This scene provides a glimpse-one of dozens we see each day –of Asia’s “thumb culture” Young cell-phone users are extremely adept at typing text messages using only their thumbs. These rapidly typed messages help them keep constantly in touch with one another. Increasingly, this constant messaging is replacing more traditional forms of communication.

Many young people think hand-written greeting cards are old-fashioned. Instead, they send a holiday greeting or birthday wish by text message. They can reach as many people as they want with a single text message. They pass on jokes and good news through digital greetings. In China , even marriage proposals have been sent in text messages!

It’s created a new health problem, known as “text-messaging injury.” Cell –phone users sometimes develop severe swelling and pain in their thumbs. This injury is caused by the thumb making the same small movements hundreds of times a day.

“Because the movements are small, they do not cause the blood to circulate,” said Andrew Chadwick, an expert from the U.K. “That means the fingers are acting like an engine without oil.”