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Friday, September 28, 2007Cockroaches Are Morons In The Morning, Geniuses In The Evening
In its ability to learn, the cockroach is a moron in the morning and a genius in the evening.
Dramatic daily variations in the cockroach's learning ability were discovered by a new study performed by Vanderbilt University biologists and published online recently in the Proceedings of the National Academy of Sciences.
"This is the first example of an insect whose ability to learn is controlled by its biological clock," says Terry L. Page, the professor of biological sciences who directed the project. Undergraduate students Susan Decker and Shannon McConnaughey also participated in the study.
The few studies that have been done with mammals suggest their ability to learn also varies with the time of day. For example, a recent experiment with humans found that people's ability to acquire new information is reduced when their biological clocks are disrupted, particularly at certain times of day. Similarly, several learning and memory studies with rodents have found that these processes are modulated by their circadian clocks. One experiment with rats found an association between jet lag and retrograde amnesia.
In the current study, the researchers taught individual cockroaches to associate peppermint — a scent that they normally find slightly distasteful — with sugar water, causing them to favor it over vanilla, a scent they find universally appealing.
The researchers trained individual cockroaches at different times in the 24-hour day/night cycle and then tested them to see how long they remembered the association. They found that the individuals trained during the evening retained the memory for several days. Those trained at night also had good retention. During the morning, however, when the cockroaches are least active, they were totally incapable of forming a new memory, although they could recall memories learned at other times.
"It is very surprising that the deficit in the morning is so profound," says Page. "An interesting question is why the animal would not want to learn at that particular time of day. We have no idea."
Most previous studies of circadian rhythm have focused on the visual system. "The advantage of eyes becoming more sensitive at night is so obvious that people haven't looked much at other sensory systems," says Page. "The fact that our study involves the olfactory system suggests that the circadian cycle could be influencing a number of senses beyond vision."
In the study, the researchers used cockroaches of the species Leucophaea maderae. It doesn't have a common name but it is commonly used in scientific experiments because it was used extensively in early physiological and endocrinological studies.
The discovery that the cockroach's memory is so strongly modulated by its circadian clock, opens up new opportunities to learn more about the molecular basis of the interaction between biological clocks and memory and learning in general. Much of the new information about the molecular basis of memory and learning has come from the study of other invertebrates (animals without backbones) such as the sea slug (Apylsia) and the fruit fly (Drosophila).
"Studies like this suggest that time of day can have a profound impact, at least in certain situations. By studying the way the biological clock modulates learning and memory we may learn more about how these processes take place and what can influence them," Page says.
The study was supported by a grant from the National Institute of Mental Health.
Note: This story has been adapted from a news release issued by Vanderbilt University.
Recent research from Vidi researcher Josef Stuefer at the Radboud University Nijmegen reveals that plants have their own chat systems that they can use to warn each other.
Therefore plants cannot be considered boring and passive organisms that just stand there waiting to be cut off or eaten up. Many plants form internal communications networks and are able to exchange information efficiently.
Many herbal plants such as strawberry, clover, reed and ground elder naturally form networks. Individual plants remain connected with each other for a certain period of time by means of runners. These connections enable the plants to share information with each other via internal channels. They are therefore very similar to computer networks. But what do plants want to chat to each other about?
Recently Stuefer and his colleagues were the first to demonstrate that clover plants warn each other via the network links if enemies are nearby. If one of the plants is attacked by caterpillars, the other members of the network are warned via an internal signal. Once warned, the intact plants strengthen their chemical and mechanical resistance so that they are less attractive for advancing caterpillars.
Thanks to this early warning system, the plants can stay one step ahead of their attackers. Experimental research has revealed that this significantly limits the damage to the plants.
However there are two sides to the coin. That is not just the case for the Internet but also for plants. It appears that plant viruses can use the infrastructure present to rapidly spread through the connected plants. The infection of one plant therefore leads to the infection of all plants within the network.
This research clearly reveals that the general image of plants is a poor reflection of reality. Who had now suspected that the majority of plants around us are constantly networking?
This research is part of the Vidi project 'Plant Intranets. Costs, benefits, & risks of communication pathways in clonal plant networks' that was funded by NWO and the Radboud University Nijmegen.
Note: This story has been adapted from a news release issued by Netherlands Organization for Scientific Research.
A two-headed turtle captured by a turtle collector is a rare example of a conjoined-twin birth, its owner said.
The turtle would have likely died in the wild because it swims awkwardly and would be an easy target for predators, according to Jay Jacoby, manager of Big Al's Aquarium Supercenter in East Norriton.
The store bought the tiny turtle from the collector for an undisclosed price and will keep it on display, he said.
The 2-month-old turtle, known as a red-eared slider, fits on a silver dollar. It has two heads sticking out from opposite ends of its shell, along with a pair of front feet on each side. But there is just one set of back feet and one tail.
The turtle is seemingly healthy, and the species can live 15 to 20 years, Jacoby said. The turtle has not yet been named.
The same exotic-turtle collector sold another Big Al's store a conjoined-twin turtle about 20 years ago, Jacoby said. The man lives in Florida, but he declined to identify him.
A U.S. soldier broke down in tears Thursday as he testified that he was ordered to shoot an unarmed Iraqi man, and that his sergeant, a North Carolina man, laughed and told the trooper to finish the job as the man convulsed on the ground.
Sgt. Evan Vela's testimony came during the court-martial of Spc. Jorge G. Sandoval, of Laredo, Texas. Sandoval is on trial for allegedly killing Iraqis and trying to cover up the deaths by planting weapons at the scene.
Vela, Sandoval and Staff Sgt. Michael Hensley of Candler, N.C., are all charged in the case.
Vela testified that Hensley told him to shoot the Iraqi man, although he was not armed and had his hands in the air when he approached the soldiers.
"He asked me if I was ready. I had the pistol out. I heard the word 'shoot.' I don't remember pulling the trigger. It took me a second to realize that the shot came from the pistol in my hand," he said, crying and speaking barely above a whisper.
Vela said that as the Iraqi man was convulsing on the ground, "Hensley laughed about it and hit the guy on the throat and said shoot again."
"After he (the Iraqi man) was shot, Sgt. Hensley pulled an AK-47 out of his rucksack and said, 'This is what we are going to say happened,'" Vela said. He was dismissed from the witness stand to compose himself.
Vela said Sandoval, who was nearby providing security, was not present during the killing outside Iskandariyah, a mostly Sunni Arab city 30 miles south of Baghdad.
Sandoval faces five charges, including an April 27 murder of an unknown Iraqi male, placing a detonation wire on his body, premeditated murder of the Iraqi on May 11, placing an AK-47 rifle on his body and failing to ensure humane treatment of a detainee - the victim.
He faces a maximum sentence of life in prison if convicted. He has pleaded not guilty.
Vela, of Rigby, Idaho, was flown from Kuwait to testify under a deal that would bar his words from being used against him when he stands before a court-martial.
The investigation began after military authorities received reports of alleged wrongdoing from fellow soldiers, the Army has said. Sandoval was arrested in June while on a two-week leave visiting his family.
Vela's defense attorney, Gary Myers, claimed earlier this week that Army snipers hunting insurgents in Iraq were under orders to "bait" their targets with suspicious materials, such as detonation cords, then kill those who picked up the items. He said his client was acting on "orders."
The Washington Post, which first reported the "baiting" program, said it was devised by the Army's Asymmetric Warfare Group, which advises commanders in unconventional conflicts.
Within months of the "baiting" program's introduction, Sandoval, Vela and Hensley were charged with murder for allegedly using those tactics to make shootings seem legitimate, according to the Post.
The Army has declined to confirm such a program existed.
The Iraq war has seen U.S. service members face prosecution in several high-profile incidents, including abuse of detainees at Abu Ghraib prison, the killings of 24 civilians by Marines in Haditha, and the rape and killing of a 14-year-old girl and the slaying of her family south of Baghdad. Iraqis have accused American soldiers of unnecessary killings or abuse.
Vela, Sandoval and Hensley are part of the Headquarters and Headquarters Company, 1st Battalion, 501st Infantry Regiment, 4th Brigade (Airborne), 25th Infantry Division, based at Fort Richardson, Alaska.
In Georgia, 21-year-old Genarlow Wilson is serving a mandatory 10-year jail sentence for aggravated child molestation. His crime: When he was 17, he had oral sex with a 15-year-old girl. In Utah, polygamist leader Warren Jeffs has been convicted as an accomplice to rape for orchestrating a sexually coercive marriage between a 14-year-old girl and her 19-year-old cousin. In Michigan, a 53-year-old prosecutor is in custody on charges of entering the state to have sex with a 5-year-old girl.
This is the reality of sex with minors: The ages of the parties vary widely from case to case. For more than a century, states and countries have been raising and standardizing the legal age of consent. Horny teenagers are being thrown in with pedophiles. The point of this crackdown was to lock up perverts and protect incompetent minors. But the rationales and the numbers don't match up. The age of majority and the age of competence are coming apart. The age of competence is fracturing, and the age of female puberty is declining. It's time to abandon the myth of the "age of consent" and lower the threshold for legal sex.
The original age of consent, codified in English common law and later adopted by the American colonies, ranged from 10 to 12. In 1885, Britain and the states began raising the age to 16, ostensibly to protect girls' natural innocence. This moral idea was later bolstered by scientific reference to the onset of puberty.
But the age of puberty has been going the other way. Over the past 150 years in the United States and Europe, the average age of menarche—a girl's first period—has fallen two to four months per decade, depending on the country. In 1840, the age was 15.3 years. By the early 1980s, it was 12.8. At first, the trend was driven by nutrition, sanitation, and disease control. Recently, some analysts thought it had stopped. But dietary changes and obesity may be pushing it forward again. Two years ago, researchers reported that the average age of menarche among American girls, which had declined from 12 years and 9 months in the 1960s to 12 years and 6 months in the 1990s, was down to 12 years and 4 months by the beginning of this decade. Among black girls, average menarche was occurring about three weeks after their 12th birthday.
Getting your period doesn't mean having sex right away. But earlier puberty does, on average, mean earlier sex. According to the most recent data from the U.S. government's Youth Risk Behavior Survey, one of every three American ninth graders has had intercourse. And that's not counting the millions of teens who have had oral sex instead.
Having sex at 12 is a bad idea. But if you're pubescent, it might be, in part, your bad idea. Conversely, having sex with a 12-year-old, when you're 20, is scummy. But it doesn't necessarily make you the kind of predator who has to be locked up. A guy who goes after 5-year-old girls is deeply pathological. A guy who goes after a womanly body that happens to be 13 years old is failing to regulate a natural attraction. That doesn't excuse him. But it does justify treating him differently.
I'm not saying 12 should be the official age of "consent." Consent implies competence, and 12-year-olds don't really have that. In a forthcoming review of studies, Laurence Steinberg of Temple University observes that at ages 12 to 13, only 11 percent of kids score at an average (50th percentile) adult level on tests of intellectual ability. By ages 14 to 15, the percentage has doubled to 21. By ages 16 to 17, it has doubled again to 42. After that, it levels off.
By that standard, the age of consent should be 16. But competence isn't just cognitive. It's emotional, too. Steinberg reports that on tests of psychosocial maturity, kids are much slower to develop. From ages 10 to 21, only one of every four young people scores at an average adult level. By ages 22 to 25, one in three reaches that level. By ages 26 to 30, it's up to two in three.