Recommended if you have access, or perhaps on world service.
The title is a bit click-bait-ish, but the science seemed sound, rounding up different types of experiments trying to determine when 'morality' starts in infants, and examining differences between murderers' brains and other peoples' in their activity areas, enquiring about any brain injuries they had (like shaken babies) that might change their brains.
Interesting stuff about the competition between oxytocin (which encourages humans to bond) and testoterone (which makes people more aggressive).
A nice demonstration with a rugby team, with men playing together in warmup and practice: levels of both hormones rise as they practice, encouraging them (theoretically) to both work together effectively, and be more 'pumped' for physical action.
The bit that really interested me was training US marine recruits in hand to hand combat.
The trainer they interviewed said that when you train men by de-humanising the enemy, by calling them names (gooks, hajjis) and making them out to be sub-human, you start to break down the sense of moral right and wrong in the person. They carry that home and start beating up on their families and being generally aggressive to everyone.
The trainer said the more effective way to train to prepare to kill hand to hand is to appeal to the marines' sense of right and wrong, where they are presented as the defender and protector (IIUC, the hero of the narrative, not the bad guy).
In this way, you can train them to kill other people without breaking down their sense of who they are, and making them generally outwardly violent all the time.
This fits well with the idea that there are 'good' wars, where it's the right thing to do to sign up to defend your country, and there are 'dirty' wars, where it is not - or where those who fight are doing it for the 'wrong' reasons.
It also fits with the 'justifiable' war idea from the middle ages, and from the church: that it's ok to kill people for the sake of reclaiming Jerusalem for the Church, or to protect pilgrims, or to ensure access to holy shrines.
Those would be the right reasons for a Christian to fight, without having to appeal to the 'they're unbelievers so killing them doesn't matter' theory, which leads to dehumanising the enemey.
This whole idea really struck me; I'd always wondered how 'warrior monks' of any creed could reconcile their conflicting beliefs without their heads exploding. Yet it's clearly possible because lots of devout people fight, in history and today, in all faiths.
Now, it seems, there's a rational (as in, one that works w/ human brains in a predictable fashion) explanation.