"The period before World War I led to the initiation of inbreeding in rats by Dr Helen King in about 1909 and in mice by Dr C. C. Little in 1909. The latter project led to the development of the DBA strain of mice, now widely distributed as the two major sub-strains DBA/1 and DBA/2, which were separated in 1929-1930. DBA mice were nearly lost in 1918, when the main stocks were wiped out by murine paratyphoid, and only three un-pedigreed mice remained alive. Soon after World War I, inbreeding in mice was started on a much larger scale by Dr L. C. Strong, leading in particular to the development of strains C3H and CBA, and by Dr C. C. Little, leading to the C57 family of strains (C57BL, C57BR and C57L). Many of the most popular strains of mice were developed during the next decade, and some are closely related. Evidence from the uniformity of mitochondrian DNA suggests that most of the common inbred mouse strains were probably derived from a single breeding female about 150–200 years ago."