But wherever the truth lies, the consequence should be an increase in fecundity that is related to the age gap.
The astonishing fecundity of all the species of salmon, and the extraordinary numbers and size of the fish that ran the rivers of Europe and America, are described in great detail.
Britain's boom will be fuelled by a mix of immigration and a comparatively high birth rate (partly a consequence of the higher fecundity of its immigrants).Besides getting bigger, Britain will also remain youthful, at least by EU standards.
That might mean reduced fecundity, and a smaller shrimp population next year.
Their fecundity is offsetting losses in central and west Africa.
By 2030, demographers say, Japan will have just two working-age people for each retired one; by mid-century, short of a rapid and unlikely return to fecundity, the ratio will rise to three for every two retirees.Can a working population support such a number of future retirees?
These might include fertility, fecundity, social status, present health, and likely resistance to future infection and infestation.
This is a country where many people entertain a widespread conspiracy theory that vaccinating for polio is a Western plot to curb Muslim fecundity.
But he also has a lot of good points to make.These mostly revolve around America's two great strengths: the vast amounts of space on which it can still build and the remarkable fecundity of its people.
A large doll often presented to the birthday girl is also said to be Puerto Rican, signalling either the end of childhood or the fecundity of the teenager on show.Mexico is responsible for such core traditions as the honour court of boy and girl escorts and very puffy dresses.
The weather may still be in the lap of the gods but the fecundity of the soil can now be improved by more down-to-earth means.
