What secret lays behind Yellow color?

In some countries in middle Asia ("also in any other countries or Continents perhaps") People says the yellow color brings separateness, just like the yellow leaves, when they become yellow the fall down or in other words become separated from the Tree. ()

Of course this is because of Fall season, but this is also true that leaves which are yellow fall down but green ones no..

My little brother likes to be in photos I take in any way he can.