I'm trying to identify a short story I read many years ago (early/mid 80s maybe?)
The story was originally published in Spanish as "La Nueva Prehistoria" in the 1967 collection La Nueva Prehistoria y Otros Cuentos by the Colombian writer René Rebetez (René Rebetez-Cortes, Wikipedia pages in Spanish and German). An English translation by Damon Knight, titled "The New Prehistory", was first published in The Magazine of Fantasy and Science Fiction, June 1983, available at the Internet Archive. It has been anthologized in The Penguin World Omnibus of Science Fiction (Sam J. Lundwall and Brian Aldiss, eds.) and The World Treasury of Science Fiction (David G. Hartwell, ed.). There is a review by James Lecky at Tales from the Computerbank. The excerpts below are from the original English publication in F&SF, starting with the editorial blurb:
René Rebetez is well known in Latin America as a writer, lecturer, and documentary film maker. He travels a good deal between Mexico City and Bogota, where he grew up. He is at work on his first novel. This story is very short, but it lingers like a vivid nightmare.
where humans who congregated together somehow joined and 'evolved' into new blob multi-creatures - I don't think it was a choice, rather it just started to happen to them.
It starts with a movie ticket line:
I felt a sudden chill; somehow I knew what was about to happen. A fat lady had grown tired of waiting, even though she was only twenty paces or so from the ticket window. She took a step, another, a third; the line curved with her. She turned her head indignantly, tried to break free; she ran and the line straightened again, dragging the poor woman back in spite of her struggles.
Now panic spread; they were all trying to break loose at once. The long line undulated in wild contortions, as if shaken by a gigantic hiccup. People were struggling, screaming and shouting. Tempers grew heated; there was a flurry of blows.
Around the newborn monster, a crowd was gathering. That was another custom in the cities, congregating to look at things: cranes, wrecking machines, blasting crews. Airplanes. Military parades. Political rallies. Crowds looking at billboards. Crowds looking at anything.
Myself, I had always hated crowds and lines of people. Not that I was antisocial, not at all; it was simply that I disliked humanity in the mass. Never had I dreamed that things would take such a turn, or that I would witness this transformation.
These new blob creatures wandered around trying to learn how to control themselves, and I think they maybe fought each other.
I don't remember how many days and nights I wandered those streets. Thousands of monsters of all sizes were roaming in the city. The lines at bakeries and bus stops had produced little reptiles of ten or so vertebrae each; the same for the lines at banks and confessionals. Larger ones had come from the lines at phone booths, movies, theaters, and other public places. The amoebas came from street crowds and public gatherings; they were spreading everywhere.
The strange ligature that had fastened the people together was really unbreakable. I saw one man who tried to cut it; the attempt ended in his painful death. The links that died by accident hung like dead leaves, without breaking the human chain. I saw a busload of people that had turned into a single mass. Unable to get out of the bus, they began destroying it. Whole buildings were being demolished by amoeba-crowds imprisoned inside. A shouting throng had formed itself into an immense clotted mass that swept away obstacles, filling the streets like a river: that one came from a political rally.
The few persons who were still separate scurried like rats to avoid touching the new organisms. All the same, most of them were being absorbed.
I don't think there was much plot or reason for this 'evolution' given.
There is no explanation whatsoever.
The story was told from the point of view of one person, who was watching and documenting the metamorphosis. At the end I think he realised he had no choice but to join with them.
No, the narrator remains free at the end of the story:
I suspect the day is not far off when they will build their own airplanes and limousines, as long as railway cars, or rounded and flat like flying saucers. The time will come, too, I have no doubt. when they will play golf.
But I don't want to know anything about that. I always hated crowds and lines of people. I cling to my human identity, to my own individual and separate personality. It's not that I'm antisocial; not at all, I repeat. But masses of humanity are distasteful to me. Never did I dream that things would take such a turn, or that I would witness this transformation.
I sit among the ruins. In the distance I can hear a gigantic chorus: the voice of the new prehistory. A new cycle is beginning.