What was the colour of earth a few hundred million years ago? Scientists at the Australian National University in Canberra detected traces of fossil chlorophyll, thus beating the record for the oldest organic pigment sample by 600 million years.

The compounds discovered by scientists come from shale deposits in the Taoudeni Basin in West Africa, a geological formation stretching from Mauritania, through Mali to Algeria. Experts examined the 1.1 billion-year-old shales by crushing them into dust and chemically analysing them to detect organic compounds. They found porphyrins in them.

Porphyrins are natural pigments and have different colours – from violet and pink to red. The name porphyrin comes from the Greek word “porphyros”, which then became the Polish “purple”.

What the Australian researchers saw in the samples, was a pale pink diluted solution. However, in nature porphyrins are more intense in colour. They play an extremely important role as they connect with metals. Combined with magnesium atoms, they form chlorophyll, which is necessary for photosynthesis, while combined with iron atoms they become part of the haemoglobin in vertebrates. They seem to be a cardinal connector of man with his natural habitat. This discovery raised a fundamental question among scientists: was the world pink before the advent of man?