Question: how did life begin

Natasha Dowey answered on 12 Mar 2019: last edited 12 Mar 2019 10:12 am

This is great question, and one that scientists have debated for a really long time. I’m not a specialist in this field, but I do know a little about it, so I’ll have a go at answering!

First of all, what do you need for life? You need a mix of molecules- nucleic acids (you may have heard of RNA or DNA), proteins, lipids, and carbohydrates.
But how did this stuff get on to Earth, and when?
We know the when a bit more than we know the how. Some scientists have suggested molecules like RNA were carried to Earth by a meteorite- but that doesn’t help us explain how they came to be on the meteorite! Some scientists think these molecules could have just arisen spontaneously on Earth, the right conditions at the right time, and there you go. Others think this is really unlikely.
There are some very, very old rocks in the world which record some of the earliest life on the planet. These rocks are called stromatolites, which were once a bit like algae, made up of a type of bacteria called cyanobacteria. We think they were the first things to photosynthesise on the planet (make oxygen from sunlight). They were really important, because they probably created a lot of oxygen that made the atmosphere a nicer place for other life to develop.
I’ve been to China and seen some stromatolite remains, hidden away in a cliff in a deep valley, that are believed to be over 3 BILLION years old! (see the pic below). The shapes they form make it look as though these algae formed thin mats that built up over time.

I’ve also been to Sharks Bay in Australia, where there are some modern stromatolites alive today- they tell us the kind of conditions the early stromatolites may have liked- perhaps they lived in shallow seas like their modern friends. See this pic below of the algae build ups under the water-

It’s a BIG question in science and we do not have all the answers by any means- it would be a very cool area of study to go into!