Some mathematicians note that their intellectual powers (at least where mathematics is concerned) seem to diminish with age, for instance Hardy. Was this griping a mere excuse for their lack of talent to begin with? Other prodigies appeared to have retained their mathematical fecundity into old age - Euler, Gauss and Newton, while others only bloomed in their fourties, for example, Weierstrass. Does anyone here think that age-related declines in fluid intelligence, or 'g', affect mathematicians more than experts in other disciplines? More importantly, can a high level of 'g' (above the level needed for scientific productivity) be maintained into old age? Can experience really compensate for deficits in computational power and clarity of mind?