DNA replication initiates at defined sites called origins, which serve as 
binding sites for initiator proteins that recruit the replicative machinery. 
Origins differ in number and structure across the three domains of life and 
their properties determine the dynamics of chromosome replication. Bacteria and 
some archaea replicate from single origins, whereas most archaea and all 
eukaryotes replicate using multiple origins. Initiation mechanisms that rely on 
homologous recombination operate in some viruses. Here we show that such 
mechanisms also operate in archaea. We use deep sequencing to study replication 
in Haloferax volcanii and identify four chromosomal origins of differing 
activity. Deletion of individual origins results in perturbed replication 
dynamics and reduced growth. However, a strain lacking all origins has no 
apparent defects and grows significantly faster than wild type. Origin-less 
cells initiate replication at dispersed sites rather than at discrete origins 
and have an absolute requirement for the recombinase RadA, unlike strains 
lacking individual origins. Our results demonstrate that homologous 
recombination alone can efficiently initiate the replication of an entire 
cellular genome. This raises the question of what purpose replication origins 
serve and why they have evolved.