Among the gases produced by volcanoes are steam, methane, ammonia and hydrogen. In 1953 Stanley Miller sparked these gases with a Tesla coil to simulate the lightning that often accompanies volcanic eruptions. Recent analysis of the resulting goop, forgotten for decades, revealed 22 amino acids, many of which are the building blocks of life (Bada, Science, Oct. 2008). If Miller had included volcanic sulfur, he may have created additional amino acids. Miller's famous 1953 paper listed only five amino acids, produced without injecting volcanic steam.

Each of life's 20 amino acids (the diagram shows 4) is coded by 3 of DNA's 4 bases (ATCG). For example, TGC represents Cystene. Amino acids are assembled (in sequences dictated by DNA) into small peptides or larger proteins.

The amino acid sequence in human oxytocin is amazingly similar to sequences in analogous peptides in other forms of life (see table), suggesting that these peptides are of vital significance. In fact, they play important roles in reproduction. Mammalian oxytocin is released during mating, birthing and nursing. It promotes maternal bonding between mother and child.

An ancestor of all vertebrates experienced a gene duplication which gave rise to a second set of neuro-peptides. Vasopressin, the mammalian type, differs from oxytocin in just 2 of its 9 amino acids. It influences the sexual behavior of males (mating, bonding and aggression toward rivals). When vasopressin is blocked in monogamous prairie voles, they become promiscuous like typical rodents. According to Young (Nature, Jan. 2009), "studies are under way to determine whether an oxytocin spray might aid traditional marital therapy".

Thus, violent volcanic eruptions billions of years ago may have facilitated the evolution of life's amino acids and peptides, some of which continue to influence the emotional behaviors of diverse animals. Ponder the connections between volcanoes and human emotions next time you attend a wedding or witness a birth.

Of course, true love is more than just chemistry. Does not the beauty of a flower transcend its reproductive function?

Oxytocin should not be confused with the addictive pain killer, OxyContin.