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Press Release
Exposure to Heavy Metal Music increases Testosterone in Developing Foetuses
Friday, April 1, 2011

(Photo: Jeroen van de Sande/STOCK.XCHNG)

Listening to Heavy Metal Music, such as Iron Maiden and Metallica, in utero has developmental implications, according to a recent longitudinal study published in the Journal of Infant Development.

Foetuses exposed to Heavy Metal music for 25 minutes a day in the second and third trimesters of pregnancy have been found to be have 18% higher levels of pre-natal testosterone, levels that do not appear to decrease until after the 5th year of development.

Dr. Hetfield, lead author of the study, claims increased testosterone can have developmental implications. "Primarily we found increased levels of trait aggression", Hetfield said. "What we didn't expect was that at these levels of Heavy Metal exposure, male infants, in particular, were born with a significant degree more hair on their scalp".

In a series of 12 follow-up studies, conducted every 6 months after birth, researchers found that infants grew slightly faster and larger than controls, continued to grow unusual lengths of head-hair, and displayed higher levels of trait aggression than controls, or levels of parental testosterone would have predicted.

"We're calling this the Metallica Effect", Dr. Hetfield said, "it is completely counter-intuitive that loud rock music should have this kind of influence over the development of the embryo". Dr. Hetfield speculates that the volume of the music, as well as the dominant percussive rhythms and unique vocal 'screaming' triggers evolutionary responses for the foetus to grow larger, stronger and more 'primal' than control. "I guess we're mimicking conditions similar to early hominid warfare. You can see the advantage in growing faster and stronger when such cues are present".


Developmental Science:

Thanks to Developmental Science for this article.

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Guest Comment
Fri, May 18, 2012, 4:28 am CDT

Did anyone else notice that this was written by Dr. Hetfield (James Hetfield from Metallica), I'm not sure if that's just a coincidence or not. But more to the point I'm not surprised that listening to heavy metal increases testosterone because some of my favourites lift my mood if I'm feeling a bit down.

Brian Krueger, PhD
Columbia University Medical Center
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Fri, May 18, 2012, 8:39 am CDT

I think you should also note the date of publication and the link to the source material ;)


Guest Comment
Sun, Sep 09, 2012, 12:04 pm CDT

i like turtles 


Guest Comment
Tue, Jan 22, 2013, 12:53 pm CST

this is hilarious


Guest Comment
Tue, Jun 18, 2013, 2:56 pm CDT

Dr Hetfield?? you kidding me right? haha

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