Carl Zimmer's Blog, page 24

Friday’s Elk: A Newsletter For Those Who Like Their Science By Email

I’ve discovered that some people who read my stuff don’t obsess over RSS, Twitter, Facebook, and the rest of the social media world the way I do, so I’ve decided to email a short newsletter every Friday. If you’d like to receive Friday’s Elk each week, sign up here. That way, not a single parasitic wasp or mouse-unculus will pass you by!

The Tree That Rules Your Daily Life: My New York Times Column on the Oil Palm Tree

“You may have never set eyes on an oil palm tree, but it’s probably an intimate part of your everyday life. Whether you start your day with a shave or an application of lipstick, you are probably putting the oil from the tree’s fruits on your face. You buy a donut on the way to work, and with each bite, you swallow some of the palm oil in which it was cooked. After work, you stop at the supermarket, and about half the products on the shelves contain palm oil. Before bed, you scrub your face with soap and brush your teeth with toothpaste. They’re both palm oil’s way of wishing you good night.”

That’s how I start my “Matter” column for the New York Times this week about a tropical tree that has infiltrated everyday life in a way few of us realize–and which has gobbled up tropical forests to feed our collective hunger. Now scientists have deciphered its genome. Will its DNA hold secrets for raising oil palm trees sustainably, or will it just accelerate the palm oil’s dominance? Those are some of the questions that I explore. Check it out.

Mouseunculus: How The Brain Draws A Little You

Inside each of us is a miniature version of ourselves. The Canadian neurologist Wilder Penfield discovered this little person in the 1930s, when he opened up the skulls of his patients to perform brain surgery. He would sometimes apply a little electric jolt to different spots on the surface of the brain and ask his patients–still conscious–to tell him if they felt anything. Sometimes their tongues tingled. Other times their hand twitched. Penfield drew a map of these responses. He ended up with a surreal portrait of the human body stretched out across the surface of the brain. In a 1950 book, he offered a map of this so-called homunculus.

Wilder Penfield’s homunculus. Source: http://cercor.oxfordjournals.org/cont...

For brain surgeons, Penfield’s map was a practical boon, helping them plan out their surgeries. But for scientists interested in more basic questions about the brain, it was downright fascinating. It revealed that the brain organized the sensory information coming from the skin into a body-like form.

There were differences between the homunculus and the human body, of course. It was as if the face had been removed from the head and moved just out of reach. The area that each body part took up in the brain wasn’t proportional to its actual size. The lips and index finger were gigantic, for instance, while the forearm barely took up less space than the tongue.

That difference in our brains is reflected in our nerve endings. Our fingertips are far more sensitive than our backs. We simply don’t need to make fine discriminations with our backs. But we use our hands for all sorts of things–like picking up objects or using tools–that demand that sort of sensory power.

The shape of our sensory map reflects our evolution, as bipedal tool-users. When scientists have turned to other species, they’ve found homunculi of different shapes, the results of their different evolutionary paths. This picture, taken from my book The Tangled Bank, shows three subterranean mammals: a mole, a naked mole rate, and a star-nosed mole.

From The Tangled Bank, 2nd ed., Carl Zimmer, Roberts & Company 2013

The top row shows their actual body shape, and the bottom row shows the relative amount of space on the sensory map devoted to each part. The expanded parts reflect the kinds of sensory information they gather. Moles dig with their hands, for example, to search for worms and other prey. They can’t rely on their sight in the dark; instead, they use their sense of smell, their whiskers, and the sensitive skin on their nose. Naked mole rats, on the other hand, use their teeth instead of their hands to dig. Star-nosed moles, finally, have evolved a bizarre hand-like structure on their noses, which they use to quickly probe the soft mud that they dig through.

Dennis O’Leary, a biologist at Salk Institute for Biological Studies, and his colleagues have spent the past few years investigating how the sensory map takes shape. They have studied mice, which have a sensory map finely tuned to their own way of life as nocturnal rodents that search for food aboveground. The mice depend on their whiskers to let them know about their surroundings. Each whisker is surrounded by a dense cluster of nerve endings, all of which feed information into the brain.

Here’s a drawing of the mouse in its actual proportions, with the whiskers and other regions of its body highlighted.

The sensory map of a mouse. Image from Zembrzycki et al. Nature Neuroscience, August 2013, doi:10.1038/nn.3454

And here is a picture of the mouse’s sensory map–what O’Leary and his colleagues have nicknamed the mouseunculus:

Image from Zembrzycki et al. Nature Neuroscience, August 2013, doi:10.1038/nn.3454

Reflecting their dependence on their whiskers, the sensory map is dominated by clusters of neurons that process whisker signals. Each of those clusters, called a barrel, is bigger than the cluster of neurons dedicated to the mouse’s entire foot.

The mouseunculus–or any other mammal sensory map–does not instantly take shape in the embryonic brain. It requires experience to grow. Before birth and afterwards, the neurons in the skin deliver signals into the brain. Those signals stimulate the growth of new neurons, as well as the emergence of connections between the cells. If the brain can’t get signals from part of its body–perhaps due to a birth defect that leads to the loss of a limb, say, or due to nerve damage–the sensory map will develop abnormally.

Does that mean that our sensory maps depend on their existence simply on the signals they receive from the skin? O’Leary and his colleagues have found that the answer to this question is no, as they report in the new issue of Nature Neuroscience. A mammal’s genes also help guide the cartographer’s pen.

The new study builds on O’Leary’s earlier discovery that mutations to certain genes alter the structure of the cortex, the thin outer layers of the brain where its most sophisticated information processing takes place. O’Leary and his colleagues decided to look at how one of those genes, called Pax6, influenced the development of the sensory map in particular.

To find out, they developed an intricate technique to shut down Pax6 only in the sensory map and nowhere else in the brain of mouse embryos. The mice were born healthy, and were able to feed their sensory maps with their typical diet of information.

A week after the mice were born, the scientists followed in Penfield’s steps and mapped the mouseunculus. And here’s what they saw:

Image from Zembrzycki et al. Nature Neuroscience, August 2013, doi:10.1038/nn.3454

The map nicely shows that without Pax6, many of the barrels only grew to a small portion of their normal size, in some cases ending up 80% smaller than in mice with Pax6 switched on in the sensory map. A few barrels never developed at all.

Clearly, O’Leary’s research shows, genes play a big part in building an accurate sensory map. But they do more. Their effects ripple downwards, to earlier steps in the information pathway through the brain.

This diagram shows some stops along that pathway. The signals from the body travel to the back of the brain, and then forward to a structure deep in the brain called the thalamus, before finally reaching the sensory map. At each step, the neurons that process the signals are also organized in maps that correspond to the mouse’s body. They have distinct clumps of neurons for each neuron, called barreloids or barrelettes depend on which part of the brain they’re found.

Image from Zembrzycki et al. Nature Neuroscience, August 2013, doi:10.1038/nn.3454

O’Leary and his colleagues found that when they shut down Pax6 in the sensory map, it wasn’t just the sensory map that changed shape. The thalamus changed too. As with the sensory map, the thalamus’s barreloids shrank or disappeared. O’Leary and his colleagues’ research indicates that the thalamus depends on signals from the sensory map to develop normally. Without those signals, some of the developing neurons in the thalamus die.

The sensory map and the neurons that feed it data turn out to be entangled in an intimate conversation. Signals rising from the skin shape the map, while the genes in the map’s neurons influence it as well–and their influence extends downward into the pathway. This dialogue may be crucial for fine-tuning the entire nervous system, so that we develop sensory maps and sensory neurons that match each other tightly.

Like Penfield’s original map, O’Leary’s research illuminates some of the fundamental questions about how the sensory map works, and it may likewise turn out to offer some practical benefits.  Mutations to genes like Pax6 may alter the sensory map, and their disruption may extend downstream to the thalamus. Those mutations may play a role in brain disorders like autism.

As O’Leary and his colleagues point out in their new paper, previous studies on people with autism have revealed some differences in the activity of genes in the brain. In particular, the genes involved in marking off different areas of the cortex have different patterns of activity.

This change to the brain-shaping genes may explain the fact that some scientists have found changes to the structure of the cortex. While the overall size of the cortex is the same in autistic brains and normal brains, the front portion of the cortex is enlarged in people with autism.

This shift may also mean that the region of the cortex further towards the back of the brain gets smaller. And it just so happens that our homunculus lurks back there. It’s possible, in other words, that in people with autism, the disruption of the cortex leaves them with a smaller sensory map.

If the sensory map is indeed smaller in people with autism, the effects might radiate outward to the thalamus. A recent study on the brains of 17 autistic people revealed that they did indeed have a smaller thalamus on average.

If this hypothesis is correct–and it’s important to note that it’s still based on the study of relatively few people–it could explain why people with autism often have trouble with processing the information of their senses. And it might even point towards new ways to treat autism, by nurturing the inner homunculus.

[Update 3 pm: This post was updated to O'Leary's correct institution--the Salk Institute, not Scripps Institute. Two great institutes very close both in space and in my mind.]

[Update 11 pm: The post initially stated moles are rodents. My bad.]

Gigantic Giant Viruses and the Endless Viral Frontier

Pandoravirus. Photo by Chantal Abergel and Jean-Michel Claverie

In my column this week for the New York Times, I write about the discovery of record-breaking viruses called pandoraviruses. They’re 1000 times bigger than a flu virus and have almost 200 times as many genes–over 2500. That’s twice as many genes as the previous giant-virus record holder, which I blogged about in 2011.

These giant viruses are important to our understanding of what the difference is–if any–between viruses and the rest of life. But they’re also part of a bigger story, one that inspired the title of my recent book A Planet of Viruses. Viruses are the most common life form on Earth, they are by far the most genetically diverse, and we have barely started to explore the viral frontier.

That frontier includes giant viruses–and tiny ones, too. Just last week, for example, Jessica Labonte and Curtis Suttle of the University of British Columbia published a survey of another group of viruses called single-stranded DNA viruses. Their ranks include parvoviruses, which cause an infection sometimes known as the Fifth Disease. If you’ve gotten it, like I did a few years ago, you know that feeling it provides you that someone has been using your body as a punching bag for hours.

The ranks of single stranded DNA viruses include many other pathogens of plants and animals, plus others that infect bacteria. They are exquisitely small, with as few as three genes.

Labonte and Suttle searched through sequenced of DNA that have been trawled up from sea water at a few sites around the world. They found a lot of single-stranded DNA virus genes, which they compared to the seven known families of the viruses. They realized they have probably discovered 129 new families.

Just another week on the viral frontier…

What Good Is Half A Sucker?

The remora is so ridiculous that no one would try to make it up. The top of its head is a giant, flat suction cup. It uses the cup to lock onto the bodies of bigger animals, such as sharks, sea turtles, and whales. As the big animal swims for miles in search of a meal, the remora hangs on for the ride. When its host finds a victim, the remora detaches and feasts on the remains. It sometimes cleans its host’s body and mouth of parasites, and then clamps its head back on for another ride.

The remora’s ridiculousness makes it a fascinating evolutionary puzzle just waiting for the solving. Other species clamp themselves onto other animals–whale barnacles, for example, grow prongs from their shells that anchor them to whale skin–but among fish, remoras are exceptional. Their closest relatives include Mahi-Mahi and amberjacks, neither of which has anything on their head that even faintly resembles the remora’s sucker. Only after the ancestors of remoras and these ordinary fish split apart some 50 million years ago, the remoras evolved a remarkably new piece of anatomy.

A pair of free-swimming remoras, displaying their suction disks. Heather Perry/National Geographic

When you look closely at the remora’s suction disk, its remarkableness only grows. It looks like a spiked Venetian blind. Pairs of slat-like bones called lamellae form a series of rows running down the length of its head, and muscles running from the remora’s skull to those bones pivot them, creating spaces between the rows.

That negative pressure pulls the remora towards its host’s body. Each lamella also has a comb-like set of pins that help make its clamp even more secure. The whole structure is surrounding by a loose fleshy lip, ensuring that no water slips in, keeping the seal tight.

As a result, remoras can create a vacuum that’s not just strong enough to attach them to an animal, but to stay attached as water rushes past them. They can even hold tight as their hosts try to scrape them off on rocks. But a remora can instantly release itself when it’s time to eat, with just a flick of its muscles.

The head of a young remora from the side, above, and the front. Photo courtesy of Ralf Britz

As impressive as the remora’s suction disk may be, however, it’s not actually all that new. As is so often the case in nature, it’s actually just evolutionary tinkering with old parts.

Scientists have gotten some clues to the remora’s origins by looking at how they grow up. When remoras hatch, they don’t yet have a suction disk. Last year Ralf Britz of the Natural History Museum in London and David Johnson of the Smithsonian made a careful study of young remoras to document their development.  They found that the bones and muscles of the remora’s sucker start out much like the bones and muscles in a fin found on the back of other fish, known as the dorsal fin. They develop in the same location and have the same structure. But later, the bones and muscles move forward to the head.

They also change shape along the way. The fin spines spread out into lamellae that sprout a comb of spikes. In ordinary fish, the fin spine sits atop a small round bone. In remoras, that small bone widens out into another set of lamellae.

While the development of embryos doesn’t recapitulate evolution, it can offer some hints about how new things evolved from old ones. Britz and Johnson’s research indicates that the remora suction disk started out, improbably enough, as a dorsal fin. The fin stretched out into a complex vacuum device and moved up to the head. The underlying similarity between sucking disks and fins only becomes clear when you see how they both develop along the same path at first before diverging.

If all this were true, you might be able to test it by looking at the fossils of early relatives of remoras. Perhaps they captured the early stages of the transition.

That is precisely what Matt Friedman at the University of Oxford and his colleagues have done, as they report today in the Proceedings of the Royal Society.

Frieman is an expert on the larger group of fish to which the remora belongs, known as spiny rayed fishes. The group has evolved into some spectacularly weird forms, including sea horses and flatfishes. In 2008, blogged about how Friedman found an intermediate flatfish, with one eye moving towards the other side. Remoras, with their own brand of weirdness, seemed to Friedman another spiny rayed fish worth spending some time on.

The only problem was that most of the fossils of remoras belonged to living lineages. Their suction disks were pretty much like what you’d find on a remora today. At least, that’s what most paleontologists who study remoras have thought.

Friedman decided to take a closer look at one of those remora fossils, called Opisthomyzon. The 30-million-year-old specimen was the first remora fossil ever found, in 1886, and it has sat in a museum in Switzerland ever since.

Opisthomyzon, a 30-million-year-old remora. White box shows suction disk.  Photo courtesy of Matt Friedman.

The specimen was in bad shape, Friedman found. It had a suction disk, for example, but it wasn’t clear if the whole disk had been pushed away from its original location. Friedman wondered if there might be other Opisthomyzon fossils hidden in other museums. Sometimes paleontologists can’t quite figure out what they’ve found, and they file away fossils without describing them.

At the National History Museum of London, Friedman found not one hidden Opisthomyzon fossil, but two. Mark Graham, a preparator at the museum, painstakingly chipped away at the underside of one of the new fossils, until all that was left was a paper-thin slab of rock. Friedman and his colleagues then compared the anatomy of Opisthomyzon to living remoras, as well as to extinct and living relatives, such as Mahi-Mahi.

Opisthomyzon proved to be exactly what Friedman was looking for: an extinct species that branched off before the origin of the living lineages of remoras. And when he and his colleagues examined its anatomy, they found exactly the kind of fish you’d expect to see from developing remoras: a fish with a suction disk still evolving from a fin.

This figure below sums up the story. The top fish is a conventional relative of remoras, with its dorsal fin bones shown to the right. In the middle is Opisthomyzon, with its corresponding suction bones. And at the bottom is a living remora.

Top: A relative of remoras without a suction disk. On the right are two bones that make up a dorsal fin spine. MIddle: Opisthomyzon, with an intermediate suction disk. Bottom: Living remora. Drawing by Matt Friedman

You can see that the suction disk on Opisthomyzon is smaller than that of living remoras and does not sit over its whole head as it does today. The lamellae themselves bear more of a resemblance to the spines of dorsal fins. Opisthomyzon’s lamellae lacked a comb of spikes, for example, still retaining a single spine at the center.

Friedman’s research now gives us a richer hypothesis for how the remora got its sucker. Some of the remora’s closest living relatives, like cobia, tag along with bigger fish to scavenge on their scraps. The ancestors of remoras may have lived a similar life.

It’s not rare for spiny rayed fishes to grow extra dorsal fin spines. In the ancestors of remoras, such an anatomical fluke may have allowed them to latch their dorsal fin into the skin of a host fish, if only briefly. Even if they could spend a little time hitch-hiking this way, they would save energy that they’d otherwise have to spend on swimming for themselves.

Gradually, the remora’s dorsal fin became better adapted to latching onto other animals. As it moved towards the remora’s head, for example, it reduced drag. And as the fin bones spread outward, they attached the remora more strongly.

Sometimes, when we look at an adaptation in living animals, it seems to exquisitely well-suited to the animal’s life that we can’t imagine how a more primitive version of it could have provided any benefit. What good is half a wing, for example? What good is half a sucker? Fossils can give our limited powers of imagination a boost, by showing us that these intermediate forms did indeed exist. Opisthomyzon probably could ride on other animals, although it may have been more prone to get peeled off along the way. Remoras are so good at clamping onto their hosts that they’ve lost some of the traits that other fishes have. Their tails are weak, and they need a strong current of water passing over them in order to breathe through their gills. It’s probably no coincidence that Opisthomyzon had a much stronger tail than living remoras. It was only part-way down the road to ridiculousness.

How Things Get Complex: My New Story for Scientific American & Quanta Magazine

For a couple years now I’ve been fascinated by some recent ideas about how complexity evolves. Darwin’s great insight was recognizing how natural selection could create complex traits. All that was needed was a series of intermediates that raised the reproductive success of organisms. But recently some researchers have developed ideas in which natural selection doesn’t play such a central role.

One idea, laid out in the book Biology’s First Law, holds that life has a built-in propensity to get more complex–even in the absence of natural selection. According to another idea, called constructive neutral evolution, mutations can change simple structures into more complex ones even if those mutations don’t provide an advantage. The scientists who are championing these ideas don’t see them as refuting natural selection, but, rather, complementing it, and enriching our understanding of how evolution works.

I’ve tried for a while to write a story about these ideas, but it’s been pretty tough. It takes some time for me to wrap my head around the arguments. They require a fair amount of space to explore, and–while I find them intriguing–they don’t have a simple news peg. At one point, in fact, I actually had an assignment from a magazine and got well into the research and writing. But I could see my story just wouldn’t end up right for them, and I withdrew it.

It was around this time that I talked with Thomas Lin, the managing editor of Simonsfoundation.org. The Simons Foundation was getting into supporting science journalism in a big way, especially stuff that might not easily find a home elsewhere. I told him about my obsession with complexity, and soon we were off to the races. I was happy to find that the editing was rigorous, and the fact-checking brutal.

Meanwhile, Lin has been very busy at Simons. Yesterday he launched a full-fledged magazine there, called Quanta. Lin described the project . I’m thrilled that my story on complexity is their first offering in this new format. You can read it here.

The Simons Foundation is following in the tradition of Pro Publica–not just as a foundation supporting journalism in tricky times, but also finding lots of ways to get journalism in front of as many readers as possible. Thus they’re collaborating with a number of existing publications. So you can also find my story over at Scientific American.

These are uncertain but exciting times for science journalism. I really appreciate that places like Simons are ready to go out on a limb.

 

Respect the Weed: My New York Times Story on One of Evolution’s Champions

For 10,000 years, we’ve created a new evolutionary arena where a new kind of plant has evolved: the weed. In today’s New York Times, I talk to evolutionary biologists who are studying how weeds first arose, and the marvelously devious strategies they’ve evolved to thrive on farms. You may have be seeing headlines these days about how GMO crops are creating “superweeds.” The new generation of resistant weeds is definitely a serious problem, but it’s not some new Frankensteinian phenomenon. Weeds are just doing what weeds have done so well before. Understanding their evolution may help farmers fight them more effectively and safely. Check it out.

The Mystery of The Rare Male Sea Monkey

Here we see a happy, typical family of sea monkeys. Note the red bow and plump lips that indicate the female of the species, and the tall body and protective stance of the male. I assume that the father’s well-placed tail blocks some other clues to his identity. The parallels between the sea monkeys and the human family (see inset) are uncanny and surely nothing more than a coincidence.

Photo by justaghost, via Creative Commons. Image linked to source.

The real life of sea monkeys (brine shrimp, or Artemia) is a pretty far cry from Ozzie and Harriet. Sea monkeys don’t live in families, for one thing. And in a lot of populations, the females have no need for males. Their eggs can develop into healthy embryos–and, eventually, adults–without the need of sperm. You can take that picture of sea monkeys and wipe Dad out.

From an evolutionary perspective, this father-free way of life has a lot going for it. Let’s say you’ve got a sexual pair of male and female shrimp in one tank, and two asexual females in the other. Let them breed for a while. Sexual species typically produce a roughly even ratio of sons and daughters. So only half of the sexual population can produce eggs, while every individual in the asexual one can. It won’t be long before the asexual population is far bigger than the sexual one. Out in the wild, this proliferation should mean that the genes for male-free reproduction should quickly dominate populations. Down with sex, in other words.

But this has only occurred in only about one in every ten thousand species of animals. Sex must have a powerful advantage that overcomes its disadvantage–what the late biologist John Maynard Smith dubbed the two-fold cost of sex.

Scientists have given this question a lot of thought, and they’ve come up with some possible answers that they’ve been testing in recent years. Maybe sex lets adaptations evolve faster, because mothers and fathers can combine genes into new combinations. Defenses against ever-evolving parasites might be especially important. There may be different explanations for different cases. Very often, when an asexual lineage emerges, it gains an extra set of chromosomes. That’s a lot of extra DNA to build when a cell divides–which requires a lot of phosphorus and other ingredients. Perhaps that’s a cost too great to balance the advantage of giving up fathers.

Or perhaps the rarity of asexual animals is the result of evolution playing out not in short-term competitions, but over vast stretches of time. Populations of sexual animals may be less prone to going extinct because they can adapt to more niches.

To better understand the evolution of sex, a number of biologists are looking to the exceptions to the rule. If the advantages of sex overwhelm its costs for 9,999 species out of every 10,000, then why is the opposite true in the remaining one? One lineage of microscopic animals called bdelloid rotifers has been asexual for 80 million years. Cornell scientists have suggested that they have remained asexual because they’ve found a way to resist parasites that’s as good as sex–by drying up and blowing away from their pathogens.

Brine shrimp. The orange masses are eggs. Photo by Paul Zahl, National Geographic

But there are other puzzles to the evolution of sex. And one involves sea monkeys. In a paper appearing in the Journal of Evolutionary Biology, Marta Maccari of the University of Hull and her colleagues describe a massive survey of brine shrimp from across Europe and Asia. They reared cysts from dozens of populations and closely examined the offspring over the course of two generations. The females in these populations can reproduce on their own. And yet in most of the populations they studied, they discovered a few males.

The males were exceedingly rare–around one in thousand in many cases, and around one in a hundred in a few. And yet they were healthy and fertile. The males couldn’t mate with females of their own population, but they readily had sex with other species. What’s more, their hybrid offspring were healthy and fertile, too.

If asexual animal species are rare, species with asexual females and rare males are even more rare. Only a few other examples have turned up, such as certain populations of snails in New Zealand. Maccari and her colleagues don’t think there’s a clear answer to why these rare males exist. But there are a few plausible possibilities.

Maybe it’s just a fluke. It’s possible, for example, that as eggs develop, a few accidentally lose a chromosome, altering their sex. Sons, in other words, are birth defects.

It’s also possible that some of the asexual brine shrimp have mutations that lead sometimes to males, and they pass their mutated genes down to their offspring. In her study on New Zealand snails last year, Maurine Neiman of the University of Iowa and her colleagues found, surprisingly, that producing a few sons that can’t mate with any females of your species doesn’t put asexual animals at a major disadvantage.

On the other hand, maybe rare males are a side-effect of brine shrimp biology. One way for females to reproduce is to combine two eggs, joining together their chromosomes into a full set. This process can produce lots of different combinations of the shrimp’s DNA, and that variation may help them adapt to the changing environment. Sometimes, though, those combinations may produce a fertile son.

The most interesting possibility Maccari and her colleagues raise is that the rare males are a way for the genes for asexuality to spread themselves. The males can’t mate with their own species, but they can interbreed with others. They may then introduce genes for asexual reproduction into the species, causing them to turn male-free. For brine shrimp, in other words, fathers may be a way of getting rid of fathers. I have no idea how you’d paint that on a box of sea monkeys, but I’d be curious to see someone try.

Mealybugs and the Essence of Life

As I continue to catch up from a week’s vacation, I realize that I neglected to point Loom readers to last week’s “Matter” column in the New York Times. It’s a fun one: a look at the species with the fewest known genes in its genome–just 120. Which raises the questions, just how low can you go? Is there some minimal essence of life? The answer is not what you might think. And it involves living inside a mealybug.

Andrew Howley over at National Geographic News Watch shares my fascination with such “Whoa…” questions, and so we exchanged some further thoughts about what it means to be alive. You can read his conversation with me here.

 

 

Bees As Tuning Forks, And Why Your Pizza Depends on Them

For this week’s “Matter” column, I write about the bees buzzing from flower to flower this summer. In particular, I take a look at the bees that pollinate 20,000 species of plants–including crops like tomatoes and potatoes–with some amazing acoustics. They vibrate hundreds of times a second to shake pollen loose from special tubes in the flowers.

That’s why you can use a tuning fork to coax some flowers to release a cloud of pollen, as this video from Anne Leonard of the University of Nevada, Reno, illustrates. Bees, in other words, are living tuning forks.