[sleepy_keita]

Was just rereading - it was the radioactivity and the large natural satellite that was unique in his universe. Tides are interesting because once you have life in the oceans, it's a kind of forcing function to adapt to land conditions

[actionfromafar]

Forcing function + making a stretch of land which is neither dry nor enterily wet. A gradient. If there are no tides the leap life has to make is much bigger.

[euroderf]

And perhaps the advantages of this gradient extend up as far as aquatic apes.

[actionfromafar]

Not sure what this means.

[IAmBroom]

I assume they are referencing the long-debunked theory that man evolved from a line of apes that became semi-aquatic for a while.

[euroderf]

Yup that's where I was aiming. Is it thoroughly debunked ? It's a cool idea.

[piker]

Fascinating

[stavros]

Why are tides a forcing function? Marine life has been perfectly content just not going near a beach.

[JumpCrisscross]

> Why are tides a forcing function?

"Nucleotide formation and polymerization are both more favored thermodynamically when subunit and nucleotide concentrations increase and the water concentration decreases (i.e., at low water activity)" [1].

Tide pools provide a regularly-cycling low-water and high-water environment. (And you get thermocycling, nutrient refreshment, and a path to the oceans, too.)

They're not a forcing function, generally, because we don't know how life formed. But I believe they're close to one in a RNA-first or metabolism-first origin-of-life universe.

[1] https://www.nature.com/articles/s41467-018-07389-2

[stavros]

Very interesting, thank you!

[sleepy_keita]

I was thinking more on the lines of "if marine life never found itself stranded on land, it wouldn't need to evolve to survive on the land"