Read the following passage and answer the item that follows. Your answer to this item should be based on the passage only.

Natural selection has no foresight: it can only favour traits that already exist within a population when a new pressure, a novel pathogen, a changed climate or a new predator, arrives, never traits a species might need decades later. This is why, in modern terms, resistance to an antibiotic already circulating at low levels in a bacterial population can spread rapidly once that antibiotic is used widely, while a bacterium cannot evolve resistance to a drug it has never encountered in anticipation of that drug's future invention. Extinction, on this view, is not a failure of some species to try hard enough; it is simply what happens when a population's existing genetic variation does not happen to include a trait suited to a pressure it did not evolve to expect.

With reference to the passage, the following assumptions have been made:

1. Only populations carrying suitable pre-existing variation will survive a genuinely novel pressure.

2. Resistance already present at low levels in a population can become widespread once the relevant pressure is applied broadly.

Which of the above assumptions is/are valid?