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Comment by gbil | Hacker News Reader

I'm not a native English speaker yet I have objections with the use of "adapted" in this sentence

  The Earth had been spinning on its axis for a billion years when the first living beings appeared. Since then, we have adapted to alternate between light and darkness.

You adapt when the environment was in a state A and changes to state B while you are already there. When you start from "scratch" in a specific stable environment, you develop/grow in that environment, not adapt. Or not ?

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The word "adaptation" has a few specific meanings in the field of biology.

https://en.wikipedia.org/wiki/Adaptation

Ah that makes sense then! So in this context it is used in the same sense as evolve. Thanks that not only makes sense but lead me to search with both terms and get this

https://education.nationalgeographic.org/resource/adaptation...

  Evolutionary adaptation, or simply adaptation...

LUCA[1] almost certainly didn't care about day/night cycles, so it seems accurate. And even if it had, the ways in which a modern mammal with a central nervous system cares are new changes brought on by the day-night cycle. An organism if an organism is changing in ways that are caused by the a specific environment, it's still adapting to the environment even if the environment isn't continuing to change.

[1]https://en.wikipedia.org/wiki/Last_universal_common_ancestor

Isn't that change/evolution though ? If the environment didn't change - talking about the very specific attribute of earth axes rotation - is it correct to use "adapt" ?

"Adapt" is perfectly valid here. After all, the beings have changed (evolved). It doesn't matter whether the environment has. Which is also the case - not just the seasons but also huge climate changes and the mass extinctions.

I think adapt is perfectly fine, but "since then" really throws a wrench in the sentence. Why not, "therefore" instead?

that is splitting hairs.

State A: No Earth

State B: Earth.

Thus, we adapted to Earth.

that is totally wrong, the premise here - as I quote - is that the Earth was already there and then the first leaving things appeared

Sorry. Was being bit sarcastic. Since every single day is a new state, State A and B are different, and we are adapting.

Organisms are continually adapting. So this question seemed to be calling into question the findings because the earth always rotated and so always had a night and day, so State A and B are identical, thus we didn't adapt.

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