ANN ARBOR, MI -Yoda, the world's oldest mouse, celebrated his fourth birthday on Saturday, April 10, 2004 . 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 Richard A. Miller, M.D., Ph.D., a professor of pathology in the Geriatrics Center of the University of Michigan Medical School.

Yoda sniffing his cage mate, Princess Leia. Dwarf mice always are housed with larger females to provide body warmth needed to protect smaller dwarf mice from freezing to death. Photo credit: Richard Miller, U-M Medical School

Yoda was born on April 10, 2000 at the U-M 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 over 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 fourth birthday. 100-year-old people are much more common than four-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 Laboratory, 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.

Contact: Sally Pobojewski

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