Autism has strong genetic roots: If one identical twin has autism, the likelihood that the other also has the disorder is about 70 percent². But the other 30 percent of the time, the twins are discordant, meaning that one has autism and the other does not.

The new study finds many differences in DNA methylation between twins discordant for autism. Methylation is a type of epigenetic change in which methyl groups are added to DNA and switch on or off the underlying gene. The researchers also found methylation differences between twins who differ on tests of autism traits.

Epigenetic marks can be influenced by any number of environmental exposures, from everyday behaviors to diet and stress. Studying identical twins, who share the same genetic material, helps researchers zero in on environmental differences, saysRobert Plomin, professor of behavioral genetics at King’s College London in the U.K., who co-led the study. “It’s a neat tool for getting at environmental factors that could be causing autism,” Plomin says.

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SFARI.org, May 2013.

The cops round up the prostitutes, usually about a dozen of them, and bring them to an area set up with food, clothes, STD testing, and legal counsel. “They walk them over and say, ‘You would be going to jail if it was Tuesday. But it’s your lucky Wednesday’,” says Sara Katsanis, an associate in research at Duke University’s Institute for Genome Sciences and Policy. The police give them two options: either go to jail, or start a 14-day rehabilitation program known as the Prostitute Diversion Initiative, or PDI. So far hundreds of prostitutes have chosen the latter.

Since PDI launched in April of 2007, it has helped many prostitutes (almost all women) find addiction counseling, housing, and lawful employment. But many girls stay in the sex industry. It’s a dangerous profession, with a death rate six times higher than average (and a homicide death rate 18 times higher).

PDI participants may voluntarily submit a saliva sample for future DNA testing. The police will test the sample only if it’s relevant to some future crime — most likely, for a post-mortem identification. In other words, the only way the prostitute’s DNA donation can help her is if she turns up dead.

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Only Human, May 2013.

We’re living in an age of genetic explanations. Consider a few headlines from the past week alone: Single Gene May Extend Lifespan by 25 Percent. Genes Show One Big European Family. Genetic Test Helps Identify Aggressive Prostate Cancer.

I certainly do my share of gene’splaining. But for all the buzz given to the studies that uncover telltale genes, rarely mentioned are the most obvious and familiar examples of how genes aren’t destiny: identical twins. They share the same genome and, usually, the same parents, same neighborhood, and same food. And yet, as anybody who’s ever met a pair knows, they are not the same person. Why?

“Ten years ago the prevailing theory was that there must be systematic differences in their environments,” says Eric Turkheimer, a professor of psychology at the University of Virginia. One twin is favored by her mother, say, or is bullied in school, or catches fewer colds. But studies looking for big, non-shared environmental influences have come up short. As Turkheimer wrote in a fascinating commentary in 2011: “Exactly what the nonshared environment consists of has been a matter of mystery and controversy for some time.”

This is a tough thing to study in people. After all, scientists can’t pluck a pair of newborn identical twins from the arms of their mother, raise them for years in absolutely identical environments, and watch how they diverge.

Scientists can do that with mice, though, and now they have. In today’s issue of Science, neuroscientist Gerd Kempermann and colleagues report that genetically identical mice raised in the same environment show striking differences in their brains and exploratory behaviors. What’s more, these individual differences — individual personalities, you might say — become more and more pronounced over time.

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Only Human, May 2013.

It was warm and sunny. A few locals had come to the secluded spot to picnic, sunbathe and read. A gray-haired woman was sitting under a tree, painting the scene from a wooden easel. I walked past them and joined a group sitting in green plastic chairs. We were there for the owners’ meeting.

The New York Marble Cemetery (not to be confused, as I did on Sunday, with the larger and showier New York City Marble Cemetery, on the other side of 2nd Avenue) was built in 1830. It has 156 underground barrel vaults, holding the remains of more than 2,000 people. There are no garish tombstones; the vaults are marked with plain stone tablets nestled in the surrounding wall. One of my ancestors — Benjamin Wright, who was chief engineer of the Erie Canal and died in 1842 — bought, and now lies in, vault 83. That makes me an owner, and it means that I have the right to go in the vault, for free, whenever my time comes. The cemetery has thousands of owners. I counted 18 at the meeting.

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The Last Word on Nothing, May 2013.

(Caveat up front: Some studies have found that exercise does not improve cognition. I will be conveniently ignoring those in this post and in life.)

The mental benefits of exercise begin while you’re doing it and continue in the hours afterward. Take two studies from the mid-90s that tested volunteers before, during, and after moderate-intensity stints on an exercise bike. In one study, students watched a screen while biking. The screen showed a square filling up with a color, and the volunteers’ task was to push a joystick button as soon as the square was full. Reaction times were significantly faster while biking than at rest.

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Only Human, May 2013.

In the 1940s, geneticist Barbara McClintock of the Cold Spring Harbor Laboratory in New York wanted to know: Why is it that some kernels show an uneven splattering of color? If the DNA in every cell in each kernel contains the same pigment gene (or genes), then why isn’t that color expressed the same way in every cell?

As McClintock would discover (and, three decades later, win a Nobel Prize for), the color variation in maize comes from transposons, or so-called jumping genes. These stretches of DNA hop out of their original spot in the genome and then wedge themselves in another, random place. When they land, they may disrupt the activities of nearby genes, including pigment genes. The jumping patterns are different in every cell, thus explaining the color variability.

Ever since McClintock’s big discovery, two ideas have dominated the scientific literature on jumping genes, notes Josh Dubnau, a neuroscientist at Cold Spring Harbor. One is that transposons are, in a sense, friendly. For example, as I wrote about a couple of weeks ago, a recent study found that jumping genes are more active in some types of neurons than others, suggesting that the brain has evolved ways of using these elements for its own (normal, healthy) specialization.

The other idea is that, while transposons may be useful in certain circumstances, they’re usually parasites. Studies have shown that when transposons jump in stem cells that become sperm or egg cells, for example, “they can destroy the germline. You can get animals that are completely sterile simply because a transposon has gone rogue,” Dubnau says. “This is the dark side of transposons.”

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Only Human, April 2013.

Patricia Kuhl of the University of Washington in Seattle has been studying language acquisition for several decades. In the new study, she used electroencephalography (EEG), a noninvasive method of measuring brain activity through electrodes on the scalp.

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SFARI.org, April 2013.

So it was refreshing, at the Cognitive Neuroscience Society meeting last weekend, to hear about a line of emotion research that does have direct clinical relevance. More than half of all people with psychiatric disorders have trouble with emotion regulation, the actions or thoughts (conscious or unconscious) we make in order to keep our feelings in check. People who have trouble regulating their emotions might have angry outbursts in response to what others would consider a minor annoyance, for example, or intentionally avoid a place where they once experienced a traumatic event, or be completely debilitated during causal conversations by fear of what the other person thinks of them.

Psychologists have long known of behavioral strategies that help people regulate their emotions. The scientists I heard at the meeting have been using brain scans to try to figure out why these strategies work so well.

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Only Human, April 2013.

Since that first meeting, Hart’s team has recruited more than fifty former N.F.L. players for an ongoing study tracking their brain connections and mental health. The scientists’ latest batch of data, presented at a meeting of the Cognitive Neuroscience Society in San Francisco on April 15th, shows that retired N.F.L. players are more likely to have memory problems and depression than non-athletes of the same age, and that these deficits may stem from damage in certain bundles of white matter in the brain. But the researchers were more surprised by what the study didn’t show: nearly sixty per cent of the group had no mood issues, cognitive disability, or irregular brain patterns.

The drug, called suramin, blocks purinergic receptors, which sit on the surface of every cell in the body. These receptors are indirectly controlled by mitochondria, organelles that provide each cell with energy.

Robert Naviaux and his colleagues at the University of California, San Diego, gave suramin to mice whose mothers had been exposed to a mock infection during pregnancy. These mouse pups have social and communication deficits and repetitive behaviors reminiscent of autism. They also have motor problems and lose Purkinje cells — a type of cells found only in the cerebellum, a region involved in movement planning and sensory integration.

Suramin improves the animals’ social behaviors and motor coordination, and prevents the loss of Purkinje cells, the study found. The drug does not improve communication deficits or repetitive behaviors.

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SFARI.org, April 2013.