Understanding evolution.

At the end of the 20th cen tury mo lec u lar ge net ics has been the cen tral theme in bi o log i cal thought. No body ques tions the im por tance of ge net ics, nor ar gues that DNA plays the role of the blue print of life for all com po nents of the liv ing cell. How ever, we still do not un der stand the gen eral mech a nism of the cell func tion and de vel op ment. The se quence of the hu man ge nome as well as other genomes is gen er ally be lieved to be the start ing point of bi o log i cal and bio med i cal in ves ti ga tions in the fol low ing cen tury and of the de bate on the or i gin of life. Life de pends on the in ter ac tion of thou sands of genes and their pro tein prod ucts, or ches trated by the reg u la tory logic of each ge nome. If we are to com pre hend this logic, we must hope that it can be dis sected into a se ries of inter linked mod ules or net works, each of which can be stud ied in rel a tive iso la tion. But even then, the com plex ity of a sin gle mod ule can be daunt ing. There is a hope that de tailed an no ta tion of the da ta base of genes and in-depth ex plo ra tion of the physi co-chemical prin ci ples of liv ing sys tems will bring us closer to the un der stand ing of the cell. The ba sis of our in sight into cell supra mo lecu lar struc ture is the doc trine of self as sem bly and self or gani sa tion which is a di rect ex ten sion of the cen tral dogma of mo lec u lar bi ol ogy from the real se quence of lin ear in for ma tion to the third di men sion of pro tein and as sem blies. The mechanism of self-assembly is very pow er ful and it op er ates far be yond atomic di men sions to form very com plex struc ture like ri bo somes or spliceosomes. At each level, novel laws can be found whose nec es sary, sep a rate study has de fined par tic u lar dis ci pline. As Phil An der son once said psy chol ogy is not ap plied bi ol ogy, it is not ap plied chem is try or it is not ap plied phys ics. The features of the very same sys tem de pend on the scale of ob ser va tion. This pre cludes the ex trap o la tion of knowl edge at one level to higher lev els, where the “com plex ity” in creases. Un der stand ing why this is so and de ter min ing Vol. 48 No. 2/2001