Washington, Aug 14 - Why do autumn leaves boast yellow hues in Europe and lustrous red in Asia and America?

A new theory provided by Simcha Lev-Yadun, professor of biology at the University of Haifa-Oranim and Jarmo Holopainen of the University of Kuopio, Finland, propose taking a step 35 million years back, to solve the mystery.

The green of a tree's leaves is from the larger proportion of the chlorophyll pigment in the leaves. The change in colour to red or yellow as autumn approaches is not the result of the leaves' dying, but of a series of processes -- which differ between the red and yellow autumn leaves.

When the green chlorophyll in leaves diminishes, the yellow pigments that already exist become dominant and give their colour to the leaves.