In the Middle Ages a man considered himself lucky if he made it to the ripe old age of 35. Now, thanks to a few key health discoveries, the thirties are just a pit stop on the geriatric highway.

In the Middle Ages a man considered himself lucky if he made it to the ripe old age of 35. Now, thanks to a few key health discoveries, the thirties are just a pit stop on the geriatric highway.

Bridging Over Troubled Waters

The power of plumbing is incredible. While good sanitation can't rid the world of all diseases, it has made a huge dent in epidemics caused by water-borne infectious diseases.

Around 1700 BC, indoor plumbing came to royalty on the island of Crete. A millennium later, Hippocrates saw the importance of clean water and recommended that ancient Romans boil water to remove pollutants.

The Romans hadn't a clue about bacteria and viruses, but we do. An easy way to pass bacterial diseases like cholera and intestinal infections is to come in contact with things that "pass through" people and animals. The moral: Don't wipe with the hand that feeds you.

Cider House Rules

Milk and cider are routinely pasteurized by a process developed by Louis Pasteur in the 1860s. Sure, the name looks egomaniacal, but in fact, Pasteur's work deserves a namesake or two.

Realizing that heat treatment of foods like milk could render "germs" harmless without altering the foods' taste was a big breakthrough. In addition to giving us fresh milk, Pasteur was the one who showed that spontaneous generation couldn't occur.

Up until that point people believed that things appeared like magic - frogs in wet mud, maggots in meat. Showing that magic wasn't to blame, and that you could indeed keep maggots out of meat, was a major leap in preventing communicable diseases.

Pea-Brained Schemes

The saying that nothing in life is more important than good breeding holds true when it comes to diseases. Some diseases aren't caught; they're based on genes you got from your parents.

Gregor Mendel first noted the idea that living things had a genetic basis in 1865. At a time when people believed that babies grew from preformed beings, Mendel grew pea plants and studied the inheritance patterns of certain traits like height and seed shape.

From simple, detailed observations, he developed laws of inheritance showing a contribution from male and female plants. Knowing this made it possible to better understand appearance patterns for diseases like sickle cell disease, cancer and Huntington's disease.

Adapted from Condensed Knowledge (HarperCollins), available at leading bookstores. For a daily dose of quirky fun visit MentalFloss.com and check out mental_floss magazine at your local newsstand.