Your Blood Holds Clues to Your Birthday

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The scene at the nursing home is grim. An elderly man lies in a pool of blood on the floor of his bedroom. Detectives also find blood from an unknown individual near the door, suggesting the victim put up a fight. Was the assailant one of the octogenarian’s fellow residents, or perhaps a nurse or an orderly? The detectives have little to go on until analysis of the unknown blood reveals it came from someone in their 20s or 30s.

That’s a fictional scenario—for now. But researchers report online today in Current Biologythat they can estimate someone’s age—give or take about a decade—simply by analyzing a drop of blood. If validated, the new forensic technique could revive police investigations that have hit a dead end.

The blood-age test relies on a peculiarity of T cells, immune cells that recognize and fight microbial invaders. As a T cell develops, it cuts up some of its DNA and splices some of it back together in various combinations; that helps it generate unique cell-surface receptors that can recognize a wide variety of bacteria or other pathogens. Any leftover DNA forms a circle that is useless to the T cell.

Researchers can quantify how many circles exist in the blood, says Manfred Kayser, a forensic molecular biologist at Erasmus University Medical Centre in Rotterdam. He and his colleagues have found that the amount declines with age because the body produces fewer and fewer new T cells as people get older. “We take advantage of this waste product,” he says.

The researchers established the promise of the forensic technique by analyzing the blood samples of about 200 people varying in age from a few weeks old to 80 years old. They probed the samples with fluorescent DNA designed to bind to the excess T cell DNA fragments, allowing them to quantify those fragments in a matter of hours. The team found a correlation between the number of T cell DNA fragments and age, one strong enough to pinpoint how old a person was, plus or minus 9 years.

That may seem like a big range, but it’s enough to place suspects into generational categories, which is very helpful to police, says Peter de Knijff, head of the forensic laboratory at Leiden University Medical Center in the Netherlands. Right now, law enforcement officials armed with a blood sample can identify its owner only if they can match it to a known suspect, or if it matches DNA in a database. With this new test, and a test for eye color, also developed in Kayser’s lab, de Knijff says that at least police can narrow down their suspect pool. “This is the best we have right now.”

Kayser says that he hopes to make the T cell test more accurate by combining it with other aging biomarkers that his team is developing. He also notes that the T cell test was still accurate on blood collected a year and a half earlier. That means it could be used to resolve cold cases as well as help police identify disaster victims.

Before the technique becomes widely available to forensic teams in the Netherlands, it will need to be verified by two independent labs, says de Knijff. There are calls for this test already, he adds, in cases where the trail has gone cold and new evidence is desperately needed.

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Fish Sleep Soundly in Mucous Cocoons

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Even the ocean has bedbugs. Tiny blood-sucking crustaceans (inset) roam the seas, nipping at the scales of passing fish. But the parrotfish (Chlorurus sordidus) has evolved an unusual defense. According to a study published online today in the Proceedings of the Royal Society B, the fish spend up to an hour spinning cocoons from their own mucous before they settle down to slumber for the night. These transparent, gelatinous balls of spit are large enough to envelope the fish from head to tail. By gently pushing fish from their cocoons without waking them, researchers showed that those sleeping without protection were 80% more likely to be bitten by the crustaceans than those they left untouched. Producing these mucous membranes costs just over 2% of the fish’s daily energy budget; apparently a worthwhile investment against things that go bite in the night.

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London’s Natural History Museum Delays Expedition

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London’s Natural History Museum (NHM) has suspended a month-long scientific expedition to a remote region of northern Paraguay in light of concern expressed by Paraguay’s government officials in a letter sent to museum officials. The letter mirrors fears raised last week by Iniciativa Amotocodie, a nongovernmental organization that represents indigenous peoples in Paraguay and has protested that scientists taking part in the expedition would run into the indigenous Ayoreo peoples who wish to have no contact with outsiders.

The expedition, which would have started this weekend, aims to explore an area called the Gran Chaco, a semiarid lowland sandwiched between the Andes and the Paraguay River that is a mecca for scientists interested in biodiversity. However, in a letter sent Friday to Richard Lane, scientific director of NHM, the director general of Paraguay’s Ministry of the Environment, Isabel Basualdo, asked for a suspension of the expedition until the concerns over contact with the Ayoreo peoples can be looked into. She writes: “The president of the Indigenous National Institute, whose responsibility it is to guarantee the rights of the indigenous population of Paraguay, warns that consent must be gained from the communities’ recognised leaders, who claim rights over the territory where such expedition will be made.” Basualdo goes on to say that in accordance with article 41 of the American Convention of Human Rights, a commission adopted in 1969 to protect the peoples of the Americas, the Paraguayan government has requested a cancellation of the expedition until such consent can be gained. But she also inidctates thet Paraguay is committed to the expedition and is working to resolve the problems as soon as possible.

The museum had been defending the expedition since the initial protest. (Here’s a video the museum posted of Lane discussing the matter). But in a statement yesterday, NHM said:

The Ministry for the Environment of Paraguay, one of our partners on the joint Natural History Museum and Paraguayan expedition to the Dry Chaco region, has decided to undertake further consultation with the Ayoreo people. The Natural History Museum supports this approach to ensure the community is properly informed and consulted. There will be a suspension of activities while this takes place. The concerns of the un-contacted people are extremely important to us. We will continue to take advice on these matters from the Paraguayan authorities. We hope that the issues can be resolved soon.

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Rethinking Brain Evolution in Insects

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As surprising at it may seem, wasps, bees, and even ants have relatively large and complex brains. That allows these “social insects” to keep track of the intricate relationships between the thousands of individuals in their colony—or so researchers thought. A new study indicates that these insects didn’t grow big brains to cope with social living; they evolved them millions of years earlier when they were solitary parasites.

The link between brain size and social living was first noted in 1850, when scientists identified mushroom bodies in the insect brain. Aptly named because they’re shaped like mushrooms, the structures contain thousands of neurons responsible for processing and remembering smells and sights. Social insects tend to have larger mushroom bodies than solitary ones, leading researchers to believe that the transition from solitary to social living increased the size of these brain regions.

But Sarah Farris has found a different explanation. Instead of comparing social insects with solitary ones, Farris, a neurobiologist at West Virginia University in Morgantown, looked into the past. To get a sense of how the wasp brain evolved over time, she and taxonomist Susanne Schulmeister of the American Museum of Natural History in New York City compared the mushroom bodies of parasitic wasps with those of nonparasitic wasps, which represent the very oldest form of wasp. The parasitic wasps had consistently larger and more elaborate mushroom bodies than the nonparasites, the duo reports online today in the Proceedings of the Royal Society B. In particular, the caps, called calyces, of the parasitic mushroom bodies were twice the size of nonparasites.

Farris points out that parasitism evolved 90 million years before social insects appear, and so “insects had big mushroom bodies for quite a while before sociality arose.” This is the first evidence that parasitism, and not sociality, was the driver of insect mushroom body complexity, she says. That may be because well-developed mushroom bodies help parasitic wasps better locate the nests of the larvae they lay their eggs in.

Francis Ratnieks, an evolutionary biologist at the University of Sussex in the United Kingdom agrees with the study’s findings, but he thinks the researchers need to also look at the brains of social insects. It would be useful, for example, to compare the brains of social worker bees, which process vast quantities of visual information as they fly from flower to flower, with those of parasitic wasps. If bees have even larger mushroom bodies than parasitic wasps, he says, this would suggest that social insects have further improved on the brains that they inherited from their ancestors.

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Controversy Rages Over Scientific Expedition to Paraguay

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A 100-person-strong scientific expedition, set to head off in the next few days for remote regions of northern Paraguay, Bolivia, and Argentina, is causing an uproar among some anthropologists and advocates of the indigenous people who live in that area. They fear that the exploring scientists could come into contact with the isolated indigenous groups, leading to violent exchanges or exposing the locals to dangerous infectious disease to which they have no immunity.

The month long expedition, organized by the Natural History Museum in London, in collaboration with their partner organization the Natural History Museum in Asunción, Paraguay, is hoped to return with several hundred new species of plants and insects. In a description of the expedition, the U.K. Natural History Museum says that such “specimens will help scientists to understand for the first time the richness and diversity of the animals and plants in this remote region. The Governments and conservation groups are able to use such information to better understand how to manage fragile habitats and protect them for future generations”.

The British and Paraguayan-led teams of scientists and research assistants, who will target two remote regions of an area of lowland, semiarid forest known as the Gran Chaco that stretches for 647,500 km2 on the eastern side of the Andes, will be traipsing through the homelands of groups of Ayoreo Indians who live in voluntary isolation and are rarely sighted. Some members of the Ayoreo tribes have fled the forest in recent years because of threats of bulldozed houses by a Brazilian company setting up a “nature reserve,” reports Survival International, a non-governmental organization that campaigns for the rights of tribal peoples. “Contact with isolated groups is invariably violent, sometimes fatal, and always disastrous,” said Jonathan Mazower, a spokesman for Survival International. “It is highly likely that there are small groups of isolated Indians scattered throughout the Chaco. The only sensible thing to do is err on the side of caution because any accidental contact can be disastrous. This has happened before [in the Chaco]. On two previous occasions, in 1979 and 1986, expeditions were sent in by U.S. missionaries to bring out Indians and people were killed on both occasions.”

Benno Glauser, director of leading indigenous peoples’ protection group Iniciativa Amotocodie, a group who aims to protect the integrity and the physical, spiritual, and cultural survival and vitality of isolated groups, says in a letter to the museum:

According to our data, the expedition you plan constitutes beyond any doubt an extremely high risk for the integrity, safety and legal rights of life and self-determination of the isolated Ayoreo, as well as for the integrity and stability of their territories . … There exists a considerable menace and risk also for the safety of the scientists taking part of the expedition, as well as the rest of expedition participants.

In an online statement reported by the Guardian, the U.K. Natural History Museum said it worked with the Paraguayan government and Ayoreo Indians to plan the expedition: “We recognise the importance of the concerns which have been taken into account during the planning of the expedition. They form part of the ongoing consultations that are still taking place with the Paraguayan authorities.”

The museum adds: “We are delighted to be working with representatives of the indigenous people. This gives us a wonderful opportunity to combine traditionally acquired knowledge with scientifically acquired knowledge to our mutual benefit. As with all expeditions, the team is continually reviewing the situation. Our primary concern is for the welfare of the members of the expedition team and the people of the Dry Chaco region.”

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Maggots Are Covered With Eyes

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Fruitfly larvae typically spend their short existence head first in a piece of rotten fruit devouring yeast. That’s perilous: If they can’t see the sun, they’re likely to shrivel under the elements. Luckily the maggots have eyes in the back of their heads—and pretty much everywhere else on their bodies. Reporting online today in Nature, researchers have found that the larvae sport light-sensitive cells (green) that run from head to tail. The cells are especially sensitive to the wavelengths common in bright sunshine, allowing the maggots to squirm into the fruit before the heat desiccates them.

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Brain Zaps Improve Math

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Need to improve your math skills or do your taxes faster? Try zapping your brain with electricity. Researchers have shown that administering a small electrical charge to the brain may enhance a person’s ability to process numbers for up to 6 months. The team says the approach, which it claims is harmless, could one day restore numerical skills in people suffering from degenerative diseases or stroke, and it may even improve the math abilities of the general population.

The brain’s math center appears to be the right side of the parietal lobe, a region that sits beneath the crown of the head. People with injuries to this region have difficulty counting, and it’s unusually active in young children learning their 1, 2, 3s. Those findings made Roi Cohen Kadosh, a cognitive neuroscientist at the University of Oxford in the United Kingdom, wonder if stimulating this part of the brain could improve a person’s ability to manipulate numbers.

Cohen Kadosh and colleagues recruited 15 university students and trained them to learn the value of nine made-up symbols, including shapes that looked like triangles and staples (see picture). To replicate what children go through when they first learn numbers, the researchers presented the volunteers with two symbols at a time and asked them which one had a higher value. At first, the volunteers had to guess, because they had never seen the symbols before. But as the training progressed, those volunteers who remembered their correct guesses began to learn the relative value of all nine symbols.

During 6 days of training, the researchers passed electrical currents into the volunteers’ brains. Using a technique called transcranial direct current stimulation (TDCS), the team attached electrodes to the scalps of the volunteers—over the right side of the parietal lobe—and applied a weak electrical current. Each day, five volunteers received a positive current for 20 minutes; five volunteers received a negative current for 20 minutes; and five volunteers received a positive current for 30 seconds. The volunteers usually report just a “tingling sensation” around the electrodes on the scalp, says Cohen Kadosh, who says that he tried out the procedure on himself before subjecting anyone else to it.

Each training day ended with a type of test known as a numerical Stroop task. In the classic version of the test, volunteers are shown, say, the word “blue” written in red ink and asked to state the color of the ink. Most of us hesitate for a second because we have good reading skills and want to say what we’ve read—i.e., “blue.” (You can try the test for yourself here.) In Cohen Kadosh’s version of the test, the volunteers were asked to look at the symbols they had learned—except this time, some of the low-value symbols were written larger than the high-value symbols—and say which of the symbols was larger in size. Students who hesitated were judged to have learned the symbols better than those who did not hesitate.

Volunteers who had received 20 minutes of positive electric current to their brains per day performed best on the test, the team reports online today in Current Biology. Specifically, they hesitated about twice as long as the group that received only 30 seconds of positive current. Students in the group that received 20 minutes of negative current per day were unable to recognize the symbols at all and didn’t respond. The effects of the electrical treatment were retained even 6 months later.

In addition to improving peoples’ numerical skills, electrically stimulating the brain could help patients recover word recognition and motor control after strokes, speculates Cohen Kadosh. And he adds that he sees no reason why this approach can’t be used to enhance word and numbers skills in people with normal math or language ability.

Silke Göbel, a psychologist at the University of York in the United Kingdom, cautions that although the people treated with TDCS may have altered reactions on the Stroop test, the research team has not yet directly shown this improves real-world math skills. “It is not clear whether this effect is really specific to number learning or would generalize to any new stimuli, … [but] this is obviously an important question for future studies”, she says.

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Ancient Tweaking

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Twenty years ago, scientists knew nothing of the scraps of RNA that are now known to influence just about every process in our bodies. Back then, the textbooks were simpler: genes code for proteins via the intermediate of RNA, and proteins called transcription factors regulate other proteins. This recipe was so entrenched in the basic orthodoxy of molecular biology that it was even given the name ‘the central dogma’ by the co-discoverer of DNA, Francis Crick.

Scientists now know, however, that this classic view of protein regulation is far too blunderingly inefficient for evolution to settle for. At some point hundreds of millions of years ago, the generation of a small stretch of RNA that could tweak this process gave an individual the edge over everyone else. And so regulatory RNA was born. These scraps of RNA – on average only 22 nucleotides long and now dubbed microRNAs, or miRNAs for short – bind to some messenger RNAs and label them for inactivation or destruction.

So far thousands of miRNAs have been identified in animals. These superintendents of protein regulation are involved in the earliest stages of an animal’s development, determining which cell types grow where and when, and how these cells differentiate into the different body parts. However, since the discovery of miRNAs, many scientists have wondered whether the same miRNAs govern specific tissues in different animals. Knowing this would not only give clues to the age of these different miRNAs, but
also to the age of the cells in which they are found.

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Shaping up HIV

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In the 1960s, a Danish company, seeking to improve on the traditional football made from the bladder and stomach of animals, invented the modern football. The designers realised that to form a perfect ball they needed to combine 20 leather hexagons with 12 pentagons, and in so doing demonstrated one of the basic laws of shape – that you cannot wrap a sheet of six-sided hexagons around a sphere. To induce the sheet to bend, the company had to introduce five-sided pentagons alongside the hexagons.

On the micro scale, the human immunodeficiency virus (HIV), which causes AIDS, faces a similar challenge during the assembly of new viral particles: how to coerce its hexagonshaped building blocks to form the spherical envelope that
surrounds its viral innards. Lifting a page from the football manual, structural biologist John Briggs, group leader at EMBL Heidelberg, wondered if HIV likewise solved this shape conundrum by introducing pentagons between the hexagons.

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