Scientists at the Australian National University have discovered the world’s oldest-known colors, and they’re pigments of bright pink.
How exactly can colors be “old,” let alone the “oldest”? Well, the bright pink molecules represent the earliest colored molecules in the geological record—600 million years older than previous findings. At about 1.1 billion years old, they even predate dinosaurs.
Nur Gueneli, a paleobiogeochemist who earned her Ph.D. at the Australian National University, discovered the molecules while studying crushed shale rock during her doctorate program.
The molecules range from blood red to deep purple in their concentrated form, and are bright pink when diluted. Gueneli and Brocks’ research on them appears in the July 9, 2018 issue of PNAS, a scientific journal.
The shale rocks containing the pigments come from the west African country of Mauritania. A mining company extracted the shale about 10 years ago from the Taoudeni Basin, beneath the Sahara desert, after drilling several hundred meters into the ground. (100 meters is about 328 feet.)
Gueneli says the bright pink pigments are “molecular fossils” from “an ancient ocean that has long since vanished.” Brocks says they really represent “the oldest biological color,” since if you dug up a Tyrannosaurus rex bone, “it would also have a color, it would be grey, or brown, but it would tell you nothing about what kind of skin color a T. Rex had,” he tells The Guardian.
“If you would now find preserved, fossilized skin of a T. Rex, so that skin still has the original color of a T. Rex, say it’s blue or green, that would be amazing,” he continues. (We actually do have a 110 million-year-old preserved dinosaur skin; scientists hope to study the microscopic residue of its original pigments.) “That’s in principle what we’ve discovered…only 10 times older than the typical T. Rex.”
Beside being the oldest colors, these bright pink molecules also tell us about the evolution of life. Although the Earth is 4.6 billion years old, large complex creatures only appeared about 600 million years ago. The 1.1 billion-year-old pigments were made by microscopic creatures. This insight sheds light on why larger creatures developed relatively slowly.
“The precise analysis of the ancient pigments confirmed that tiny cyanobacteria dominated the base of the food chain in the oceans a billion years ago, which helps to explain why animals did not exist at the time,” Gueneli said in the ANU press release.
To get larger life, you need larger—non-microscopic—food.