not wishing to poo-poo my learned friends, i have heard differently, though can't quote the source (some wildlife programme), which stated that most animals live to around 70 million (70 billion? i remember a factor of 70) heartbeats - the count is perhaps irrelevant but the point is that they do tend to live the same amount of heartbeats, hence small animals with fast heartbeats living only a few years (the hamster in the "animals and nature" question is a good example) whereas slow-beating animals live much longer (the tortoise etc). THIS SAID - the human is the exception to the rule - again i can't remember the facts or numbers but human heartbeats are a) erratic in statistical analysis (i.e. little/no correlation) and b) influenced by too many external factors - health, lifestyle, surroundings, diet etc... so i'm afraid your plan for immortality is impossible