Author: Théophile Niyitegeka

{Study shows how mammal jaws evolved to help our earliest ancestors eat a more diversified diet}

You probably haven’t given much thought to how you chew, but the jaw structure and mechanics of almost all modern mammals may have something to do with why we’re here today. In a new paper published this week in Scientific Reports, David Grossnickle, a graduate student in the Committee on Evolutionary Biology at the University of Chicago, proposes that mammal teeth, jaw bones and muscles evolved to produce side-to-side motions of the jaw, or yaw, that allowed our earliest ancestors to grind food with their molars and eat a more diversified diet. These changes may have been a contributing factor to their survival of the mass extinction at the end of the Cretaceous Period 66 million years ago.

The terms “pitch” and “yaw” usually describe movements of airplanes, but biologists also use them to describe basic movements of body parts such as the jaw. Pitch rotation results in basic up and down movement, and yaw rotation results in side-to-side, crosswise motion (think of a cow munching away on some grass). Almost all modern mammals, including placental mammals, like humans and deer, and marsupials, like kangaroos and opossums, share similarities in their jaw structures and musculature that allow for both pitch and yaw movements. This allows mammals to have especially diverse diets today, from cutting pieces of meat to grinding tough plants and vegetables. For early mammals, these characteristics meant they could be more resourceful during tough times.

“If you have a very specialized diet you’re more likely to perish during a mass extinction because you’re only eating one thing,” Grossnickle said. “But if you can eat just about anything and 90 percent of your food goes away, you can still live on scraps.”

Using 2D images of early mammal fossils from previous publications and 3D data collected from modern specimens at the Field Museum, Grossnickle analyzed the structure of teeth, jaw bones, and how the muscles that control them were attached to the skull. He saw that as species began to develop a projection on the upper molars that fit into a corresponding cup or basin on their lower counterparts, the musculature of the jaw also changed to provide greater torque for side-to-side yaw movements. This way the animal could grind its food between the molars like a mortar and pestle, as opposed to cutting it with simple up and down pitch movements.

Grossnickle, who works in the lab of Zhe-Xi Luo, PhD, professor of organismal biology and anatomy, studies the early origins of mammals, and is interested in broader questions about why certain mammal groups have diversified through time and survived extinction events. He says the adaptations of the jaws and teeth may have been key.

“Mammals rebounded from those events and kept diversifying and persisting, and that’s one of my interests. Why are we in the Age of Mammals, not still in the Age of Dinosaurs?” he said. “This study begins to address that question from a functional perspective, looking at what changes occurred that might’ve given some mammals functional or dietary advantages over other groups.”

Source:Science Daily

{For mothers of new infants, going back to work may pose a number of obstacles to continued breastfeeding. Workplace policies affecting the ability to breastfeed — and the role of nurse practitioners (NPs) in helping to overcome those obstacles — are the topic of a special article in The Nurse Practitioner, published by Wolters Kluwer.}

“Breastfeeding yields many important benefits to both mother and infants, yet workplace barriers contribute to low rates of breastfeeding,” according to the article by Rhonda Winegar, DNP, RN, FNP-BC, CPN, CCRN, and Alisha Johnson, MSN, RN. “Nurse practitioners often serve as the initial point of education for new mothers and may impact decisions to breastfeed.”

Workplace Policies May Make It Harder for Women to Continue Breastfeeding

Breastfeeding is widely recommended as the best nutrition for infants, providing health benefits for babies and mothers alike. As such, measures to encourage breastfeeding have the potential to lower healthcare costs. “Society in general benefits from mothers and infants who are healthier,” according to the authors.

But while 75 percent of women choose breastfeeding after delivery, only 40 percent will continue breastfeeding after they return to work. “In the United States, breastfeeding is considered a personal choice, and legislation in support of breastfeeding in the workplace is more limited than in most other countries,” Rhonda Winegar and Alisha Johnson write.

Employer policies can have a major impact on women’s ability to continue breastfeeding after returning to work. One study found that women who work at companies with policies to support breastfeeding are more likely to continue breastfeeding for at least six months, as recommended by current guidelines.

The article identifies key elements of a successful workplace breastfeeding policy include providing appropriate breaks and a suitable area for women to pump breast milk, as well as a storage facility for the expressed milk (such as a refrigerator), if requested. The costs of such policies are relatively low — and are likely to be offset by the potential savings from fewer employee absences, lower healthcare costs, and less employee turnover.

And yet, employers may be unlikely to adopt breastfeeding promotion programs unless there are regulations to support them. The ‘Break Time for Nursing Mothers’ provision of the Affordable Care Act includes protections covering some employees and workplaces. In addition, 28 states (along with Puerto Rico and the District of Columbia) have laws in place regarding breastfeeding in the workplace. “Nurse practitioners should stay current on current legislation and community resources that are available to support breastfeeding once these patients return to work,” the authors write.

Other steps to promote continued breastfeeding range from prescribing an electric breast pump or arranging for a lactation consultant, to dealing with common concerns such as milk leakage on work clothes. Rhonda Winegar and Alisha Johnson conclude, “NPs can positively influence the incidence of breastfeeding and ultimately improve the health of society in general.”

The article appears as part of a special Doctor of Nursing Practice (DNP) theme issue of The Nurse Practitioner. In a video podcast, Rhonda Winegar discusses the personal experiences that led to her advocacy for policies to support breastfeeding in the workplace, and inspired her to become a DNP.

Source:Science Daily

{After a rough night’s sleep, your ability to recognize whether those around you are happy or sad could suffer, according to a study led by a University of Arizona psychologist.}

The research, published in the journal Neurobiology of Sleep and Circadian Rhythms, found that study participants had a harder time identifying facial expressions of happiness or sadness when they were sleep deprived versus well-rested.

The sleepy participants’ ability to interpret facial expressions of other emotions — anger, fear, surprise and disgust — was not impaired, however. That’s likely because we’re wired to recognize those more primitive emotions in order to survive acute dangers, said lead researcher William D.S. Killgore, a UA professor of psychiatry, psychology and medical imaging.

While emotions such as fear and anger could indicate a threat, social emotions such as happiness and sadness are less necessary for us to recognize for immediate survival. When we’re tired, it seems we’re more likely to dedicate our resources to recognizing those emotions that could impact our short-term safety and well-being, Killgore said.

“If someone is going to hurt you, even when you’re sleep deprived you should still be able to pick up on that,” Killgore said. “Reading whether somebody is sad or not is really not that important in that acute danger situation, so if anything is going to start to degrade with lack of sleep it might be the ability to recognize those social emotions.”

The data used in the study was part of a larger research effort on sleep deprivation’s effects on social, emotional and moral judgment. Killgore began the project while working as a research psychologist for the U.S. Army.

The current study is based on data from 54 participants, who were shown photographs of the same male face expressing varying degrees of fear, happiness, sadness, anger, surprise and disgust. Participants were asked to indicate which of those six emotions they thought was being expressed the most by each face.

In order to assess participants’ ability to interpret more subtle emotional expressions, the images presented were composite photos of commonly confused facial expressions morphed together by a computer program. For example, a face might show 70 percent sadness and 30 percent disgust or vice versa. Participants saw a total of 180 blended facial expressions at each testing session.

Participants’ baseline responses to the images were compared to their responses after they were deprived of sleep for one night.

Researchers found that blatant facial expressions — such as an obvious grin or frown (90 percent happy or 90 percent sad) — were easily identifiable regardless of how much sleep a participant got. Sleep deprived participants had a harder time, however, correctly identifying more subtle expressions of happiness and sadness, although their performance on the other emotions was unchanged.

When participants were tested again after one night of recovery sleep, their performance on happiness and sadness improved, returning to its baseline level.

While the difference in performance was not overwhelming, it’s enough that it could have a significant impact in critical social interactions, Killgore said.

“As a society, we don’t get the full seven to eight hours of sleep that people probably need to be getting. The average American is getting a little less than six hours of sleep on average, and it could affect how you’re reading people in everyday interactions,” Killgore said. “You may be responding inappropriately to somebody that you just don’t read correctly, especially those social emotions that make us human. Or you may not be as empathic. Your spouse or significant other may need something from you and you’re less able to read that. It’s possible that this could lead to problems in your relationships or problems at work. To me, that is one of the biggest problems — how this affects our relationships.”

Killgore’s research builds on existing work on the effects of sleep deprivation on the brain’s ventromedial prefrontal cortex — an area that helps people make judgments and decisions using their emotions.

A prior study, published by Harvard’s Seung-Schik Yoo and colleagues, showed that when people are sleep deprived, a disconnect occurs between the prefrontal cortex and the amygdala — one of the key emotionally responsive areas of the brain.

“So, in simplistic terms, the part of the brain that controls your emotions and the part that sees faces and responds to the emotional content basically start to lose their ability to communicate,” Killgore said. “We wanted to test that out and see if it plays out in terms of how people read facial expressions — and, in fact, it looks like it does.”

Source:Science Daily