Research on "sea monkeys" shows that having sex with a time traveler might be bad for your health
Sea monkey sexual behavior is particularly interesting to scientists because it is so deadly and risque. For instance, male sea monkeys have evolved specialized "claspers" which hold tight to a female during the mating process to prevent her from escaping and mating with other males. Because this can be harmful and oppressive to the females, the females have developed a few tricks of their own. Some females deploy acrobatic wrestling skills which help them pry off overly aggressive males. Developing these skills can save a female's life, since clasped males can prevent them from feeding or escaping from predators.