Quantifying morphological evolution from low to high redshifts

Establishing the morphological history of ordinary galaxies was one of the original goals for the Hubble Space Telescope, and remarkable progress towa rd achieving this this goal has been made. How much of this progress has be en at the expense of the Hubble sequence? As we probe further out in redshi ft space, it seems time to re-examine the underlying significance of Hubble 's tuning fork in light of the the spectacular and often bizarre morphologi cal characteristics of high redshift galaxies. The aim of this review is to build a morphological bridge between high-redshift and low-redshift galaxy populations, by using quantitative morphological measures to determine the maximum redshift for which the Hubble sequence provides a meaningful descr iption of the galaxy population. I will outline the various techniques used to quantify high-redshift galaxy morphology, highlight the aspects of the Hubble sequence being probed by these techniques, and indicate what is gett ing left behind. I will argue that at higher redshifts new techniques (and new ideas) that place less emphasis on classical morphology and more emphas is on the link between morphology and resolved stellar populations are need ed in order to probe the evolutionary history of high-redshift galaxies.