Being smart is the most expensive thing we do. Not in terms of money, but in a currency that is vital to all living things: energy. One study found that newborn humans spend close to 90 percent of their calories on building and running their brains. (Even as adults, our brains consume as much as a quarter of our energy.) If, during childhood, when the brain is being built, some unexpected energy cost comes along, the brain will suffer. Infectious disease is a factor that may rob large amounts of energy away from a developing brain. This was our hypothesis, anyway, when my colleagues, Corey Fincher and Randy Thornhill, and I published a paper on the global diversity of human intelligence.

A great deal of research has shown that average IQ varies around the world, both across nations and within them. The cause of this variation has been of great interest to scientists for many years. At the heart of this debate is whether these differences are due to genetics, environment or both.

One in three women suffer from the 'post-sex blues', according to Australian scientists.

More than 200 young women were quizzed on life between the sheets and 33 per cent reported feeling depressed after sex at some point in their lives.

The researchers are now trying to understand why some people experience the phenomenon.

Study author Robert Schweitzer, from the Queensland Institute of Technology, said: 'Under normal circumstances, the period just after sex elicits sensations of well-being, along with psychological and physical relaxation.'

But, he added, rather than any afterglow, some people instead have feelings of 'melancholy, tearfulness, anxiety, irritability or restlessness'.

'The findings are so counter-intuitive,' he continued. 'Everyone imagines sex as an enjoyable experience. But there seems to be a group of people who, in fact, experience distress following intercourse.

A new understanding of how the brain processes time could one day allow scientists to tweak an individual's sense of timing.

New research suggests timekeeping in the brain is decentralised, with different neural circuits having their own timing mechanisms for specific activities.

Not only does it raise the possibility of artificially manipulating time perceptions, but the finding could also explain why our sense of time changes in different conditions - such as when we are having fun or are under stress.

Two researchers from the University of Minnesota in Minneapolis trained to rhesus macaques to perform tasks requiring them to move their eyes between two dots in regular one-second intervals, New Scientist reported.

Despite having to external cues to help them keep track of time, after three months the monkeys had learned to move their eyes between the dots with average intervals of 1.003 and 0.0973 seconds respectively.

Using electrodes, the researchers then recorded brain activity across 100 neurons in the monkeys' lateral intraparietal cortex - the brain region associated with eye movement - as they performed the task.

Scientists from the Florida campus of The Scripps Research Institute (TSRI) have shown that a single protein plays an oversized role in intellectual and behavioral development. The scientists found that mutations in a single gene, which is known to cause intellectual disability and increase the risk of developing autism spectrum disorder, severely disrupts the organization of developing brain circuits during early childhood. This study helps explain how genetic mutations can cause profound cognitive and behavioral problems.

The study was published in the November 9, 2012, issue of the journal Cell.

The genetic mutations that cause developmental disorders, such as intellectual disability and autism spectrum disorder, commonly affect synapses, the junctions between two nerve cells that are part of the brain's complex electro-chemical signaling system. A substantial percentage of children with severe intellectual and behavioral impairments are believed to harbor single mutations in critical neurodevelopmental genes. Until this study, however, it was unclear precisely how pathogenic genetic mutations and synapse function were related to the failure to develop normal intellect.

When people make hasty decisions, they tend to make more mistakes. Now, a new study on monkeys explains why: Brain cells become hypersensitive to new information, even bad information, making us likelier to draw faulty conclusions.

"When we try to do things too quickly, we tend to make more errors and then when we slow down we tend to be more accurate," said study co-author Richard Heitz, a neuroscientist at Vanderbilt University. "Your brain sees things differently when you're placed into a situation where you have to make snap decisions."

The findings, which are detailed in the Nov. 7 issue of the journal Neuron, could shed light on the faulty decision-making of people with schizophrenia or other mental disorders.

To explain the phenomenon, Heitz and his colleagues trained two macaque monkeys to play a game in which they had to pick out the letter L in a sea of Ts or vice versa.

Before each round, a colored circle flashed on the screen to indicate whether the macaques would be rewarded for speed or accuracy.

Surgeons have been using general anesthesia since the 19th century, but until now physicians and neurologists didn't know exactly how brain activity correlates to the loss of consciousness.

A new study from Massachusetts General Hospital (MGH) and Massachusetts Institute of Technology (MIT) that was recently published in the journal PNAS demonstrated how distinctive brain activity patterns are associated with the loss of consciousness.

"How anesthetics produce unconsciousness is a major scientific mystery, so this finding is very important because it suggests a specific mechanism for how propofol, one of the most widely used anesthetic drugs, works," said study author Patrick Purdon, from MGH and Harvard Medical School. "The pattern that we found marks a new brain state in which neurons in different areas become inactivated at different times, impairing communication between different brain regions."

The study focused on three patients who had electrodes surgically implanted into their brain as a part of epilepsy treatment. Just before the surgery to remove the electrodes, patients were given the anesthetic propofol and then asked to push a button whenever they heard a tone, which was sounded every four seconds. If a patient missed two tones in a row, that time period was identified as the point when consciousness was lost.

Measurements of the action of single neurons by the still-functioning electrodes showed a reduction in overall activity 30 seconds after consciousness had been lost.

How do you know when you're attracted to a new face? Thank your medial prefrontal cortex, a brain region now discovered to play a major role in romantic decision-making.

Different parts of this region, which sits near the front of the brain, make a snap judgment about physical attraction and about whether the person is Mr. or Ms. Right - all within milliseconds of seeing a new face, a new study from Ireland finds.

The research is the first to use real-world dating to examine how the brain makes fast romantic judgments.

To conduct the study, researchers recruited 78 women and 73 men, all heterosexual and single, from Trinity College Dublin to participate in a speed-dating event. Like any typical speed-dating night, participants rotated around the room and chatted with one another for five minutes. After this meet-and-greet, they filled out forms indicating whom they'd like to see again.

But before the speed-dating event, 39 of the participants had their brains imaged. Using a functional magnetic resonance imaging machine (fMRI), researchers recorded the volunteers' brain activity as they saw pictures of the people they'd soon meet at the event. For each picture, the volunteers had a few seconds to rate, on a scale of 1 to 4, how much they would like to date that person. They also reported their physical attraction to each person and how likeable they thought each person was.

Humans can smell fear and disgust, and the emotions are contagious, according to a new study.

The findings, published Nov. 5 in the journal Psychological Science, suggest that humans communicate via smell just like other animals.

"These findings are contrary to the commonly accepted assumption that human communication runs exclusively via language or visual channels," write Gün Semin and colleagues from Utrecht University in the Netherlands.

Most animals communicate using smell, but because humans lack the same odor-sensing organs, scientists thought we had long ago lost our ability to smell fear or other emotions.

To find out, the team collected sweat from under the armpits of 10 men while they watched either frightening scenes from the horror movie The Shining or repulsive clips of MTV's Jackass.

Sexual harassment is devastating in and of itself for its victims, but new research shows there can be an even more insidious and troubling consequence that goes along with it:

When confronted with sexual harassment, we don't stand up for ourselves to the extent we believe we will, and because we use false predictions as a benchmark, we condemn others who are passive in the face of sexual harassment, according to a new study co-authored by Ann Tenbrunsel, professor of business ethics at the University of Notre Dame.

In "Double Victimization in the Workplace: Why Observers Condemn Passive Victims of Sexual Harassment," forthcoming in Organization Science, Tenbrunsel, and researchers from the University of Utah and Brigham Young and Northwestern Universities, conducted five studies that explored observers' condemnation of passive victims.

Pointing to the 1991 Senate confirmation hearings for Clarence Thomas' appointment to the Supreme Court, the researchers note that Anita Hill testified she had been sexually harassed by Thomas during his tenure as head of the Equal Employment Opportunity Commission. She testified that despite being harassed numerous times years before, at no point did she confront Thomas about his behavior or take any action against the harassment. Her claim of repeated sexual harassment and perpetual inaction led to public suspicion with and condemnation of Anita Hill.

Believe it or not, there's a lot to be learned from babies. In the 1890s the American philosopher and psychologist William James speculated that infants do not enter the world as 'blank slates' as had been previously thought.

Flying in the face of conventional wisdom, James suggested that rather than passively absorbing information from their environment, babies come equipped with a great deal of built-in cognitive machinery already in place to help them interact with, understand and process the foreign world that they enter into.

One of the challenges of developmental psychology has been to understand how an infant's pre-installed cognitive hardware interacts with and processes its environment over time to acquire an understanding of things like social cues, the emotions of others, language and even the basic laws of physics.

One significant part of the challenge of understanding cognitive development in babies can be traced to the very simple fact that they have only a very limited ability to communicate. In fact, one could almost say that babies speak binary: They cry when they're displeased and smile when they're happy - and there doesn't seem to be a whole lot in between.

And yet for a group of scientists in London, the language of laughter is a rich and informative one that can help us to unlock many secrets in the development of the infant mind.