The mystery of the lake that gave birth to our oldest ancestors

The earliest signs of life on Earth may have appeared and evolved in ancient lakes with extremely high phosphorus levels, new research from the University of Washington (USA) has revealed.

Phosphorus is an element that makes up about 1% of the human body and is an essential part of all living things on Earth. It is one of the six major chemical elements of life, the “backbone” of the molecules of DNA and RNA. But this mineral is extremely scarce.

So for 50 years, scientists have been trying to figure out how the early and lifeless Earth could produce enough phosphorus to ” mould” all species.

The mystery of the lake that gave birth to our oldest ancestors
The beautiful Mono Lake in the US is a modern version of the mysterious lakes that once gave birth to all species – (photo: Mathew Dillon).

In this study, just published in Proceedings of the National Academy of Sciences , scientists have the answer: some lakes on Earth are rich in carbon, a condition for phosphate molecules to not be destroyed, so enough phosphorus is stored to lead to the chemical reactions that produce the primordial DNA and RNA chains.

To possess that condition, these lakes must form in a dry environment, with a high evaporation rate, the water in the lake is a salty and alkaline solution. It is what we call an “alkaline lake” or “soda lake” , which can be found on all 7 continents of the modern Earth.

And the more modern versions of those mysterious and magical lakes are Mono Lake in California, Lake Magadi in Kenya and Lake Lorna in India. The water from these lakes was brought back to the lab, and the scientists found that compared to seawater, they could contain more than 50,000 times a phosphate molecule containing a phosphorus atom.

In most other lakes on Earth, the element calcium normally binds with phosphorus to form the solid mineral calcium phosphate, which is not intended for life. But given the carbon-rich environment of these lakes, the carbon won’t bond with the calcium, so the phosphorus is free and ready for “reaction life”.

Many years ago, the young Earth had many such lakes, with a large part originating from meteorite impacts.

This seems in line with an earlier study led by the University of Hawaii (USA), which demonstrated that particles covered with carbon dioxide, phosphorus and water have adhered to meteors and comets, falling to Earth. , sowing seeds of phosphate and diphosphatesphoric acid , the two main elements that make up the ” building blocks of life”.

So it can be said from ancient versions of these mysterious and strange lakes that the ancestors of all species, including us, were born on Earth.