While most people born in rich countries will live longer by 2030 – with women in South Korea projected to reach nearly 91 – Americans will continue to have one of the lowest life expectancies of any developed country, a new study predicts. Scientists once thought an average life expectancy beyond 90 was impossible but medical advances combined with improved social programs are continuing to break barriers, including in countries where many people already live well into old age, according to the study’s lead researcher, Majid Ezzati of Imperial College London.