The term sarcopenia has not been in common usage for very long (see graph), but the condition has been around forever. Sarcopenia is the loss of muscle tissue that occurs as a natural part of the aging process. According to this article, Why You're Aging Ungracefully, there are two things we can do to help maintain our muscle as we age - lift weights and eat high-quality protein.
A quote from the article:
Sarcopenia begins naturally in the 4th and 5th decades of life, making your 40s and 50s an ideal time to increase dietary protein and weight training, but even those in their 60s and beyond can benefit."
"The stronger you are, the more muscle you have, the less likely you are to become sick or die."