From the standpoint of heart health, the Tsimane are a model group. A population indigenous to the Bolivian Amazon, the Tsimane demonstrate next to no heart disease. They have minimal hypertension, low prevalence of obesity and and their cholesterol levels are relatively healthy. And those factors don’t seem to change with age.
Also minimal is the incidence of Type-2 diabetes. Which leads scientists to consider the role of diet in the Tsimane’s cardiovascular health — and how it might be impacted over time as the population becomes more exposed to globalization and market forces.
A Heart Healthy Diet
That’s where UC Santa Barbara anthropologists Thomas Kraft and Michael Gurven come in. They are part of the Tsimane Health and Life History Project, an initiative supported by the National Institutes of Health, which conducted the first systematic study that examines what the Tsimane consume on a regular basis and compares it to that of the Moseten, a neighboring population with similar language and ancestry, but whose eating habits and lifeways are more impacted by outside forces. The researchers’ findings appear in the American Journal of Clinical Nutrition.
“Our prior work showed that the Tsimane have the healthiest hearts ever studied, so naturally there’s a lot of interest in understanding why and how,” said Michael Gurven, a professor of anthropology at UC Santa Barbara, co-director of the Tsimane Health and Life History Project and the paper’s senior author.
“The obvious first contender is, what are they eating? And are they eating what we think is best for heart health?
“We conducted a detailed analysis of the Tsimane diet and then compared it to what modern Americans typically eat, and to the diets that claim to be heart healthy,” he continued.
“Maybe the Tsimane just happen to follow one of those without knowing about them.”
These diets — Paleo, Okinawan and DASH, among others — are often promoted because of their proposed health benefits, and in the case of Paleo, that our bodies have evolved to benefit from particular types of food.
Changes Over Time
The connection to the Moseten is an added benefit of the study. Ethnolinguistically and genetically very similar to the Tsimane, the Moseten, an isolate in Bolivia, are much more acculturated in a number of ways than are the Tsimane.
“They provide a forecast of what Tsimane health might look like 20 years from now,” Gurven said.
“They represent what is happening to many indigenous populations over time. To what extent may changes in their diet increase the prevalence of heart disease and diabetes?”
Using the same measurement strategy employed by the U.S. Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey, the researchers interviewed 1,299 Tsimane and 229 Moseten multiple times about everything they had eaten or drunk in the previous 24 hours. Using published and their own nutritional estimates for all items, and a variety of methods to estimate portion size, they provided a detailed breakdown of daily food intake.
The high-calorie (2,433-2,738 kcal/day) Tsimane diet was characterized by high carbohydrate and protein intake, and low fat intake (64, 21 and 15 percent of the diet, respectively). In addition, the Tsimane don’t eat a wide variety of foods, relative to the average U.S. or Moseten diet. Almost two-thirds of their calories are derived from complex carbohydrates, particularly plantains and rice. Another 16 percent comes from over 40 species of fish, and 6 percent from wild game. Only 8 percent of the diet came from markets.
Despite the low dietary diversity, the researchers found little evidence of micronutrient deficiencies in the Tsimane’s daily intake. Calcium and a few vitamins (D, E and K) were in short supply, but the intake of potassium, magnesium and selenium — often linked to cardiovascular health — far exceeded U.S. levels. Dietary fiber intake was almost double U.S. and Moseten levels.
Over the five years of study, the researchers saw the Tsimane’s total energy and carbohydrate intake increase significantly, particularly in villages near market towns. Their consumption of food additives (lard, oil, sugar and salt) also has increased significantly. The Moseten, the researchers noted, consumed substantially more sugar and cooking oil than did the Tsimane.
Quantity and Quality
The conclusion: A high-energy diet rich in complex carbohydrates is associated with low cardiovascular disease risk, at least when coupled with a physically active lifestyle (Tsimane adults average 17,000 or so steps per day, compared to Americans’ 5,100). Moving away from a diet that is high in fiber and low in fat, salt and processed sugar represents a serious health risk for transitioning populations. Evidence of nutrition transition in Bolivia parallels trends in increasing body fat and body mass index among Tsimane, suggesting the low prevalence of cardiovascular disease — as among the Tsimane — may not persist.
According to Gurven, avoiding the pitfalls of changing diets and lifestyles will be critical for groups like the Tsimane. Many other indigenous populations in South America, Africa and Southeast Asia are in similar situations. And rates of obesity, type-2 diabetes and heart disease are high among indigenous groups whose lifeways are no longer traditional — including many North American Indian and Australian aboriginal populations.
And for the Tsimane, change is not far on the horizon.
“This is a key time,” said Thomas Kraft, a postdoctoral researcher in anthropology at UC Santa Barbara and the paper’s lead author.
“Roads are improving in the area, as is river transport with the spread of motorized boats, so people are becoming a lot less isolated compared to the past. And it’s happening at a pretty rapid pace.”
Added Sugar and Fat
Anecdotally, Gurven added, the Tsimane Health and Life History Project’s biomedical team is seeing more diabetic patients among the Tsimane than they have previously. That’s likely due to the increased regular intake of refined sugar and fat that occurred over the course of the study. As Kraft noted, with the Tsimane’s ability to buy large kilo bags of sugar and liters of cooking oil, the researchers calculated a 300 percent rise in consumption of those products.
“They’re basically deep frying and adding lots of sugar to drinks when they can,” he said.
And consuming a lot of calories.
“But they’re also physically active — not from routine exercise, but from using their bodies to acquire food from their fields and the forest,” added Gurven, “which is also an important lesson. You can’t look at what you’re eating irrespective of what you’re doing with your body. If you’re physically active, you can probably get away with more flexibility in the diet.”
Calorie count aside, the high carbohydrate content of the Tsimane diet isn’t “unprecedented,” according to Kraft.
“One of the other artery-protecting diets is the Okinawan diet from Japan. It comes out at about 85 percent carbohydrate. But a common feature they share is that pretty much across the board, they’re complex carbohydrates — it’s sweet potatoes in the Okinawan diet; here it’s plantains and manioc.”
The Moseten diet has fewer total calories and less carbohydrates than the Tsimane diet, but the Moseten eat a broader range offoods, including more fruits, vegetables, dairy and legumes. The Moseten also buy more of their food, including soda, bread, dried meat and processed items. The Moseten diet could provide insight into the Tsimane diet of the future, the researchers suggest.
“We’re still analyzing their health indicators, but we expect the Moseten to show more risk factors related to diabetes and heart disease,” said Gurven.
The Energy Balance
In addition to finding that the Tsimane consume more calories per day than the Moseten do, the researchers note the Tsimane are also more physically active (with much of their labor devoted to the hard work of slash and burn farming, hunting, fishing and foraging). They expend more energy activity, but may also have a higher resting energy expenditure due to higher rates of infection and persistent immune activity.
Overall, the findings suggest that no single diet protocol offers the key to health. The picture is much more complicated.
“It definitely sheds light on the diversity of diets that are compatible with good cardiovascular health,” said Kraft.
Added Gurven, “We’re at a unique point in history where for many of us, our daily decisions are more about what not to eat. We have to work hard not to overeat. Throughout most of human history, it was the opposite. It was so hard to get those calories we needed to survive.”
And in terms of the Tsimane’s eagerness to incorporate sugar and other additives into their diets despite the associated health risks,
“Telling folks to watch what they’re eating, don’t eat too much of this or that — that mentality is hard to convey when getting food is unpredictable and a daily grind,” Gurven continued. “Getting calories cheaply with less effort — who wouldn’t?”
Face It. Our Faces Don’t Always Reveal Our True Emotions
Actor James Franco looks sort of happy as he records a video diary in the movie “127 Hours.” It’s not until the camera zooms out, revealing his arm is crushed under a boulder, that it becomes clear his goofy smile belies his agony.
That’s because when it comes to reading a person’s state of mind, visual context — as in background and action — is just as important as facial expressions and body language, according to a new study from UC Berkeley.
The findings, to appear online this week in the journal Proceedings of the National Academy of Sciences, challenge decades of research positing that emotional intelligence and recognition are based largely on the ability to read micro-expressions signaling happiness, sadness, anger, fear, surprise, disgust, contempt and other positive and negative moods and sentiments.
Implications include the potential limitations of facial recognition software.
“Our study reveals that emotion recognition is, at its heart, an issue of context as much as it is about faces,” said study lead author Zhimin Chen, a doctoral student in psychology at UC Berkeley.
Researchers blurred the faces and bodies of actors in dozens of muted clips from Hollywood movies and home videos. Despite the characters’ virtual invisibility, hundreds of study participants were able to accurately read their emotions by examining the background and how they were interacting with their surroundings.
The “affective tracking” model that Chen created for the study allows researchers to track how people rate the moment-to-moment emotions of characters as they view videos.
Chen’s method is capable of collecting large quantities of data in a short time, and could eventually be used to gauge how people with disorders like autism and schizophrenia read emotions in real time and help with their diagnoses.
“Some people might have deficits in recognizing facial expressions, but can recognize emotion from the context,” Chen said.
“For others, it’s the opposite.”
Moreover, the findings, based on statistical analyses of the ratings collected, could inform the development of facial recognition technology.
“Right now, companies are developing machine learning algorithms for recognizing emotions, but they only train their models on cropped faces and those models can only read emotions from faces,” Chen said.
“Our research shows that faces don’t reveal true emotions very accurately and that identifying a person’s frame of mind should take into account context as well.”
For the study, Chen and study senior author David Whitney, a UC Berkeley vision scientist, tested the emotion recognition abilities of nearly 400 young adults. The visual stimuli they used were video clips from various Hollywood movies as well as documentaries and home videos that showed emotional responses in more natural settings.
In the first of three experiments, 33 study participants viewed interactions in movie clips between two characters, one of which was blurred, and rated the perceived emotions of the blurred character. The results showed that study participants inferred how the invisible character was feeling based not only on their interpersonal interactions, but also from what was happening in the background.Study participants went online to view and rate the video clips. A rating grid was superimposed over the video so that researchers could track each study participant’s cursor as it moved around the screen, processing visual information and rating moment-to-moment emotions.
Next, approximately 200 study participants viewed video clips showing interactions under three different conditions: one in which everything was visible, another in which the characters were blurred, and another in which the context was blurred. The results showed that context was as important as facial recognition for decoding emotions.
In the final experiment, 75 study participants viewed clips from documentaries and home videos so that researchers could compare emotion recognition in more naturalistic settings. Again, the context was as critical for inferring the emotions of the characters as were their facial expressions and gestures.
“Overall, the results suggest that context is not only sufficient to perceive emotion, but also necessary to perceive a person’s emotion,” said Whitney, a UC Berkeley psychology professor.
“Face it, the face is not enough to perceive emotion.”
Working Long Hours Linked To Depression In Women
Women who work more than 55 hours a week are at a higher risk of depression but this is not the case for men, according to a new UCL-led study with Queen Mary University of London.
The study of over 20,000 adults, published today in the BMJ’s Journal of Epidemiology & Community Health, found that after taking age, income, health and job characteristics into account, women who worked extra-long hours had 7.3% more depressive symptoms than women working a standard 35-40 week. Weekend working was linked to a higher risk of depression among both sexes.
Women who worked for all or most weekends had 4.6% more depressive symptoms on average compared to women working only weekdays. Men who worked all or most weekends had 3.4% more depressive symptoms than men working only weekdays.
“This is an observational study, so although we cannot establish the exact causes, we do know many women face the additional burden of doing a larger share of domestic labour than men, leading to extensive total work hours, added time pressures and overwhelming responsibilities,” explained Gill Weston (UCL Institute of Epidemiology and Health Care), PhD candidate and lead author of the study.
“Additionally women who work most weekends tend to be concentrated in low-paid service sector jobs, which have been linked to higher levels of depression.”
The study showed that men tended to work longer hours in paid work than women, and having children affected men’s and women’s work patterns in different ways: while mothers tended to work fewer hours than women without children, fathers tended to work more hours than men without children.
Two thirds of men worked weekends, compared with half of women. Those who worked all or most weekends were more likely to be in low skilled work and to be less satisfied with their job and their earnings than those who only worked Monday to Friday or some weekends.
Researchers analysed data from the Understanding Society, the UK Household Longitudinal Study (UKHLS). This has been tracking the health and wellbeing of a representative sample of 40,000 households across the UK since 2009.
Information about working hours, weekend working, working conditions and psychological distress was collected from 11,215 working men and 12,188 working women between 2010 and 2012. Depressive symptoms such as feeling worthless or incapable were measured using a self-completed general health questionnaire.
“Women in general are more likely to be depressed than men, and this was no different in the study,” Weston said.
“Independent of their working patterns, we also found that workers with the most depressive symptoms were older, on lower incomes, smokers, in physically demanding jobs, and who were dissatisfied at work.”
She added: “We hope our findings will encourage employers and policy-makers to think about how to reduce the burdens and increase support for women who work long or irregular hours — without restricting their ability to work when they wish to.
“More sympathetic working practices could bring benefits both for workers and for employers — of both sexes.”
Brain Response To Mom’s Voice Differs In Kids With Autism
For most children, the sound of their mother’s voice triggers brain activity patterns distinct from those triggered by an unfamiliar voice. But the unique brain response to mom’s voice is greatly diminished in children with autism, according to a new study from the Stanford University School of Medicine.
The diminished response was seen on fMRI brain scans in face-processing regions and learning and memory centers, as well as in brain networks that process rewards and prioritize different stimuli as important.
The findings were published Feb. 26 in eLife.
“Kids with autism often tune out from the voices around them, and we haven’t known why,” said the study’s lead author, Dan Abrams, PhD, clinical assistant professor of psychiatry and behavioral sciences at Stanford.
“It’s still an open question how this contributes to their overall difficulties with social communication.”
The results suggest that the brains of children with autism are not wired to easily tune into mom’s voice, Abrams said. The study also found that the degree of social communication impairment in individual children with autism was correlated with the degree of abnormality in their brain responses to their mother’s voice.
“This study is giving us a handle on circuits and vocal stimuli that we have to make more engaging for a child with autism,” said the study’s senior author, Vinod Menon, PhD, the Rachael L. and Walter F. Nichols, MD, Professor and professor of psychiatry and behavioral sciences.
“We now have a template for targeting specific neural circuits with cognitive therapies.”
An important social cue
Mom’s voice is an important social cue for most children. For instance, tiny babies recognize and are soothed by their mother’s voice, while young teenagers are more comforted by words of reassurance spoken by their mothers than the same words sent by their mothers via text message, prior research has shown. The response to mom’s voice has a distinct brain-activation signature in children without autism, a 2016 paper co-authored by Abrams and Menon demonstrated.
Autism is a developmental disorder that affects 1 in 59 children. It is characterized by social and communication difficulties, restricted interests and repetitive behaviors. The disorder exists on a spectrum, with some children more impaired than others.
Mom’s voice is the primal cue for social and language communication and learning.
The new study included 42 children ages 7 to 12. Half had autism, and the other half didn’t. The children had their brains scanned using functional magnetic resonance imaging while listening to three different recorded sounds: their mother’s voice; the voices of unfamiliar women; and nonvocal environmental sounds. In the voice recordings, the women said nonsense words to avoid activating language comprehension regions in the brain.
The researchers compared patterns of brain activation and brain network connectivity between the two groups of children. They also asked the children to identify whether each brief (956-millisecond) voice recording they heard came from their mother or an unfamiliar woman. Children without autism correctly identified their mothers’ voices 97.5 percent of the time; those with autism identified their mothers’ voices 87.8 percent of the time, a statistically significant difference.
The brain response to unfamiliar voices, when compared with the response to environmental sounds, was fairly similar in children with and without autism, although those with autism had less activity in one area of the auditory association cortex.
When comparing the brain response to mom’s voice versus unfamiliar voices, children without autism had many more brain areas activated: Mom’s voice preferentially lit up part of the hippocampus, a learning and memory region, as well as face-processing regions. Brain-connectivity patterns measured in a network that included auditory-processing regions, reward-processing regions and regions that determine the importance, or salience, of incoming information also distinguished children with autism from children without autism. The network impairments in individual children with autism were also linked to their individual level of social communication impairment.
‘Really striking relationship’
“There is this really striking relationship between the strength of activity and connectivity in reward and salience regions during voice processing and children’s social communication activity,” Abrams said.
This suggests that brain responses to mom’s voice are a key element for building social communication ability, he added.
The findings support the social motivation theory of autism, which suggests that social interaction is intrinsically less engaging for children with the disorder than those without it.
Many current autism therapies involve motivating children to engage in specific types of social interaction. It would be interesting to conduct future studies to see whether these therapies change the brain characteristics uncovered in this study, the researchers said.
“Mom’s voice is the primal cue for social and language communication and learning,” Menon said.
“There is an underlying biological difference in the brain circuitry in autism, and this is a precision-learning signal we can target.”
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Face It. Our Faces Don’t Always Reveal Our True Emotions
Actor James Franco looks sort of happy as he records a video diary in the movie “127 Hours.” It’s not...
Working Long Hours Linked To Depression In Women
Women who work more than 55 hours a week are at a higher risk of depression but this is not...
Brain Response To Mom’s Voice Differs In Kids With Autism
For most children, the sound of their mother’s voice triggers brain activity patterns distinct from those triggered by an unfamiliar...
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