Human blood at 400x magnification, by Eleanor Farmer.
Priming is a psychological phenomenon in which being exposed to a word or a stereotype can make us more likely to later act according to the prior stimulus, even if we have no conscious recollection of it. For example, people are more likely to complete a word stem like “TH” with “think” if they were previously exposed to that word. One widely cited study published in 1996 found that subjects exposed to words relating to old age in a word-scrambling task would walk more slowly down a hallway after completing the task. Slowness, of course, being a trait stereotypically associated with the elderly. The authors took this to be evidence that the word-task had primed the subjects to act old. But a new study led by Stéphane Doyen presents evidence that it may all be in the heads not of the subjects but of the experimenters.
In science, experiments are often double-blind, that is, neither subjects nor experimenters know which one of the possible conditions the subject is in. This is to prevent the unconscious expectations of either subjects or experimenters from influencing the outcome. Doyen attempted to replicate the 1996 findings, but devised a very strict protocol to ensure that the experiment was indeed double-blind, as expected. This experiment failed to reproduce the original findings. No one showed evidence of priming. However, Doyen then did another experiment, this time manipulating the experimenters’ expectations. Half of the experimenters were told to expect that the primed subjects would walk more slowly. The other half were told the subjects would walk faster. Lo and behold, that is exactly what Doyen observed. When the experimenters expected primed subjects to walk faster, they did; when they expected them to walk slower, they walked slower. (The actual measuring of walking time was done automatically using infrared sensors.)
The priming was real, but it had nothing to do with the unrelated word-task. It was all about what was going on in the experimenters’ heads, and how the subjects picked up on it and acted accordingly. Which, as Ed Yong points out, isn’t so different from Clever Hans, the horse who mastered arithmetic.
Stained Wolbachia pipensis inside wasp egg.
Wolbachia is a very common and very interesting group of bacteria. It infects insects and arthropods, living inside their cells, and is known for modifying the reproduction of host species in a variety of ways. It may play a role in rapid speciation, lateral gene transfer, and has potential as a vector in genetic engineering.
Some of the ways Wolbachia modifies reproduction:
Wolbachia can also cause bidirectional incompatibility. This may lead to rapid speciation. For example, Nasonia is a wasp genus consisting of three sibling species. They can’t reproduce with each other, and each species has its own strain of Wolbachia. It is, however, unclear which one preceded the other.
Vertical gene transfer is the usual, parent to offspring. Gene transfer outside parent-to-offspring is called lateral gene transfer. It’s uncommon to see lateral gene transfer between prokaryotes and multicellular eukaryotes, but scientists have found evidence of gene transfer between Wolbachia and insect as well as roundworm species. Some species had the entire Wolbachia genome embedded in their own.
Finally, there’s the potential for using these bacteria in biological control. Genetic engineers prefer to piggyback on nature: that way is a lot easier. Genetically modified Wolbachia can potentially be used to control insects that carry diseases like Malaria, either by transferring genes that make the carriers unable to carry the parasite, or by using Wolbachia’s manipulation of reproduction to reduce the fertility of the insect population.
The largest balls in the world: the bush cricket Platycleis affinis, apparently, has the largest testicles around. 70 mg may not sound like much, but it’s an impressive fourteen percent of the cricket’s body mass. A little back-of-the-envelope calculation of what a human male would have to sport in order to compete: assuming the average male weighs 75 kg, he would have to have balls weighing 75/100*14 = 10.5 kilograms. If this mass were to be concentrated in an average pair of testicles, whose volume is about 36 cm3, the density would be 10500g/36cm3 = 292g/cm3. That’s twice as dense as the core of the Sun.
The guys who measured bush cricket balls didn’t do it just to settle who’s bigger. They found “that testis mass increased with the degree of polyandry, but decreased with increasing ejaculate mass.”
First images of a newly discovered primate, the Burmese snub-nosed monkey. “Local people claim that these monkeys are easy to find in the rain, because they often get rainwater in their upturned noses, causing them to sneeze.” It’s expected that the new species will be classified as critically endangered, as there are only about 300 of them, and their habitat is under threat from logging and development.
The concept of vitamins is a hundred years old this year.
During the late 19th century, there were outbreaks of fatal beriberi in East Asia. The study of this disease would lead to the discovery of vitamins. Kanehiro Takaki, a doctor in the Japanese navy, took a special interest in the disease. The navy was plagued by illness: between 1878 and 1881, in a sample of a thousand men, each man in the navy fell ill an average of four times every year, and beriberi accounted for a third of the cases. Takaki noticed that beriberi was common on some ships and rare on others, and set out trying to find why. He noticed that the disease was uncommon among higher-ranking officers, and more common among sailors; after eliminating other factors, he became convinced that the cause lay in their diet.
In the 1880s, the germ theory of disease was the new kid on the block, only verified and commonly accepted in the last few decades. Ignaz Semmelweis had discovered in the 1840s that requiring physicians to wash their hands after examining dead bodies and before examining living patients reduced the incidence of puerperal fever. John Snow traced the source of a 1854 cholera outbreak in London to contaminated drinking water, thus disproving the prevailing “miasmal” theory of disease (that disease was caused by noxious air). Robert Koch had identified the bacterium responsible for anthrax in 1875. It was only natural to look for a bacterial cause of beriberi. But none could be found.
Takaki found that by introducing a more varied diet to the sailors, who mostly ate polished rice, beriberi was eliminated almost completely.
Around the same time, in the Dutch East Indies (now Indonesia), Christian Eijkman noticed that hens fed polished rice developed beriberi-like symptoms. The disease could be cured by feeding them rice bran. Adolphe Vorderman continued this work by studying beriberi in prisons on Java. He found that it was common in prisons that served mostly white rice, but extremely rare in prisons that served unpolished rice. Beriberi wasn’t caused by some bad substance introduced to the patients; it was caused by the lack of a good substance the body needs. By 1900, beriberi was believed to be a deficiency disease, and it turns out that it isn’t the only one.
Finally, the Polish biochemist Casimir Funk did a series of chemical studies of the magic substance in rice bran that could cure beriberi. He found it to contain nitrogen. In 1912, he published a paper called The Etiology of the Deficiency Diseases. In it, he presents the idea that there is a certain class of amines (derivatives of ammonia, or NH3) the body needs, but can’t synthesize itself: hence the need to introduce them through our diet. We only need tiny amounts of these substances, but if we lack them, we get sick. Funk called these compounds vital amines, or vitamines.
As it turns out, not all vitamins are amines, but the name stuck. We now know that beriberi is caused by thiamine (vitamin B1) deficiency. Scurvy is caused by vitamin C deficency, and pellagra by the lack of niacin (vitamin B3).
Eijkman shared the Nobel Prize in Medicine for his work. Today, of course, nutritional science holds a prominent place in medicine and the public consciousness, and we all know how important a healthy and varied diet is. But we learned all this in the last hundred years. It isn’t longer since the time doctors couldn’t even imagine that a limited diet might cause disease.
I think this story also underlines the cooperative and cumulative aspects of science. None of the scientists mentioned in this post could have discovered vitamins on their own, yet all of them provided necessary pieces of the puzzle. This is one of the reasons science needs to be open, transparent and accessible to as many people as possible.
Mass death of herring in Kvænes, northern Norway, found on the morning of New Year’s Eve. Estimates say there’s 20 tons of dead fish. No one knows why they’re dead (or rather, why they’re beached), but possible causes include washing ashore during a recent storm, being chased by predatory pollock, or getting trapped by a current.
Synthetically grown bismuth crystals. (pic 1, pic 2). Naturally occurring bismuth looks visually uninteresting, but you can grow these colorful, hoppered crystals in the lab. In fact, since bismuth melts at 271 °C, you can make them at home. The colorful exterior is formed when the outside is exposed to air and oxidized; the color varies with the thickness of the oxide layer. The crystal grows faster at the edges than the interior, giving this hollowed-out look.
Bismuth was long thought to be heaviest stable element; as it turns out, Bi is ever so slightly radioactive, but its half-life is a billion times the age of the universe.
Oxytocin is on its way up in the world. The hormone, whose name is medical Greek for “quick birth”, has led a relatively anonymous life since its discovery early in the 20th century, then known for its ability to induce uterine contractions in pregnant women and stimulate breast feeding. But in recent years, researchers have found it to be heavily implicated in social behavior. Paul Zak is betting on it as the moral molecule. Perhaps more interestingly, it has been linked to social disorders like autism, and may cure some of its symptoms.
Lower levels of oxytocin in the blood plasma have been documented in children with autism. Mutations in the oxytocin receptor gene have been found to occur in autistic individuals. Conversely, the ability to mind-read—to infer other people’s mental states by interpreting subtle cues—has been shown to improve after administering oxytocin intranasally, both in neurotypical and autistic individuals.
Rats with defective oxytocin receptor genes exhibit a sort of social amnesia: they can’t learn to recognize the smell of their peers, but they can still learn to recognize non-social smells. This amnesia can be cured by administering oxytocin to the rats, or induced in healthy rats via an oxytocin antagonist.
Oxytocin reduces social fear. It’s released during orgasm. It’s been speculated that the feelings of empathy and closeness caused by MDMA, the active component of Ecstasy, may be due to oxytocin release caused by MDMA’s stimulation of serotonin receptors.
Oxytocin can be administered to the brain as a nasal spray, allowing it to cross the blood-brain barrier. In a few years, you could be spraying it up before a date, a job interview, or to alleviate symptoms of autistic spectrum disorders. Oxytocin release can also be stimulated by hugs, sex, or other natural forms of human contact. On the other hand, people with Williams syndrome—a syndrome characterized by, among other things, pathological trust of strangers—may learn to be less gullible with the help of an oxytocin antagonist.
We should be very careful not to reduce complex phenomena like trust, social interaction and morality to the actions of a single molecule. There is almost certainly a more complex picture here, and one that science will continue to unravel in the years to come. But right now, oxytocin is looking really good.
It’s that time of year again: for a few weeks, writers everywhere can get away summarizing what they’ve already said rather than writing anything new. As a reader, I appreciate it, because I don’t obsessively follow every magazine, every blog, so it’s likely I’ll have missed something in the roundups. Like last year, here is a collection of some of the more interesting stuff that passed through these virtual pages in 2011.
The sound of Saturn dwarfed everything in terms of traffic this year. Some have claimed that post was misleading or outright wrong. It is not wrong: everything in it is accurate. It may be misleading. Here is another stab at explaining what’s going on: there’s auroras around Saturn’s poles! And the Cassini space probe has picked up these radio waves that are sent out into space as the auroras dance around there. This is an interpretation of those radio waves as sound (but unlike radio waves on Earth, no one intended for these waves to encode sound). This interpretation (the sound has been shifted into the hearing range and time-compressed to be listenable) happens to sound like special effects from an old science fiction movie.
I think this is wonderfully evocative, even if it isn’t the sort of thing scientists usually concern themselves with. And the fact that so many people get excited about space can’t be wrong, can it?
The domesticated silver fox, a fox bred to behave like a dog. You can keep one as a pet.
Infrasound may help explain hauntings. The experience of ghosts occurs in most cultures, so it’s definitely a valid topic for scientific query. But most “paranormal researchers” put the emphasis on the paranormal. Real scientists who do peer-reviewed research rarely concern themselves with ghosts, usually issuing blanket dismissals. The thing is that if you do investigate apparent violations of physical laws, you might find some really neat applications of physical laws. Infrasound is one such thing. It turns out that sound in frequencies below what humans can consciously pick up (less than 20 Hz) can instill a sense of dread in humans and even cause visual hallucinations. In particular, one haunted laboratory was exorcized by turning off a fan emitting sound around 19 Hz. Although not widely studied, it seems plausible that infrasound could be the cause of many a haunting.
Tickling the dragon, an experiment in which a screwdriver slipping is the difference between safety and supercritical, deadly nuclear reaction. On May 21, 1946, it all went wrong. A cautionary tale.
Mathematical personalities: Kurt Gödel and Évariste Galois.
Of Penis Panics, Cannibalistic Spirits and Dancing Manias. What do penis thieves, cannibalistic spirits and medieval Europeans dancing themselves to death have in common?
Aperiodic tilings, found in medieval Islamic wall mosaics, described in the language of math in the 1970s, and instantiated on the atomic level in quasicrystals, the discovery of which earned Dan Shechtman a Nobel in chemistry this year.
As a bonus, a great story I never linked: inside the mind of an octopus.
