Not just markers: Diverse implications of molecular data from wild primate populations Clifford J. Jolly1,2 1Center for the Study of Human Origins, Department of Anthropology, New York University, 2New York Consortium in Evolutionary Primatology (NYCEP) Abstract The definition of evolution as “descent with modification” encapsulates the fact that the heritable variation among taxa, from Phyla down to intra-specific populations and kindreds, carries two kinds of information. On the one hand are conserved attributes signalling ancestor-descendant relationships, on the other, novel features generally attributable to the action of evolutionarily recent natural selection. The two sets of information are mirror images, in the sense that signal for each of them is noise for the other. Historically, each new set of molecular information (antigens, proteins, DNA sequences) has been hailed as an unambiguous key to phylogeny, and subsequently shown to be influenced, to varying degrees, by both heritage and habitus, and thus demanding sophisticated statistical and analytical treatment to distinguish signal from noise. Over its long history, our examination of the Awash and other baboon hybrid zones has used each of these sources of molecular information, as well as more traditional datasets. The distinct patterns of variation that have emerged seem to exemplify the interplay between “descent” and “modification”.