The Amazing Gene-Stealing Clam

I just read this article titled "Crazy Sex Trick Fuels All-Male Clam Species" over at Wired:

Amidst the animal kingdom’s menagerie of sexual practices, those of Corbicula clams stand out.

A common freshwater genus about the size of a half-dollar, most Corbicula species reproduce by cloning. That’s odd, albeit not extraordinary. They’re also physically hermaphroditic but genetically male — again odd, but not extraordinary.


What’s really strange is that, once in a great while, they hijack fresh DNA from other clams.

“They can steal the eggs of other species,” said David Hillis, a University of Texas at Austin computational biologist whose Corbicula investigations are described May 23 in the Proceedings of the National Academy of Sciences. “Usually, the whole maternal genome is then kicked out. But sometimes they keep some of the genes, and incorporate them into their own genome.”


At a glimpse, Corbicula reproduction seems to be of the unexceptional, sperm-meets-egg-in-the-water marine variety. But in most cases, sperm and egg come from the same clam, which produces both. Then, after fertilization, egg genes are ejected from the embryo. Should currents happen to mix sperm and egg from different clams, the same happens. In either case the result is a clone descended from one original clam’s sperm.


Cloning’s great advantage is that it lets organisms quit worrying about finding the right mate, which is of course themselves, and channel all that time and energy elsewhere. Once considered an evolutionary aberration, cloning is now seen as a fairly common and successful reproductive strategy. But every self-cloning species is confronted by what Hillis calls the Xerox principle: with each round of copying, errors are introduced. Genomes become smudged and, over time, unreadable.


Cloners have evolved a variety of solutions to this problem. Some species of fungi, along with a fish called the Amazon molly, reproduce sexually just often enough to prevent their gene pools from drying. Certain all-female lizards can alternate between single and double-sexed–species status as needed, or rely on chromosome mix-up mechanisms that bootstrap them into genetic diversity. One class of animals can even absorb the DNA of its deceased (see sidebar). But how Corbicula stayed genetically vital was unknown.


In the new study, Hillis and colleagues scanned the genomes of 19 different Corbicula species from around the world, searching for patterns that could reveal the clams’ trick. They found odd spikes — groups of genes that belonged to one species, but inexplicably showed up in another.
According to Hillis and colleagues, the most plausible explanation involves rare fertilization events when sperm mets egg that doesn’t just come from another clam, but from another Corbicula species. Most of the time, development proceeds normally, with egg DNA jettisoned — but every so often, once in thousands or even millions of generations, some of the egg’s genes are allowed to stay. The clone’s lineage is replenished.


“This is the signature you’d expect to find to find from these genetic-capture events,” he said. “It’s exactly what we observe.”


Hillis is now curious as to whether there’s a relationship between this reproductive habit and Corbicula’s propensity for sudden population booms, which in some areas has made it a pipe-clogging pest. He’s also interested in whether all-male species, which seem to be a rarity among single-sex reproducers, are actually more common than thought.


In a recent Systematic Biology paper, Hillis described how the cells of various organisms, from other mollusks to oak trees, contain DNA traces from other related species. These are generally explained as the genetic remnants of past hybridization events, but to Hillis the patterns don’t look right. He suspects that androgenesis — the technical name for father-only reproduction — is responsible.


“There are all kinds of interesting questions now about asexual systems. A lot of them we don’t know much about, and biologists never even spent any time thinking about them,” said Hillis. “When it comes to sexual systems, almost anything you can imagine, and a lot of things we never imagined, happen somewhere in nature. ”

Monkeys See Selves In Mirror, Open a Barrel of Questions

If I had followed my original plans upon entering college in 2001, I probably would be some sort of microbiologist or geneticist right now, perhaps even some sort of post-Skinner behaviorist. Having chosen the route of philosophy and writing instead, I find myself most interested in the science involved with the brain, thoughts and consciousness on the one hand, and the composition of the universe on the other. The first hand that I mentioned has been experiencing a scientific hand full ever since I read the Wired article Monkeys See Selves In Mirror, Open a Barrel of Questions which raises the question of whether other animals are capable of mental acts we'd previously limited to human consciousness.

Monkeys may possess cognitive abilities once thought unique to humans, raising questions about the nature of animal awareness and our ability to measure it.

In the lab of University of Wisconsin neuroscientist Luis Populin, five rhesus macaques seem to recognize their own reflections in a mirror. Monkeys weren’t supposed to do this.

“We thought these subjects didn’t have this ability. The indications are that if you fail the mark test, you’re not self-aware. This opens up a whole field of possibilities,” Populin said.

Populin doesn’t usually study monkey self-awareness. The macaques described in this study, published Sept. 29 in Public Library of Science One, were originally part of his work on attention deficit disorder. But during that experiment, study co-author Abigail Rajala noticed the monkeys using mirrors to study themselves.

So-called mirror self-recognition is thought to indicate self-awareness, which is required to understand selfhood in others, and ultimately to be empathic. Researchers measure this with the “mark test.” They paint or ink a mark on unconscious animals, then see if they use mirrors to discover the marks.

It was once thought that only humans could pass the mark test. Then chimpanzees did, followed by dolphins and elephants. These successes challenged the notions that humans were alone on one side of a cognitive divide. Many researchers think the notion of a divide is itself mistaken. Instead, they propose a gradual spectrum of cognitive powers, a spectrum crudely measured by mirrors.

Indeed, macaques — including those in Populin’s study — have repeatedly failed the mark test. But after Rajala called attention to their strange behaviors, the researchers paid closer attention. The highly social monkeys only rarely tried to interact with the reflections. They used mirrors to study otherwise-hidden parts of their bodies, such as their genitals and the implants in their heads. Mark tests not withstanding, they seemed quite self-aware.

“I think that these findings show that self-awareness is not an all-or-nothing phenomenon,” said Lori Marino, an Emory University evolutionary neurobiologist who was not involved in the study. “There may be much more of a continuum in self-awareness than we thought before."

According to Emory University primatologist Frans de Waal, the new findings fit with his work on capuchin monkeys who don’t quite recognize themselves in mirrors, but don’t treat the reflections as belonging to strangers. “As a result, we proposed a gradual scale of self awareness. The piece of intriguing information presented here may support this view,” he said.

However, de Waal cautioned that “many scientists would want more tests and more controls” — a warning especially salient in light of a high-profile controversy involving Marc Hauser, a Harvard University evolutionary biologist who appears to have overstated the cognitive powers of his own monkeys.

“What you’re seeing in the videos is subject to all kinds of interpretations,” said Gordon Gallup, a State University of New York at Albany psychologist who invented the mirror test, and has administered it with negative results to rhesus monkeys. “I don’t think these findings in any way demonstrate that rhesus monkeys are capable of recognizing themselves in mirrors.”

Populin said his monkeys may have developed an unusual familiarity with mirrors, which are given to them as toys during infancy. The presence of saltshaker-sized implants screwed into their skulls may also have captured their interest more readily than an inked mark.

Marino, who helped demonstrate self-recognition in bottlenose dolphins, disagreed with Gallup. “The videos are absolutely convincing,” she said. “I have been trying to find an alternative explanation for the results – and haven’t come up with one yet.”

Marino said the findings fit with other research on monkey cognition, including a since-replicated Journal of Experimental Psychology study in which macaques displayed unexpectedly sophisticated math skills and passed other, non-mirror-based tests of self-awareness.

“There are many ways to look at animals. Mirror tests are not the end-all and be-all,” said Diana Reiss, a mammal cognition specialist at the City University of New York.

If research continues to find that monkeys possess higher-than-expected awareness, it could influence how researchers and the public think about biomedical research on monkeys. Macaques were critical in the development of a polio vaccine during the 20th century and, more recently, the refinement of embryonic stem cell techniques.

“I would absolutely hope that we do not stop using them now. Their contributions have been immense,” said Populin, who studies how ritalin affects the brain’s prefrontal cortex.

“There are decisions I would make with a monkey, that I would not feel comfortable making with a chimpanzee,” said University of Wisconsin psychologist Chris Coe, who was not involved in the study. “Some of the other cognitive abilities that monkeys would have to show, I don’t believe they do. I don’t believe they sit and ponder their fate, or reflect on the past, or fret about the future, because they are able to see themselves in a mirror,” he said.

“We don’t know whether they have a sense of past or future,” said Marino, who called Coe’s research distinction an ethical non-sequitur. “Whether an animal has a sense of the past or future is irrelevant to the issue of whether they can suffer in the present.”

Even if Coe accepts human-benefiting research involving contagious diseases or invasive procedures in monkeys that he wouldn’t in chimps, however, he said the findings underscore the importance of improving research animal conditions. The macaques’ unexpected self-awareness certainly influences the equations by which society must continually balance the harms and benefits of research.

“A study such as this one, that pushes our own awareness of what monkeys can and can’t do, challenges us,” Coe said. “I’m not going to argue that having animals live in small cages is so wonderful. One has to reflect on that.”

A more accurate understanding of animal awareness may ultimately require better tools. Many researchers are skeptical of the mirror test, which Marino said “is shaped more by the cognitive limitations of human researchers than anything else.”

Wrote Marino in an e-mail, “Other animals may be more deeply contemplative than humans – we just don’t know.  That’s really the bottom line. Any scientist who tells you they know that other animals don’t think as richly or as complexly as humans — is, well, not being scientific.”

Office for Outer Space Affairs

If you've been watching the news, you'll find that it's getting harder and harder to deny the possibility of extraterrestrial life. The first time I was really astounded by the new wave of interest in aliens was when my friend Emily reported that she was watching reports of UFOs on FOX NEWS. The fair and balanced network (devoted to reporting on all sides of the anti-Obama propaganda) took time away from smearing democrats and setting up straw enemies (Have you ever seen Glenn Beck? Now, have you ever heard Glenn Beck use anything remotely resembling logic?) to report on mass UFO sightings. I haven't seen anything like it in years.

Many residents of Tucson, Arizona reported some strange UFOs in their vicinity in late September (Tucson UFO Sighting: Event witnessed by many remains a mystery). Only one video surfaced (Tucson UFO sighting: UFO enthusiast captures object on video), but massive audiences reported objects in the sky that they could not explain. I'm sure you've also heard the news of mass UFO reports in China (UFOs frequently appear over Taiyuan, Shanxi). It's getting harder and harder to deny the existence of extraterrestrial life now that the evidence is not just coming from oddball ufologists like Dan Aykroyd; the evidence is coming from the population, educated and uneducated alike, of entire cities and provinces.

If I'm not asking you to read the Wired article about the new Cowboys Stadium (Cowboy Upgrade: Welcome to the NFL's Next Flagship Arena) then I'm asking you to read the Wired article about Gleise 581g, the first habitable planet we've been able to find outside of our solar system (A Habitable Exoplanet - for Real This Time). Add to this the fact that scientists have been dealing with a strange laser-like signal from the general vicinity of Gleise 581g for two years (Strange Signal Comes From Alien Planet, Scientist Says), long before Gleise 581g was reported to be capable of sustaining life, and you're dealing with another significant piece of data regarding extraterrestrial life.

A decent amount of the public and some scientists here and there seem convinced that extraterrestrial life is possible, but does that mean that there's any significant reason for anyone else to believe? Perhaps not. But there are certainly some people in very high places who believe that we need to be ready for the possibility that reports we could encounter alien intelligence within my lifetime. About the same time as the massive alien sightings and the discovery of a habitable exoplanet, the UN appointed Malaysian astrophysicist Mazlan Othman as the head of the UN's Office for Outer Space Affairs (Alien diplomacy: The UN's secretive alien ambassador). Before I read this article, I was going to jokingly title this blog "Office of Alien Affairs," only to find that the actual office has a much better early-20th-century science fiction vibe to it. This means that the people who represent all humanity on our planet (well, most) have decided that despite worldwide economic turmoil it is necessary to pay for a group of people to deal with possible extraterrestrial encounters.

What does this mean? Is the UN privy to secret information on the existence of extraterrestrial life? Is the scientific community putting together the pieces? Is this all a massive conspiracy of viral marketing for the upcoming film Skyline? I don't have enough evidence to know one way or another. I can conclude that it's a great time to look to the skies, that America needs a kick start to its collective imagination after all of the economic troubles we've faced. And what better impetus than evidence that the things we imagine may really exist

Cowboy Upgrade: Welcome to the NFL's Next Flagship Arena

Recently, I had the great pleasure of watching the Dallas Cowboys play the Chicago Bears at Cowboy Stadium in Arlington, Texas, the largest domed structure in the world. As excited as I was to witness my first live NFL game, I was much more excited at the technological wonder that is Cowboy Stadium. Many people responded to my exciting journey with words of, "Screw the Cowboys," or "Screw the Bears," and quite often a mixture of the two. My response was that this building is to the modern world what architectural wonders like the Colosseum were to the ancient world. It is equipped with HD screens so large (in fact, the largest in the world) that practical rulings had to be decided ahead of time for the event that someone hits the screen during a kick-off or punt. I've taken art classes where it is suggested that if you do not understand the wonder of architecture, you have no way of understanding the wonder of divinity. Let's just say that I'm a wee bit closer to divinity today, having experienced Cowboy Stadium firsthand.

I wrote this blog post because I have kept repeating the following phrase time and time again in reference to this Sunday well-spent: "Have you read the Wired article about Cowboys Stadium?" The article is titled "Cowboys Upgrade: Welcome to the NFL's Next Flagship Arena," and it is available on-line at Wired. Read this article here, and try to tell me that you're not amazed at the existence of this building.