Animal studies show that administration of the amino acid taurine prolongs life span in multiple species. Would taking taurine as a nutritional supplement at a 1000 mg daily dose be safe and have significant health effects, including enhanced longevity?

This would have significant health benefits and is a good idea across the board. The effect on longevity will be modest but it will be present. More important is the quality of life along the way as this will add, subtly, to a number of bodily functions that keep things running harmoniously. If you think about the issue of longevity, having a balanced, well-functioning system overall is centrally important because without it, things will be in decline and that can develop a downward spiral with a momentum of its own and become a foregone conclusion that the life will peter out.