It's said that humans can become addicted to cats. The cause? A little parasite called toxoplasmosis gondii. Toxoplasmosis, the disease that is caused by the parasite, can affect nearly all living creatures, though it is most common in cats. Despite that statistic, it's been documented in humans as far back as the days of Ancient Egyptians , as evidenced by their mummies. And many think the parasite can influence humans to engage in risky, even psychotic behavior. A bit less seriously, scientis…