Dr. Steven Novella

They were waiting.

But they weren't just waiting.

They were evolving, right, over that billion years.

And what else is happening on Earth, you know, at this time, do you think?

the great oxidation event.

So oxygen's building up in the atmosphere and in the oceans, and eukaryotes have mitochondria, which uses oxygen to make energy, right?

And so the question is, when did eukaryotes get their mitochondria, and where were they getting their oxygen?

And it's, again, pretty, I think it's pretty firm.

Endosymbiosis, it's called.

Yeah, the Cambrian explosion also was a result of oxygen sort of reaching critical levels and allowing for bigger, more complicated multicellular creatures.

But we're a long ways before that, right?

We are, you know, 800 million years before that.

So the question was then, well, where were the eukaryotes living?

What were they doing?

So they reviewed all of the fossil eukaryotes that we have, basically like mats and stuff of these creatures.

And it turns out they were all living near the ocean floor.

They weren't chemosynthetic.

Were they chemosynthetic?

No.

So that's the question.