Among health issues that some advocates have linked to chemical exposures: early pubescence in girls (BPA hastens the onset of pubescence in juvenile rats); asthma (car and truck exhaust can induce or worsen lung inflammation), and genital malformation (phthalates have been linked to lower sperm count and deformed penises in rats). (blogs.scientificamerican.com)
Accordingly, we feel justified in cautiously advancing and empirically cultivating the theoretical possibility that there is some kind of an ancestral relationship between the playful chirps of juvenile rats and infantile human laughter. (scientificamerican.com)
Aside from anecdotes, we know very little about nonhuman primate laughter and humor, but some of the most significant findings to emerge in comparative science over the past decade have involved the unexpected discovery that rats — particularly juvenile rats — laugh. (scientificamerican.com)