and emotionally affecting they were, and whether they experienced the event first-hand or observed it from afar. Finally, each person completed a standard questionnaire to score how optimistic they are.

Their thoughts bore the clear signs of an optimistic bias. They rated future happy events more positively than past ones and they imagined that these windfalls would happen much sooner than negative events would. They also conjured up happy future events from a first-hand viewpoint, while they were more likely to see sad future events from an outsider's perspective.

While the volunteers daydreamed away, Sharot was busy scanning their brains with a technique called functional magnetic resonance imaging (fMRI). She identified two parts of the brain that were more strongly activated when they envisaged positive future events compared to negative ones - the rostral anterior cingulated cortex, or RACC, and the right amygdala.

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'Brainbow' paints individual neurons with different colours

Thu, 01 Oct 2009 10:01:58 -0500

This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.

At Harvard University, a group of creative scientists have turned the brains of mice into beautiful tangles of colour. By mixing together a palette of fluorescent proteins, they have painted individual neurons with up to 90 different colours. Their technique, dubbed 'Brainbow', gives them an unprecedented vision of how the brain's cells are connected to each other.

The art of looking at neurons had much greyer beginnings. Over a century ago, a Spanish scientist called Santiago Ramón y Cajal, one of the founders of modern neuroscience, became the first person to get a clear look at the neural network that houses our thoughts. He found that neurons stood out among other cells when stained with a silver chromate salt.

These monochrome images told us what neurons were, but made it very difficult to work out how they joined up into a network. It would be like trying to make sense of London's famous tube map if all the lines were coloured with the same dull grey. Nowadays, neuroscientists can 'tag' neurons with fluorescent proteins, but even these are available in only a few shades.

Enter Brainbow, the brain-child of Jean Livet, Jeff Lichtman and colleagues from Harvard. It uses combinations of just four basic fluorescent proteins - which glow in either red, orange, yellow or blue - to paint neurons with a vast range of hues. It works like a TV, which combines red, green and blue light to form the entire colour spectrum.

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Bdelloid rotifers - 80 million years without sex

Wed, 30 Sep 2009 10:00:11 -0500

This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.

Sex is, on the whole, a good thing. I know it, you know it, and natural selection knows it. But try telling it to bdelloid rotifers. These small invertebrates have survived without sex for some 80 million years.

While many animals, from aphids to Komodo dragons, can reproduce asexually from time to time, it's incredibly rare to find a group that have abandoned sex altogether. The bdelloid rotifers (pronounced with a silent b) are an exception.

They live in an all-female world and since their discovery, not a single male has ever been found. Genetic studies have confirmed that they are permanently asexual, and females reproduce by spawning clone daughters that are genetically identical to them.

The bdelloids pose a problem for evolutionary biologists, who have struggled to explain how they could make do without a strategy that serves the rest of the animal kingdom very well. Now, Natalia Pouchkina-Stantcheva, Alan Tunnacliffe and colleagues from the University of Cambridge have found out how they do it.

Sexual animals have two copies of each gene that have only minimal differences between them. But the asexual bdelloid lifestyle has uncoupled the fates of each copy in a gene pair, allowing them to evolve in new directions. They get two genes for the price of one.

One of the vaunted benefits of sex is that it acts as a crucible for genetic diversity. Animals receive one pair of every gene from their mother and one from their father. As the pairs are united in the embryo, they are often shuffled into new combinations.

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The evolution of the past tense - how verbs change over time

Tue, 29 Sep 2009 10:00:11 -0500

This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.

For decades, scientists have realised that languages evolve in strikingly similar ways to genes and living things. Their words and grammars change and mutate over time, and new versions slowly rise to dominance while other face extinction.

In this evolutionary analogy, old texts like the Canterbury Tales are the English language's version of the fossil record. They preserve the existence of words that used to be commonplace before they lost a linguistic Darwinian conflict with other, more popular forms.

Now, Erez Lieberman, Martin Nowak and colleagues from Harvard University are looking at this record to mathematically model how our verbs evolved and how they will change in the future.

Today, the majority of English verbs take the suffix '-ed' in their past tense versions. Sitting alongside these regular verbs like 'talked' or 'typed' are irregular ones that obey more antiquated rules (like 'sang/sung' or 'drank/drunk') or obey no rules at all (like 'went' and 'had').

In the Old English of Beowulf, seven different rules competed for governance of English verbs, and only about 75% followed the "-ed" rule. As the centuries ticked by, the irregular verbs became fewer and far between. With new additions to the lexicon taking on the standard regular form ('googled' and 'emailed'), the irregulars face massive pressure to regularise and conform.

Today, less than 3% of verbs are irregular but they wield a disproportionate power. The ten most commonly used English verbs - be, have, do, go say, can, will, see, take and get - are all irregular. Lieberman found that this is because irregular verbs are weeded out much more slowly if they are commonly used.

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How India became the fastest continent

Mon, 28 Sep 2009 10:00:11 -0500

This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.

You don't normally hear continents described as speedy, but it's now clear that some are much faster than others. India, in particular, is the Ferrari of continents and now, scientists have discovered why.

Rewind 150 million years and the Earth looked very different. Most of the land in today's southern hemisphere were united in a single super-continent called Gondwana, including Africa, Australia, South America, Antarctica, India and Arabia.

The Earth's crust is not a stationary shell but an ever-shifting mosaic of tectonic plates that constantly (albeit slowly) reshape the face of the planet. Underneath the crust lies the much hotter mantle, and plumes of super-heated rock occasionally erupt out of this layer, causing hotspots of volcanic activity.

Geologists believe that a particularly large 'mantle plume' kick-started the break-up of Gondwana. Now, Prakash Kumar and colleagues from the National Geophysical Research Institute in India have found that the plume also gave India a turbo boost.

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Elephants smell the difference between human ethnic groups

Sun, 27 Sep 2009 10:00:11 -0500

This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.

It's tempting to think that elephants have their own PR agency. Just last week, their mighty reputation was damaged by the revelation that they are scared away by bees but they have bounced back with a new study that cements their standing among the most intelligent of animals.

Lucy Bates and colleagues from the University of St Andrews have found that African elephants (Loxodonta africana) can tell the difference between different human ethnic groups by smell alone. They also react appropriately to the level of threat they pose.

The Massai, for example, are a group of cattle-herders, whose young men sometimes prove themselves by spearing elephants. Clearly, it would pay to be able to sort out these humans from those who post little threat, like the Kamba.

At the Amboseli National Park in Kenya, Bates found that elephants reacted more fearfully to clothes previously worn by a Massai man than to clean ones or those worn by a Kamba man. She placed the three types of cloth near 18 family groups and watched what happened.

When the first individual caught whiff of a new scent, it raised its head and curled its trunk towards the source of the smell. If they smelled Massai clothes, they moved away particularly fast, travelled about five times further and took more than twice as long to relax. They could clearly tell the difference between the two groups based on smell and reacted more defensively to the dangerous one.

Every single time the elephants smelled Massai on the wind, they moved downwind and didn't stop until they reached tall elephant grass, over 1m in height. They only sought tall grass in about half of the trials with Kamba clothes, and almost none of the trials with clean clothes. To Bates, this was a clear sign of planned action for elephant grass only covers about 7% of Amboseli.

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Ants herd aphids with tranquilisers in their footsteps

Sat, 26 Sep 2009 10:00:11 -0500

This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.

In your garden, there's a fair chance that a farmer is currently tranquilising her livestock with a chemical cocktail she secretes from her feet. Don't believe me? Look closer...

Humans aren't the only species that farms other animals for food - ants do it too and their herds consist of aphids. They feed on plant sap and excrete a sweet and nutritious liquid called honeydew, which the ants drink.

In return, the ants run a protection racket, defending the aphids from predators like ladybirds. It seems like a nice two-way partnership that suits both partners, and aphid colonies tended by ants tend to be larger than unattended ones. But new research from two London universities suggests that ants are manipulating their herds more than previously thought.

Aphid-farming ants similar problem to human farmers - their herds are likely to wander away and it's in the ants' interests to prevent this. Earlier work showed that they sometimes bite the wings off aphids that have them or produce chemicals from glands in their jaws that subdue the development of wings in the first place.

None of that stops the several wingless individuals from just walking away, so the ants use another trick. Thomas Oliver from Imperial College London found that the black garden ant (Lasius niger) secretes chemicals in its footsteps that effectively tranquilise aphids.

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Buzzing bees scare elephants away

Fri, 25 Sep 2009 10:00:11 -0500

This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.

It's a myth that elephants are afraid of mice, but new research shows that they're not too keen on bees. Even though they fearlessly stand up to lions, the mere buzzing of bees is enough to send a herd of elephants running off. Armed with this knowledge, African farmers may soon be able to use strategically placed hives or recordings to minimise conflicts with elephants.

Iain Douglas-Hamilton and Fritz Vollrath from Kenyan conservation charity Save the Elephants first suspected this elephantine phobia in 2002, when they noticed that elephants were less likely to damage acacia trees that contained beehives.

Animals as powerful as the African elephant can go largely untroubled by predators. Their bulk alone protects them from all but the most ambitious of lion prides.

But these defences do nothing against the African bees, which can sting them in their eyes, behind their ears and inside their trunks. Against these aggressive insects, the elephants are well justified in their caution and local people have reported swarms of bees chasing elephants for long distances.

Lucy King, a graduate student from the University of Oxford confirmed this theory by using camouflaged wireless speakers to play recordings of angry buzzing bees to herds of elephants resting under trees.

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Ancient plants manipulate insects for hot, smelly sex

Thu, 24 Sep 2009 10:00:11 -0500

This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.

For plants too, sex can be a hot and smelly affair. In most plant-insect partnerships, the pollinator seems to do most of the work by voluntarily transferring pollen from plant to plant in exchange for a meal.

But an ancient lineage of plants - the cycads - takes more active steps to ensure its future with a bizarre combination of heat and smells. In the afternoon, they use heat and a toxic stench to drive insects out of male cones only to lure them into female cones in the evening with a more alluring scent.

Cycads were around before the time of the dinosaurs and their six-legged puppets are a group of similarly ancient insects called thrips. The thrips make their homes among the single large cone that sits atop the cycad trunk, looking like an enormous pine cone.

The thrips prefer the male ones, for their cracks are laden with nutritious pollen that the insects and their larvae eat. But their lodgings aren't free. Irene Terry and colleagues from the University of Utah found that the cycads manipulate them into earning their keep.

When the time comes to pollinate, the cycad cones heat up. By rapidly metabolising stores of fats, sugars and starches, they can raise the temperature of the cones to 12C above the surrounding temperature, up to about 37C.

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Doctors repress their responses to their patients' pain

Wed, 23 Sep 2009 10:00:11 -0500

This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.

Many patients would like their doctors to be more sensitive to their needs. That may be a reasonable request but at a neurological level, we should be glad of a certain amount of detachment.

Humans are programmed, quite literally, to feel each others' pain. The neural circuit in our brains that registers pain also fires when we see someone else getting hurt; it's why we automatically wince.

This empathy makes evolutionary sense - it teaches us to avoid potential dangers that our peers have helpfully pointed out to us. But it can be liability for people like doctors, who see pain on a daily basis and are sometimes forced to inflict it in order to help their patients.

Clearly, not all doctors are wincing wrecks, so they must develop some means of keeping this automatic response at bay. That's exactly what Yawei Chang from Taipei City Hospital and Jean Decety from University of Chicago found when they compared the brains of 14 acupuncturists with at least 2 years of experience to control group of 14 people with none at all.

They scanned the participants' brains while they watched videos of people being pricked by needles in their mouths, hands and feet, or being prodded with harmless cotton swabs. Sure enough, the two groups showed very different patterns of brain activity when they watched the needle videos, but not the cotton swab ones.

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Genes affect our likelihood to punish unfair play

Tue, 22 Sep 2009 10:00:11 -0500

This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.

As a species, we value fair play. We're like it so much that we're willing to eschew material gains in order to punish cheaters who behave unjustly. Psychological games have set these maxims in stone, but new research shows us that this sense of justice is, to a large extent, influenced by our genes.

When it comes to demonstating our innate preference for fair play, psychologists turn to the 'Ultimatum Game', where two players bargain over a pot of money. The 'proposer' suggests how the money should be divided and the 'receiver' can accept of refuse the deal. If they refuse, neither player gets anything and there is no room for negotiation. In a completely rational setting, the proposer should offer the receiver as little as possible, and the receiver should take it - after all, a very little money is better than none at all.

Of course, that's not what happens. Receivers typically abhor unfair offers and would rather that both parties receive no money than accept a patronisingly tiny amount. Across most Western countries, proposers usually offer the receivers something between 40% and 50% of the takings. Any offers under 10% are almost always rejected.

The uniformity of responses across Western countries suggests that culture has a strong effect on how people play the game, but until now, no one had looked to see how strongly genes asserted their influence. Bjorn Wallace and colleagues from the Stockholm School of Economics decided to do just that, and they used the classic experiment for working out heritability - the twin study.

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Sabre-toothed cats had weak bites

Mon, 21 Sep 2009 10:00:11 -0500

This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.

The sabre-toothed cat is one of the most famous prehistoric animals and there is no question that it was a formidable predator, capable of bringing down large prey like giant bison, horses, and possibly even mammoths. The two massive canines - the largest teeth of any mammal - are a powerful visual. But while they were clearly powerful weapons, scientists have debated their use for over 150 years.

Now, a new study shows that Smilodon, the most iconic of the sabre-tooths, had a surprisingly weak bite. They were a precision weapon that were used to deliver a single, final wound to an already subdued victim - the equivalent of an assasin's stiletto rather than a swordsman's blade.

Earlier suggestions pictured Smilodon using its teeth to hang onto the back of large prey, to slash their abdomens open, or to impale them at the end of a flying pouce. One of the most popular theories said that the cat would have used its teeth to sever arteries and airways with a decisive bite to the throat - a quicker technique than the suffocating neck bites used by modern lions.

Working out how strongly Smilodon could bite would go a long way towards deciding on one of these theories and to do that, palaeontologists have studied the animal's fossilised skull. Even then, opinions have gone either way depending on which bit of the skull they looked at. The muscle attachment points suggest it has small jaw muscles, but the bite could have been powered from the neck. The lower jaw is smaller, but strongly built, lending weight to the idea of a powerful bite.

To get some clearer answes, Colin McHenry and colleagues from the University of Newcastle, Australia decided to put Smilodon's skull through a digital crash-test. They used a technique called 'finite element analysis' or FEA, which is typically used in mechanical engineering and crash-testing for cars.

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Paper wasps - caring mothers evolved into selfless workers

Sun, 20 Sep 2009 10:00:11 -0500

This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.

Imagine that one day, you make a pact with your brother or sister, vowing to never have children of your own and instead spend your life raising theirs. You'll agree to do the grocery shopping, cook for them, clean their rooms and bathe them, until you die.

That seems like a crazy plan, but it's one that some of the most successful animals in the world - the social insects - have adopted. It's called 'eusociality' and it's a puzzle for evolutionary biologists. Why should an animal forgo the chance to reproduce in order to help rear its siblings and their young?

The strategy makes sense if you share enough genes with your close relatives. In helping them, you indirectly ensure the transmission of your own genetic material. But even if this explains the existence of eusociality, it doesn't explain how such an extreme form of co-operation evolved.

Now, Amy Toth and colleages at the University of Illinois have found a clue in the genes of the paper wasp, Polistes metricus, which suggests that their altruistic actions evolved from motherly behaviour.

Scientists have suggested this theory before as a possible origin for eusociality. It doesn't take a great leap of imagination to picture how a group of wasp sisters living together and communally looking after their young could become a society in which only a few individuals reproduce and the others share the care. But until now, that theory had never been tested at a genetic level.

Truly eusocial insects like honeybees have physically distinct castes with strongly segregated jobs. The queen's sole purpose is to lay eggs and she never takes on the menial foraging and brood care of the smaller workers.

Paper wasps are only halfway down the road to eusociality, which makes them an ideal choice for studying its evolution. They have different castes, but they all look much the same and their castes are far less strictly segregated. The roles that individuals perform depends on the age of the colony and fall into four different groups.

Foundresses, females that establish new colonies and care for young as well as laying eggs. After creating the first generation, these females become queens and focus solely on laying more eggs. Their daughters, the workers, take up the task of caring for their new siblings to the exclusion of their own reproduction. Later on in the colony's life, the queen gives birth to gynes, that neither care for young or lay eggs - their job is to mate with males and become foundresses themselves in the following spring.

Toth decided to look at the patterns of gene activity in these four groups. She reasoned that if the workers' altruistic actions had originated in maternal care, they would share similar genetic profile to the foundresses, the only other group that also cares for young.

Complex behaviours like caring for young and foraging were hardly going to be the province of a single gene. Toth needed a way to analyse a myriad of genes across the entire wasp genome - a genome that has not yet been fully sequenced.

To overcome this problem, the team took a streamlined approach. They specifically looked at genes that were strongly activated in the brains of 87 wasps from all four groups. Using a powerful sequencing technique from the 454 Life Sciences company, they identified almost 400,000 stretches of relevant DNA across their genomes.

Toth matched these hits to the genome of the closely related honeybee (Apis mellifera), which was fully sequenced last year. They focused on 32 genes, whose honeybee counterparts are involved in worker behaviour. Even though bees and paper wasps started down different evolutionary roads some 100 million years ago, the proteins encoded by these genes have remained very similar.

As predicted, Toth found that the activation pattern of these 32 genes was closest in workers and foundresses, and were distinct from those of queens and gynes, which don't practice maternal care. Regardless of whether the wasps focused on their siblings or their young, their caring behaviour was governed by similar sets of genes, supporting the idea that eusociality evolved from maternal care.

Today, the vast majority of solitary wasps provide food for their helpless young, often in grisly or murderous ways. During the course of evolution, the twin behaviours of egg-laying and maternal care started to separate.

In the intermediary paper wasps, the behaviours are separated in time - the foundresses practice both at first and then focus on just one when they turn into queens. As this happens, their brain undergo dramatic changes and different sets of genes are switched on.

The final stage down this evolutionary path is the one seen in true eusocial wasps, where egg-laying and maternal care are separated in space, in the bodies of queens and workers.

The study also shows that many evolutionary problems can be addressed without the complete sequence of an animal's genome. For every full genome we have, we can use next-generation sequencing technology to compare it to the partially sequenced genes of closely-related species, just as the bee and wasp proved here.

Reference: toth, Varala, Newman, Miguez, Hutchison, Willoughby, Simons, Egholm, Hunt, Hudson & Robinson. 2007. Wasp gene expression supports and evolutionary link between maternal behaviour and eusociality. Sceince

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