Even heat was effective in bringing about prebiotic reactions.
At elevated temperatures aqueous solutions of formaldehyde (HCHO)
and hydroxylamine (HO-NH2) yielded
amino acids and short polymers.
Solutions of HCN kept at 90°C for several days yielded adenine,
as shown at the left. Perhaps the fact that adenine is simply a
pentamer of HCN and is so easily formed abiotically is the reason
it is used in the energy storage ATP molecules, in preference to
guanine, cytosine, thymine, or uracil.
Comparable experiments showed possible synthetic pathways for purines,
pyramidines, and carbohydrates. Given ultraviolet radiation, electrical
discharge, and other energy sources on the primitive Earth, and
a reducing atmosphere, one might expect the inevitable appearance
of amino acids, purines, pyramidines, ribose and deoxyribose, and
even nucleosides and nucleotides.
At least the building blocks of life would have been available
on the primitive Earth.
The "Haldane soup" was real.