Robots are great at what they do — if the job is dull and predictable. Throw in the unexpected, and robots can do the unpredictable.

The task of programming a robot’s brain for the real world can be gnarly, says Josh Bongard, an assistant professor in the University of Vermont College of Engineering and Mathematical Sciences. “It turns out that building a robot, and programming it to do something interesting is a very non-intuitive process, and it’s a difficult one for humans to do well.”

The real world, he says, “is quite messy.”

Robots, in the jargon, need “adaptive behavior” to accommodate changing circumstances, says Bongard. When programming a free-roaming robot, “We are not likely to factor in a lighting change or people moving in and out of the field of view.”

It’s not clear how animals or people make adaptations, Bongard says, “and so it’s difficult to program a robot to do them.”

Robots: Are they alive?

Bongard, like a number of roboticists, is turning to biology for answers. But he does not want to emulate living structures. Instead, he wants to use evolution to craft robot control.

The process is akin to the “artificial selection” that helped lay the foundation for the science of evolution. Darwin, after all, wrote about how animal breeders had changed their livestock by repeatedly breeding the best animals and eating the rest.

In January, 2011, Bongard reported that he had taught four-legged, digital robots to stand and run toward a light source, by grading their control software on its ability to meet those goals.

Adaptive behavior was necessary, he says, because the light source could appear anywhere, or even take evasive action, “so the robot can’t just move its legs blindly every time.”

The robots had five seconds to do or die, and their first movements were grotesque because the control software initially moved their body parts at random. After every attempt, the control programs were graded by their ability to walk, stay upright and approach the light.

It’s brutal. More than 100 million failed programs went to the virtual graveyard in the name of science, Bongard says. The programs that showed some promise were retained, randomly varied and re-tested.

The same process is found in nature, where successful genes that face random mutation are re-tested by tomorrow’s environment.

Like the average biological mutation, the mutated robot software usually failed. But over a year of supercomputer time — equivalent to 1,000 years on a desktop computer — the winning programs evolved the ability to walk toward the light.

Weird winners

Considering the amount of trial and error, that was a satisfying but not necessarily surprising result. But here’s something to chew on. Bongard found that robots “born” with four legs had a handicap. During repeated simulations, the robots that started as snakes and developed legs during the five-second experiment were much quicker to learn the task.

You might guess — we would have — that the quick learning would have occurred in robots with full-time four-leg drive, given their longer experience with legged locomotion, but Bongard says the leg-free starters benefited by chunking the challenge: a) learn to approach the light, and b) learn to walk.

These robots “could evolve the ability to go from point A to point B while they still look like a snake, they don’t have to worry about balance, because they are already on the ground,” Bongard says. “Once evolution has figured out how to move toward the light, the ability to move on four legs could evolve.”

Meanwhile, the four-legged counterparts may still be flipping, flopping and floundering (Note to self: sell soul as political hit-man if science-writing gig crash-burns?) “The robots that had to stand upright would fall over, and it took evolution a long time to master balance,” Bongard says.

The approach — take the winners and vary them for a retest — resembles directed chemical evolution, which aims to create a better antibiotic by modifying and retesting molecules that show some ability to kill bacteria. “It’s basically the same idea,” says Bongard, “but instead of a candidate drug, we have virtual robots, and instead of selecting for … resistance to disease, they are selected for the ability to get to the light.”

Robots resemble rodents?

As a final exam for the digital robots, Bongard tested their balance with a blast of air. Although the leg-less robots “had evolved into legged robots that looked exactly like the other species, they were better able to run around under simulated windy conditions,” Bongard reports.

Bongard is first to acknowledge that he is “stealing from biology to help us build better robots,” but says, “the more interesting question is what this tells us about biological evolution. This recent work suggests that robots that change their bodies gain an adaptive advantage … and you see the same radical changes in body plan in nature: in insects, reptiles and in humans as they develop from infant to adult.”

Astronomers have just discovered two Earth-size, rocky planets around a nearby star. Though the planets are way too broilsome for life, they suggest that steady improvements in telescope technology has made the discovery of habitable planets just a matter of time.

But as astrobiologists continue to search for life in space, geo-biologists (ok, we coined that) continue to find bizarre life in strange places on Earth: in the dark ocean depths, between grains of sand, and at roasty-toasty temperatures once considered deadly.

Hot, humid, and totally alive!

Fifty years ago, nobody believed organisms could survive near the boiling point of water. When Thomas Brock started probing the hot springs in Yellowstone in the 1960s, he was not looking to overthrow a ground rule of biology. Instead, the University of Wisconsin-Madison professor, then at Indiana University, sought to study bacteria in a simplified, real-world environment.

At the time, and even today, precious little was known about how bacteria live their lives — unless they cause disease.

As Brock sampled his way up a hot stream, he approached its source in a hot spring, and the water temperature rose steadily.

At the time, biologists thought life would not tolerate temperatures near 80° C. But Brock kept finding bacteria, so he kept looking. Eventually, he found some that could live and reproduce near the temperature of boiling water — 100° C.

The prize of his collection was a bacterium he named Thermus aquaticus (for its hot-water habitat) and placed in a public repository for study by other scientists.

Over the years, T. aquaticus proved interesting indeed. For one thing, it was the first of more than 50 species of thermophilic bacteria known to tolerate or require temperatures near water’s boiling point.

For another, it was the first of the Archaea (ancient ones), primitive microorganisms that scientists now regard as a separate and highly primitive kingdom of life.

Deep roots indeed

Because thermophiles are Archaeans, and prefer the steamy conditions typical of early Earth, many scientists think they may tell us about the origin of life itself.

To any basic scientist, those contributions would be enough. But because their enzymes work in high temperatures, where chemical reactions are faster, the thermophiles have proven to be extraordinarily useful.

Today, enzymes derived from thermophiles are used to convert millions of pounds of corn (maize) into sugar to sweeten soft drinks.

But more important, at least to scientists who don’t guzzle fizzy pop at the lab bench, T. aquaticus supplied TAQ polymerase, the essential enzyme for polymerase chain reaction, AKA PCR.

PCR is an artificial technique that does what living critters do every day — replicate DNA. But PCR is the rocket ship of replication, since it allows you to multiply a piece of DNA a billion times in a few hours. That produces enough DNA to analyze to your heart’s content — for genetic engineering, biotechnology and forensic purposes.

PCR depends on TAQ polymerase.

Aware that PCR and soda pop are both billion-dollar industries, corporations and scientists around the world have frantically searched for other thermophiles that may have equally useful enzymes. They’re looking in odd places — not just hot springs and volcanoes, but also deep-sea vents, hot petroleum-bearing rock, the outflow of geothermal power plants, and smoldering piles of garbage.

Prowling for glow-in-the-dark squid

Call me Bob.

Short for bobtail squid. (Did I mention that I’m a 3-4 centimeter cephalopod, formally Euprymna Scolopes?)

Anyway, I hang out in shallow waters around Hawaii. Save your crocodile tears — somebody’s got to live in the sunny, tropical ocean. Anyway, here’s my problem: Even though I have 10 tentacles, I don’t have spines, poisons, or any other decent defense.

So I spend my days burrowed in sand at the ocean bottom, trying to keep out of mischief. Still, a fellow’s got to eat, don’tcha know, so I cruise at night, looking to grab a bite.

Here’s the snag: All sorts of nocturnal predators seem to have this thing about calamari sushi.

Light before flashlights

A long time ago, my ancestors evolved a nifty defense against their big teeth: stealth. Even their tiny squid brains figured out that predators could see them from below, as tasty dark blobs against the bright ocean surface.

Since this was before flashlights, my relatives had to improvise. So they press-ganged billions of luminescent bacteria into making light for them. The idea was to make us just as bright as the ocean surface — and hence invisible.

At least, this is how my great-aunt Tentacla tells it. To tell the truth, I think it had more to do with the evolutionary advantage of being hard to see.

Anyway, my ancestors fed the bacteria, and gave them a home in two specialized light-emitting organs. These “photophores” have a reflective membrane to shine all their light down, toward the hungry predators. They use a diaphragm to control brightness, and even have a lens to spread the light.

The photophore reminds me of a backwards eye — one that makes light rather than detects it.

My folks even figured out how to switch the bacteria “on” when needed.

In return, the bacteria got room and board, in the biological deal they call “symbiosis” or “mutualism.” Sometimes I think people could learn from this cooperative spirit….

But that’s enough thinking for today. My squid brain is squashed.

As I burrow into the sand for another daytime nap, permit me to introduce somebody who considers me almost as fascinating as I do.

Seriously speaking…

Margaret McFall-Ngai, a biologist at University of Wisconsin-Madison, says the bobtail squid may pretend it’s cooperating in a symbiosis with those light-making bacteria, but the reality is more ominous.

She says there’s evidence that this may be slavery, not symbiosis, since the squid, “inhibits the growth of the bacteria to enhance their luminescence.” The bacteria, Vibrio fischeri, could make a better living drifting in the ocean, or in the gut of another marine animal, McFall-Ngai observes.

The concept of bacterial enslavement broadens our perspective on the many possible relationships in the living world.

Most people, if they think about bacteria at all, conjure up disease and decay, but people would be dead without bacteria, since the little critters play essential roles in producing vitamins and preventing disease.

Since the bacteria in our guts vastly outnumber the cells in our bodies, it helps that they’re helpful!

Nevertheless, and for understandable reasons, bacteriologists have traditionally focused on disease-causing organisms, and, for simplicity, on one species at a time. But that skews our view of how bacteria actually live, says McFall-Ngai.

Three cheers for complexity!

Complexity and subtlety may be the hallmarks of these interactions, and the complexity begins by recognizing that V. fischeri is closely related to V. cholerae, which causes the human intestinal disease, cholera.

Cholera is caused by a V. cholera toxin similar to a toxin produced by the light-emitting bacterium. But far from harming the poor little bobtail, that toxin signals it to secrete food for V. fischeri, so the toxin is really a chemical “dinner bell.”

And this raises the intriguing notion that a cholera bug secretes toxins not to kill its host but to discuss its menu. If so, our whole notion of pathogenesis may need rewriting, McFall-Ngai suggests. “Maybe when we’ve been studying cholera pathogenesis we’ve been studying an aspect of a normal conversation that’s gone wrong.”

Indeed, the traditional bacteriological view of bacteria as pathogens to be studied in pure culture may be “like trying to understand the complexity of all the cultures that lived in Paris by studying the activity of the Nazi occupiers,” McFall-Ngai suggests. “You are studying groups that don’t belong there, and have disrupted the normal activities.”

Want more on how the flashlight squid bullies its bacterial brethren?

Between the grains

(1996 story, only photos have been updated)

To zoologist Robert Higgins, small is beautiful. His infatuation with small creatures — “meiofauna” — dates to a student job in a biology lab that paid 35 cents an hour. Instead of quitting for more lucrative work, Higgins was intrigued.

He’d heard about tiny, amazingly diverse creatures, and put grains of sand and muck through a fine mesh, and used a microscope to find hundreds of organisms.

Forty-four years later, Higgins has retired from the Smithsonian Institution, but he’s still goggling at meiofauna — a complex group of animals found in most Earthly environments.

Indeed, a handful of wet sand could contain more biological diversity than a whole rain forest, Higgins says.

In the course of peering through countless microscopes, Higgins has discovered hundreds of species. With Danish biologist Reinhardt Kristensen, he found an entire phylum, called Loricifera.

Phyla are the broadest categories of organisms, based on structure, and according to the International Association of Meiobenthologists, “The majority of recognized phyla have meiofaunal representatives. Currently, 20 phyla considered to be meiofaunal from the 34 recognized phyla of the Kingdom Animalia. Out of these 20 phyla, five are exclusively meiofaunal in size.”

Photo: Giulio Melone, department of biology, Milan University.

A bdelloid (a type of meiofauna) shrinks when it undergoes anhydrobiosis. The dormant, dehydrated bdelloid has greater resistance to environmental stress but is ready to spring back to the active form in conducive conditions.

Meiofauna living between grains of sand have made some fancy adaptations to their harsh environment. Some have hooks on their feet, used to grab the sand. Others have hooked mouthparts, also useful for locomotion.

Beyond freeze-dried

To survive a difficult environment, meiofauna called tartigrades have evolved an amazing adaptation called “anhydrobiosis.” In this form of suspended animation, the animals replace water in their cell membranes with sugar, protecting the membrane from destruction through radiation and freezing. Microorganisms die when their cell membrane ruptures.

During anhydrobiosis, organisms are rather like plant seeds or bacterial spores, Higgins explains. “They can dry up for 100 years, and be rewetted, and come right back to active metabolism.”

Fun is fun. But what is the practical importance of studying stuff that can hardly be seen, doesn’t seem to cause disease, and is — at least to some — utterly ugly?

In other word, who cares about microscopic beach crud?

Meet the beach-cleaning crew

Anybody who likes to hang on the sand should be interested, Higgins says. “This is the system that helps keep our beaches clean.” Plankton, bacteria, all sorts of dead material is continually washing ashore, and a lot of people love to sit on beaches.

There’s a public-health angle here. Hookworms occur on beaches where dogs defecate, but meiofauna may consume hookworms, along with other nematodes. “So if we upset that, we could upset beach cleanliness,” Higgins says.

Higgins notes that meiofauna comprise a basic part of the food web, and disturbing them could have unforeseen consequences for the entire system.

Still, it’s hard to escape the notion that most of the motivation here is the pure scientific urge to discover, to classify, to understand. Meiofauna, Higgins notes, were seen under the microscope Anton van Leeuwenhoek invented in 1683.

The key to finding these things, Higgins indicates, in patience, technology, curiosity — and institutional support. “If you stare through a microscope for hour after hour, you have a chance of finding these things, but if you need to get out a certain number of papers each year, you have to take shortcuts and you won’t find as much.”

Fantastic freak show

If you drop a worker ant from an Amazonian treetop, what happens? In the species Cephalotes atratus, 87 percent of the time, that ant will wind up back where it started — a few meters lower down the same tree. Drop things that drift down at random, and only 5 percent of them will hit the tree.

In other words, these ants are controlling their flight — even though they don’t have wings.

That finding, which Stephen Yanoviak, Robert Dudley and Michael Kaspari¹ reported in 2005, provides a great starting point for untangling one of the mysteries of biology:

When and how did so animals take to the air?

Fly high

Flight is pretty common — among critters with wings, or something that resembles them, like a stretched membrane of skin. Birds, bats, moths and butterflies can fly. Even some lizards, snakes, fish and squirrels can glide under control toward the ground, which is not the same thing as falling.

Studies of ants in South America provide good data on “controlled aerial descent,” says Dudley, a professor of integrative biology at the University of California at Berkeley. In the course of some rather entertaining research, he and his colleagues have found that Cephalotes atratus ants:

During the controlled descent, at speeds above 4 meters per second, the ants perform “rapid postural adjustments,” Dudley says. “The limbs are moving, it’s not like a paper airplane.”

Dudley, an expert in the biomechanics of flight, says hundreds of species of tree-living ants in tropical Amazonian forests have evolved controlled gliding. Dropping to the forest floor can make them a meal for a mean and hungry ground-dwelling ant.

Looking at evolution

Perhaps the coolest part of the story is its evolutionary angle. Previously, scientists intrigued by the origin of flight have looked for evidence of wings and feathers, which appear more than 100 million years back in the fossil record.

But if flight really originated in arthropods that could not survive a fall from a tree or a cliff, that could wind the evolutionary clock back a good deal further. (Arthropods are animals with external skeletons and jointed legs, including spiders, insects and crustaceans like the horseshoe crab.)

Gliding under control is neither rare nor constrained to ants, Dudley says. “There are wingless aphids and flat spiders that live under the bark that can glide at a 45° angle. Controlled aerial descent has hundreds or thousands of independent origins in terrestrial arthropods.”

As old as the hills?

Over all, Dudley says, directed descent probably originated about 280 million years. If jumping like a flea or grasshopper is also deemed a form of flight, the origin could date back more than 400 million years.

The gliding hypothesis would not only help explain the origin of a common and cool behavior, but could take wind out of the sails for a favorite anti-evolutionary argument. Creationists, Dudley notes, have long demanded to know how wings evolved by asking, “What good is half a wing?” But according to the gliding hypothesis, wings unable to hold an animal airborne could still have evolved to help control a descending behavior that had long been in existence.

Flight of the control freaks?

Controlled gliding, Dudley says, “preceded the origin of wings, and so the evolution of flight is more about control than about the formation of wings.”

The new analysis “addresses qualms about the [supposed] lack of intermediate forms in the fossil record,” Dudley says. “Here is a viable intermediate form. There are lots of behavioral and ecological contexts where stubby, partial airfoils are useful.”

– David J. Tenenbaum

Poke deep inside an insect cell, and you may be in for a shock. At least we were startled to learn that bacteria live inside many insects, including the fruit fly, one of the workhorses of biology.

Photo: Biodiversity Institute of Ontario

The star of the study, Drosophila mauritiana.

Today, we hear how bacteria of the genus Wolbachia boost egg production in certain fruit flies. The mechanism, says Horacio Frydman, an assistant professor of biology at Boston University, involves a two-step: first the fly makes more egg cells, and then it blocks a process that would normally prune away extra eggs.

Insects, like other animals, are frequently “married” to bacteria in a relationship that benefits one or both parties. This is common: Bacteria in the cow’s rumen break down cellulose eaten by the cow. Bacteria in the human gut form vitamin K, necessary for blood clotting.

And bacteria in aphids synthesize essential amino acids that the aphids cannot make by themselves.
Wolbachia are not essential to the fruit flies, but their presence can quadruple egg production.

Speeding breeding

Producing four times as many offspring “is a powerful driver of infection,” Frydman says. “Wolbachia manipulate their host reproduction to favor their own spread in nature,” noting that in less than 20 years after Wolbachia was detected in fruit flies in southern California, the infection had spread as far as Canada. “It’s considered one of the largest pandemics in the recent evolution of life. Because Wolbachia influence their host reproduction, they also impact the evolutionary history of innumerable hosts.”

Wolbachia have been linked with a wide variety of effects in the insect realm. Wolbachia “lives in at least 20 percent of the world’s arthropods, including insects, spiders, mites, and crustaceans,” according to the Wolbachia project, making them an active area of investigation.

How could this symbiosis work to increase the number of offspring?

Using sophisticated microscopy, Frydman, Ph.D. student Eva Fast and colleagues tracked the location of Wolbachia in fruit flies. In D. mauritiana, a species native to the Mauritius Islands in the Indian Ocean, the bacteria congregate in the germline stem cell niche — a structure that supports stem cells that develop into eggs. In D. melanogaster, the bacteria accumulate in the niche that harbors a different type of stem cell, which produces the eggshell.

In the germline stem cell niche, the bacteria actually outnumber mitochondria, organelles involved in making energy for the fly.

Having the bacteria in the germline stem cell niche doubled the rate of division among those stem cells. Further investigation showed that the bacteria later also halved the rate of programmed cell death.
So the bottom line was a four-fold increase in egg production.

The virtue of pruning

“It’s remarkable that there are two mechanisms being manipulated by the bacteria, the rate of egg production and the rate of programmed cell death,” says Frydman.

Hitting both systems makes sense, Frydman adds, although the mechanisms remain unclear. “It is not surprising that Wolbachia would evolve to manipulate those two process, because they are key in controlling the rate of egg production, and therefore it has a profound impact in the reproductive success of the infected host and in spreading of bacteria in nature.”

Anything that increases the number of eggs and offspring is likely to be favored by natural selection, Frydman adds.

Photo: CDC, #373

Parasitic worms cause elephantiasis, which afflicts this man from the Philippines. Could killing Wolbachia prevent this disfiguring disease?

A healthy thing?

Beyond an insight into the fascinating biology of symbiosis, the finding could also have health implications. Parasitic worms that cause diseases like elephantiasis seem to benefit from Wolbachia infection.

And Wolbachia can affect insect immunity: Tests have shown that infected fruit flies are more resistant to some viruses, for example. And a recent paper in Nature found that mosquitoes in Australia could not transmit dengue fever if they carried a Wolbachia strain derived from Drosophila.

Mosquitoes also transmit malaria. Conceivably, better knowledge of the interaction between Wolbachia and insects might convert mosquitoes from a carrier of this ancient scourge into a defense against it.

– David J. Tenenbaum

If you think slavery has been abolished, consider the case of the gypsy moth and the virus. For more than 100 years, people have noticed that some gypsy moth caterpillars climb to the top of trees before they die and decompose, or “melt.”

Melting releases more virus particles and is the normal fate of these caterpillars, but why did only some caterpillars perform this ascending death march?

Gypsy moths are voracious insects that have been spreading across the United States for a more than a century, so nobody is feeling too sorry for them, especially people who have seen them strip forests bare.

Still, it’s nice to read a good explanation for this peculiar “climb, croak, melt” behavior.

All the better to infect you with, my dear!

A study published today identifies a viral gene that blocks one stage of maturation in gypsy moth caterpillars, which normally hide during the day. But when Kelli Hoover, a professor of entomology at Penn State, and her colleagues infected bottled caterpillars with the virus of doom, the caterpillars showed the same climbing ‘n’ dying behavior that appears in the field.

In nature, those caterpillars would melt and then rain virus down to infect other gypsy moths.

The moth misbegotten

Gypsy moths were introduced to Massachusetts in the late 1800s by a bumbler who wanted to raise silk by crossbreeding them with silkworms — a different species, says Hoover. “It was crazy; this guy did not know anything about species, apparently.”

Still, the gypsy moths did bring fecundity and a ferocious appetite to the table — or forest. “They eat so many different kinds of trees and plants … in a bad outbreak, the insect frass dropping down sounds like rain, so you need a hat,” Hoover says.

We had to look it up to be sure, but frass is basically insect poop.

Gypsy moths are such effective defoliators that authorities try to control them with Bt, a bacterial spray that unfortunately kills beneficial insects, not just harmful ones.

Hoover’s study focused on a viral gene called egt, which inactivates a hormone that starts molting – a process that ends each stage, or “instar,” of the caterpillar’s development. “When they stop molting, they keep feeding, and that’s why we looked at egt,” Hoover says.

Photo: USDA APHIS Pest Survey Detection and Exclusion Laboratory

The battle against gypsy moths was joined before 1900, when an unknown chemical was sprayed against the invader.

ENLARGE

A dangerous meal

In every case, Hoover says, “if the gene was active, the moth died at the top of the bottle. If the gene was inactivated, it died at the bottom.”

It’s not clear, Hoover says, exactly why the gene changes behavior, but this is the first time it was traced to a single gene.

Because LdMNPV (the Lymantria dispar nucleopolyhedrovirus) infects only gypsy moths, and kill them at a young age, it might work as a biocontrol agent against a disastrous insect invasion. However, Hoover says, “the experiment’s goal was more basic – to understand how the virus enslaves its host.”

Certainly there is evolutionary logic behind changing your host’s behavior for your own benefit, assuming you are a pathogen or parasite, and “body-snatching” is well-known. For example, a fungus forces ants to climb, zombie-like, and die where they can easily spread fungal spores.

And it’s not just insects. The rabies virus, Hoover adds, “causes dogs, raccoons and bats to become more aggressive, to be out during the day, where they approach people and try to bite them,” which spreads the virus even though it endangers the animal.

And toxoplasmosis, a parasite, can make mice less fearful of cats, Hoover says, “so they are more likely to get eaten and infect the cat.”

There is even speculation that toxoplasmosis may cause men to behave with greater jealousy, Hoover says, “but the only thing that’s really been looked at is that mice with toxoplasmosis have a higher level of dopamine,” a feel-good neurotransmitter.

Is slavery therefore not all drudgery?

— David J. Tenenbaum

No duh.

Year after year, the greeting card and flower industries goad us to honor our mothers, and we Whyfilers are glad to comply. This year, we celebrate by exploring what we learned about mothers at the February, 2011, meeting of the American Association for the Advancement of Science — the AAAS.

It may sound obvious, but understanding mothering helps us understand our world!

In early life, your mother is likely to be your most important person, emotionally, cognitively and behaviorally.
Photo: Din Jimenez

Mothers make us better people (Duh?)

More than 50 years ago, when University of Wisconsin psychologist Harry Harlow separated infant monkeys from their mothers, they grew up anxious, jittery, emotional wrecks. It’s amazing to think somebody needed to prove the value of mother’s love, but during Harlow’s time, behaviorism — a psychology rooted in the study of rats — was ascendant.

Academic psychologists focused on stimulus and response, not on the intricacies of the heart.

Today, Harlow’s findings seem like simple common sense, but they made him a rock star to the public — and eventually to his academic colleagues.

Stephen Suomi, one of Harlow’s last graduate students, has continued this line of research at the National Institute of Child Health and Development, again using rhesus macaque monkeys to model human behavior.

Genes don’t equate with destiny.

Back in Harlow’s day, genes were seen as destiny. Now, scientists like Suomi are finding a more interesting and flexible interaction among genes, environment, behavior, hormones and brain structure.

Suomi says that like people, “Between 5 and 10 percent of macaques are unusually impulsive; they do stupid things that most monkeys would not try. They will confront a dominant monkey. Most monkeys know how to back off, but when these monkeys are in an aggressive encounter, somebody can get hurt.”

Similarly, by age 2, some children “are identified as highly aggressive and likely to stay highly aggressive as they grow up,” Suomi says. “At school, they cause classroom disruptions. By their teens, many can be found in prison or the morgue.” In both monkeys and people, “these features show up very early and are remarkably stable.”

Aggression shows up early in some people, often leading to time behind bars.
Photo: Washington State Legislature

Stay close, my baby

Psychologically and physically, the infant monkey is reliant on its mother. Infant macaques “are almost always in physical contact or within arm’s length of their mother,” says Suomi, “which forms a strong, enduring attachment bond that is the functional equivalent of the one that human infants form with a caregiver.”

After a couple of months, that bond is established and the infant starts to explore, using mother as a “secure base,” Suomi says. “If they lose access to her, any motivation to explore will disappear; they get unhappy.” As these developing monkeys spend hours playing with peers, “every behavior pattern for normal functioning is established.”

Harlow raised infant monkeys with inanimate replacements for the mother and saw a range of deranged behavior. These days, Suomi removes young monkeys from mother and raises them with other youngsters. These “peer-reared” monkeys (are you thinking Lord of the Flies?) — develop what Suomi calls “hyper attachments. They spend excessive amounts of time clinging to each other when they should be exploring their world.”

Under these circumstances, play never reaches the normal “intensity and complexity,” Suomi adds.

Peer-reared monkeys spend more time clinging to one another than being Curious Georges.
Photo: Noneotuho

I’m afraid. Why aren’t you?

To understand why this is of more than theoretical interest, we need to meet serotonin, a key chemical for communication among neurons. Some variants of the serotonin genes are linked to high rates of suicide, depression and incarceration, and serotonin metabolism is affected by Prozac and other drugs.

In behavior, Suomi says, the peer-reared monkeys resemble the 5 to 10 percent of normal monkeys that are naturally fearful, anxious and aggressive. Both groups have a defective use of serotonin, but in the peer-reared monkeys, “this is not a product of genetics, it’s a product of social experience.”

Certain variants of the serotonin gene — and also certain experiences — are associated with increased desire for alcohol, Suomi says. When adolescent monkeys attend “the monkey version of a happy hour, some consume more than others, and the peer-reared ones consume considerably more.”

Early experience, in fact, affects the activity of one-fifth of monkey’s entire genome, Suomi says.

Suomi’s studies also show that drinking behavior is crucially dependent on upbringing: a good “childhood” can cancel out the effects of “negative” genes. “If the monkey has a good mother, it doesn’t make a damn bit of difference. It does not matter which alleles [variants] are present; you have normal serotonin metabolism. A good mother protects those who carry this allele, and it’s the same story in aggression, the same story with alcohol. With a good mother, you drink less.”¹

Why does momma matter?

The role of genetics has been a highly controversial area in development. A century ago, genes were destiny: people were essentially robots acting out immutable genetic instructions.

Then the focus shifted to external factors, and autism, for example, was blamed on a “cold” mother. Within a few decades, the advances in analyzing the structure of genes returned genetic determinism to vogue, and researchers began to search, for example, for an autism gene.

That approach quickly faded, W. Thomas Boyce of the University of British Columbia told the AAAS, in favor of a more sophisticated “behavioral genetics” focused on gene-environment interactions.

Genetics is getting more complicated, less deterministic, and more interesting. In the new genetics, mommas matter, even after birth!
Photo: Jen Watson

Now, in recognition that chemicals that are modified by experience affect the activity of genes, that picture is being enlarged in a discipline called epigenetics. In this new view, genes affect our environment, and environment affects whether and how genes act.

“The old metaphor of the genome being a blueprint for constructing the developing brain is faulty in certain ways,” says Boyce. “It may be more accurate to say that we begin with a blueprint, and partly build the house, then the family moves in and the blueprint gets modified. There is a feedback that alters the expression of the blueprint, based on the experience of the individual living in the house.”

The long shadow of poverty

How does this play out in the real world? Unstable and unmarried families tend to be poor, and social class correlates with higher rates of asthma, disease and injuries, says Boyce. At birth, physicians routinely record measures like weight and gestational age as a rough gauge of health, but Boyce thinks they ought to add social factors to the mix.

In fact, a study² that tracked health and education in 4,667 infants born in Winnipeg, Canada, for 19 years showed that the traditional biological measurements were less predictive than social factors related to health and education.

Growing up economically poor could mean growing up with poorer health, too.
Photo: Bread for the World

Since “half the world’s children grow up in poverty,” Boyce says it would make sense to look more closely at social risk factors, rather than focus on physical measures. Given that “15 to 20 percent of the overall population is responsible for over half of medical, psychiatric morbidity, and physician and health care use,” understanding social risk factors could be a key step to ameliorating poor health, he says.

The fragile family

As the American family has changed — some would say disintegrated — social scientists have shifted their focus from divorce, to the “fragile families” formed by unmarried couples. In some fragile families, the mother is single; in others she and the father are cohabiting.

“About 40 percent of American children are born into an unmarried family now,” says Jeanne Brooks-Gunn of Columbia University, a principal investigator on the Fragile Families and Child Wellbeing study.

The study is looking at the environments in which children are being raised, and which factors are most harmful to their health, welfare and education. “Some situations are stable, while others are not,” says Brooks-Gunn.

The Fragile Families study has followed about 5,000 children for nine years, with a focus on “stability and chaos, how they affect resources and investments in child well-being” Brooks-Gunn says. “Nobody will ever do this again; getting approval at 75 hospitals was a nightmare.”

Study personnel interviewed the mother within 24 hours of birth, and also a rather surprising 75 percent of the unwed fathers, Brooks-Gunn said. “Babies are darling, and everybody comes to the hospital to see them.”

The researchers then observed the children at home at ages 3, 5 and 9, to gather data on physical, social and psychological development, and they found the original optimism fading.

While rates have declined a bit, one quarter of all children, and half of black children, live with a single parent. Researchers continue to find high rates of physical, social and economic difficulties in non-married families.
Graph: The State of our Unions 2010, The National Marriage Project

“At birth, everybody expects things will go well; 75 percent of the [unwed] mothers believe they will marry the father,” Brooks-Gunn says, “but by year five, the relationship with the biological dad has ended for two thirds of these mothers. There is a huge increase in new partners, and in having children with a new partner.”

As a rule, the fathers who spent time with their children were those who had not had a child with another woman, says Brooks-Gunn. “And when the mother has a new partner, the father is out of the picture.”

The Fragile Family study³ found that:

• At age 3, children in stable families (whether married, co-habiting or a single mother), had better vocabulary than children of married or cohabiting parents in an unstable relationship.
• Children’s cognitive scores improved when their unwed parents marry.
• Each additional change in family structure increases the odds of behavioral problems. With more family and residential transitions, the mother becomes more likely to report stress and hitting her children.
• Conflicts in the parental relationship intensify behavior problems in children, regardless of the stability of the family structure.
• Having a single mother raises the odds of obesity, asthma, hospitalization and accidents.

Children of stable married couples scored best on the Peabody Picture Vocabulary Test-Revised, a standard intelligence test, implying better cognitive development. Beware: This does not prove that a stable marriage makes kids smarter; socioeconomic status and other factors still matter.
Data: FFCWS. Graph: J. Waldfogel et al, (2010). Fragile Families and Child Wellbeing. Future of Children, 20(2): 87-112.

This is not to say that simply being unmarried is the direct cause of all problems, given the many other factors in play, as Brooks-Gunn and colleagues noted. “While children born to unwed parents are at higher risk of low birth weight … women who are not married at the time of the birth are also more likely to smoke cigarettes and use illicit drugs during pregnancy, and less likely to receive prenatal care in the first trimester of their pregnancy, all of which are associated with low birth weight.”

Many factors may explain how a parental relationship affects children, Brooks-Gunn indicated:

• Parental resources: How much time, money and education?
• Parenting quality: How do the parents interact with the child?
• Father involvement: How present is he?
• Parental relationship: Are the parents stable and loving? Do they interact well with the child?
• Parental mental health: How well are the parents, psychologically?

Child-rearing outside of marriage is increasing among all women, especially among those with the least education.
Graph: The State of our Unions 2010, The National Marriage Project

The Fragile Family studies “add to a large body of earlier work that suggested that children who live with single or cohabiting parents fare worse as adolescents and young adults in terms of their educational outcomes, risk of teen birth, and attachment to school and the labor market than do children who grow up in married-couple families,” Brooks-Gunn and colleagues concluded.

Overall, the findings are distressing, Brooks-Gunn told the American Association for the Advancement of Science in February. “Our findings are more negative than I would expect. There is a lot of instability, and that affects this incredible disparity in how children are doing. This has incredible consequences for society. Forty percent of all kids are born into a non-married household. We are talking about diverging destinies.”

Ecuadorian mother and child
Photo: paggre

– David J. Tenenbaum

Trust Charles Darwin to be his own severest critic. Having expounded a revolutionary evolutionary theory of natural selection, he realized that the past gives birth to the present. Darwin knew about fossils, including the famous, three-section trilobites, that dated to the Cambrian period, now known to have begun about 540 million years ago.

Never one to duck logic, Darwin wrote:

Indeed, according to J. William Schopf, professor and director of the Center for the Study of Evolution and the Origin of Life at UCLA, what came before was totally mysterious when Darwin wrote “Origin of Species” in the 1850s. “Darwin knew about the Cambrian era, and the big extinctions after that were known, but he knew nothing about the earlier fossil record. This was the case for about 100 years.”

And then, starting in 1953, University of Wisconsin-Madison geologist Stanley Tyler noticed ring-like structures in rocks in Minnesota and Ontario’s Gunflint formation.

The rock — a fine-grained quartz relative called chert — was 1.9 billion years old – almost four times as old as the earliest Cambrian fossils.

Tyler, collaborating with Elso Barghorn at Harvard, recognized the circular structures as stromatolites, mushroom-shaped rocks formed by layers of microorganisms called cyanobacteria. In 1965, the two reported that stromatolites were the oldest fossils ever seen.¹

I can see you now!

Why did it take so long for Precambrian life to be recognized? “They had assumed that it would be like younger life, there would be coral, snails and trilobites,” said Schopf, an expert on the oldest life. “The basic problem was that a wrong assumption had been made. Life in the Precambrian turned out to be substantively different in organization and size.”

By exploring the interior of rocks using an increasing array of scientific techniques, Schopf and a growing group of colleagues have found life as early as 3.5 billion years ago.

Not bad for a planet with an estimated age of 4.7 billion years.

Double-not-bad, considering the exceeding scarcity of truly ancient rocks, hidden through the constant tectonic churning of the crust. The oldest rocks yet located are 3.8 billion years old, but any fossils they contain have been distorted by severe heat and pressure.

Still, Schopf said, four lines of evidence show the ancient roots of life on our planet: microfossils, molecular biomarkers, proportions of carbon isotopes and stromatolites. Stromatolites are layered rock formed by layers of microorganisms called cyanobacteria (formerly blue-green algae), which produce oxygen in sunlight.

While some of the fossilized microorganisms found in ancient rock apparently have gone extinct, the cyanobacteria closely resemble living organisms, Schopf told an audience at the University of Wisconsin-Madison on April 26. “Cyanobacteria do the same sort of photosynthesis as a blade of grass today. These are the guys that invented this process, probably 3-plus billion years ago.”

As testimony to nature’s predilection for retaining stuff that works, other fossil microorganisms resemble modern counterparts that require oxygen, cannot tolerate oxygen, or use it when convenient. “We’ve found 12 to 15 major families of cyanobacteria, the same ones that are important today, the same ones that are seen throughout the geological record,” Schopf says.

Tyler did not live to see the publication of his 1965 article, but it revolutionized paleontology, and has been cited by scientists at least six times since 2010.

“Stanley Tyler was a hero for this world,” says Schopf. “As [microbiologist Louis] Pasteur said, chance favors a prepared mind. Here was an economic geologist [concerned with finding minerals and mines] … and yet he saw these scrubbly things, and thought, ‘I bet they are fossils,’ even though they were almost two billion years old. This is the guy who made the discovery.”

– David J. Tenenbaum

Admit it: You love your dog, your cat, even your white rat.

And so you’re planning to lavish a platter of filet mignon on your doggy-love… a plank of sushi-grade tuna on kitty numero-uno, and some aged cheese on your rodent.

But do our dogs, cats and rats love us back?

Sure, parrots are endlessly uttering “I love you” on You Tube, and some bereaved dogs seem to grieve for their dead owners.

And yes, some animals “love” to spend time together.

But that doesn’t answer our nagging question: Can animals really love?

Or are we projecting our own feelings of affiliation, closeness, and passion on beasts that don’t have the mental machinery to love?

Almost like being in love?

More than half a century ago, Harry Harlow, a research psychologist at the University of Wisconsin-Madison, performed experiments that forever changed our view of human and animal emotions. At a time when academic psychologists explored learning and behavior by studying rats, when low-grade learning in a “Skinner Box” was considered high-grade science, when hospitals limited contact between mothers and their newborns, Harlow focused on maternal touch and the emotional life of monkeys.

Harlow removed infant macaques from their mothers, then raised them with a mother surrogate made of cloth or wire. In some experiments, both surrogates were present.

Monkeys with the cloth mommas grew up fairly normal, but infants raised with only the wire monkey became fearful and desperate. Their behavior was so bizarre that they seemed psychologically broken by the lack of a loving — or at least a cuddly-if-inanimate — mother.

Infants that had access to both types of bogus mother still relied on the cloth mother for reassurance even if the wire monkey held their bottle.

Harlow interpreted the lifelong devastation of maternal deprivation as proof that infant monkeys need love, and that became early, influential evidence that animals can love, says his biographer¹, Deborah Blum, a professor of journalism at UW-Madison. “Up until that point, people were arguing that these animals were not capable of having emotions. Harlow led the way in demonstrating that these animals loved, had affection, mattered to each other. He used the word ‘love’ very deliberately,” Blum adds, even though his fellow psychologists were highly skeptical, not to say scornful, of that notion.

It didn’t take popular psychology, aided by Harlow’s humorous, down-to-earth approach, long to realize that the then-current “scientific” preference for antiseptic infancy would deprive young people of necessary contact, Blum notes. The instinctive desire to hug an infant, it turned out, gained support from the most rigorous scientific experiments.

My romance

Scientists who say that primates need maternal love are no longer mocked by their peers. But what is love? Charles Snowdon, a UW-Madison professor of psychology who has explored primate behavior for 35 years, offers this definition: “a preference for one other individual that is more or less exclusive and long-lasting, and that transcends other relationships.”

Animal love is evident in behavior when animals are separated from their mates, Snowdon says. “In species that form lifelong attachments, if a mate dies or disappears, often the remaining mate does not form a new pair bond at all.”

Snowdon says the cotton-top tamarin he studied form strong attachments. “If they were separated, they would begin long calls, at a rate much higher than they would give when together. These plaintive calls would last for the entire 30 minutes of separation. When they were reunited, they cuddled and often had sex.”

As if that did not sound human enough, Snowdon next floored us by discussing “romantic love.” Decades ago, psychologists worked overtime to avoid being accused of anthropomorphism — projecting human qualities onto animals. Now it’s kosher to talk about an emotion once restricted to the primates that buy heart-shaped tchotchkes each February.

Snowdon says romantic love supports the bond in a mated pair, and it’s not just about primates. “Albatrosses and geese appear to form lifelong pair bonds, and robins, blue jays and cardinals might form relationships that last for at least one breeding season; these are strong attachments.”

Snowdon adds that experiments with titi monkeys belie the notion that the sole goal of animal attachment is to nurture the next generation. “If you separate the mother, father and infant from each other, and give them a choice, mothers and fathers choose to be with each other and ignore the baby. It is clear that pairs want to be with each other, to the exclusion of the baby.”

Like someone in love

While Harlow relied on observing behavior, today scientists study the brain chemicals that mold the Valentine’s heart. One key subject is the hormone oxytocin, which plays a critical role in social bonding and love, both animal and human.

Oxytocin, originally identified for its role in helping mothers bond with newborns, also rises in men and women after sex and other close, emotional encounters. In the big picture, oxytocin enables attachment in humans and other animals, Snowdon says. “You don’t find oxytocin elevated in animals unless they form an adult attachment with one other individual.”

The brain responds to dopamine, a feel-good chemical that is released during many pleasurable activities, including drug-taking. Dopamine also plays a role in animal love – and “marital” fidelity. Mated prairie voles have a higher level of a specific dopamine receptor in a brain region called the nucleus accumbens, says Karen Bales, an associate professor of psychology at the University of California at Davis. “When these are turned on, that prevents them from forming a second pair bond.”

When owners interact with their dogs, both sides have surges in oxytocin, says Bales, who studies primates at the California National Primate Research Center. “That puts a check in the ‘dogs can love’ box.”

Love fur sale

Because dogs are the most glaring example of an animal that seems to love people, we phoned Patricia McConnell, an author³, and animal behaviorist at UW-Madison. She gave us two key reasons why dogs can love: “Their physiology for creating social attachment is so similar to ours, and they behave in ways that, if any human did it, we’d label it love, attachment.”

Like many other mammals, dogs respond to oxytocin: “It’s a huge part of social attachment, and physiologically it’s almost an exact replica of oxytocin in humans,” McConnell says.

Dogs appear to grieve, McConnell adds. “They get distressed when someone they are attached to is gone. There are lots of credible examples of dogs risking their lives to save a human. We are so different from dogs in so many ways, but in some ways, we are more similar to them than to other animals. What other species is obsessed with the fate of a ball?”

If dogs love us, what about each other? “Absolutely, yes,” says McConnell. “I have seen dogs behave as if they instantly fell in love: they are animated, their eyes were shining, they were extra playful. But I’ve also seen dogs that clearly took an instant dislike to each other.”

Dogs, like people, are picky, so it’s not always possible to replace a deceased member of a tight pair, McConnell says. “When people get another dog, they’re often surprised that the resident dog is not thrilled. We see the exact same thing in people: Personalities can clash or meld. When someone you know dies, it will not help if a stranger walks in off the street.”

You don’t know what love is

Still, animals can’t say what they are feeling, and so we must rely on measurements and observations. Interpreting animal behavior can be difficult, says Marga Vicedo, a historian of science at the University of Toronto who has written about Harlow’s experiments.⁴

Vicedo recalls members of an animal-behavior seminar who would “discuss, week after week, how you would interpret it when they look left — or right? You are seeing a behavior, and from the behavior, you have to hypothesize about the emotions, but there is not a perfect correlation between animal and human emotions.”

Interpreting the emotional basis of behavior is difficult enough with people, Vicedo observes. “We may laugh at a meeting, but inside we are depressed. You can only observe behavior, and have to figure out its relationship to emotion and feeling.”

Stephen Marc Breedlove, who studies hormones and behavior at Michigan State University, reiterated that problem. “Whether you think your dog loves you or your boyfriend loves you, there is the same problem: you see the behavior and from that, you infer these feelings. With a partner, you can ask, but since people do lie, that is not completely reliable.”

My one and only love?

Our improved understanding of what’s going on inside the brain provides more ways to analyze animal emotion, Breedlove says. “In certain species, there is neural circuitry that helps monogamous pairs stay attached to one another. We know the same systems can be present in humans — and although we don’t know they serve the exact same function, there is some danger in insisting we are absolutely unique in every way. Natural selection produces a continuum of traits, we can’t have something arise from nothing.”

Indeed, evolution is a great re-user of its own inventions, as Breedlove stresses. “What is the evidence that makes you think love arose absolutely de novo [without precedent] in our species? And then, when did it arise, in Mesopotamia?”

The notion that animals can love is part of a scientific sea change. Once upon a time — even after Harlow — identifying emotions in animals was considered anthropomorphism, a fatal fallacy that could ruin a career in psychology or animal behavior.

Now, we have seen a “change in the zeitgeist [the spirit of the time],” says Breedlove. “People are open to the possibility that animals have emotions, and I think that is a step forward, a sign of maturity of the field. Anthropomorphism is definitely a risky business, but people are less worried that they will be written off as cranks just because they say something that could be interpreted as anthropomorphism.”

As we’ve seen, many scientists are even willing to discuss parallels in animal and human love. Heresy!

Almost like being in love

In burying the old “animals are just beasts that cannot have feelings” mentality, nobody has been more influential than primatologist Frans de Waal of Emory University. When we asked whether animals can love, he responded, “Mammals are almost made for attachment, because of their maternal care obligations, the female is attached to her offspring and vice versa. There is a whole brain circuitry attached to that.”

Still, the subjective aspect is hard to know, de Waal admits. Even though studies find attachment, affiliation — and arguably love — in rodents, dogs and primates, “what they experience is not something we can know, but given that they show all the signs of attachment, they spend time together, are distressed if they are separated, and show what looks like happy behavior when they are reunited,” it’s unclear why we should deny the obvious explanation: these animals have emotions.

“If a chimp’s offspring dies,” de Waal says, “it usually keeps carrying it around until it falls apart, so even though the offspring is dead, the attachment stays intact; these are all signs of strong attachments.”

Comes love

We asked de Waal if we could summarize his view as, ‘It looks like love, but we’ll never know?’ but he said we had it backwards. “My assumption is the other way around, that if animals that are closely related to us, as monkeys and chimps certainly are, and do similar things under similar circumstances, we have to assume the psychology behind it is similar. It would be very inefficient for nature to produce the same behavior in different ways in a monkey and a human, it would have to create a different mechanism, a different psychology and neurology. From the Darwinist standpoint it does not make sense that monkeys would arrive at the same place via a different way.”

de Wall said his view is that “If chimps show strong attachment, we have got to assume the psychology is similar, and that would include the experience. That is not an assumption that is easily verified, but I think it is better than the opposite, that it looks the same, but is probably different.”

Image: M.J. Grimson & R.L. Blanton

The single-celled amoeba Dictyostelium discoideum has no brain, but its complicated social cycle enables farming.

Amoeba, single-cell, shape-shifters that eat bacteria and live in the dirt, don’t get much respect. When they run out of food, they gang up and move their sorry selves to greener pastures.

Pastures with edible bacteria, that is.

If ever a creature needed re-branding, this is it.

Could labeling amoeba as farmers boost their brand? In the human realm, farming gave rise to cities, writing, metallurgy and the computer in front of your face.

Amoeba don’t use the Internet. And although they do have a cell nucleus, nobody claims they have an ounce of smarts.

But now we know that some amoeba move “seeds” of bacteria to a new location and plant them as a food source. In other words, they farm.

Ants grow fungus. Termites and some saltwater snails do ditto. Damselfish grow algae. But until now, nobody has identified any life form that “farms” bacteria, and nobody has identified any single-celled farmers, says Debra Brock, a graduate student in ecology and evolutionary biology at Rice University.

Adds Brock, whose report on farming amoeba appears in Nature tomorrow, “Certainly there has never been an amoeba that’s known to farm.”

Bring on the rebranding!

Working with the well-studied amoeba Dictyostelium discoideum (“dicty” to you and me) Brock noticed that the fruiting bodies — reproductive structures that distribute the amoeba in new habitat — seemed to contain bacteria. That was odd, Brock admits. “To get anybody to believe me, I had to prove that the little spots were bacteria, and not an infection.”

When she spotted the sorus (mass of spores) on growth medium, colonies of bacteria grew on some of the plates — showing that about one dicty in three transports bacteria. The bacteria didn’t seem to be a harmful infection, since amoebas with and without bacteria grew similarly, she says.

She fed the shape-shifters antibiotic to kill their bacterial cargo, but when the amoebas resumed eating bacteria, some bacteria showed up in the sorus. Since this only happened with amoebas that had originally carried bacteria, Brock concluded that this was normal, healthy behavior for those amoeba, although she’s can’t yet say whether the bacteria are inside or alongside the amoeba spores.

Photo: Scott Solomon

Fruiting bodies of the amoeba Dictyostelium discoideum contain bacteria and spores of amoebas. Each sorus is attached to a single slug, comprised of about 100,000 individual amoebas.

Wild about amoeba

The project began when Brock was studying wild amoeba rather than a strain that had been living in labs since the 1930s, and she noticed that some clones consistently carried bacteria.

Brock says dictys are “social amoeba” because “they have a structured society, and can exist in two states.” Individual amoebas in the soil eat bacteria, divide and eat some more. So long as edible bacteria are available, “they are perfectly happy to do this,” says Brock. “But if they use up all the food, they start talking to each other with chemical signals: ‘Wow! There’s not enough food!’ And then approximately 100,000 come together to form a slug.”

The slug serves as a truck to haul amoeba to new territory, Brock says. “During the multi-cellular part of the life cycle, they are starving, and they want to go somewhere else.”

The slug eventually shoots up a stalk containing amoeba spores, and among the farmers, bacteria. When the sorus opens, the bacteria can plant themselves as amoeba food.

Reminds us of Johnny Appleseed…

The Darwinian decision

Why does the same species of dicty use two survival strategies? Why do some farm while others don’t? “It’s a smart evolutionary strategy,” says Brock. “It’s bet-hedging. If you happen to land in a patch without bacteria, farmers have a great advantage because they bring their food with them, which allows them to grow and divide and bear a huge number of progeny while the poor non-farmers have nothing to eat.”

But while the farmers quit eating before they remove all bacteria from their old location, non-farmers can eat all those bacteria, so non-farmers do benefit if the new home already contains edible bacteria.

Apparently, both strategies work, because both have survived the evolutionary gauntlet. Brock is exploring whether a “farmer gene” causes some amoeba to hoard bacteria…

It’s enough to give a person a new respect for protozoans, which offers a firm basis for rebranding. “From quite a long time ago, we’ve thought we are so special,” says Brock, “but you can’t imagine the number of genes the amoeba has that are just like human genes. It’s scary; it takes you down a notch or two.”

– David J. Tenenbaum

When Deepwater Horizon blew up and melted down in April, the wound it tore in the Earth’s crust released a gusher of crude oil, estimated at 4.2 million barrels, into the Gulf of Mexico.

The massive microbial munching of methane during the BP spill may be the only good news from the Deepwater Horizon disaster.

The blowout also released about 160,000 tons of methane. If you counted molecules in BP’s blowout, methane (CH₄), the simple hydrocarbon that fuels stoves, furnaces and electric generators, was the single most abundant one.

But a report published in today’s Science shows that BP’s methane was totally devoured by microbes in the Gulf of Mexico, leaving less than .01 percent of the methane to enter the atmosphere. “We measured the sea-to-air flux of methane and found it was completely negligible,” says first author John Kessler, an assistant professor of oceanography at Texas A&M University.

Within four months of the April 20, 2010, blowout, a population explosion among methane-eating bacteria native to the Gulf decomposed virtually all of the methane, mainly in deep water, says Kessler.

Study author John Kessler extracts a water sample from a device that detects changes in water conductivity and temperature with depth.
NOAA Pisces.

The study offered three lines of evidence that bacteria were “eating” the released methane:

• Methane levels in the Gulf fell up to 10,000 times between June and October.
• Methane-munching microorganisms became extremely abundant downstream of the blowout. “Over the summer, the methane degraders were higher than we have ever seen at any other place in the world,” says Kessler.
• Dissolved oxygen in the water dropped as methane and oxygen reacted to form carbon dioxide and water, Kessler says. “Once we summed up all the lost oxygen in the area of the methane plume, we saw that it could only be explained by a complete [microbial] consumption of this methane.”

Although oxygen depletion is already a concern in the Gulf’s “Dead Zone,” the average loss was only 3 percent, Kessler says.

In a previous study, ethane and propane, two other natural gases that BP also released, decomposed even faster than methane, and were no higher than background levels by early fall. In both studies, Kessler collaborated with David Valentine of the University of California at Santa Barbara.

Cool news for your atmosphere

In the short term, spilled methane is less environmentally dangerous than crude oil, but it can pose a global warming problem in the long term, since a molecule of methane stores much more heat than a molecule of carbon dioxide.
Methane seeps are frequently found at ocean floors, where methane from decomposition enters the ocean. And unfathomable quantities of frozen methane are stored beneath the seabed.

So inquiring minds want to know: If and when this methane enters the ocean, could it reach the atmosphere and accelerate global warming?

Pisces, a research ship of the National Oceanic and Atmospheric Administration, was a floating laboratory to study Deepwater Horizon's aftershocks.
Photo: John D. Kessler/TAMU

The giant Deepwater spill contained too little methane to affect atmospheric levels, says Kessler, “but it does simulate a very energetic release from a seep or a methane hydrate, and so we were interested in using it as an analog for understanding how a massive submarine release of methane might behave.”

Although the microbes-eat-methane story provides a rare bright spot in BP’s ecological disaster, it’s not clear what would happen in shallow water, and in places lacking natural methane and a ready supply of methane eaters.

“The Gulf of Mexico has many natural methane seeps,” says Kessler, “that probably account for why Gulf waters are populated with these microorganisms, which are ready to degrade methane once there is a massive restocking of their ‘buffet.’ How this may play out at another place, without the natural seeps, I’m not sure.”

Within four months, bacteria had spawned enough offspring to devour essentially all of the added methane in the Gulf. “But if the bacteria are at lower abundance, would this take five months or two years? We don’t know.”

– David J. Tenenbaum