Why do we cradle babies in one specific arm?
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PROFESSOR AUDREY VAN DER MEER HAS SPENT HER ENTIRE CAREER STUDYING INFANT DEVELOPMENT, PARTICULARLY WHEN IT COMES TO BRAIN DEVELOPMENT AND MOVEMENTS. NOW SHE'S TAKING A LOOK AT WHY PARENTS CRADLE THEIR BABIES IN A PARTICULAR SIDE OF THEIR BODY. HERE, WITH MAJA IN THE CROOK OF HER LEFT ARM, VAN DER MEER EXPLAINS SHE IS “EXTREMELY RIGHT-HANDED”.
view moreCREDIT: PHOTO: ELIN IVERSEN, NTNU
You probably haven’t ever given it much thought, but almost everyone cradles a baby in one specific arm. The vast majority of people always cradle a baby in the crook of their left arm.
Why is that?
“Researchers have been trying to explain this phenomenon,” says Audrey van der Meer, a professor of neuropsychology at the Norwegian University of Science and Technology (NTNU’s) Department of Psychology.
It is undoubtedly a phenomenon and several studies confirm it; the vast majority of people prefer to cradle a baby in the crook of their left arm. Artists have also noticed this.
“The Virgin Mary is usually depicted cradling baby Jesus in the crook of her left arm,” says Professor van der Meer.
The professor has previously studied the phenomenon and has now investigated it in more detail in a review article that includes the latest empirical data and meta-analyses in the field. This work was published in Infancy, an academic journal.
Three out of four people cradle babies in their weakest arm
When van der Meer and Åsmund Husby worked together a few years ago, Husby was a psychology student. He wrote an experimental bachelor’s thesis on the phenomenon under van der Meer’s supervision.
During that year, Husby was one of 35 undergraduate students who collected cradling data from family and friends, kindergartens, schools and sports clubs. Everyone had to perform the doll test on 20 people, and at least 5 of these had to be left-handed.
They tested 765 people aged 4-86. These people were asked to cradle a doll in the crook of one arm. The researchers found that 567 of these (75 percent) cradled the doll in the crook of their non-dominant arm. They tested the subjects’ handedness using a continuous scale.
Article: Handedness as a major determinant of functional cradling bias (tandfonline.com) https://www.tandfonline.com/doi/full/10.1080/13576500500513565
Heartbeat or hearing?
One theory is that most people cradle a baby to the left so that it can hear their heartbeat better. In almost all people, the heart is located on the left. Can the sound of a beating heart soothe a baby or connect it more closely to an adult?
Or maybe it has something to do with our hearing? Humans often perceive information in the form of sound faster with their left ear than their right. The theory is that most people cradle a baby to the left because we then use our left ear and eye to get information about the baby’s emotional state. Signals from the left are sent to the right hemisphere of the brain, which is specialised for interpreting emotions and faces.
However, perhaps the most intuitive explanation is also the most correct.
Associated with the dominant arm
A few years ago, van der Meer published an empirical study together with researcher Åsmund Husby. This theory holds that the phenomenon is closely related to the arm we use the most.
“Interestingly, this has not been regarded as an adequate explanation, even though it intuitively seems logical,” says Professor van der Meer.
New findings have strengthened this theory.
“Nine out of 10 people in the world are right-handed. We still believe that this is the best explanation why the vast majority of people cradle babies in the crook of their left, non-dominant arm,” says van der Meer.
We are usually doing something else while holding a baby, not just posing for a picture or showing it off. So, we basically do what is most convenient.
We want our ‘best arm’ free to do other things
Most of us cradle a baby to the left in order to have our right hand free. Generally speaking, it is most natural for left-handed people to cradle a baby in the crook of their right arm.
“It is perhaps interesting to mention that there are many pictures of William, the Prince of Wales, cradling a baby in the crook of his right arm. He is left-handed,” says Professor van der Meer.
However, right-handed Kate, the Princess of Wales, cradles babies in her left arm, like most of us.
This does not mean that van der Meer uses royal preferences as proof of the phenomenon. Instead, she has taken other theories into account and focused on the empirical data, and her conclusion is clear.
“The explanation that we cradle babies in the arm we use the least is also true if other factors are taken into account,” says van der Meer.
However, the phenomenon applies only to babies. As children get bigger and heavier, most people tend to carry them using their dominant and stronger arm.
JOURNAL
Infancy
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
People
ARTICLE TITLE
Handedness as a major determinant of lateral bias in human functional cradling
Protecting newborns: Research lays the groundwork for a lifesaving vaccine
Transmitted through the birth process, the bacteria Streptococcus agalactiae can have potentially lethal consequences
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NEW RESEARCH INTO GROUP B STREP INFECTIONS CONDUCTED AT BINGHAMTON UNIVERSITY, STATE UNIVERSITY OF NEW YORK, COULD LEAD TO A LIFE-SAVING VACCINE.
view moreCREDIT: "PREGNANT WOMAN" BY KYLIEAQUINO01 IS MARKED WITH PUBLIC DOMAIN MARK 1.0.
BINGHAMTON, N.Y. -- Researchers from Binghamton University, State University of New York are unraveling the workings of Group B Strep (GBS) infections in pregnant women, which could someday lead to a vaccine.
One in five pregnant women carry Streptococcus agalactiae (Group B Strep or GBS) in the vaginal tract, which is typically harmless — except when it isn’t.
The bacterial infection poses serious and even fatal consequences for newborns, including pneumonia, sepsis and meningitis, which can have long-term effects on the child’s cognitive function.
Researchers from Binghamton University’s Biofilm Research Center and the School of Pharmacy and Pharmaceutical Sciences (SOPPS) are unraveling the workings of GBS infections, which could someday lead to a vaccine. Their article, “In silico and experimental analysis of the repeated domains in BvaP, a protein important for GBS vaginal colonization,” was recently published in Infection and Immunity.
“This research has identified and characterized a novel protein that could serve as a vaccine candidate to fight a bacterium that impacts women’s reproductive health and neonatal outcomes,” said first author Lamar Thomas PhD ’23, now a postdoctoral fellow at the University of California, San Diego, in the Department of Pediatrics. “I hope this work will inspire others to explore other novel proteins and microbial agents that may potentially aid in improving global health.”
When most people think of “strep,” they have in mind Streptococcus pyogenes — Group A Strep or GAS, which causes strep throat and necrotizing fasciitis, a “flesh-eating” infection, explained Assistant Professor of Biological Sciences Laura Cook, a co-author of the paper along with Nicholas Faiola of the Biofilm Research Center and Emily Canessa and Yetrib Hathout of SOPPS.
“There are many other pathogenic species of Streptococcus as well, including GBS and Streptococcus pneumoniae, which also causes many diseases, especially in the elderly,” she said.
GBS can pass from mother to child in utero, potentially causing preterm birth, or after birth via close contact like breastfeeding, but these infections are rare. Most commonly, the infection is transmitted from mother to child during the birthing process, likely due to the aspiration of contaminated bodily fluids. Because of the risks, pregnant women in the United States are tested during their last trimester and treated with antibiotics if they are found to be positive. While antibiotics have decreased the rates of neonatal GBS disease in developed countries, the World Health Organization has placed a high priority on developing a vaccine.
To successfully colonize, the bacteria create a biofilm that allows them to stick to each other and the human host. Key to that biofilm is a protein known as BvaP, which Cook’s lab established in previously published research.
Blocking surface proteins such as BvaP could be key to developing a successful vaccine, protecting newborns from infection. Cook’s lab is now looking at the regulation of this protein, how this affects its function and how it may interact with other GBS proteins and the host.
“Even if BvaP does not prove to be a viable vaccine candidate, the process of host colonization is essential to understand for developing treatment strategies against bacterial pathogens,” Cook said.
JOURNAL
Infection and Immunity
ARTICLE TITLE
In silico and experimental analysis of the repeated domains in BvaP, a protein important for GBS vaginal colonization
Graduate student Lamar Thomas speaks with Assistant Professor of Biological Sciences Laura Cook in a laboratory in the Biotechnology Building at the Innovative Technology Complex.
Laura Cook, assistant professor of biological sciences, speaks with graduate student Lamar Thomas in a laboratory in the Biotechnology Building at the Innovative Technology Complex.
CREDIT
Binghamton University, State University of New York
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