The human life span is typically around 72 years, though some people live shorter or longer depending on their lifestyle and health. Factors such as diet, exercise, smoking, alcohol consumption, and environmental health can all have an effect on life span. Genetics also play an important role in determining how long an individual will live. Generally speaking, advances in medical technology and public health have resulted in an increase in life expectancy over the past century. In the United States, the average life expectancy for men and women is 79 and 83 years respectively.