Another is whether a set of bacteria is essential for basic human physiology-in other words whether humans really are symbiotic creatures who would die without their collaborators.

So they agreed to organise a trip to Dignitas, a Swiss organisation set up in 1988 to help those suffering from terminal illnesses or unbearable pain to die "with dignity".

This is, in part, because old ones never die; they just set their meetings to occur on the sidelines of the shiny new institutions' gatherings.