"It suggests that this major morphological change did not occur through the acquisition of new genes but by simply modifying their activities," added Dr. Marie Kmita.

I don't understand the difference between acquiring new genes and modifying activities of genes... I thought these are protein molecule chains. What is the difference between "acquiring new" molecule chains and "modifying activities" of molecule chains? Surely it's different pattern permutation of same elements from both points of view, no?