A sneak preview of the October 14, 2010 episode of Grey's Anatomy, "Can't Fight Biology." It's an emotional episode from the looks of it.
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A promo for "Can't Fight Biology," the fourth episode of the Grey's Anatomy season. There's some intense stuff going on, it looks like.
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Grey's Anatomy Season 7 Episode 4 Quotes

(to Meredith) You know this isn't normal.

Derek

Biology determines much of the way we live. From the moment we're born we know how to breathe and eat. As we grow older new instincts kick in. We become territorial. We learn to compete. We seek shelter. Most important of all, we reproduce. Sometimes biology can turn on us though. Yeah, biology sucks sometimes.

Meredith

Grey's Anatomy Season 7 Episode 4 Music

  Song Artist
Until the last falling star Until The Last Falling Star Matthew Perryman Jones iTunes
Tumblin down Tumblin Down Jenna Andrews iTunes
Song Further Correatown iTunes