tense inconsistency

[hanuman_2000]

Sir,

Man also found that when two stones struck against each other,they produced fire.

Here the statement is about past, but the fact is still true.

So, Can we use "they produce fire " in place of "they produced fire".

Thanks.

[Alan]

Informally, yes. In formal/careful usage, however, tense concord requires the preterite, irrespective of applicability at the time of speaking.