In an earlier column addressing toxic friendships, I briefly described the "social exchange" theory of friendship development: Friendships and other relationships involve their own versions of economic systems, in that we make investments in them using "relationship acumen" akin to "financial acumen."

This may sound callous, but the truth is that few of us are willing to invest time and energy into activities or relationships that do not promise some measure of return. In business, we hear about the metric called Return on Investment, or ROI. When the expected return outweighs projected costs - in terms of cash, publicity, good will, exposure, leverage, or a host of different currencies - it is much more likely that the investment will be made.

Friendships also involve an ROI analysis, even if we don't consciously crunch any numbers or measure our expectations for outcome. Friendships are often established on the basis of shared interests, proximity, or similarity between acquaintances. We slowly open ourselves up to a growing relationship with another person with whom we feel some affinity.

The Earth may not be flat nor is it the center of the universe, but that doesn't mean old-world intellectuals got everything wrong. In fact, in recent years, modern science has validated a number of teachings and beliefs rooted in ancient wisdom that, up until now, had been trusted but unproven empirically.

A full 55 pages of Arianna Huffington's new book, Thrive: The Third Metric to Redefining Success and Creating a Life of Well-Being, Wisdom, and Wonder, are dedicated to these scientific breakthroughs that often confirm the power of ancient psychology and contemplative practices. On an intuitive level, we've known for centuries that these lifestyle practices can help us lead happy, healthy and balanced lives. But now, with the support of hard science, we can embrace these pieces of ancient wisdom and start really living them.

The latest neuroscience research is presenting intriguing evidence that the brains of certain kinds of criminals are different from those of the rest of the population.

While these findings could improve our understanding of criminal behavior, they also raise moral quandaries about whether and how society should use this knowledge to combat crime.

The criminal mind

In one recent study, scientists examined 21 people with antisocial personality disorder - a condition that characterizes many convicted criminals. Those with the disorder "typically have no regard for right and wrong. They may often violate the law and the rights of others," according to the Mayo Clinic.

Brain scans of the antisocial people, compared with a control group of individuals without any mental disorders, showed on average an 18-percent reduction in the volume of the brain's middle frontal gyrus, and a 9 percent reduction in the volume of the orbital frontal gyrus - two sections in the brain's frontal lobe.

On an average day, 105 Americans lose their lives to suicide. And counterintuitively, more of these lives are lost when the weather is warm and the sun shines bright.

Folk wisdom holds that winter is the most common time for suicides, with depressive symptoms exacerbated by cold, dark weather. Another myth suggests that suicides spike around the holidays, when struggling people feel left out of the cultural cheer.

In fact, studies dating back to the late 1800s find that suicides peak in the spring and are lowest in winter. One 1995 study published in the journal Social Science & Medicine examined monthly suicide rates in 28 countries and found that in 25 in the Northern Hemisphere, suicides were most common in May and ebbed in February.

Similar findings occur in the Southern Hemisphere - in South Africa, for example, suicides peak in the southern spring, in September and October, according to a 1997 study in the journal Psychiatry Research.

The reason for this seasonality is unknown, but there are hints. Some researchers think weather or the ebb and flow of sociality drives the trend; others blame inflammatory processes that increase in spring.

American Randy Gardner holds the record for the longest ever scientifically documented intentional period without sleep. Without the aid of stimulants, he managed to stay awake for 264.4 hours, or 11 days and 24 minutes. Part of his motivation was to show that sleep deprivation wasn't that bad for you. He was wrong: it is bad for you.

In fact he suffered paranoia, hallucinations, moodiness and a whole host of psychological problems, many described below. It's just he did not notice many of the problems: that's how sleep deprivation gets you.

Here are 10 of the most profound psychological effects of sleep deprivation, on top of the fact that it feels horrible.

1. Sleepy brains work harder

Since brains that are sleep deprived aren't as efficient, they have to work harder.

This has been demonstrated in brain imaging studies which show the brains of the sleep deprived desperately pumping energy into the prefrontal cortex, trying to overcome the effects of sleep deprivation.

The study of psychology results is useful knowledge about how we think and act, which (we hope) can be used to make our lives better. But the knowledge gained can also be used to manipulate people. The various forms of psychological manipulation are usually subliminal, meaning they happen without the conscious awareness of their use by the target. I've reported on these techniques before, and will continue to do so.

My goal isn't to provide you with tools to do nasty things, but to make you aware of tricks that might be used on you. Also, this information is just plain interesting. So with that in mind, here is what you need to know (or might like to know) about cognitive dissonance and how it is used for psychological manipulation.

The fear of math has a genetic component, according to a new study to be published in the Journal of Child Psychology and Psychiatry (Wang et al., 2014).

The avoidance of mathematical problems and equations by children and adults isn't just down to bad early experiences with math or poor teaching.

To reach this conclusion, the study looked at the math anxiety of twins to tease out the genetic component. Zhe Wang, lead author of the study, explained the results:

"We found that math anxiety taps into genetic predispositions in two ways: people's cognitive performance on math and their tendency toward anxiety."

In other words people are anxious about math not just because they are generally anxious people and they're anxious about everything, but also because of genetically poor math/thinking skills.

New research from Emory University School of Medicine, in Atlanta, has shown that it is possible for some information to be inherited biologically through chemical changes that occur in DNA.

During the tests they learned that that mice can pass on learned information about traumatic or stressful experiences - in this case a fear of the smell of cherry blossom - to subsequent generations.

According to the Telegraph, Dr Brian Dias, from the department of psychiatry at Emory University, said: "From a translational perspective, our results allow us to appreciate how the experiences of a parent, before even conceiving offspring, markedly influence both structure and function in the nervous system of subsequent generations.

"Such a phenomenon may contribute to the etiology and potential intergenerational transmission of risk for neuropsychiatric disorders such as phobias, anxiety and post-traumatic stress disorder."

This suggests that experiences are somehow transferred from the brain into the genome, allowing them to be passed on to later generations. The researchers now hope to carry out further work to understand how the information comes to be stored on the DNA in the first place.

Stressed males tend to become more self-centered and less able to distinguish their own emotions and intentions from those of other people. For women the exact opposite is true. Stress, this problem that haunts us every day, could be undermining not only our health but also our relationships with other people, especially for men. Stressed women, however, become more "prosocial," according to new research.

These are the main findings of a study carried out with the collaboration of Giorgia Silani, from the International School for Advanced Studies (SISSA) of Trieste. The study was coordinated by the Social Cognitive Neuroscience Unit of the University of Vienna and saw the participation of the University of Freiburg. This is the main finding of a study just published in Psychoneuroendocrinology, carried out with the collaboration of SISSA in Trieste.

While previous studies have suggested a connection between contagious yawning and empathy, new research from the Duke Center for Human Genome Variation finds that contagious yawning may decrease with age and is not strongly related to variables like empathy, tiredness and energy levels.

The study, published March 14 in the journal PLOS ONE, is the most comprehensive look at factors influencing contagious yawning to date.

The researchers said a better understanding of the biology involved in contagious yawning could ultimately shed light on illnesses such as schizophrenia or autism.

"The lack of association in our study between contagious yawning and empathy suggests that contagious yawning is not simply a product of one's capacity for empathy," said study author Elizabeth Cirulli, Ph.D., assistant professor of medicine at the Center for Human Genome Variation at Duke University School of Medicine.

Contagious yawning is a well-documented phenomenon that occurs only in humans and chimpanzees in response to hearing, seeing or thinking about yawning. It differs from spontaneous yawning, which occurs when someone is bored or tired. Spontaneous yawning is first observed in the womb, while contagious yawning does not begin until early childhood.

Why certain individuals are more susceptible to contagious yawning remains poorly understood. Previous research, including neuroimaging studies, has shown a relationship between contagious yawning and empathy, or the ability to recognize or understand another's emotions. Other studies have shown correlations between contagious yawning and intelligence or time of day.