35 Essays on Infinite Lifespans   Aubrey de Grey generations  of  therapies,  without  limit.  Two  decades  is  an eternity in science, especially in well-funded science (which life extension will certainly be at this time). Second-generation therapies are thus virtually certain to arrive in time. Hence, as soon as we reach the point of extending life expectancy by even a couple of decades, we can be confident that most beneficia- ries of such therapies will survive to benefit from subsequent ones. Those people’s life expectancy will thus be indefinite, even though they are still aging. The analogy with a projectile propelled from the Earth at greater than escape velocity is not perfect, but I find it evocative. IMPROVING OUR LEAD-TIME For the reasons surveyed above, I consider it appropriate to regard the WOA as ending when first-generation SENS thera- pies become widely available. Thus far, however, I have only discussed specific, identifiable problems – which are, necessar- ily, unimaginatively similar to the targets of the first-generation therapies. What about things we have not thought of? I predict that this point will motivate – starting as the WOA nears its end – a research project that will dwarf even the WOA itself. Our unarguably limited ability to predict what aging will throw at us next could, it would seem, only be addressed reliably by clairvoyance. Or could it? Could we metaphori- cally press the fast-forward button to discover what the future holds? We are exceedingly fortunate that such an option is indeed available. Specifically, I predict that humanity will create and maintain a very large colony of non-human primates of several different species – probably totaling tens of thousands of animals – on which  to  test  novel  life  extension  therapies.  Primates  have three characteristics which, jointly, motivate this action: They