The world’s oldest biological colour is pink. Bright neon pink. Or so the scientists announced in 2018, describing research done at the ANU in Canberra. They had extracted organic molecules called porphyrins from marine black shale rocks from Mauritania in Africa — shales that were well known as containing microbial fossil cyanobacteria. Porphyrins are ring molecules important for the colour of biological substances such as hemoglobin and chlorophyll. On this occasion the porphyrins had a purple colour, which becomes pink if diluted.
The scientists were awestruck thinking that these colour molecules could survive for such a long time. How long? 1,100,000,000 years. That is the alleged evolutionary age of the Precambrian strata in which the shales with the fossils, were positioned.
But that age is impossible for any organic substance. The laws of chemistry dictate that organic substances will gradually decompose — even in the fridge, that KFC chicken left over from the party last week is going to break down quite soon.