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.

A molecule of Adenine