Are we an alien organism?

[u/Horror_Program_1878]

Ever since I found out that we didn't exist during the Dinosaurs, I've been thinking if we came from the the asteroid that wiped the dinosaurs, and my speculation is that the asteroid have organisms in it and after the extinction event and the earth stabilize again the organisms that got spread all over by the asteroid started waking up and evolving, resulting to a lot of new species that are not dinosaurs to sprout including us humans

[u/tigersharkwushen_]

We are not. We know this because we can trace the many steps of evolution from before the Dinosaurs to now.

Also, we did exist during the dinosaurs, just not in our current form.

[u/TerrapinMagus]

We are a surviving lineage of Synapsids, which actually ruled the world well before the Dinosaurs did. Most Synapsids died out in the Permian-Triassic extinction event, leaving a very small number that survived and persisted as tony generalist while Dinosaurs had their time in the spot light. When the K-Pg extinction event happened, the dinosaurs were reduced down to just avians, which gave the surviving synapsids (early mammals) that had been underfoot all that time a chance to explode in diversity.

[u/the_syner]

Aside from the science firmly pointing in the direction of all life on earth being related 66Myrs is hardly enough to time for microbes to evolve into us. Not that it matters since we can trace our evolutionary lineage back very far and given the sort of impact energies involved any biochemistry would very probably have have been sterilized/vaporized

[u/atlvf]

No, all scientific evidence suggests that all life on Earth, humans included, originated from the same, singular genesis event. The specifics of that genesis event are still up for debate (tidal pools, deep sea vents, etc.), and panspermia is certainly possible, but… if humans are aliens, then so were dinosaurs, and so is all other life on Earth.

[u/ExpectedBehaviour]

How did the asteroid impact kill all the dinosaurs but not the organisms in the asteroid?

Also – how do we have clear genetic, physiological, and biochemical links to all other known life on Earth, including those with lineages that predate the K-T extinction?

[u/jkurratt]

We are part of the life of this planet, that we call "DNA".
We literally have common ancestors with banana.

[u/NearABE → u/jkurratt]

The aliens commandeered the native DNA.

[u/Lilbrainertoot]

Now that u say that, that actually makes sense