On the face of it, revenge is a simple thing - someone slights us, we feel angry, and we want payback.
But there's much more to it than that.
Swiss scientists have been able to show for the first time how this desire - and how we quell it - manifests at the deepest level of our brains.
The researchers developed a game in which a participant is confronted with the fair behaviour of one player, and the unfair provocations of another.
They then observed, through brain imaging, which areas were activated as the study participant experienced unfairness and anger.
Later, they gave the participant the opportunity to take revenge, which revealed the location in the brain that quickly suppressed the act.
The more active the dorsolateral prefrontal cortex was during the provocation, the less the participant took revenge.
The breakthrough led the researchers to ponder whether stimulating this area of the brain could ultimately stop people from striking back.
Is smartphone addiction personal?
Is there a relationship between personality traits, smartphone use and addiction?
International researchers found a significant correlation between the "big five" personality traits - that's neuroticism, extraversion, openness, agreeableness and conscientiousness - and smart phone addiction.
In the study of over 700 high school and university students, they looked at things like the number of hours spent using the smartphone, its general use, attitudes towards it and anxiety without technology and found more than a quarter of the participants met the definition of a smartphone addict.
The researchers found those with higher neuroticism, lower conscientiousness and lower openness were more likely to be smartphone addicts.
The researchers say emotions like anger, irritability and feelings of insecurity could explain the link between specific personality traits and smartphone addiction.
The science of... sexy selfies
In other smartphone-related science, Australian researchers have suggested that women tend to sexualise themselves in environments with greater economic inequality, rather than where they might be oppressed because of their gender.
The University of New South Wales team analysed tens of thousands of social media posts across 113 countries.
Lead author Dr Khandis Blake said her team tracked posts where people had taken selfies and then noted that they were tagged sexy, hot or similar.
"We then looked at where in the world these things happened most," she said.
"The number one way that psychologists usually look at women's preoccupation with their appearance is that it happens because of patriarchal pressures – that women live in societies that value their appearance more than their other qualities.
"The argument is usually that when you see sexualisation, you see disempowerment.
"What we found instead is that women are more likely to invest time and effort into posting sexy selfies online in places where economic inequality is rising, and not in places where men hold more societal power and gender inequality is rife."
The findings were consistent across different geographic locations, even after taking into account and controlling for other factors that could influence patterns, like population size, human development and internet access.
The researchers say that income inequality increases competitiveness and status anxiety amongst people at all levels of the social hierarchy, making them sensitive to where they sit on the social ladder and wanting them to do better than others.
"That income inequality is a big predictor of sexy selfies suggests that sexy selfies are a marker of social climbing among women that tracks economic incentives in the local environment," Blake said.
"Rightly or wrongly, in today's environment, looking sexy can generate large returns, economically, socially, and personally."
Genetic link to cannabis addiction?
The biggest ever study into genetic predisposition for cannabis use has turned up a list of genes that influence whether people are likely to ever use the drug.
The team of scientists also identified genetic links between cannabis use, some mental health conditions and certain personality traits amid DNA samples from more than 180,000 people worldwide.
"We examined millions of genetic variants and identified 35 genes that influence whether a person is likely to use cannabis during their lifetime," said Professor Eske Derks, of Brisbane-based QIMR Berghofer Translational Neurogenomics Laboratory.
"Together, the genetic variants we examined account for one quarter of the genetic or inherited influence on cannabis use.
"Of course, there are also social and environmental factors that contribute to whether a person will use cannabis."
The researchers also found that there was a genetic overlap between cannabis use and certain mental health disorders, personality traits and use of other substances.
"We found that there was a genetic link between cannabis use, tobacco and alcohol use, risk of developing schizophrenia and bipolar disorder, and certain personality traits including risk-taking behaviour," Derks said.
"In other words, the genes that increase the likelihood of cannabis use also influence these other traits and conditions."
The study also examined the link between cannabis use and schizophrenia in more detail.
"We used a new technique and found that the genes that contribute to developing schizophrenia also make people more likely to use cannabis," Derks said.
"In other words, people who are genetically predisposed to developing schizophrenia are at higher genetic risk of using cannabis."
This may suggest that people with schizophrenia use cannabis to cope with the symptoms.