The essentials for human life
Element Life expectancy
Oxygen a very few seconds
Clean water supply a few days
Nourishing food supply maby a week
Tender loving care One generation
An intellectual challange A few generations
Oxygen, without which the human brain would cease in a very few seconds, a clean supply of water, similarly but a little longer, a nourishing supply of food, longer but still not long , tender loving care (human contact without which we never emerge that is realize that 'I' am not all there is in the universe) and finally the intellectual challenge, the problem to overcome.