The partnerships between flowering plants and the animals that pollinate them are some of the most familiar in the natural world. The active nature of animals typically casts the plants as the passive partners in this alliance, but in reality, they’re just as involved. That becomes particularly apparent when the animals renege on their partnership.

Nicotinia attenuata, a type of wild US tobacco, is usually pollinated by hawkmoths. To lure them in, it opens its flowers at night and releases alluring chemicals. But pollinating hawkmoths often lay their eggs on the plants they visit and the voracious caterpillars start eating the plants. Fortunately for the plant, it has a back-up plan. It stops producing its moth-attracting chemicals and starts opening its flowers during the day instead. This simple change of timing opens its nectar stores to a very different pollinator that has no interest in eating it – the black-chinned hummingbird. 

Danny Kessler from the Max Planck Institute first noticed the tobacco plant’s partner-swapping antics by watching a population of flowers that was overrun by hawkmoth caterpillars. Nearly every plant was infested. To Kessler’s surprise, around one in six flowers started opening between 6 and 10am, rather than their normal business hours of 6 and 10pm. To see if the two trends were related, Kessley deliberately infested plants from another population with young hawkmoth larvae. 

Eight days later, and 35% of the flowers had started opening in the morning, compared to just 11% of uninfested plants. The flowers use a cocktail of various chemicals to lures in night-flying moths, but the main ingredient is benzyl acetone (BA). A large plume gets releases when the flower opens at night. It’s so essential that genetically modified plants, which can’t produce BA, never manage to attract any moths. Nonetheless, the flowers that opened in the morning never produced any BA.

By artificially boosting the nectar yield of specific flowers, Kessler showed that hawkmoths are more likely to lay eggs on plants that reward them with the most nectar. So by putting off the adult hawkmoths from visiting the flowers, the plants gained a reprieve from future onslaughts by their larvae.

The larvae themselves prompt the switch. As they munch away, their saliva releases complex mixtures of fats and amino acids into the wounds they create. This cocktail trigger a genetic alarm in the plant’s cells, which culminates in a burst of jasmonic acid. This all-important plant chemical coordinates a variety of defences, from producing poisons to summoning predators and parasitic wasps. In this case, it’s responsible for shifting the flowers’ blooming schedule.

Kessler demonstrated the role of the caterpillars’ saliva and jasmonic acid through a clever series of experiments. Even if no larvae are around, just adding their saliva to artificial wounds causes some plants to switch to the morning opening hours. If the plants are genetically modified so that they can’t produce jasmonic acid, the entire process grinds to a halt, rescued only by the artificial addition of jasmonic acid.

Having solved the problem of the very hungry caterpillars, the plants still need pollinators. Again, the revised opening schedule provides the solution. Through painstaking field observations, Kessler showed that hummingbirds were strongly attracted to the morning blossoms, almost always visiting these flowers first. The birds have apparently learned to associate the shape of the opened flowers with the prospect of a rich, early-morning beakful of nectar. The plant gets a new partner, while avoiding the unwanted shenanigans of its old one.

Hummingbirds, of course, never eat other parts of the plant but if they’re such compliant partners, why doesn’t the tobacco plant always open its flowers in the morning? We don’t know, but Kessler suggests that the birds, for all their strengths, may not be quite as reliable as the moths. Hummingbirds are more likely to drink from multiple flowers on the same plant, which would lead to a lot of self-fertilisation. They’re more restricted by geographical factors, such as the presence of nearby nest sites. And, unlike hawkmoths, they can’t be summoned across long distances through the simple use of smell.

Picture by Stan Shebs

Reference: Kessler et al. 2010. Changing Pollinators as a Means of Escaping Herbivores. Current Biology http://dx.doi.org/10.1016/j.cub.2009.11.071

More on pollination:

• Of flowers and pollinators – a case study of punctuated evolution
• Tiny treeshrews chug alcoholic nectar without getting drunk
• Ancient plants manipulate insects for hot, smelly sex
• Orchid lures in pollinating wasps with promise of fresh meat

Deep beneath the ocean’s surface lie the “black smokers“, undersea chimneys channelling superheated water from below the Earth’s crust. Completely devoid of sunlight, they are some of the most extreme environments on the planet. Any creature that can survive their highly acidic water, scorching temperatures and crushing pressures still has to contend with assaults from predatory crabs. What better place, then, to look for the next generation of body armour technology?

The scaly-foot gastropod (Crysomalion squamiferum) was discovered just 9 years ago at an Indian black smoker and it may have one of the most effective animal armours so far discovered. Its shell is a composite, made of three layers, each with different properties and made of different minerals. Together, they form a structure that’s completely unlike any known armour, whether natural or man-made. It can protect the animal from the searing heat of its habitat, stop its precious minerals from dissolving away in the acidic water and resist the crushing, penetrating, peeling claw-attacks of predatory crabs.

Animals have been protecting themselves with armour long before humans starting shaping steel and Kevlar. To create a protective covering, human designers must account for a mind-boggling array of physical traits including thickness, geometry, strength, elasticity and more. But evolution can take all of those factors into account without the guiding hand of a designer, putting thousands of structures through the test of natural selection and weeding out the best combinations. The results are the culmination of millions of years of research and development and they are striking in their effectiveness.

Haimin Yao from MIT works in the lab of Catherine Ortiz, a group that has been studying the defences of animals including sea urchins, chitons, a group of marine molluscs, to the Senegal bichir, a type of armoured fish.  

Yao discovered the secrets behind the snail’s shell by slicing through it in cross-sections and studying its structure at a nanometre level. He even attacked it with a diamond-tipped probe, to simulate the crushing attacks of the crabs that frequent the black smokers. Using this data, Yao created a virtual simulation of the shell and put it through a digital crash-test, crab claws and all.

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The mighty insect colonies of ants, termites and bees have been described as superorganisms. Through the concerted action of many bodies working towards a common goal, they can achieve great feats of architecture, agriculture and warfare that individual insects cannot.

That’s more than just an evocative metaphor. Chen Hou from Arizona State University has found that the same mathematical principles govern the lives of insect colonies and individual animals. You could predict how quickly an individual insect grows or burn food, how much effort it puts into reproduction and how long it lives by plugging its body weight into a simple formula.  That same formula works for insect colonies too, if you treat their members as a collective whole.

Life is fundamentally about the use of energy, about effectively harvesting it from food and channelling it into existence and offspring. As animals get bigger, their changing use of energy ripples across all aspects of their lives. Because of economies of scale, larger and more complex animals need less energy for each individual cell. They grow and reproduce more slowly and they live longer.

The astounding thing is that this variety can be captured by a deceptively simple equation. An animal’s metabolic rate is proportional to its mass to the power of three-quarters (0.75). So a cat that is 100 times heavier than a mouse would have a metabolic rate that was around 32 times greater, and a human that is 10 times heavier than a cat would have a metabolic rate around 6 times greater. This beautiful three-quarters “power law” links all animals from mice to elephants.

Hou showed that it applies to insect colonies. He gathered data on over 168 species of social insects and noted the total mass of all their members. They ranged from species of fire ants whose colonies weigh little more than 2 milligrams, to African termite colonies that tip the scales at around 4kg.

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Now that is how you do a conference. Massive thanks to Bora and Anton for organising ScienceOnline 2010, one of the most enjoyable science shindigs I’ve had the pleasure of attending. I’ll stick up more on the conference later, after I’m done recovering from the horrendous American plague that I may or may not have contracted from SciCurious. For the moment, some random musings:

• I love the feeling of meeting people who you know relatively well for the first time. That face-to-face interaction is invaluable for building relationships that started online, and people’s online personas largely correlated with their meatspace personalities.
• One of the upshots of meeting people in the flesh is that I can now read their online words in their actual accents.
• Despite the frequently cited demise of science journalism, almost every session on this topic was totally packed – empirical support for my Cambrian explosion metaphor.
• Science writers look out for each other. We’ve all had big breaks because of the goodwill of friends and colleagues, and we’re keen on repay the favour by helping out promising newbies. To some extent, this has always happened but new tech like Twitter makes it easier to do.  
• If Americans like you, they will tell you about it. At great length. Seriously, the self-deprecating British part of my cortex nearly imploded.
• I spoke to many people whose breadth of experience just floored me – people who blog, write books, do science, practice journalism, teach, make films, and so on. The Internet makes it easier to don multiple hats and doing so successfully is the way of the future.
• The atmosphere at the conference was electric. There really isn’t anything like getting 250 passionate, excited, down-to-earth people in the same place. These really are charmed times to be interested in science.
• Even if you explicitly say that journalists vs. bloggers is old and tired, some people just can’t f**king help themselves 

Anyway, you may be able to tell that I had a great time. Meeting people I only knew from avatars or thumbnails was the best part, and in no particular order, it was a pleasure to meet Abel  Pharmboy, Carl Zimmer, Rebecca Skloot, SciCurious, Janet Stemwedel, Sheril Kirshenbaum, David Dobbs, John Timmer, Jennifer Ouellette, Tom Levenson, Ivan Oransky, Nancy Shute, Dr Isis, Bora and Catherine Zivkoivic, PalMD, Arikia Millikan, Erin Johnson, T Delene Beeland, Brian and Tracey Switek, Ben Landis, Dave and Greta Munger, Chris Rowan, Anne Jefferson, Tamara Krinsky, Miriam Goldstein, Kevin Zelnio, Craig McClain, Eric Michael Johnson, Allie Wilkinson, Christie Wilcox, Zuska, DrDrA, Vanessa Woods, Natalie Villalobos, Darlene Cavalier, Chris Mooney, Clifton Wiens, John Logsdon, Allyson Bennett, James Hrynyshyn, Sandy Porter, Mary Spiro, Glendon Mellow, Fabiana Kubke, Joanne Manaster, Fenella Saunders, Jonathan Eisen, Kelly Chi. Stephanie Zvan, Nate Silver, Eric Roston, Kiki Sanford, Elia Ben-Ari and Michael Specter.

I’ve just flown from London to North Carolina, a trip of around 6,200km. As flights go, it’s a pathetic one, a mere jaunt in the park compared to the epic voyage of the Arctic tern. Every year, this greatest of animal travellers makes a 70,000 km round-trip, in a relentless, globe-trotting pursuit of daylight. In summer, it spends its time in the sun-soaked Arctic and in winter, it heads for the equally bright climes of Antarctica. In its 30 years of life, this champion aeronaut flies more than 2.4 million kilometres – the equivalent of three return journeys to the Moon.  

The Arctic tern’s marathon flight is fairly familiar, but estimating the length of such a massive trek isn’t easy. It would be charitable to forgive scientists for getting it wrong, given that they had to rely on observations at sea and capturing banded birds at different places. But few would have predicted just how wrong the textbook figures are. They typically suggest that the tern covers 40,000km in a year. The bird should be insulted – in reality, it flies almost twice that amount.

Its true itinerary has only just been revealed through the use of tiny tracking devices. Similar machines have already exposed the travel plans of larger seabirds like albatrosses, petrels and shearwaters. But these gadgets been too large and clunky to attach to smaller fliers – strapping a 400g recorder to a 100g bird isn’t going to give you an accurate picture of its flying abilities.

Carsten Egevang from Denmark’s Aarhus University changed all of that by developing tiny geolocators, less than 1g in weight. These locators can track the movements of migrating birds by recording the amount of light falling upon it at different points in its journey, and they’ve already been baptised by recording the entire migration of songbirds. Egevang strapped them to the leg of 50 terns, and managed to retrieve 11 of them the following season, when the birds returned.

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Men who think that size really matters should probably not think too hard about the Y chromosome. This bundle of genes is the ultimate determinant of manliness, and it happens to be a degenerate runt.  Over a few hundred million years, it has shrunk considerably, jettisoning around 97% of its original genes. Where it was once a large library of genes, now it’s more a struggling independent bookstore. This loss of information defined the youth of the Y chromosome but nowadays, things are different. Renovation is the order of the day.

Jennifer Hughes from MIT revealed the recent history of the Y chromosome by comparing the human and chimp versions. They are incredibly different. They have rapidly evolved since the two species last shared a common ancestor 6 million years ago. In this relatively short span of time, the two Ys have accumulated differences that other chromosomes would take 310 million years to build up. It’s the sort of genetic disparity you’d expect to see between humans and chickens, not between us and our closest relatives!

This drastic remodelling contradicts the current view of Y evolution, which suggests that the chromosome has stagnated. It has lost so many of its genes that some scientists thought it might waste away altogether within another 10 million years. But rumours of its impending demise had been greatly exaggerated. In 2005, Hughes showed that Y isn’t shrinking at the breakneck pace of old.

That result was based on a comparison of individual genes on the two chromosomes. Since then, Hughes has managed to fully sequence the chimp Y, the first time this has been accomplished for a non-human animal. Considering how small the chromosome is, sequencing it is remarkably tricky. It has lots of long, repetitive sequences that are subtly different and hard to tell apart through conventional means.

Nonetheless, Hughes managed it. By comparing the two sequences, she found that the Y chromosome is an island of difference in a sea of resemblance. The chimp and human genomes are famous for their similarity; they’re a 98.8% match for each other. And indeed, where the chimp and human Y sequences align, they are a 98% match, just like the rest of the genome. But they don’t align very well. Around 30% of the chimp Y chromosome has no human counterpart and vice versa.

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For something intangible, a glance can be a powerful thing. It can carry the weight of culture and history, it can cause psychological harm, and it can act as a muzzle. Consider the relatively simple act of a man staring at a woman’s body. This is such a common part of modern society that most of us rarely stop to think of its consequences, much less investigate it with a scientific lens.

Tamar Saguy is different. Leading a team of Israeli and US psychologists, she has shown that women become more silent if they think that men are focusing on their bodies. They showed that women who were asked to introduce themselves to an anonymous male partner spent far less time talking about themselves if they believed that their bodies were being checked out. Men had no such problem. Nor, for that matter, did women if they thought they were being inspected by another woman.

Saguy’s study is one of the first to provide evidence of the social harms of sexual objectification – the act of treating people as “de-personalised objects of desire instead of as individuals with complex personalities”. It targets women more often than men. It’s apparent in magazine covers showing a woman in a sexually enticing pose, in inappropriate comments about a colleague’s appearance, and in unsolicited looks at body parts. These looks were what Saguy focused on.

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Next week, I’ll be chairing a session at the Science Online 2010 conference called Rebooting science journalism in the age of the web. I’ll be shooting the breeze with Carl Zimmer, John Timmer and David Dobbs about the transition of journalism from sheets of plant pulp to wires and wi-fi. The title of the talk had been set before the panel was assembled but, being biologists at heart, we’re going to shift the metaphor from a technological one to an evolutionary one.

As a species, science journalists (in all their varied forms and behaviours) have found themselves thrust into a new digital ecosystem that presents fresh challenges to their survival. Some individuals will have adaptive traits that allow them to thrive in this brave, new world, while others are riddled with maladaptive qualities and face extinction. In this post (and hopefully, during the session), we’ll consider what the new ecosystem looks like, what opportunities and threats it presents, and how journalists can adapt to survive in it. Let’s start with opportunities (I’m bucking the trend by starting a blog post about science journalism on a positive note).

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Weaver birds are the artisans extraordinaire of the bird world. As their name suggests, they fashion intricate nests out of plant material, carefully threaded and woven into a solid structure. All of it is done, quite literally, without lifting a finger.

These birds were all building nests in a tree outside a delightful winery called Delheim, which does an exceptional line of dessert wines. While my wife was inside sampling them, I was outside snapping away at this colony.

The males are the ones who do the weaving, and their efforts advertise their skill and quality to potential mates. By picking the best structure, a female gets not only the most comfortable home but some assurance about the genetic standards of the home-maker. In the picture below, the nest on the far right is one of the most complete. The long downward-pointing entrance tube is an anti-thief feature, and it’s the last to be added.

South Africa is home to many species of weaver birds that are distinguished by relatively small differences in the size of their yellow and black markings, the colour of their eyes and so on. If anyone wants to take an educated stab as to what species these are, be my guest.

If you read this blog regularly, then chances are you care about science and about writing. If that’s the case, you can help to get an incredible piece of science writing into the bestseller charts.
My colleague, the gifted Rebecca Skloot, has finished her debut book The Immortal Life of Henrietta Lacks, which is due to launch next month. It’s an incredible story and the culmination of 10 years of hard investigative research. It has been graced with some of the finest reviews I’ve ever seen for a popular science book.
There’s a description below, and you can visit Rebecca’s site or follow her on Twitter (@rebeccaskloot) to find out more about the book. If you’re interest, I urge you to pre-order it from Amazon (UK or US site). If the book gets lots of pre-orders, Amazon will publicise it more heavily and there’s a chance that it’ll debut on the bestseller lists. You benefit too – the book’s currently selling for a third off the cover price, a discount that will vanish when it launches. Fancy supporting good science writing and excellent investigative journalism? You know what to do.

Her name was Henrietta Lacks, but scientists know her as HeLa. She was a poor Southern tobacco farmer who worked the same land as her slave ancestors, yet her cells–taken without her knowledge–became one of the most important tools in medicine. The first “immortal” human cells grown in culture, they are still alive today, though she has been dead for more than sixty years. If you could pile all HeLa cells ever grown onto a scale, they’d weigh more than 50 million metric tons–as much as a hundred Empire State Buildings. HeLa cells were vital for developing the polio vaccine; uncovered secrets of cancer, viruses, and the effects of the atom bomb; helped lead to important advances like in vitro fertilization, cloning, and gene mapping; and have been bought and sold by the billions.
Yet Henrietta Lacks remains virtually unknown, buried in an unmarked grave.
Now Rebecca Skloot takes us on an extraordinary journey, from the “colored” ward of Johns Hopkins Hospital in the 1950s to stark white laboratories with freezers full of HeLa cells; from Henrietta’s small, dying hometown of Clover, Virginia–a land of wooden slave quarters, faith healings, and voodoo–to East Baltimore today, where her children and grandchildren live, and struggle with the legacy of her cells.
Henrietta’s family did not learn of her “immortality” until more than twenty years after her death, when scientists investigating HeLa began using her husband and children in research without informed consent. And though the cells had launched a multimillion-dollar industry that sells human biological materials, her family never saw any of the profits. As Rebecca Skloot so brilliantly shows, the story of the Lacks family–past and present–is inextricably connected to the dark history of experimentation on African Americans, the birth of bioethics, and the legal battles over whether we control the stuff we are made of.
Over the decade it took to uncover this story, Rebecca became enmeshed in the lives of the Lacks family–especially Henrietta’s daughter Deborah, who was devastated to learn about her mother’s cells. She was consumed with questions: Had scientists cloned her mother? Did it hurt her when researchers infected her cells with viruses and shot them into space? What happened to her sister, Elsie, who died in a mental institution at the age of fifteen? And if her mother was so important to medicine, why couldn’t her children afford health insurance?
Intimate in feeling, astonishing in scope, and impossible to put down, The Immortal Life of Henrietta Lacks captures the beauty and drama of scientific discovery, as well as its human consequences.