Fish can count, too

One, two, three...

Timeline, 2008: We tend to think of a few things we do as being uniquely human. And then we keep finding other organisms that can do them, too. Walking on two legs? Meet the orangutan, walking upright in the trees. Tool use? Crows can make a hook to fish meat out of a tube. The ability to talk? Seems that Neanderthals might have had that, also. OK, well what about counting, having number sense? Baby chickens share this trait with us. To the growing list of other animals that do as well—which includes dolphins, rats, and some monkeys—you can now add the mosquitofish.

Mosquitofish vs Munduruku

Yes, apparently fish can also count, in some cases as well as infants ages 6 to 12 months. In fact, when compared to some natives of the Amazon, the Munduruku, which have limited number language, the fish may even be comparable. The Munduruku people see no value in having a construct for counting beyond five. The mosquitofish, on the other hand, can count about that high and estimate with even higher numbers.

Number sense: It’s not just for people any more

Number sense can be broken down into three paths of perception. We can visually estimate what we see, as people do when they report crowd counts for huge parades or demonstrations. We can also visually count individual units, as we might do just looking at the fingers on one hand. And humans also have the ability to verbally count, theoretically to infinity given sufficient time. While mosquitofish obviously do not count out loud, they do appear to have visual estimation and counting abilities.

Neither is sexual harassment

Their estimation abilities first emerged as a result of sexual harassment. Researchers studying the guppy-like fish noticed that when a male harassed a female, the female fish would take refuge with a group of fish nearby. If there was a choice of groups, or shoals, of different sizes, she would choose the larger of the two. Of course, her ability to tell “larger” might have had nothing to do with actual numbers but instead with the area that the fish occupied. To assess this possibility, researchers performed a number of complex experiments. Their results showed that the females were not relying in occupied area to figure out which group had more fish. They really were using visual number estimation to decide.

In fact, they seem to use ratios in their determinations, but the ratios need to meet a threshold of difference for the estimations to work. For example, a mosquitofish seems able to distinguish a group of 16 fish as being larger than a group of 8 fish, a ratio of 2:1. But the fish cannot tell a group of 12 from a group of 8, proving unable to distinguish a 3:2 ratio.

Estimating, counting: These fish are brilliant

With lesser numbers, up to about four, however, the fish discard visual estimation and rely instead on actual visual counting. In what really was a clever set of experiments, the research team let an individual female fish spend an hour exploring two areas of an aquarium. In one area, she could see a group of four fish but could only see each fish one at a time. In the other area was a group of three fish, again only visible to the female one at a time. After letting her explore, the researchers then determined where the female spent more time. The fish spent about twice as long swimming close to the larger group. In other words, the fish seems to have counted the number of individuals in each group and based on their counting, figured out which area of the aquarium had the larger group.

Pretend you’re a fish

To get in tune with how meaningful this ability is, visualize the experiment yourself as a human (you’re human, right?). Stand in front of two open doorways. In one doorway, four people appear, one at a time. In the other doorway, three people appear, one at a time. You can count them, distinguishing each different individual, and can tell which doorway leads to the larger group of people. That’s how smart the mosquitofish is.

Advertisements

Why we love our blankies

The box that "duplicated" precious objects

Timeline, 2007: My oldest son is like Linus. He will not part with his “fuzzy,” a blanket that has now survived almost six years of nightlong hugging, trips by plane, train, and automobile, a lonely overnight at a Gymboree, and endless variations on superheroes, ghosts, and pirate headwraps. A professor at the University of Bristol, working with another researcher from Yale, found that children appear to attach a property beyond the physical to these objects of their sleepytime need. The two professors, Bruce Hood and Paul Bloom (of Yale), tested children ages 3 to 6 who had an attachment toy, something that they slept with regularly and had owned for at least one-third of their lives.

For the study, the grownups played a trick on the children. They showed the kids a conjurer’s box with a lot of fancy knobs on it and told them that it was a copying machine that could duplicate objects. To demonstrate, the grownups placed a green block in the machine, fooled around with some of the knobs, and made the first box buzz. Then, the second box of the machine buzzed, and when the doors opened, there was an identical green block behind door number 2.

Linus was engaged in magical thinking

A total of 22 children had brought their attachment objects for the study. After witnessing the amazing abilities of the copying box, four of them simply refused to allow their special object to be “copied” at all. The remaining 18 did allow it, but when choosing between the “copy” and the original, only five selected the “copy.”

Another group of children had brought nonattachment objects for the study. Every child consented to the copying process, and when it came time to choose between their object and the “duplicate,” almost two-thirds opted for the “new” version. Once the study was completed, all children learned that the object they had selected was, in fact, their original toy or blanket.

The Queen’s chalice

The researchers also conducted a different set of experiments in which they placed a goblet in the machine and told the child that it was special either because it was made of silver or had belonged to the “Queen,” presumably the Queen of England. Children who thought it was made of precious metal felt that the “copy” was worth the same as the original; however, children who were told that the original was the Queen’s thought it was of superior value to the “duplicate.”

What drives this kind of irrational, magical thinking? According to Hood, from the University of Bristol, humans are evolved to seek explanations for what cannot be seen, such as gravity. Because mechanisms for many natural phenomena cannot be directly observed but must be inferred, we rely heavily on our intuitive thinking to reach conclusions. This reliance leaves the door open to believing supernatural explanations for what we otherwise cannot explain. Attachment objects may be a substitute for a child who sleeps separately from his mother. But children also appear to confer on the object an “essence,” some meaning beyond its physical worth, something that makes it different from an exact physical duplicate.

The killer’s cardigan

Children are not alone in their reliance on credulity. Grownups use superstition as a way to cope with situations or feel more control over them or to explain the unexplainable. Hood demonstrated the adult tendency to believe an “essence” very clearly in a recent presentation. He offered audience members the chance to earned a quick $25 just for putting on a worn old blue cardigan. Numerous volunteers raised their hands. When he then mentioned that the cardigan had been the property of a notorious mass murderer, most volunteer hands disappeared. The few people who did put on the sweater, which had not really belonged to a murderer, found that the other members of the audience avoided them while they wore it. Scientists are not immune—plenty of us would simply refuse to exchange our wedding rings for an exact copy, for example, even though physically, it is no different from the original we wear on our ring finger.

Nematode may trick birds with berry-bellied ants

Comparison of normal worker ants (top) and ants infected with a nematode. When the ant Cephalotes atratus is infected with a parasitic nematode, its normally black abdomen turns red, resembling the many red berries in the tropical forest canopy. According to researchers, this is a strategy concocted by nematodes to entice birds to eat the normally unpalatable ant and spread the parasite in their droppings. (Credit: Steve Yanoviak/University of Arkansas)

Timeline, 2008: Host-parasite relationships can be some of the most interesting studies in biology. In some cases, a parasite requires more than one host to complete its life cycle, undergoing early development in one host, adult existence in another host, and egg-laying in still another. There’s the hairworm that turns grasshoppers into zombies as part of its life cycle, and the toxoplasma parasite, which may alter the behavior of humans and animals alike. Often, the infection ends with the host engaging in life-threatening behaviors that lead the parasite to the next step in the cycle.

A recent discovery of a most unusual host-parasite relationship, however, results in changes not only in host behavior but also in host appearance. The infected host, an ant living in the forest canopy in Panama and Peru, actually takes on the look of a luscious, ripe fruit.

Berry-butted ants

Researchers had traveled to the Peruvian forest on a quest to learn more about the airborne acrobatics of these ants, Cephalotes atratus. This ant is a true entomological artist, adjusting itself in midair if knocked from its perch. Re-orienting its body, it can glide back to the tree trunk, grabbing on and climbing to where it belongs, avoiding the dangers of the forest floor.

As the investigators monitored the colony, they became aware of some odd-looking members of the group. These ants had large red abdomens that shimmered and glowed and looked for all the world like one of the tropical berries dotting the forest around them. Curious about these odd ants, the scientists took some to the lab for further investigation. Ant researchers are an obsessive breed, and they had even placed a bet over whether or not these berry-bellied ants were a new species.

A belly full of another species’ eggs

When they sliced open one of the bellies under a microscope, what they found surprised them. Inside, a female nematode had packed the ant’s abdomen full of her eggs. The bright red belly was an incubator and, the researchers surmised, a way station on the nematode’s route to the next step in its life cycle. This was the same old C. atratus with a brand new look.

Tropical birds would normally ignore these ants, which are black, bitter, and well defended with a tough, crunchy armor. But any tropical bird would go for a bright, red, beautiful berry just waiting to be plucked. The scientists found that in addition to triggering changes to make the ant belly look like a berry, the nematode also, in the time-honored manner of parasites, altered its host’s behavior: the berry-bellied ants, perched on their trees, would hold their burgeoning abdomens aloft, a typical sign of alarm in ants. A bird would easily be tricked into thinking that the bug was a berry. One quick snap, and that belly full of nematode eggs would be inside the belly of a bird.

Poop: A life cycle completed

And then the eggs would exit the bird the usual way, ending up in the bird’s feces. The ants enter the picture again, this time collecting the feces and their contents as food for their colony’s larvae. The eggs hatch in the larvae and the new nematodes make their way to the ant belly to start the cycle anew.

The nematode itself is a new find, a new species dubbed Myrmeconema neotropicum. And it seems that earlier discoverers of the berry-bellied ants also thought they had a new species on their hands: the researchers turned up a few previous berry-bellied specimens in museums and other collections labeled with new species names. No one had thought that the difference in appearance might be the result of a parasitic infection: this relationship is the first known example of a parasite causing its host to mimic a fruit.

Birds remain the missing link

There is one hitch to the newly discovered nematode-ant-bird association: the researchers never actually saw a tropical bird snap up a juicy, fruit-mimicking ant. They report seeing different species of birds scan the bushes where such ants sheltered, but there were never any witnessed ant consumptions. Thus, this inferred piece of the puzzle—the involvement of birds and their droppings in the life cycle of this nematode—remains to be proven.

Genetic analysis: my results and my reality

A few months ago, it was National DNA Day or something like that, and one of the genetics analysis companies had a sale on their analysis kits, offering a full panel of testing for only $100. Giddy with the excitement of saving almost $1000 on something I’d long been interested in doing, I signed on, ordering one kit each for my husband (a.k.a. “The Viking”) and me. Soon, we found ourselves spending a romantic evening spitting into vials and arguing about whether or not we’d shaken them long enough before packaging them.

The company promised results in six weeks, but they came much faster than that, in about three weeks. Much to my relief, I learned that neither of us carries markers for cystic fibrosis and that I lack either of the two main mutations related to breast cancer. Those basic findings out of the way, things then got more complex and more interesting.

How it works

First, a bit of background. These tests involve sequencing of specific regions to look for very small changes, a single nucleotide, in the DNA. If there is a study that has linked a specific mutation to a change in the average risk for a specific disorder or trait, then the company notes that. The more data there are supporting that link, the stronger the company indicates the finding is. Thus, four gold stars in their nomenclature means, “This is pretty well supported,” while three or fewer slate stars means, “There are some data for this but not a lot,” or “The findings so far are inconsistent.”

Vikings and Ireland

The Viking is a private person, so I can’t elaborate on his findings here except to say that (a) he is extraordinarily healthy in general and (b) what we thought was a German Y chromosome seems instead to be strictly Irish and associated with some Irish king known as Niall of the Nine Hostages. Why hostages and why nine, I do not know. But it did sort of rearrange our entire perception of his Y chromosome and those of our three sons to find this out. For the record, it matches exactly what we learned from participating in the National Geographic Genographic project. I’d ask the Viking if he were feeling a wee bit o’ the leprachaun, but given his somewhat daunting height and still Viking-ish overall demeanor (that would be thanks to his Scandinavian mother), I’m thinking he doesn’t. Lord of the Dance, he is not.

Markers that indicate an increased risk for me

I have an increased risk of…duh

Looking at the chart to the left (it’s clickable), you can see where I earned myself quite a few four gold stars, but the ones that seem most relevant are those with a 2x or greater increased risk: lupus, celiac disease, and glaucoma. The first two do not surprise me, given my family’s history of autoimmune disorders.

If you focus on a list like this too long, you can start to get a serious case of hypochondria, worrying that you’re gonna get all of these things thanks to those glaring golden stars. But to put it into context, for the lupus–for which my risk is 2.68 times higher than a regular gal’s–that still leaves me in the population in which 0.66 persons out of every 100 will develop this disorder. Compare that to the 0.25 out of every 100 in the regular-gal population, and it doesn’t strike me as that daunting.

Some of those other things on there? Well, let’s just say they’re close. My risk of thyroid cancer might be raised…but I no longer have a thyroid. Hypertension risk is increased–and I have stage 2 hypertension. Gallstones, gout, alcholism, asthma…based on family history, it’s no surprise to me to see some mixed or clear risk involved with these, although I have none of them. Does that mean that someone else with these increased risks will have related real-life findings? No. It only means that you’re at a bit more risk. It’s like riding a motorcycle vs. driving a car. The former carries more risk of a fatal wreck, but that doesn’t mean you’re absolutely gonna die on it if you ride it.

Disorders for which my risk is allegedly decreased

I have a decreased risk of...

None of my decreased risk findings are very eye catching in terms of actual drop in risk except for Type II diabetes (now where is my bag of sugar?). As I have been under evaluation for multiple sclerosis and have a family member with it, it’s interesting to see that my risk for it, based on existing studies and known polymorphisms, is decreased. And even though I know that much of this is largely speculative and based on little firm data, it’s still sort of comforting to see “decreased risk” and things like “melanoma” in the same group.

Don’t make my brown eyes blue!

And they didn’t. They nailed the eye color and other trait-related analysis, such as level of curl to the hair, earwax type, alcohol flush reaction, lactose intolerance (unlikely), and muscle performance (I am not nor have I ever been a sprinter). And even though I do not have red hair, they reported that I had a good chance of it, also true given family history. I am not resistant to malaria but allegedly resistant to norovirus. I wish someone had informed my genes of that in 2003 when I was stricken with a horrible case of it.

Ancestral homeland

Yep. They nailed this one. One hundred percent European mutt. Mitochondria similar to…Jesse James…part of a haplogroup that originated in the Near East about 45,000 years ago then traveled to Ethiopia and Egypt and from there, presumably, into Europe. It’s a pretty well traveled haplotype and happens to match exactly with the one identified by the National Geographic Genographic project. When it comes to haplotypes, we’re batting 1000.

In summary

Some of these findings are reliable, such as the absence of the standard breast cancer mutations or the presence of certain mutations related to autoimmune disorders, while other findings are iffy. The company duly notes their iffiness  in the reports, along with the associated citations, polymorphisms, and level of risk identified in each study. They don’t promise to tell you that your ancestors lived in a castle 400 years ago or hailed from Ghana. From this company, at any rate, the results are precise and precisely documented, and as I noted, pretty damned accurate. And they’re careful to be a clear as possible about what “increased risk” or “decreased risk” really means.

It’s fascinating to me that a little bit of my spit can be so informative, even down to my eye color, hair curl, and tendency to hypertension, and I’ve noted that just in the days since we received our results, they’ve continually updated as new data have come in. Would I be so excited had I paid $1100 for this instead of $200? As with any consideration of the changes in risk these analyses identified, that answer would require context. Am I a millionaire? Or just a poor science writer? Perhaps my genes will tell.

Think the eye defies evolutionary theory? Think again

The compound lens of the insect eye

Win for Darwin

When Darwin proposed his theory of evolution by natural selection, he recognized at the time that the eye might be a problem. In fact, he even said it was “absurd” to think that the complex human eye could have evolved as a result of random mutations and natural selection. Although evolution remains a fact, and natural selection remains a theory, the human eye now has some solid evolutionary precedence. A group of scientists that has established a primitive marine worm, Platynereis dumerilii, as a developmental biology model has found that it provides the key to the evolution of the human—and insect—eye.

Multiple events in eye evolution, or only one?

The divide over the eye occurred because the insects have the familiar compound-lens—think how fly eyesight is depicted—and vertebrates have a single lens. Additionally, insects use rhabdomeric photoreceptors, and vertebrates have a type known as ciliary receptors. The rhabdomeric receptors increase surface area in the manner of our small intestine—by having finger-like extensions of the cell. The ciliary cells have a hairy appearance because of cilia that pop outward from the cell. A burning question in evolutionary biology was how these two very different kinds of eyes with different types of photoreceptors evolved. Were there multiple events of eye evolution, or just one?

Just once?

P. dumerilii work indicates a single evolutionary event, although the usual scientific caveats in the absence of an eyewitness still apply. This little polychaete worm, a living fossil, hasn’t changed in about 600 million years, and part of its prototypical insect brain responds to light. In this system is a complex of cells that forms three pairs of eyes and has two types of photoreceptor cells. Yep, those two types are the ciliary and the rhabdomeric. This little marine worm has both kinds of receptors, using the rhabdomeric receptors in its little eyes and the ciliary receptors in its brain. Researchers speculate that the light receptors in the brain serve to regulate the animal’s circadian rhythm.

How could the existence of these two types of receptors simultaneously lead to the evolution of two very different kinds of eyes? An ancestral form could have had duplicate copies of one or both genes present. Ultimately, if the second copy of the rhabdomeric receptor gene were recruited to an eye-like structure, evolution continued down the insect path. But, if the second copy of a ciliary cell’s photoreceiving gene were co-opted for another function, and the cells were ultimately recruited from the brain for use in the eye, then evolution marched in the vertebrate direction.

All of the above is completely speculation, although this worm’s light-sensitive molecule, or opsin, is very much like the opsin our own rods and cones make, and the molecular biology strongly indicates a relationship. It doesn’t completely rule out multiple eye-evolution events, but it certainly provides some nice evidence for a common eye ancestor for insects and vertebrates.

Note: This work appeared in 2004 and got a detailed writeup at Pharyngula.

Columbus Day post: Failed Columbus settlement found no silver

Christopher Columbus

Columbus may have made his name for the history books by “finding” the Americas, but his real claim to fame may have been his world-class snake oil salesman ability. After returning from his famed voyage of 1492, Columbus bowed before his patrons, Spain’s King Ferdinand and Queen Isabella, and spun a tale of precious metals in the new world. His fairy stories about a land of silver and gold lit a fire under the Spanish royals, leading them to finance a much larger second expedition to the New World Columbus had stumbled on.

Tall tales of silver and gold

His tall tales also attracted a huge crowd of settlers with gold in their eyes and riches on the brain. This hapless group, 1500 strong, landed on the north shore of today’s Dominican Republic in 1494, only to find a land of sand and hardship, not the streets of gold they’d expected. Catastrophe piled on top of catastrophe in the form of hunger, disease, hurricanes, and conflicts with the indigenous people. Mutiny not unnaturally followed, and four years after the settlement was established, the few hundred remaining settlers abandoned the effort and returned home.

This failed first European town in the New World left behind a treasure trove for archaeologists, however. Among the finds was about 100 pounds of galena, a lead ore containing silver. Medieval people used galena to determine how much silver a substance contained. They could create galena with a known amount of silver, or galena could be found and its silver content compared with galena containing the known amount of ore.

Why is all this galena lying around?

For many years, scholars had thought that the galena found at the settlement, which its founders had called La Isabela after the financier queen, was the result of the settlers’ discovery of silver in the area. The odd thing was, no settler ever left a written record of such a discovery. Given the 100 pounds of it and the detailed records people on such expeditions tended to leave, such a find usually would have earned a mention.

In addition to the pounds of galena, researchers also found several hundred pounds of slag, which turned out to be lead silicate with flecks of silver in it. This slag also could have been the result of settlers’ attempts to extract silver from a local discovery. But again, there was no mention in the record of what would have been a significant operation, given the 400-plus pounds of slag. The galena and slag were discovered near a building that was used to store royal property.

Starving and desperate for silver

To address the discrepancy between the written record and archeological inference, a group of researchers applied chemical analysis to the galena and slag and compared it to known samples of Caribbean ores. They found that the galena and slag did not come from a Caribbean location and instead probably traveled with the settlers from Spain. The researchers speculate that the settlers, starving and desperate, were frantically trying to extract silver from items in the royal coffers.

Supporting this idea is the fact that the lead in the galena would normally have been more useful to them, for things like musket balls or supports for a ship. The waste, in the form of the lead silicate slag, was of no use to them at all.

An expert in medieval chemistry told the researchers that people of that era commonly mixed galena with ores they thought might contained a precious metal, using galena with a known quantity as a marker for how much gold or silver their discovered ore contained. This explanation may provide the reason the settler had galena with them in the first place.

Mystery spot in the night sky baffles astronomers

The mystery light that baffled astronomers

In 2006, astronomers working on the Supernova Cosmology Project, which scans the universe for supernovae, or exploding stars, noted something no one had ever seen before. An unidentified light appeared, grew increasingly brighter for about 100 days, and then over the next 100 days faded away completely.

Not a supernova

Sure, there are other things in the night sky that behave that way, including supernovae themselves, but this particular burst of brightness carried completely unrecognizable features. The light came to our attention thanks to the Hubble Space Telescope, which wanders the universe sending back pictures of very cool things for us to investigate. In this case, Hubble was trained on a cluster of galaxies in a constellation known as Bootes, which is home to Arcturus, said to be the fourth brightest star in the night sky. But this mystery light in 2006 briefly gave Arcturus more competition than a supernova.

A supernova gives off an intense amount of light that can actually outshine a galaxy during its relatively brief period of existence. But supernovae do not last longer than 70 days, and usually are radiant for only about three weeks. The mystery light, on the other hand, burned for 200 days. Another example of light changes in the night sky is microlensing, in which light from a distant object bends around something of enormous mass, such as a cluster of galaxies, thanks to gravitational pull. This light didn’t fit that description, either.

No signature matches

In fact, when astronomers compared its atomic spectra signature with all known signatures in their databases, they found nothing that matched. Spectral signature analysis is one way we determine the elemental makeup of something that is light years away. The signature results from a pattern of light wave frequencies, which begin thanks to the vibrations of electrons. Electrons within an atom can vibrate at different frequencies, so atoms emit light waves at different frequencies. We see those differences as bands of color when we look at them through a device that separates the wavelengths, and different elements exhibit different banding patterns: hydrogen, for example, has a different color banding pattern than helium. Thus, we can look at light traveling from billions of miles away and determine the elemental makeup of its source based on the banding patterns of these emissions.

But the banding signature of the mystery light didn’t match that of any known cosmic object. What also remained mysterious was exactly how far away the light was. Astronomers could roughly say that it was no closer than 130 light years because it lacked parallax motion, which diminishes with distance. For a good example of how parallax motion changes with distance, close one eye and hold your thumb up close to your face. Now, switch eyes, closing one and opening the other. Switch back. You’ll see that your thumb appears to shift position. That’s parallax motion. Now, hold your thumb at arm’s length and do the same thing. You’ll see that the shift is considerably less. At a predictable distance—130 light years—such a shift on a cosmic scale would be undetectable. But all astronomers can really say is that it’s no closer than that and no farther away than 11 billion light years, based on the lack of a hydrogen signature.

Destined to remain an engima

So right now, the Mystery Light (otherwise known as SCP 06F6) that’s not too close and, in cosmic terms, not that far away, remains an enigma. Some have suggested that it was the radiant remnant of an enormous interstellar collision, perhaps between a white dwarf, an incredibly dense star at the end of its life, and a black hole. But the signs—from the spectral signature to the lack of microlensing—don’t really fit that scenario. Whatever it was, this light that grew in brightness by 120 times before fading away completely will remain a mystery for the foreseeable future.

Beautifully lifeless: the clearest ocean in the world

Thermohaline circulation

Because of the ability of UV light to shred biological molecules, researchers have speculated that life on Earth may have arisen in some dark corners, possibly under rocks or in the ocean depths where UV waves cannot reach. If that’s the case, we can rest assured that wherever life arose, it couldn’t have been a place containing the “clearest ocean waters on Earth.” That recognition today goes to a patch of water the size of the Mediterranean but lying in the middle of the Pacific, an ocean with a reputation for bounty. This area of the Pacific, however, although boasting waters of a unusual, deep violet color, is as lifeless as it is lovely.

Tough research job, but someone’s gotta do it

Researchers traveling to the area in October 2004 had been attracted to this part of the Pacific—stops included Tahiti, French Polynesia, Easter Island, and Chile—because of satellite images suggesting remarkably low chlorophyll levels in the area. This imaging allows scientists to track chlorophyll abundance in the Earth’s oceans, an important indicator of change on a major scale. When chlorophyll is low, life is scarce.

Indeed, when they traveled to the area, the researchers found some of the clearest ocean waters they had ever seen. According to one scientist on the project, the water was as clear as any of the clearest freshwater anywhere on the planet. He compared it, for example, to the clarity of the water from Lake Vanda, a pristine Antarctic lake lying buried under mountains of ice.

No chlorphyll, little life, but great clarity

But this clarity arises from a lack of chlorophyll and a lack of life. The researchers found that UV could penetrate to extraordinary depths in this area of the Pacific, as deep as 100 meters below the ocean surface. This depth sets a record for UV penetration in ocean waters, and its DNA-destroying properties carry responsibility for the dearth of life in this patch of the Pacific.

The mystery of the organic carbon

The researchers did find some evidence of a food web, however. But the organisms that live there, generally bacterial, must survive in a sort of closed system, constantly recycling the nutrients they need to live, such as nitrogen and phosphorus. Strangely, the team found that this particular part of the ocean was full of dissolved organic carbon, which is of biological origin. How an area so devoid of life could produce so much carbon derived from life remains a mystery. Researchers speculate that the bacteria are so busy addressing their nutrient needs in their limited system that they simply do not get around to degrading the carbon.

Out of the mix

Why would the Pacific harbor this clear, beautiful dead zone? The formation of this odd stretch of sea relies on several factors. The Earth’s oceans are a connected, global system of currents, water running not only at the surface but also at the depths. The thermohaline circulation, also known as the “global conveyor belt,” is one of these currents, driven by changes in the density of water in different parts of the globe. As water warms or becomes more saline, its density changes—warmer water is less dense than cold, and saltier water is more dense. As wind-driven currents move water toward the poles, the water cools and sinks when it gets to the high latitudes. This heavier water then flows back into the ocean basins and eventually wells up again. The oldest waters can take 1600 years to make this trip, but in the meantime, waters mix in the basins, making all of the Earth’s oceans pretty similar as they move their components around the planet.

The clearest ocean water on Earth, however, misses the trip. Its location in the middle of the South Pacific ensures that it doesn’t benefit from global river or ocean circulation. It never cools because it’s in the South Pacific, and thus, the water just stays put, clean and clear and almost completely lifeless.

Giant Mesozoic badger turned mammalian dogma on its head

Juvenile badger with dinosaur dinner

Check your biology book. If it says anything about mammals during the age of dinosaurs, it probably depicts the mammals as small, shrew-like animals scuttering around at night, barely scratching out a living as they scurry away from the thudding feet of a Tyrannosaurus rex.

Mammals ate dinosaurs–tasted like chicken

Banish the thought and rewrite the book. Yes, many of the mammals that lived in the Mesozoic—from about 248 to 65 million years ago—were shrew- or rat-like critters that probably stayed out of the way of most dinosaurs. But recent fossil finds demonstrate that some of the mammals in the age of the dinosaur not only got in the path of dinosaurs, they ate them.

In China, there is a famous fossil bed best known for the fossils of feathered dinosaurs it has yielded. But paleontologists have also turned up some other intriguing remnants, among them the mineralized bones of species from the Repenomamus genus. These animals were long, squat-bodied creatures with strong jaws and very sharp, pointy teeth. Researchers at the site had already reported finding R. robustus, a carnivorous mammal weighing in at about 15 pounds.

Giganticus, indeed

But two other finds reported in Nature flip common Mesozoic mammal dogma upside down. The first discovery was that of a fossil species now dubbed Repenomamus giganticus, a cousin of R. robustus, but with some distinctive features: this specimen probably weighed about 30 pounds and grew to be up to a meter long. Think about a mid-sized dog, say a large basset hound, with a badger-like face and rodent-like sharp teeth, and you’ve got your R. giganticus. Not something you’d want to go hand-to-tooth with when it’s in a bad mood.

Died with dinner inside (& more dog breed comparisons)

That, at least, is what researchers concluded after their second find: a fossil of R. robustus, the smaller species, with a juvenile dinosaur skeleton where the R. robustus stomach would have been. Not only did these hardy Repenomamus species look scary, for juvenile, leaf-eating dinosaurs, they were deadly. Experts estimate, based on mammalian habits of today, that mammals can kill and consume prey that is up to half of their body weight. If R. robustus could snack on a 5-inch dinosaur baby, then presumably R. giganticus could have put back a dinosaur the size of a dachshund.

The scientists who identified and named R. giganticus had a couple of hurdles to overcome. First, they had to determine that this was a genuine average version of R. giganticus, not simply R. robustus with a pituitary problem. The error that would result would be akin to finding the skeleton of the world’s tallest man and assuming that it represented our entire species.

Badger or human, your teeth show your age

But they looked at the teeth that accompanied the skull and jaw fossils, and the molars held the clues to the animal’s age at death. The last molar of the lower jaw appeared to have just erupted when the animal died, and it had little wear. Based on this clue, the researchers concluded that fossilized remains were from a juvenile representative of the new R. giganticus species.

Making the case that a Mesozoic mammal had actually consumed a dinosaur also required some consideration and discarding of various possibilities. The little dinosaur skeleton, from a Psittacosaurus, was a small patch of bones within the ribcage of some R. robustus fossil remains. The bones were located right where the stomach is on today’s mammals, and appeared to have been broken, torn apart, and displaced from one another. The fossil bones of the accompanying R. robustus skeleton were not in this condition. The Psittacosaurus specimen also had teeth, most of which were worn, implying that this animal was not scavenged from an egg as an embryo. Based on these clues, the researchers concluded that this R. robustus had caught and eaten the hapless Psittacosaurus—dismembering it and swallowing it in chunks—shortly before meeting its own death.

Tricky little orchids

Orchids attract collectors all over the world. One of the things that draws us to these unusual plants is their Machiavellian approach to life. They unfeelingly employ deception to their benefit, usually practicing their art on unsuspecting members of the insect community. Research has revealed that one species of orchid, Anacamptis morio (or Orchis morio), or the green-winged orchid, lays its bold insect trap in an attempt to avoid a trap itself.

Inbreeding avoidance: not just for royalty

Although plants can do many things that most members of the animal kingdom cannot—self-fertilize or increase chromosome numbers in a generation—they’re still better off when reproductive measures result in an increase in genetic variation. As with most organisms, inbreeding is not a healthy thing for a plant, and many plants have mechanisms to avoid it.

The idea of inbreeding avoidance led researchers to a theory to explain the remarkable behavior of many orchids. These beautiful, much-coveted flowers attract humans and insects with their alluring fragrances and colors. For insects, some orchids add to the attraction by mimicking the female of the insect species, or wafting the scent of eau d’ dung for insects that prefer laying their eggs in such places. But of the 30,000 known orchid species, about 10,000 have nothing to offer the hapless insect in return: their flowers have no nectar.

Why keep coming back for nothing?

Researchers have sought to explain why insects would continue to visit such a stingy plant, and why the plants continue to get away with and employ their nectar-free strategy. The strategy itself seems in violation of so much of our understanding of the natural world, a place typically characterized by tradeoffs. In fact, orchids without nectar are not wildly popular among insects—it is difficult in many cases to witness a bee pollinating a green-winged orchid in the wild—but they still do manage to get pollinated.

Scientists investigated wild-growing green-winged orchids on a Swedish island and figured out why this species cheats insects so mercilessly. It’s about genetic variation. The flowers attract the bugs, but offer the foraging insects nothing, driving them on to explore other plants. Although the orchids have not provided food, they have given the unsuspecting insect a payload of a different kind: pollen. The bug—still on a quest for nectar—forages in other plants, pollinating as it goes along. Voila! No self-pollination. Plants that result from self-pollination are usually weak and unhealthy, and self-pollinating can be a waste of precious pollen.

Interviewing bees

Scientists detected this self-pollination avoidance by interviewing bees. They queried specific bees with plants that had been artificially dosed with nectar or with plants in their natural nectar-free state. The researchers found that bees stayed around the nectar-ful plants twice as long and investigated twice as many flowers on the same plant, which would promote self-pollination. Bees that found no nectar moved along to other plants, promoting cross-pollination.

One thing that could confound the interpretation of these results is that bees can remember how a plant smells. If a bee strikes out with one orchid, it will remember that orchid’s smell and not waste its time foraging around in other flowers that smell the same.

In separate research performed by a team in Switzerland, scientists found that the flowers of a nectar-producing orchid species all smell very much the same. But flowers on different plants of the green-winged orchid all smell different. A bee might have failure at one green-winged orchid and remember the smell, but then fly straight into another green-winged orchid plant because its smell is different. The unhappy bee falls into the orchid’s trap and gets nothing, but the deceitful orchid itself has had a great success: avoiding the trap of self-pollination.

%d bloggers like this: