Feeding habits of teenage galaxiesNew observations made with ESO's Very Large Telescope are making a major contribution to understanding the growth of adolescent galaxies. In the biggest survey of its kind astronomers have found that galaxies changed their eating habits during their teenage years -- the period from about 3 to 5 billion years after the Big Bang. At the start of this phase smooth gas flow was the preferred snack, but later, galaxies mostly grew by cannibalising other smaller galaxies.
Source: Feeding habits of teenage galaxies (http://www.sciencedaily.com/releases/2012/03/120314100707.htm)