Australian National University biogeochemistry lab manager Janet Hope holds a vial of pink-coloured porphyrins representing the oldest intact pigments in the world. Photo | Australian National UniversityAustralian National University biogeochemistry lab manager Janet Hope holds a vial of pink-coloured porphyrins representing the oldest intact pigments in the world. Photo | Australian National University

Scientists have discovered what they say are the world’s oldest surviving biological colours, from ancient rocks beneath the Sahara desert.

The 1.1 billion-year-old pigments have a bright pink hue, but range from blood red to deep purple in their concentrated form.

The pigments are fossilised molecules of chlorophyll produced by sea organisms, Australian scientists said.

Researchers ground shale rocks into powder to extract the pigment.

“Imagine you could find a fossilised dinosaur skin that still has its original colour, green or blue… that is exactly the type of discovery that we’ve made,” Associate Prof Jochen Brocks from the Australian National University (ANU) told the BBC.

“These are actual molecules, the oldest coloured molecules in the world.

“When held against the sunlight, they are actually a neon pink.”

STUDENT MADE DISCOVERY

ANU PhD student, Dr Nur Gueneli, discovered the pigments after running an organic solvent through the powdered rock. Mr Brocks said the extraction process was “similar to a coffee machine”.

“I heard her screaming in the lab when it came out, and she ran into my office,” Asst Prof Brocks said.

“At first I thought it had been contaminated. It is just amazing that something with a biological colour can survive for such a long time.”

A mining company had found the rocks in a marine shale deposit in the Taoudeni Basin in Mauritania, West Africa about 10 years ago, after drilling a hole several hundred metres deep, he said.

An analysis of the pigments found they had been produced by cyanobacteria in the seas at the time. Prof Brocks said this contributed to understanding on the evolution of life forms on Earth.

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