>As we all know, time travelers have to be very careful when they visit the past, because their evolved immune systems allow them to harbor pathogens that the olde timey people are defenseless against.
Actually it goes both ways. Evolution doesn't have an arrow, and a because their evolved immune systems allow them to harbor pathogen that the 10.000B.C people had evolved to defend against might be lethal in the 22nd century.
Actually it goes both ways. Evolution doesn't have an arrow, and a because their evolved immune systems allow them to harbor pathogen that the 10.000B.C people had evolved to defend against might be lethal in the 22nd century.