The force is with Yoda

World's oldest mouse reaches milestone birthday

Yoda, the world's oldest mouse, celebrated his 4th birthday April 10. A dwarf mouse, Yoda lives in quiet seclusion with his cage mate, Princess Leia, in a pathogen-free rest home for geriatric mice belonging to Dr. Richard Miller, professor of pathology in the Geriatrics Center of the Medical School.

Yoda was born April 10, 2000, at the Medical School. At 1,462 days old, Yoda is now the equivalent of about 136 in human years. The life span of the average laboratory mouse is slightly more than two years.

"Yoda is only the second mouse I know to have made it to his fourth birthday without the rigors of a severe calorie-restricted diet," Miller says. "He's the oldest mouse we've seen in 14 years of research on aged mice at U-M. The previous record-holder in our colony died nine days short of his 4th birthday; 100-year-old people are much more common than 4-year-old mice."

Miller is an expert on the genetics and cell biology of aging. To study the aging process, he has developed strains of mice, derived from wild mice captured in Idaho, that live longer, stay smaller and age more slowly than ordinary mice. Although extremely low-calorie diets have been shown by other scientists to produce very long-lived mice, the genetic approaches used in Miller's laboratory achieve longevity without the need to restrict food intake.

Miller's mouse colony also includes strains of mutant dwarf mice, developed at Jackson Laboratories, which are very small and long-lived. Yoda is the longest-living member of this unusual tribe.

Miller's geriatric mice are providing important clues about how genes and hormones affect the rate of human aging and risks of disease late in life. His current work focuses on identifying defects in T cells from aged mice that interfere with a normal immune response, and finding ways to reverse those defects.