There are gaps in evolution that can not be explained. Why did man take giant leaps forward about 100,000-50,000 BC? A lot of Sumerian tablets from 10,000 BC. Why couldn't someone live 1000 years while the humans genes where radically changing/altered. I don't agree or disagree, but it is not impossible. We are trying to figure out how now to live a 1000 years.
The basic body has a limited warranty? It rejuvenates/recreates/heals for 70 years. Was it by design, or by failed attempts at more? We have so many things now that harm the body - foods, technology, flooding the planet with electronic waves, passing unknown/inexperienced/unplanned-for diseases around. You can't necessarily apply modern day life expediencies.