Insect diet helped early humans build bigger brains, a new study, "Seasonality, extractive foraging and the evolution of primate sensorimotor intelligence" suggests. To read the full study, click here. It's published in a special issue, June 2014 of the Journal of Human Evolution.
Is eating insects an important survival technique in harsh environments for modern and in the past for prehistoric people? After all, on those survival TV documentaries, you see the survivalist eating certain insects, with a knowledge of what bugs are nourishing, edible, and safe to eat and whether they need to be cooked first. In places where bugs are eaten, you see people eating various types of grubs, scorpions, grasshoppers, and other insects. You can check out the PDF article, "Edible Insects - Future prospects for food and feed security."
The prospect may not appeal to vegans, vegetarians, and those with a strong disgust factor about looking at bugs, let alone eating them. But in reality, prehistoric peoples ate bugs, and people in different areas of the world still eat them. Researchers' quest for elusive bugs spurred primate tool use, problem-solving skills, according to the July 2, 2014 news release, "Insect diet helped early humans build bigger brains, study suggests," also posted online June 25, 2014. You may wish to take a look at the U.S. News Travel article, "Countries That Eat Bugs."
What does this all mean for hominids (modern as well as prehistoric humans)?
While it’s hard to decipher the extent of seasonal dietary variations from the fossil record, stable isotope analyses indicate seasonal variation in diet for at least one South African hominin, Paranthropus robustus. Other isotopic research suggests that early human diets may have included a range of extractable foods, such as termites, plant roots and tubers.
Modern humans frequently consume insects, which are seasonally important when other animal foods are limited. This study suggests that the ingenuity required to survive on a diet of elusive insects has been a key factor in the development of uniquely human skills: It may well have been bugs that helped build our brains.
Surviving on a diet of insects
Figuring out how to survive on a lean-season diet of hard-to-reach ants, slugs and other bugs may have spurred the development of bigger brains and higher-level cognitive functions in the ancestors of humans and other primates, suggests research from Washington University in St. Louis. “Challenges associated with finding food have long been recognized as important in shaping evolution of the brain and cognition in primates, including humans,” said Amanda D. Melin, PhD, according to the July 2, 2014 news release, "Insect diet helped early humans build bigger brains, study suggests."
Melin is an assistant professor of anthropology in Arts and Sciences at Washington University in St. Louis and lead author of the study. “Our work suggests that digging for insects when food was scarce may have contributed to hominid cognitive evolution and set the stage for advanced tool use.” Melin has been investigating the visual and foraging ecology of white-faced capuchins in the tropical dry forests of Guanacas, Costa Rica, since 2004.
Did increased manual dexterity advance based on first eating a diet of bugs?
Based on a five-year study of capuchin monkeys in Costa Rica, the research provides support for an evolutionary theory that links the development of sensorimotor (SMI) skills, such as increased manual dexterity, tool use, and innovative problem solving, to the creative challenges of foraging for insects and other foods that are buried, embedded or otherwise hard to procure.
The study is the first to provide detailed evidence from the field on how seasonal changes in food supplies influence the foraging patterns of wild capuchin monkeys. It notes that many human populations also eat embedded insects on a seasonal basis and suggests that this practice played a key role in human evolution.
“We find that capuchin monkeys eat embedded insects year-round but intensify their feeding seasonally, during the time that their preferred food – ripe fruit – is less abundant,” Melin said, according to the news release. “These results suggest embedded insects are an important fallback food.”
Previous research has shown that fallback foods help shape the evolution of primate body forms, including the development of strong jaws, thick teeth and specialized digestive systems in primates whose fallback diets rely mainly on vegetation
This study suggests that fallback foods can also play an important role in shaping brain evolution among primates that fall back on insect-based diets, and that this influence is most pronounced among primates that evolve in habitats with wide seasonal variations, such as the wet-dry cycles found in some South American forests.
“Capuchin monkeys are excellent models for examining evolution of brain size and intelligence for their small body size, they have impressively large brains,” Melin said, according to the news release “Accessing hidden and well-protected insects living in tree branches and under bark is a cognitively demanding task, but provides a high-quality reward: fat and protein, which is needed to fuel big brains.” But when it comes to using tools, not all capuchin monkey strains and lineages are created equal, and Melin’s theories may explain why.
Perhaps the most notable difference between the robust (tufted, genus Sapajus) and gracile (untufted, genus Cebus) capuchin lineages is their variation in tool use. While Cebus monkeys are known for clever food-foraging tricks, such as banging snails or fruits against branches, they can’t hold a stick to their Sapajus cousins when it comes to the innovative use and modification of sophisticated tools.
One explanation, Melin said, is that Cebus capuchins have historically and consistently occupied tropical rainforests, whereas the Sapajus lineage spread from their origins in the Atlantic rainforest into drier, more temperate and seasonal habitat types. “Primates who extract foods in the most seasonal environments are expected to experience the strongest selection in the ‘sensorimotor intelligence’ domain, which includes cognition related to object handling,” Melin said, according to the news release. “This may explain the occurrence of
tool use in some capuchin lineages, but not in others.”
Genetic analysis of mitochondial chromosomes suggests that the Sapajus-Cebus diversification occurred millions of years ago in the late Miocene epoch
“We predict that the last common ancestor of Cebus and Sapajus had a level of SMI more closely resembling extant Cebus monkeys, and that further expansion of SMI evolved in the robust lineage to facilitate increased access to varied embedded fallback foods,
necessitated by more intense periods of fruit shortage,” she said, according to the news release.
One of the more compelling modern examples of this behavior, said Melin, according to the news release, is that the seasonal consumption of termites by chimpanzees, whose use of tools to extract this protein-rich food source is an important survival technique in harsh environments.
The study is co-authored by biologist Hilary C. Young and anthropologists Krisztina N. Mosdossy and Linda M. Fedigan, all from the University of Calgary, Canada.
Only 25 minutes of mindfulness meditation alleviates stress, say researchers
New research, "Brief mindfulness meditation training alters psychological and neuroendocrine responses to social evaluative stress," from Carnegie Mellon University is the first to show that brief mindfulness meditation practice – 25 minutes for three consecutive days – alleviates psychological stress. Published in the journal Psychoneuroendocrinology, the study investigates how mindfulness meditation affects people's ability to be resilient under stress. Stress can raise cortisol levels, which in turn, could lead to more belly fat, or insulin resistance, but mindfulness may reduce too high cortisol levels.
Mindfulness meditation has become an increasingly popular way for people to improve their mental and physical health, yet most research supporting its benefits has focused on lengthy, weeks-long training programs. The question for readers interested in holistic health is whether mindfulness can become more automatic and easy to use with long-term mindfulness meditation training, which may result in reduced cortisol reactivity?
"More and more people report using meditation practices for stress reduction, but we know very little about how much you need to do for stress reduction and health benefits," said lead author J. David Creswell, according to the July 2, 2014 news release, "Only 25 minutes of mindfulness meditation alleviates stress." Creswell is an associate professor of psychology in the Dietrich College of Humanities and Social Sciences.
For the study, Creswell and his research team had 66 healthy individuals aged 18-30 years old participate in a three-day experiment. Some participants went through a brief mindfulness meditation training program; for 25 minutes for three consecutive days, the individuals were given breathing exercises to help them monitor their breath and pay attention to their present moment experiences. A second group of participants completed a matched three-day cognitive training program in which they were asked to critically analyze poetry in an effort to enhance problem-solving skills.
Saliva samples were taken to measure levels of cortisol, the stress hormone
Following the final training activity, all participants were asked to complete stressful speech and math tasks in front of stern-faced evaluators. Each individual reported their stress levels in response to stressful speech and math performance stress tasks, and provided saliva samples for measurement of cortisol, commonly referred to as the stress hormone.
The participants who received the brief mindfulness meditation training reported reduced stress perceptions to the speech and math tasks, indicating that the mindfulness meditation fostered psychological stress resilience. More interestingly, on the biological side, the mindfulness mediation participants showed greater cortisol reactivity.
"When you initially learn mindfulness mediation practices, you have to cognitively work at it – especially during a stressful task," said Creswell, according to the news release. "And, these active cognitive efforts may result in the task feeling less stressful, but they may also have physiological costs with higher cortisol production."
Creswell's group is now testing the possibility that mindfulness can become more automatic and easy to use with long-term mindfulness meditation training, which may result in reduced cortisol reactivity.
In addition to Creswell, the research team consisted of Carnegie Mellon's Laura E. Pacilio and Emily K. Lindsay and Virginia Commonwealth University's Kirk Warren Brown. The Pittsburgh Life Sciences Greenhouse Opportunity Fund supported this research.
You also may find noteworthy the abstracts of these other studies, "Is stress affecting our ability to tune into others? Evidence for gender differences in the effects of stress on self-other distinction." Or take a look at, "Cortisol and cognitive function in midlife: The role of childhood cognition and educational attainment." There's also a study of interest to those concerned with abdominal fat issues exacerbated by chronic stress, "Chronic stress increases vulnerability to diet-related abdominal fat, oxidative stress, and metabolic risk."
In that study, researchers found that chronic stress is associated with enhanced vulnerability to diet-related metabolic risk (abdominal adiposity, insulin resistance, and oxidative stress). Stress-induced peripheral NPY may play a mechanistic role. About NPY, also known as perhipheral neuropeptide Y, in preclinical studies, the combination of chronic stress and a high sugar/fat diet is a more potent driver of visceral adiposity than diet alone, a process mediated by peripheral neuropeptide Y (NPY), the study's abstract explains.