Attractiveness is certainly a complex matter. Previous research has suggested that people (and rats!) prefer the smell of potential partners who are genetically dissimilar (judged on the basis of large molecules -- MHC -- which help our immune systems distinguish native from alien cells). But a new study has found women regard men with similar MHCs as more facially attractive. So sight and smell appear to be giving contradictory messages about which partners to choose. Of course, women are contrary creatures; just because we regard men as good-looking doesn't mean we'd choose them as mates!

American Scientist has a brief interview with Michael Gazzaniga in the wake of his latest book, The Ethical Brain. There's an interesting comment that neuroscience might help us eventually work out what the interviewer calls a "secular, scientific basis for morality". An intriguing notion.

New York Times has an article about musical hallucinations. It's a problem that mainly afflicts older people, and particularly those who are partly deaf. I hadn't thought of it as a problem myself -- I hallucinate music sometimes, and I never thought of it as a problem, just slightly weird. It's always music that I've been hearing a lot of recently (not usually my own, oddly enough -- it usually seems to be music my son or partner have been playing a lot). In any case, I always assumed it was simply my brain hearing something it couldn't interpret (a not infrequent occurrence; I suspect I'm a touch deaf), and "filling in" with the closest familiar thing. This latest research seems to bear out my assumption. Full-blown auditory hallucinations are apparently more annoying than my own experience, however, and the rise in cases may reflect the much more constant musical background in our lives.

There's a fascinating article on Science News about a phenomenon that appears remarkably common, although not widely known -- that of sleep paralysis. Sleep paralysis is a dreaming state quite distinct from night terrors, or nocturnal panic, or even nightmares (although apparently this is the origin of our word for nightmares -- the word has changed its meaning over the centuries). Sleep paralysis is associated with dreams of evil spirits, monsters, demons, aliens ... often crushing your chest, or simply standing ominously nearby (or performing experiments on you!) The phenomenon is often widely acknowledged in pre-industrialized cultures (where presumably it is acceptable to talk about dead or evil spirits visiting you), but not in modern Western society. However, sleep paralysis is now becoming of scientific interest, probably because of its surprising frequency -- in surveys, roughly 30% have claimed to have had at least one such experience.

It's always been vaguely worrying that mice and men (sorry, don't mean to be sexist, just couldn't resist the alliteration and, of course, the Burns' reference) are so similar that their reactions in lab experiments are (rightly) considered indicative of human responses. Here's an interesting example -- 3 years ago, researchers quite accidentally deleted from a strain of lab mice a gene that's important for brain development. In so doing, they turned the mice into rabidly aggressive little monsters (in the behavioral sense! I don't mean to imply they were deformed in any way). Understandably intrigued by this, the researchers decided to give the next generation the human version of the gene they were missing, and voila, the nasty turned nice!

Does this mean we can breed aggression out of the human race? (Should we if we could?)