I have an old barbed wire fence on back of my property. The previous owners put it up in the early 80's and they salvaged the wire. The wire has to be like from the 40's or earlier (it's very dry here). They don't make a barbed wire like this anymore, I've looked. The barbs are really different and it's more primitive looking.
It's just a small section of fence and doesn't actually connect to anything, but I don't have the heart to take it down. The next guy might want to see it in 30+ years and I think it will last that long.
One day I'm going to research it and see if I can figure out how old it is.
A barb typically extends off a "pointy piece" to prevent it from being removed easily without further injury. For example, some fishhooks and arrowheads. The fences aren't designed to poke and then stick in the flesh.
The tangled history of barbed wire - https://news.ycombinator.com/item?id=10284497 - Sept 2015 (4 comments)
The history of barbed wire - https://news.ycombinator.com/item?id=9252709 - March 2015 (27 comments)
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Barbed wire fences were an early DIY telephone network - https://news.ycombinator.com/item?id=30231837 - Feb 2022 (63 comments)
Old-time ranchers used barbed-wire fences as phone network - https://news.ycombinator.com/item?id=19506811 - March 2019 (1 comment)
Barbed Wire Telephone Lines Brought Isolated Homesteaders Together - https://news.ycombinator.com/item?id=15951230 - Dec 2017 (22 comments)
Ethernet over barbed wire - https://news.ycombinator.com/item?id=15910263 - Dec 2017 (53 comments)