The MPrize, or Methuselah Mouse Prize, is a growing $4.5 million prize, started in 2003 to award money to scientists setting records in mouse longevity and rejuvenation. The overall goal is to break what chief scientists Aubrey de Grey calls the "pro-aging trance" — the notion that aging is inevitable and no biotechnological interventions can stop it. De Grey and his foundation, the Methuselah Foundation, which administers the prize, hope that extensions of mouse lifespans will lead to the realization among the public that aging is not inevitable, and that with enough biological research, it may be overcome.
De Grey hopes to use the MPrize to kickstart what he calls the "War on Aging". The MPrize was inspired by similar technology prizes, such as the prize won by Charles Lindbergh for crossing the Atlantic, and the X-Prize for private space development.
A typical lab mouse lives about 3 years, and a mouse with diverse genetics — not like the lab mice which have similar genes — lives about 4 years. As of 2007, the record for lab mouse lifespan is just under 5 years, achieved by genetically knocking out the mouse's growth hormone receptor.
The MPrize makes a distinction between mouse longevity and rejuvenation. Longevity means total lifespan with interventions allowed at any age, while rejuvenation refers to interventions taking place at middle age for the mouse. Different portions of the purse are awarded to both categories, and a formula describes the exact payout. For the rejuvenation prize, every day up until treatment begins counts double for the scientist. This helps encourage late-onset rejuvenation techniques which would be in great demand for humans if they could be developed.
The current record-holder for the rejuvenation MPrize is a mouse that lived 3.7 years instead of the usual 3. The mouse was raised in an enriched environment and put on a caloric restriction diet.