In research that recalls 1920s experiments with <a href="http://en.wikipedia.org/wiki/Muzak" target="_blank">muzak</a>, primate specialists have discovered what sounds make monkeys happy... Metallicaaaa!!!!  I think I'd have been pretty irritated myself listening to what the tamarins were presented with.

From the <a href="http://www.guardian.co.uk/science/2009/sep/23/monkey-music-tamarins" target="_blank">Guardian</a>:

<em>In the study, 14 cotton-top tamarins were played 30-second blasts of music while the researchers noted any changes in their behaviour. The animals were played Samuel Barber's Adagio for Strings and a soft piano piece from The Fragile by rock band Nine Inch Nails, followed by Metallica's Of Wolf and Man and an excerpt from The Grudge by rock band Tool.</em>

<em>They then heard the specially composed monkey music.</em>

<em>The only human music that elicited any response was the heavy metal band Metallica, whose music had the unexpected effect of calming the monkeys.</em>

<em>The research could lead to a rethink of animal husbandry guidelines, as it showed that monkeys rarely respond positively to human music. "Lots of primate research laboratories use radios to provide what is called 'enrichment' for their animals, but you can't expect another species to be interested in our music just because we are human," Snowdon said. "Why should a tamarin find our music comforting? I find the monkey music quite irritating"</em>

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