sciencemag.org

COLD DISCOMFORT

Ask medieval historian Michael McCormick what year was the worst to be alive, and he's got an answer: "536." Not 1349, when the Black Death wiped out half of Europe. Not 1918, when the flu killed 50 million to 100 million people, mostly young adults. But 536.
ONE FOR THE RESEARCH LOGS

No buts about it, the butthole is one of the finest innovations in the past 
540 million years of animal evolution. Now, several unprecedented videos of gelatinous sea creatures called comb jellies, or ctenophores, threaten to upend the standard view of the evolution of the so-called through-gut.