WASHINGTON — More than 30,000 years ago, someone living in a cave in the Caucasus Mountains twisted wild flax together and dyed it, producing the earliest known fibers made by humans, scientists report.

“Making strings and ropes is a sophisticated invention,” said Ofer Bar-Yosef, a professor of prehistoric archaeology at Harvard University. “They might have used this fiber to create parts of clothing, ropes or baskets — for items that were mainly used for domestic activities.”

The fibers were discovered in clay deposits in Dzudzuana Cave in what is now Georgia, Bar-Yosef and co-authors report in today’s edition of the journal Science. The earliest previous evidence of fibers worked by humans was from Dolni Vestonice, a site in the Czech Republic dated to 28,000 years ago.

Some of the fibers appear to have been dyed using plant materials common in the area, the researchers said. The color range included yellow, red, blue, violet, black and green.

“The colored fibers may indicate that the inhabitants of the cave were engaged in producing colorful textiles,” they reported. There was also evidence of processing fur and skin at the site.