Where did life on Earth begin?

If you trace it back far enough, there's a point where everything converges, and that point is the entity known as LUCA.

The name is grand: Last Universal Common Ancestor, the last common ancestor of all life forms.

In simple terms, it's the organism that sits at the top of the lineage connecting everything from the bacteria alive today to whales.

Previously, it was thought that LUCA appeared about 4 billion years ago.

After Earth was formed, around 600 million years later, it was believed that life began to emerge.

However, a study released in 2024 pushes this date back even further... to a staggering 4.2 billion years ago.

This means that life existed just about 400 million years after the Earth was formed.

This period is known geologically as the 'Hadean,' and the name itself gives a sense of its nature.

It was a hellish environment, with meteor strikes, volcanic eruptions, and boiling oceans... a time when conditions were far from suitable for human life, let alone the concept of life itself.

Yet, LUCA was already roaming around in that environment. Quite remarkable.

How did scientists figure this out? They compare the genes of all living organisms today.

Then they calculate how much has changed since they diverged from their common ancestor. It's like a genetic clock.

By reversing this process, they found, "Oh, this is much older than we thought."

It sounds simple, but the calculations are incredibly complex. Genes exchange and mutate, making modeling quite challenging.

Even more interesting is the nature of LUCA. It's easy to assume it was just a simple bacterium, but that's not the case.

Research suggests that LUCA likely had some form of immune system.

This means it was already fighting against primordial viruses. The war began as soon as life started. There was never a peaceful beginning.

It's also likely that LUCA didn't live alone. Other microorganisms consumed the substances produced by LUCA, which in turn altered the environment... indicating that a primitive ecosystem was already in place.

This suggests that the natural cycles we see today existed in a very rudimentary form back then.

After hearing all this, one might think, "So, isn't everything figured out?" Not at all. This is just the beginning. The time before LUCA remains shrouded in mystery. We still don't know how life began from nothing or how the first community was formed. Despite significant advancements in science, this area remains untouched.

However, based on what we know so far, tracing the roots of life on Earth could lead us back 4.2 billion years.