As previously discussed, humans exhibit an exponential(time) death-rate curve, Gompertz law, which is really bad news for those who'd like to live. Furthermore, it looks like there are no remarkably long-lived mammals. The longest lived besides humans are (?) elephants, the oldest known elephant lived to age 86 in Taipei zoo. If we ask for animals that lived longer than the human record of 122 years, the only known advanced animals that clearly do that are several varieties of tortoises, which can live at least 250 years in some cases. And there are a few other birds and reptiles which might be able to exceed 122 years although it has never been observed to happen. Humans might be able to live longer via genetic engineering, more precisely genetic "theft," from a few of those long-lived animals. DNA sequencing could shed light. E.g. elephants were just sequenced and found to have about 50 copies of the p53 tumor-suppressor gene (humans have only 1 copy) which perhaps explains why elephants get cancer much less than humans do. Some primitive lifeforms can, however, entirely avoid Gompertz law -- which could be regarded as immortality, at least by comparison to us -- at least as far as anybody has been able to tell, their DeathRate(age) curves are asymptotically constant. These include "hydra." So perhaps Gompertz law only happens to "complex" animals, not to "simple" ones. Biochemically speaking, of course even hydra is a extremely complex object, but, e.g. it has few or no "organs" so perhaps the problem is the cell differentiation and macroscopic-development processes that happen in advanced animals, which perhaps are entirely absent in hydra. The mathematical question is: what really is the underlying cause of Gompertz law? Which as far as I know, was never really understood. -- Warren D. Smith http://RangeVoting.org <-- add your endorsement (by clicking "endorse" as 1st step)