Human behaviour during these outbreaks often changes dramatically. People may start using face masks, or stop using them prematurely. Also, public fear of the pathogens may end up driving the wrong type of behaviour if the public's information is incorrect. Bauch and his co-author Joe Pharaon formulated the new mathematical model to study the influence of social behavior on the competition between pathogen strains with different virulence. Using computer simulations, they analysed how the model behaved under various possible scenarios that might occur to populations to explore the logic of the hypothesis that social behaviour plays a role in the evolution of the strain. The full findings are present in the Journal of Theoretical Biology. Middle-aged people who get roughly half their daily calories from carbohydrates live several years longer on average than those with meat-heavy low-carb diets, researchers reported Friday. The findings, published in The Lancet medical journal, challenge a trend in Europe and North America toward so-called Paleo diets that shun carbohydrates in favour of animal protein and fat. Proponents of these 'Stone Age' diets argue that the rapid shift 10,000 years ago - with the advent of agriculture - to grains, dairy and legumes has not allowed the human body enough time to adapt to these high-carb foods. For the study, receiving less than 40% of total energy intake from carbohydrates qualified as a low-carb regimen, though many such diets reduce the share to 20% or less. At the other extreme, a 70% or higher share of carbohydrates - such as pasta, rice, cakes, sugary drinks - can also reduce longevity, but by far less, the scientists found. 'Low-carb diets that replace carbohydrates with protein or fat are gaining widespread popularity as a health and weight loss strategy,' said lead author Sara Seidelmann, a researcher at Brigham and Women's Hospital in Boston. 'However, our data suggests that animal-based low carbohydrate diets might be associated with shorter overall lifespan and should be discouraged.' Replacing meat with plant-based fats (such as avocados and nuts) and proteins (such as soy products and lentils) reduces the risk of mortality, Seidelmann and her team found. The optimal balance of food groups for longevity remains hotly debated. Many studies have concluded that eating carbohydrates in moderation - 45 to 55 % of total calorie intake - is best, but others report improved short-term, cardio-metabolic health with high-protein, high-fat diets. Measures of metabolic health include blood pressure, good and bad cholesterol, and blood sugar levels. Human behaviour during these outbreaks often changes dramatically. People may start using face masks, or stop using them prematurely. Also, public fear of the pathogens may end up driving the wrong type of behaviour if the public's information is