> perhaps another interesting question - how to deliberately leave an indicator that we did exist? Replace as many plants and animals as we can with geneticall

> perhaps another interesting question - how to deliberately leave an indicator that we did exist? Replace as many plants and animals as we can with genetically engineered versions that have messages encoded in their junk DNA. That would not be good enough to tell aliens who visit long after all life on Earth has gone extinct that we were here, but could work for future intelligent species that evolve from existing Earth life after humanity is long gone.