The results of numerical calculations, which show how the free nucleon structure function F2N ( A = 1) evolves to the deuteron ( A = 2) and helium ( A = 3 and 4) structure functions, are presented in the left plot. The evolution, which starts from the deuteron structure function F2D, is shown in the plot on the right. Contrary to what is observed for nuclei with masses A > 4, the pattern of the oscillation of rA(x) changes its shape in the range of A < 4.