Science of smell points to design

New research shows the sense of smell has even more complexity than previously thought.

“Codes, information, efficient strategies—this is intelligent design territory,” Discovery Institute experts wrote of the findings on the organization’s blog.

Researchers from Peking University in China built on what scientists already knew about the olfactory system. As molecules of odorants—substances that give off a smell—flow into the nasal cavity, they bump into receptor cells on tiny hair-like projections called cilia. An odorant molecule must have a specific shape and composition to bind to a specific receptor and trigger electrical impulses that instantly flow along nerves to the brain.

In a study published last month by Nature Communications, researchers reported new findings from fruit flies about how the olfactory system works. Until now, scientists assumed olfactory receptors worked by sending a simple yes-or-no response to the brain. But, much to the researchers’ surprise, they discovered that when a receptor cell fires, it can generate either an excitatory or inhibitory signal. In the nervous system, excitatory signals trigger certain behaviors that might involve something like moving away from a bad odor or toward a pleasant aroma. Inhibitory signals generally decrease behavioral responses.

The new research shows the olfactory bulb in the brain not only needs to process information about whether a receptor cell sent a signal but also whether that signal was excitatory or inhibitory. In other words, receiver cells must process twice as much information as scientists previously thought. More surprising, they found inhibitory responses caused the same type of avoidance or attraction behaviors as excitatory responses.

Scientists also found olfactory receptors can fire spontaneously, even without an odorant present, and the same odorant can trigger either excitation or inhibition. Inhibition and excitation can coexist, and the combination of responses makes it possible to discriminate odor mixtures.

Like the senses of vision and hearing, the new study shows a complexity in the sense of smell that defies natural selection explanations and would make Charles Darwin’s toes curl.

Touch affects babies on a molecular level

When caregivers hold an infant frequently, the baby’s DNA changes, researchers in British Columbia found. According to the study, published this month by Cambridge University Press, babies deprived of an adequate amount of holding showed genetic underdevelopment that still persisted at age 4.

The scientists asked parents of 94 5-week-old, healthy infants to keep a daily diary of their babies’ behaviors such as sleeping, crying, fussing, or feeding, as well as the length of time the caregivers provided bodily contact. Four and a half years later, the researchers analyzed the children’s DNA samples. Their results showed consistent differences between children who experienced much physical contact as infants and those who didn’t. The differences occurred at five specific DNA sites, two of which fall within genes that play a role in the immune system and metabolism.

The researchers plan further studies to see if the genetic changes they detected will negatively affect the overall health of the children. “If further research confirms this initial finding, it will underscore the importance of providing physical contact, especially for distressed infants,” Sarah Moore, lead author of the study, said in a statement. —J.B.

Monkey amputees control robotic arm with thoughts

Researchers at the University of Chicago Medical Center recently discovered that monkey amputees can learn to control a robotic prosthesis through electrodes implanted in their brains. Former research involved paralyzed patients, but this is the first to study amputees.

The researchers studied three rhesus monkeys and found that both sides of the brain, the side that controls the natural limb and the side that previously controlled the amputated limb, can create new connections to learn how to control the robotic prosthetic, even several years after an amputation.

Next, the team plans to experiment with the sense of touch. “That’s how we can begin to create truly responsive neuroprosthetic limbs, when people can both move it and get natural sensations through the brain-machine interface,” Nicho Hatsopoulos, senior author of the study, said in a statement. —J.B.

Scientists make working DNA

Synthetic biologists have figured out how to use lab-made microbes to produce new proteins that do not occur in nature. The researchers engineered the new bacteria by using chemical reactions to introduce synthetic nucleotides, the molecules that make up DNA, to the bacteria E. coli.

The study, reported last month by the journal Nature, shows the altered E. coli read the synthetic DNA code just as efficiently as they read natural DNA, and the bacteria used the new information to produce a protein unlike any found in nature. Scientists hope to learn how to use synthetic microbes to develop designer drugs, biofuels, and other products. —J.B.

Supposed yeti evidence debunked

Scientists have never found evidence for the existence of the yeti, or abominable snowman, said to inhabit the high regions of the Himalayas. But decades of reports of yeti sightings have stirred the imaginations of many. In a new DNA study that will appear in Proceedings of the Royal Society B, researchers analyzed nine DNA samples of bone, tooth, skin, and feces purportedly from yetis that they obtained from museums and private collections. The results showed that one specimen came from a dog and the other eight from bears, indicating that the lovable abominable snowman in the Rudolph the Red-Nosed Reindeer classic animated TV special is, like Rudolph, just a myth. —J.B.