Behavior on two sinking ships

Imagine you were on a sinking ship, people around you were running, screaming and crying. A great panic was clearly underway and you soon realized this was a life-or-death situation and of course, you, like anybody else, want to survive. Now what would you do? Will you fight your way through to reach the lifeboat or will you be such a gentleman and follow the norm of letting the women and children go first? A recent study shows that, this really depends.

Using two datasets from two real accidents, the sinking of Titanic and Lusitania, researchers found out that under extreme conditions, people may behave drastically different. One critical factor is the scarcity of time.

"...differences in context are likely to matter in life-or-death situations. The comparison between the Titanic and the Lusitania suggests that when time is scarce, individual self-interested flight behavior predominates, while altruism and social norms and power through social status become more important if there is suffificient time for them to evolve..."

Sounds plausible, but a more myterious question is further imposed, how long will be sufficient enough to develop an altruistic norm? Aren't there always people with quite stable altruistic preferences? Why wouldn't these preferences take over instantly? What's the relationship between the severity of the situation and the time we need to develop an altruistic norm?

Also, there could be other important but untouched factors, one of which is the cause of the disaster. Whether the situation is totally man-made or largely natural may have direct effects on people's behavior.