“A problem well stated is a problem half-solved” – Charles Kettering
The biggest current obstacle to extending human lifespan is a lack of understanding of what aging is. The question of “why do we age” is still unanswered, which is rather embarrassing for the field of biology as a whole when you think about it, because the process of aging is so universal. The problem is similar to observing that all animals have lungs, but lacking any unified theory as to how lungs evolved or what purpose they may serve. A basic understanding of lung function and physiology would be a minimum requirement before doctors could go about systematically treating any lung-related diseases. It is not much of an exaggeration to say that we are in a similar state today. So many of the diseases that plague humanity are diseases associated with aging, and yet a truly satisfactory understanding of why we age is still absent. Scientists know a multitude of individual events that happen during the aging process – many of which are even common among a broad range of living creatures – and yet a unified theory of aging is still absent. (Note: The lack of theory isn’t from a lack of effort. There are literally dozens of published hypotheses attempting to explain the universality of the aging process. What we lack, in my opinion, is one answer that incontrovertibly encompasses all of the evidence.)
I have heard the argument that the theory aspect of aging isn’t critical for extending human lifespan, since it’s only the details – the specific events that go wrong during the aging process – that need to be treated. I believe that this statement might at best be half-true since it’s an issue of proximal causation versus ultimate causation. The proximal cause of an event is the most immediate thing causing that event. The proximal cause of a sinking ship might be a fist-sized hole below the waterline of the hull, and the presence of that hole might be the only thing you need to know to patch it and keep sailing. The ultimate cause however is the highest-level thing responsible for an event. For the ship example, the ultimate cause might be icebergs, and knowing that you are sailing into iceberg-filled water, and taking steps to avoid slamming into them, is likely the best strategy to continue sailing long-term. We know many of the proximal causes of the aging process. What we lack is a ultimate cause to guide an anti-aging strategy.