2 dogs 1 keeps licking others head

Question
hi i have 2 male golden retrievers ( not related ) the younger one 3yrs, has recently started to lick the older ones top of the head 5yrs any ideas why?

Answer
As I just said on another site, why is often speculative.  It may be the 3 year old is now mature and is messing with the top of the older dog's head to challenge it for pack rank.  Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog.  Life is much easier if the 2 legged pack members outrank the 4 legged ones.  You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/  For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm  It leads to fewer problems if they are competing for second place.