Jonathan Lambert

And from that, they did some fancy probabilistic modeling to account for horizontal gene transfer. That gene sharing we talked about earlier. And they assigned each gene a probability of having been a part of Luca's genome. This created like a fuzzier picture, but probably a more accurate one.

Luca was pretty complicated. They estimate this single cell, our last common ancestor, had a genome roughly the size of some modern bacteria. Whoa. It had like 2,600 proteins, so quite a bit bigger than many scientists thought.

Luca was pretty complicated. They estimate this single cell, our last common ancestor, had a genome roughly the size of some modern bacteria. Whoa. It had like 2,600 proteins, so quite a bit bigger than many scientists thought.

Luca was pretty complicated. They estimate this single cell, our last common ancestor, had a genome roughly the size of some modern bacteria. Whoa. It had like 2,600 proteins, so quite a bit bigger than many scientists thought.

And one of the coolest things they found was that Luca had all of these different CRISPR-Cas9 genes.

And one of the coolest things they found was that Luca had all of these different CRISPR-Cas9 genes.

And one of the coolest things they found was that Luca had all of these different CRISPR-Cas9 genes.

Yeah, yeah. So we humans hijacked it to bioengineer, but in nature, bacteria use these CRISPR genes to slice and dice viruses. And so the fact that LUCA had these genes suggests that it might have had some kind of ancient immune system.

Yeah, yeah. So we humans hijacked it to bioengineer, but in nature, bacteria use these CRISPR genes to slice and dice viruses. And so the fact that LUCA had these genes suggests that it might have had some kind of ancient immune system.

Yeah, yeah. So we humans hijacked it to bioengineer, but in nature, bacteria use these CRISPR genes to slice and dice viruses. And so the fact that LUCA had these genes suggests that it might have had some kind of ancient immune system.

Yeah. So Luca likely made its living without oxygen and converted carbon dioxide or hydrogen gas into energy. Wow. Many scientists think that life might have emerged at hydrothermal vents deep in the ocean. Yes. And this probabilistic LUCA could have lived there eating up the gas that spews from these vents. But those gases could have also come from the atmosphere too.

Yeah. So Luca likely made its living without oxygen and converted carbon dioxide or hydrogen gas into energy. Wow. Many scientists think that life might have emerged at hydrothermal vents deep in the ocean. Yes. And this probabilistic LUCA could have lived there eating up the gas that spews from these vents. But those gases could have also come from the atmosphere too.

Yeah. So Luca likely made its living without oxygen and converted carbon dioxide or hydrogen gas into energy. Wow. Many scientists think that life might have emerged at hydrothermal vents deep in the ocean. Yes. And this probabilistic LUCA could have lived there eating up the gas that spews from these vents. But those gases could have also come from the atmosphere too.

So this LUCA might have lived closer to the ocean's surface too.

So this LUCA might have lived closer to the ocean's surface too.

So this LUCA might have lived closer to the ocean's surface too.

Totally, totally. And another theory is that Luca might have dined on the waste of other organisms.

Totally, totally. And another theory is that Luca might have dined on the waste of other organisms.

Totally, totally. And another theory is that Luca might have dined on the waste of other organisms.

Phil and his colleagues argue no. Those researchers think that Luca was actually part of a complex ecosystem of microbes that have since gone extinct. They don't have evidence for this since any traces of those lineages are long gone, but essentially they argue that something as complicated as their version of Luca couldn't have evolved in isolation.