The ocean was cooler than previously thought when life first appeared on Earth, according to two researchers who analysed rocks from South Africa. The paper is published in the journal Sciences Advances.
Following the analysis of rocks, a pair of researchers, Maarten de Wit and Harald Furnes, concluded that the temperature of the ocean at the time when life first appeared on Earth was not as low as it was previously thought.
The researchers found potential discrepancies in data obtained from previous studies conducted on certain rocks from South Africa that are said to date back to around 3.5 billion years ago, during the era when life is thought to have first appeared on our planet. According to these researches, the rocks are said to have been at the bottom of the ocean at that time when its temperature would have been around 55 to 85 degrees Celcius. The actual figure might be much lower, according to de Wit and Furnes.
The new study suggests that the initial estimate is not accurate because the possibility of the presence of hydrothermal vents in the vicinity of the rocks was not taken into consideration; this would mean that the rocks might have been in a part of the ocean where the water was warmer than the rest.
Therefore, to confirm whether this actually affected the estimate, Furnes and his colleague examined other nearby rocks which would be of similar age, but which would not have been near a vent because their formation was from ocean sediments. These rocks showed signs of the presence of gypsum which is known to currently grow only in cold deep sea. Furthermore, the rocks revealed tiny pieces of iron that were present at the time of their formation — this information indicates that the rocks might have come from low latitudes, near the equator.
The body of evidence was interpreted as suggesting that the oceans and the atmosphere back then were similar to current conditions. This means that the new results might dismiss what has generally been assumed that life could only have come into existence on Earth when the oceans were warmer than today.
The researchers add that their findings imply that the Earth was in the Goldilocks zone (where the conditions are not too hot or too cold for life to exist) for all the time life has existed on the planet.