A faint, red, cross-hatched design discovered in a cave in South Africa just might be the oldest known drawing in history, researchers say.

In a paper published in the journal Nature, a team led by Christopher Henshilwood from the University of Bergen in Norway reveals the discovery of a decorated piece of stone – of a type known as silcrete – excavated at an archaeological site called Blombos Cave, 300 kilometres east of Cape Town.

The stone flake features a cross-hatched pattern, which the researchers say microscopic and chemical analysis confirms was applied deliberately with an ochre “crayon” fashioned into a tip between one and three millimetres wide.

The design – which has been dubbed the world’s first hashtag – might originally have been part of a larger, more complex piece.

The sediment layer in which the decorated stone was recovered has been reliably dated as 73,000 years old. The find is highly significant, because it pre-dates the earliest known abstract and figurative drawings discovered in Africa, Europe and southeast Asia by at least 30,000 years.

Henshilwood and his colleagues note that the same sediment layer in the Blombos Cave has previously yielded other artefacts, including shell beads.

The latest find, they write, “demonstrates the ability of early Homo sapiens in southern Africa to produce graphic designs on various media using different techniques”.

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