THE ANIMAL KINGDOM

Honeybees may look pretty much all alike to us. But it seems we may not look all alike to them. A study has found that they can learn to recognize human faces in photos, and remember them for at least two days. The findings toss new uncertainty into a long-studied question that some scientists considered largely settled, the researchers say: how humans themselves recognize each other’s faces. The results also may help lead to better face-recognition software, developed through study of the insect brain, the scientists added.

Many researchers traditionally believed facial recognition required a large brain, and possibly a specialized area of that organ dedicated to processing face information. The bee finding casts doubt on that, said Adrian G. Dyer, the lead researcher in the study. He recalls that when he made the discovery, it startled him so much that he called out to a colleague, telling her to come quickly because “no one’s going to believe it—and bring a camera!”

Dyer said that to his knowledge, the finding is the first time an invertebrate has shown ability to recognize faces of other species. But not all bees were up to the task: some flunked it, he said, although this seemed due more to a failure to grasp how the experiment worked than to poor facial recognition specifically. In many cases, some humans also can’t recognize faces, Dyer noted; the condition is called prosopagnosia.

In the bee study, reported in the Dec. 15 issue of the Journal of Experimental Biology, Dyer and two colleagues presented honeybees with photos of human faces taken from a standard human psychology test. The photos had similar lighting, background colors and sizes and included only the face and neck to avoid having the insects make judgments based on the clothing. In some cases, the people in the pictures themselves looked similar.

The researchers tried to train the bees to realize that a photo of one man had a drop of a sugary liquid next to it. Different photos came with a drop of bitter liquid instead. A few bees apparently failed to realize that they should pay attention to the photos at all. But five bees learned to fly toward the photo horizontally in such a way that they could get a good look at it, Dyer reported. In fact, these bees tended to hover a few centimeters in front of the image for a while before deciding where to land.

The bees learned to distinguish the correct face from the wrong one with better than 80 percent accuracy, even when the faces were similar, and regardless of where the photos were placed, the researchers found. Also, just like humans, the bees performed worse when the faces were flipped upside-down.

“This is evidence that face recognition requires neither a specialised neuronal [brain] circuitry nor a fundamentally advanced nervous system,” the researchers wrote, noting that the test they used was one for which even humans have some difficulty. Moreover, “Two bees tested two days after the initial training retained the information in long-term memory,” they wrote. One scored about 94 percent on the first day and 79 percent two days later; the second bee’s score dropped from about 87 to 76 percent during the same time frame.

The researchers also checked whether bees performed better for faces that humans judged as being more different. This seemed to be the case, they found, but the result didn’t reach statistical significance.

The bees probably don’t understand what a human face is, Dyer said in an email. “To the bees the faces were spatial patterns (or strange looking flowers),” he added.

Bees are famous for their pattern-recognition abilities, which scientists believe evolved in order to discriminate among flowers. As social insects, they can also tell apart their hivemates. But the new study shows that they can recognize human faces better than some humans can—with one-ten thousandth of the brain cells.

This raises the question of how bees recognize faces, and if so, whether they do it differently from the way we do it, Dyer and colleagues wrote. Studies suggest small children recognize faces by picking out specific features that are easy to recognize, whereas adults see the interrelationships among facial features. Bees seem to show aspects of both strategies depending on the study, the researchers added.

The findings cast doubt on the belief among some researchers that the human brain has a specialized area for face recognition, Dyer and colleagues said. Neuroscientists point to an area called the fusiform gyrus, which tends to show increased activity during face-viewing, as serving this purpose. But the bee finding suggests “the human brain may not need to have a visual area specific for the recognition of faces,” Dyer and colleagues wrote.

That may be helpful to researchers who develop face-recognition technologies to be used for security at airports and other locations, Dyer noted. The United States is investing heavily in such systems, but they still make many mistakes.

Already, the way that bees navigate is being used to design “autonomous aircraft that can fly in remote areas without the need for radio contact or satellite navigation,” Dyer wrote in the email. “We show that the miniature brain can definitely recognize faces, and if in the future we can work out the mechanisms by which this is achieved, this might suggest ideas for improved face recognition technologies.” Dyer said that if bees can learn to recognize humans in photos, then they reasonably might also be able to recognize real-life faces. On the other hand, he remarked, this probably isn’t the explanation for an adage popular in some parts of the world—that you shouldn’t kill a bee because its nestmates will remember and come after you.

Researchers led by Timothy Q. Gentner, a psychologist at the University of California, San Diego, have found that starlings can understand a key feature of grammar.

This feature, called recursive center-embedding, is what lets speakers make new sentences by inserting words and clauses within other sentences.

Thus, for example, “Oedipus ruled Thebes” can become “Oedipus, who killed his father, ruled Thebes” or “Oedipus, who killed his father, whom he met on the road from Delphi, ruled Thebes.” This can theoretically go on without limit.

Some researchers, including followers of the highly influential U.S. linguist Noam Chomsky, have held that this is a universal feature of human language, unique to humans, and which forms the logical core of our language.

The new findings challenge that view, Gentner said. “If birds can learn these patterning rules, then their use does not explain the uniqueness of human language.” The finding also “re-invigorates the search” for the evolutionary roots of language among animals, said Daniel Margoliash, a coauthor along with Gentner of a paper describing the findings. The study appears in the April 27 issue of the research journal “Nature.”

The scientists created artificial starling songs that followed two different rules. One allowed a sound to be inserted in the middle of a series of sounds, the simplest form of recursive center-embedding. The other allowed for sounds to be added only at the beginning or end of a string.

The researchers used recordings of eight different “warbles” and eight different “rattles” produced by the same male starling to build 16 songs. Eight of these followed the first patterning rule, and eight the second.

They then taught 11 adult birds to distinguish the two sets of songs. The birds received a food reward for pecking at a button when they heard songs from the first group, and for not pecking when they heard songs from the second set. Nine starlings eventually learned to distinguish the patterns, although it took months and a few tens of thousands of trials, the researchers reported.

When tested with different combinations of rattles and warbles that followed the same rules, the starlings performed well above “chance” levels, the researchers said. That suggests the birds had learned the abstract patterns and not just memorised specific songs, they added.

The researchers also checked whether the birds responded to “ungrammatical” strings, that violated the established rules. The starlings treated these differently, they reported. The experimenters then studied whether the birds could grasp a key feature of human grammars: Could they extrapolate these rules to distinguish among longer strings of sounds? Remarkably, Gentner said, they could.

The finding that starlings can grasp even simple grammatical rules, Gentner said, suggests humans and other animals share pattern recognition skills and possibly other cognitive abilities.

“There might be no single property or processing capacity,” the researchers wrote, “that marks the many ways in which the complexity and detail of human language differs from non-human communication systems.”

More generally, Gentner said, “The more closely we understand what nonhuman animals are capable of, the richer our world becomes. Fifty years ago, it was taboo to even talk about animal cognition,” he continued. Now, “no one doubts that animals have complex and vibrant mental lives.”

Elephants can recognise themselves in a mirror -- an important test of awareness that puts them in an exclusive club with humans, chimpanzees and dolphins.

One elephant in a study at the Bronx Zoo in New York went so far as to use the mirror to touch and explore a white "X" that had been painted on her head, the researchers reported in this week's issue of the Proceedings of the National Academy of Sciences.

"Maxine, Patty and Happy immediately went over to the mirror when they were let out, which was really a surprise to us because most animals, when exposed to a mirror, act immediately as if it were another animal," study participant Josh Plotnik said. Elephants would be expected to be a bit stand-offish at first, he said.

The researchers set up a cumbersome experiment at the Bronx Zoo, spending weeks to install a pachyderm-proof covered mirror in the pen of the three female Asian elephants."They would go over smell it and then leave," Mr Plotnik said. “But when the mirror was opened, the three elephants noticed right away. The three of them went straight to the mirror and immediately were touching and smelling it," he said.

"I was really surprised that there was no audible vocalization. These elephants are extremely vocal. They went straight for it -- there was a lot of smelling the very first day. Both Maxine and Patty tried to climb the mirror wall and look over it."

Before the elephant study, humans, chimpanzees and dolphins were believed to be the only animals capable of recognizing themselves in a mirror. Anyone who has seen a kitten jump at its reflection or a caged bird peck at a mirror knows there is a difference between looking at a mirror and recognizing one's self in it. One elephant in the Bronx Zoo study moved her head in and out of the mirror's reflection.

"Then we saw self-directed behavior, which is what humans do in front of the mirror -- picking our teeth, picking our noses or whatever," Mr Plotnik said. "Maxine grabbed her left ear and pulled it slowly forward. All three put their trunks in their mouths, as if they were exploring."

But the big test came when they painted a white mark on each of the elephant's heads. To ensure that the elephants were seeing the mark, and not just checking to see what had been done to them, a "sham" mark using a similar but invisible compound was painted on the other side.

"Happy never touched the sham mark and she touched the other mark repeatedly in front of the mirror," Mr Plotnik said. The other two did not but the researchers were not surprised.

"Chimpanzees and humans groom by taking things off their bodies. Elephants don't do that at all," he said. "It is possible the other two saw this white mark on their heads and thought it inconsequential."

A team of scientists has discovered a tiny caterpillar in Hawaii that binds snails with silk webbing before devouring them whole. The caterpillar starts munching at the wide opening of the helpless snail's shell and continues until there is nothing left, Science magazine reports.

The creature [Hyposmocoma molluscivora] is a first because scientists have never before witnessed a caterpillar eating a snail. The team wants to know why this strange caterpillar lives only in Hawaii.

"Caterpillars and terrestrial snails co-occur widely on all the continents where they are present, but only in Hawaii have caterpillars evolved to hunt snails," Daniel Rubinoff and William Haines, from the University of Hawaii, wrote.

“This provides fresh evidence for the importance of isolation in the evolution of novel traits. The caterpillars of the newly discovered species Hyposmocoma molluscivora are the first to be seen using silk to paralyse their prey. Although all caterpillars have silk glands, this predatory caterpillar uses silk in a spider-like fashion to capture and immobilise prey," Dr Rubinoff and Haines wrote.

When it comes across a suitable snail, the juvenile moth will spin a web anchoring the snail's shell to the leaf it is sitting on. The larva then stretches its body out of its own silk jacket and pursues the retreating snail to the end of its shell, where there is no escape.

Scientists want to know why Hawaii has more than its share of strange creatures Scientists are curious to notice that this unique predatory behaviour seems to occur nowhere else on Earth. Since the Hawaiian islands are the most remote place in the world, scientists are tempted to conclude that isolation is a key factor in the development of unusual hunting strategies, although it is not quite clear why.

"Specialised predatory behaviour by lepidopteron larvae, an extremely rare phenomenon worldwide, has independently arisen at least twice in Hawaii," Dr Haines and Rubinoff wrote. "[This] provides fresh evidence for the importance of isolation in the evolution of novel traits."

Beware Of The Argentine Invasion

The most common ant in southern California is the Argentine ant (Iridomyrmex humilis). It is a small, dark-colored ant about 3 mm (1/8 inch) long that invades homes in search of food and water. They are especially fond of sweets, but will feed on practically any food. They love the yolks of hard boiled eggs and carry minute yellow clumps of yolk back to their nest in endless ant columns. These ants are extremely well adapted to urbanized areas of the United States with mild climates and well-watered gardens. They pose a serious threat to native wildlife by upsetting delicate food webs. They are especially formidable due to their aggressive behavior and the enormous size of their colonies which can literally "team up" with other colonies.

If you live in southern California, you probably have seen endless single file columns of uninvited six-legged guests walking through your home. They follow a pre-marked pheromone "scent" trail initially laid down by scouts who were searching for goodies in your pantry. Although they prefer the outdoor life style, they primarily enter houses for food and water. They are fond of sweets, tuna, syrups (even cough syrup), juices, eggs, dead spiders and rodents, vomit, feces and just about any other organic matter they can find.

They are essentially scavengers and they play a valuable role in the natural ecosystem--but preferably in Argentina. In hot, dry weather they often search your home for water, including bathroom faucets and drains. I once followed an ant safari into my bathroom where they were neatly stacking their precious cargo of tiny eggs inside my toilet tank. They also relish the "honeydew" secretion of aphids, and protect their aphid friends from natural predators. In the fall months as the nights get chilly, they once again seek the warmth and shelter of your cozy home.

The first Argentine ants set foot on U.S. soils in the late 1890's, as coffee ships from Brazil unloaded their cargo in New Orleans. Being prolific breeders and constantly on the go, they moved across the southern half of the United States. A single colony may contain 10,000 female workers, and there may be hundreds of colonies around your home; the total number of ants could easily reach a million. Although they cannot sting, they can bite; however, they are only about 3 mm long and there tiny mandibles are too small to hurt humans.

But, in the world of insects, these ants are truly a living terror. They are very aggressive and readily overtake other ant species, even ants that are much larger and with powerful stings. Argentine ants are relentless and simply outnumber their adversaries until the enemy colony is destroyed. They even attack paper wasp nests under the eaves of a house, forcing the huge wasps to flee their nests in terror. Even nests of large carpenter bees are no match for these relentless ants. A "killer bee" nest probably could not withstand an invasion of Argentine ants. They also will attack bird nests, driving off the mother bird and killing the helpless young. One possible redeeming quality about these little warriors is that they may attack dry-wood (aerial) termite colonies in your home. I have observed this Lilliputian massacre in a termite infested table in the Palomar College greenhouse.

Most ant colonies are very territorial, and will fight different colonies of the same species. Since Argentine ants in the United States originated from the original colonizers in Louisiana, they are all closely related with very similar DNA. They apparently will accept ants from different colonies as members of their gigantic family. In fact, Argentine ants from different colonies will actually "team up" and attack together in vast swarms. They simply outnumber and overpower their enemy.

Argentine ants have become a serious threat to the coast horned lizard (Phrynosoma coronatum) in southern California. The primary food source for these endangered lizards are native harvester ants; however, the native ants are being eliminated by Argentine ants. Apparently the horned lizard is not fond of Argentine ants, and is actually attacked by them in enormous swarms. Colonies of Argentine ants need a damp area to survive, and have not invaded some of the dry habitats where native harvester ants and desert horned lizards (P. platyrhinos) live. Of course, that can readily colonize urbanized desert areas inhabited by people. Well watered gardens with stepping stones and concrete slabs provide the idea living requirements for these ants. In their native Argentina they live under rocks.

Argentine ants are a terrible nuisance in gardens and orchards because they tend and protect scale insects and aphids. They even carry aphids to the tender buds of your prized roses. In return, the ants consume a sweet secretion from the aphids called "honeydew." In addition, swarms of these ants will invade orchard trees, destroying the fruit crop. This is especially serious in figs (Ficus carica) where the symbiotic pollinator wasps are destroyed.

According to entomologist David Faulkner, if you have a 10 x10 foot (3 x 3 m ) patio slab, you could have a million or more individuals and possibly 20 or 30 queens. They get along fine because they're all related to the original colonizers in Lousiana, perhaps from the original pregnant female who arrived there. Workers live a month or more as adults, but queens live up to 10 years or more. With other ants, when the queen dies, the one-queen colony dies because no more ants are being produced. With multi-queen Argentine ants, another queen simply moves in and takes over the role of the deceased queen. In fact, a queen from San Diego would probably be accepted in a colony elsewhere in California.

In their native homeland of Argentina, different colonies of Argentine ants are not so friendly to each other because their DNA has developed much greater variation. Neighboring colonies may fight each other, even though they are only 200 yards (200 m) apart. Also there are many native predators in Argentina, including fungal parasites and bacteria. The narrow genetic variability that has kept all the California populations on friendly terms may eventually backfire due to excessive inbreeding. Perhaps some day these ants may not have the genetic variability to adapt to a changing environment.

How To Control Invasions of Argentine Ants

Empty your trash often and make sure your house is free of crums and food particles that might attract ants. Make sure that food containers are tightly closed, without residual traces of the food on the sides of containers. These ants can even get into screw-top jars without seals. They follow the spiral threads until they are inside! Avoid using toxic aerosol insecticides inside your home--unless you don't care about your lungs or your bone marrow.

Try spraying a deodorant detergent (Pine Sol® or peppermint Castile® soap), Windex® or rubbing alcohol on ant trails in your home. This may erase the scent trail and cause the ants to become confused and disoriented.

Go on search & destroy missions around your home, spraying Diazinon® on ant colonies beneath stepping stones and other cool, damp places.

Documented Aggressiveness of Argentine Ants:

They devoured the termite colonies inside the rotten legs of a wooden table that was removed from the Palomar College greenhouse. Within days the termites were exterminated. Note: These were dry-wood (aerial) termites, not subterranean termites. Several reports on the Internet (search: Argentine ant + termite) suggest that Argentine ants may be used in the biological control of subterranean termites; however, the effectiveness of this method is still open for discussion.

They invaded the nests of paper wasps (Polistes fuscatus) under the eaves of a house, undoubtedly in search of the meaty larvae and pupae. The adult female wasps could not defend against this Lilliputian invasion and were driven away.

They invaded the nest of carpenter bees (Xylocopa brasilianorum) in a large redwood log near the Life Sciences building. Again, they were probably attracted to the larvae or pupae within chambers in the wood. The adult female bees were either killed or driven away.

They invaded the nest of a mourning dove (Zenaidura macroura) under the eaves of a house. The mother dove was driven away and the young were attacked and killed. Coast horned lizard (Phrynosoma coronatum). Metallic green fig beetles (Cotinus texana) gorging themselves inside a fleshy, ripe syconium of the Calimyrna fig (Ficus carica). Although masses of minute, aggressive Argentine ants (Iridomyrmex humilis) are also foraging in the syconium (white arrow), the beetles are protected by their tough, impervious exoskeleton. These attractive beetles spend their juvenile larval stage in the ground, often beneath manure piles, compost and haystacks.