New research pushes back the data of the earliest Last Universal Common Ancestor (LUCA) to 4.09–4.33 billion years ago, a mere few hundred years after Earth formed. Furthermore, that life was complex too; perhaps having ~2,600 proteins and a primitive immune system. Implying it existed in a biological community (perhaps on another planet), and did not arise on Earth as an isolated primitive lifeform.
There's more support for the idea that microorganisms may be very widespread throughout the galaxy. Researchers now think there is a vast biome extending as far as 8km down from the Earth's surface. These microbes may have lifetimes of thousands or even millions of years, and don't need sunlight or oxygen.
This vastly expands the number and type of exoplanets that may harbor life, and this makes Panspermia via asteroid ejecta even more likely as an explanation for how life came to Earth.
One of the central assumptions of our current search for alien life is that if we find it, it must have independently arisen in that location. Even in places as nearby as Mars. Should we change our assumptions? Assume Mars did, and probably still does have life, and that we were both seeded from elsewhere?
Life happened fast
It’s time to rethink how we study life’s origins. It emerged far earlier, and far quicker, than we once thought possible
The Pursuit of Life Where It Seems Unimaginable
Isn't it the eucaryote cell that made all the difference? Happened only once, 400M years ago IIRC.