ABSTRACT
Abstract N early half of the human and primate genome is derived from ancient transposable elements, primarily retroelements. This surprising fact alone suggests that retroelements have played a major role in genome organization and evolution. Here we review stud-
ies performed in the last 20 years on the chromosomal arrangements of human retroelements, including the exogenous and endogenous retroviruses. We also discuss biological mechanisms or evolutionary forces that may influence their ultimate distribution patterns.
