Ribose helps dissolve the borate minerals that shield it from breakdown, lab tests suggest

Borate binds ribose and helps keep it from breaking down ^[3]. The open question has been the dose. Tests of that protective effect often use simple mixtures of purified ingredients ^[4]. If "a few percent" means 2 to 5 percent, some of those mixtures hold roughly 20 to 50 times more dissolved boron than the water at Puga ^[1]. At Puga, borate crust covers the ground like snow ^[5].

Natural minerals were the right material for testing that gap ^[8]. A purified borate salt shows how much boron a chemist can put in a flask. A crust collected from a real spring shows what the ground will give up ^[4]. With ribose in the water, borate minerals dissolved more readily and fewer solid grains formed, so more boron stayed in solution ^[9]. "Borate protects ribose from breakdown, while ribose helps keep borate dissolved and available," the authors wrote ^[10].

That account of the study was written by the researchers themselves ^[14]. It does not report how much more boron dissolved, or how much ribose it took to get there.

The thing this doesn't tell you is whether an early-Earth pool ever held enough ribose to move borate chemistry at all. Researchers estimate that around a million tons of carbon a year could have arrived during the early bombardment ^[12]. That figure covers every carbon compound, and the ribose in the Murchison meteorite sits among other sugars ^[13]. A loop in which the sugar raises the level of its own protector needs a starting stock of sugar. That stock also has to last: heated ribose breaks down into brown goop, much as table sugar turns to caramel ^[2].

In my view this is a well-aimed experiment. It takes one concrete objection to borate-protected ribose, that natural water cannot hold enough boron, and tests it with minerals from a real site ^[8]. The finding is how Himalayan crusts behave in laboratory water with ribose present ^[9]. The crusts came from a modern spring, chosen because it may resemble the places where life began ^[5]. Earth four billion years ago had little oxygen in the atmosphere, far more active volcanism and green, iron-rich oceans ^[11].

The study concerns ribose and borate. RNA, whose backbone contains this sugar, does not form easily ^[15], and assembling it is a separate problem from keeping its sugar intact.