But let’s not get carried away. That “of our time” qualifier is hugely important. We’ve already done most of what is possible to allow humans to live out a natural life span.
The invention that enabled this advance was germ theory. Equipped with germ theory – one of the few useful theories in biology – scientists quickly created vaccines and antibiotics, and governments implemented clean water and clean food programs. In a couple of generations, premature death and disability from infectious disease were virtually eliminated in developed countries…
…and life-expectancy shot up:
The diseases that kill us now are, overwhelmingly, the diseases of old age: cancer, heart disease, stroke, COPD. Even if CRISPR-enabled medicines find cures for every one of these diseases, our life-expectancies won’t go up by more than a few years.
Obesity presents the biggest opportunity for medical interventions to impact the health of society
A number of human genetic loci have now been associated with obesity. These genes could be targets for CRISPR therapies. But the total obesity risk associated with these loci is not very large  . Environment plays a much larger role. Human gene therapies are not going to end obesity.
Bacterial gene therapies might. The only truly effective medical intervention for obesity is gastric bypass surgery. It appears that these surgeries work not so much by mechanically constricting the stomach as they do by changing the gut microbiome .
CRISPR is a great tool for making multiple and complex changes in bacterial genomes . Some early-stage studies suggest that engineered bacteria can reduce obesity in animal models  . CRISPR could enable thorough engineering of bacterial genomes to provide effective therapies for obesity and perhaps other chronic diseases .
CRISPR will no doubt find application in correcting simple genetic defects in humans. But its true medical potential lies in engineering our microbiomes.