I think it is natural selection. genetic variation also could be a factor for physical variation over the years.
Answer: Adults ate about 1,300 mg of sodium in a single fast-food sitting, which is more than half of the upper recommended limit for the day. Yet the average guess was just 200 mg, says study author Alyssa Moran, a registered dietitian and doctoral student at the Harvard School of Public Health. They were off by about 650%
Explanation:
It's possible to for you to exceed your normal heart rate by a minimum range
