The Paleolithic diet, eating like our ancient ancestors, is a diet fad that seeks to emulate the diet of early humans during the Stone Age. But what does that mean? Almost anything people want because ancestral diets differed substantially over time and geography, notes a paper in The Quarterly Review of Biology.

The review examines anatomical, paleoenvironmental and chemical evidence, as well as the feeding behavior of living animals. While early hominids were not great hunters, and their dentition was not great for exploiting many specific categories of plant food, they were most likely dietary "jacks-of-all-trades."

Relational aggression, such as malicious rumors, social exclusion and rejection, are considered something that girls do more often. The movie "Mean Girls" epitomized it to hilarious effect. A trio of scholars used surveys to show that boys are being shortchanged in popular accounts of mean-ness.

620 randomly selected sixth graders were followed through their senior year, filling out an annual survey talking about victimization. Using group-based trajectory modeling the female co-authors determined that boys are actually meaner than girls - or at least they brag about it more on surveys. Boys were more often to call themselves relational aggression perpetrators while girls reported being victims more.

This has as much in common with actual paleolithic culture as the paleolithic diet does. Flickr/George , CC BY-NC-SA

By Darren Curnoe

Necessity may be the mother of invention, at least if war is a necessity. And perhaps it is.

In the early days of humanity, survival was a combination of hardiness, keen engineering and intelligence - and nothing spurred on technological progress and vast social changes like the need to work together to kill other people, according to a new paper in Journal of the Royal Society Interface.

There has been concern about a lessening of social engagement, mostly created by older people who see young people behaving differently than they did (and do). Last decade it was noted that young people were
less likely to join clubs, had fewer close friends, and were less likely to perceive others as trustworthy.

So young people don't join the Masonic Lodge in their college years. Does that mean they are less social? 

No, there has been an increase in extraversion and self-esteem, according to a paper in Personality and Social Psychology Bulletin. In a review, the authors examined past studies that utilized the Revised UCLA loneliness scale (R-UCLA) to analyze changes in loneliness over time, and gender differences in loneliness.

King's College Chapel: beauty, art, profundity – but truth? Tom Thai, CC BY-SA

By Simon Blackburn, University of Cambridge

We may talk about a battle of the sexes when it comes to our species, but in the rest of the primate world, it really is a battle. We have the luxury of cultural hand-wringing about the shirt a Rosetta mission engineer wore in a YouTube video, but when it comes to chimpanzees, a shirt is the least of female problems.

Male on female violence among chimpanzees is frequent - and it has to do with sex. 

An analysis of two African tribes has led anthropologists to suggest that men evolved better navigation ability than women because men with better spatial skills - the ability to mentally manipulate objects - can roam farther and have children with more mates.

Policy makers and amateur psychology pundits think "necessity is the mother of invention" - and sometimes it is, that is why that became a saying, but plain old opportunity matters a lot. Natural gas had been around for 70 years, for example, and the United States has plenty of coal, but hydraulic fracturing, a modern form of extraction, has made natural gas cheaper and led to reduced greenhouse gas emissions, a competitive advantage and a 'win' for the environment - it was developed due to opportunity, not necessity.

If you're a native of rural Mozambique who contracts a disease and becomes symptomatic, you'll likely consult a traditional healer before getting medical advice.