During the 17-plus-months of their virtual voyage, the crew took part in various studies to assess theeffect their isolation was having on their psychological and physiological well being.
It is based on a piece of evolutionary theory called the founder effect, which shows how theisolation of small populations from larger ones can accelerate evolutionary change, because a small population's average characteristics are likely to differ from those of the larger group from which it is drawn.
"We have got to be clear that the requirement for the carriers is part of a joint requirement for defence as a whole, and theeffect they provide is a joint effect, not a maritime effect in isolation, " he said.