"Why did witchcraft persecution peak in the period 1560-1660? Perhaps the weather was to blame. This was a cold century. The Thames River froze over in 1565, 1595, 1608, 1621, 1635, 1649, and 1655; it has not done so as often in any one hundred year period since.
Cold winters traumatize rye and increase the risk of ergot alkaloid formation. Such alkaloids may have caused the symptoms of bewitchment. When the incidence of these symptoms increased, so did the incidence of witchcraft persecution. ... Ergot is the source of lysergic acid diethylamide (LSD), and it may include natural alkaloids that act like LSD. People under the influence of this compound tend to be highly suggestible. They may see formed images for instance, of people, animals, or religious scenes whether their eyes are open or closed. These hallucinations can take place in the presence or absence of social cues."

The brainier male bats are, the smaller their testicles, according to a new study. Researchers suggest the correlation exists because both organs require a lot of energy to grow and maintain, leading individual species to find the optimum balance. The analysis of 334 species of bat found that in species where the females were promiscuous, the males had evolved larger testes but had relatively small brains. In species, where the females were monogamous, the situation was reversed. Male fidelity appeared to have no influence over testes or brain size.

[Researcher Scott] Pitnick and his colleagues had predicted that, in species with promiscuous females, males would require bigger brains in order avoid being cuckolded. So they were surprised to find the opposite: "Perhaps monogamy is more neurologically demanding." [read full article in New Scientist]