steve5
how long has serving been around ?
That's a worthwhile question to ask.
As a guess, a long time.
Cordage was expensive stuff, especially in shipboard lengths. You needed a lot of decent-quality (or better) fiber to make up the yarns & threads. To then make up the ropes, lines, hawsers, and cables.
That was all hand labor on long, long sheds. Each increase in size lost some mount in length, and with ever-increasing amounts of labor required to make up the product.
You needed some number of men to man the cranks, who must needs stay in unison. You needed some number to man the bobbin, and still more along the length to tuck in the loose bits. So, the manhours involved were great. The final product also wanted stretching and time to take a "set" into its final shape. And, you needed someplace to store the final product that did not expose it to damp, dry rot, risk of fire or rodents or the like.
So, the notion of protecting a valuable line with marline or similar yarn/thread product was probably recognized early. Serving the gaps with line and wrapping in canvas probably followed quickly after using pine tar/sap to protect line, too.
Maybe.
Perhaps.