Can there be ethics without Torah?

Is there an ethical norm that exists independent of Torah, or is ethical behavior just a side-product of proper observance of the mitzvos? There is a machlokes in Zevachim whether Yisro came before mattan Torah or after mattan Torah. R' Kook explains (I forget where I saw this) that the machlokes is not just historical, but philosophical. Yisro was a man of ethics, a man searching for truth and goodness. Can the ethical man symbolized by the personality of Yisro precede the Torah, perhaps as a prerequisite for Torah (the Sefas Emes writes that the opnion that Yisro preceded mattan Torah is based on the idea of "derech eretz kadma l'Torah), or is ethics only possible a a result of the religious experience?
The Netziv has an interesting comment on the Torah's promise of long life in Eretz Yisrael for proper observance of kibbud av v'eim. Explains the Netziv, the ideal fulfillment of Torah is only in Eretz Yisrael. However, one might have the mistaken notion that this is true of the ritual of Torah, but not ethical mitzvos. In truth, however, ethicals and ritual are one and the same; we observe kibbud av v'eim not because it is morally correct, but simply because the Torah commands such. Even ethical mitzvos should be viewed only as gezeiros of Hashem. The Torah underscores this by emphasizing that ethics too can only be fully fulfilled in Eretz Yisrael.