Based on phylogenetic analyses of the mineralcorticoid and glucocorticoid receptors and the presence or absence of their ligands (glucocorticoids and aldosterone) in certain vertebrates, it would appear that hormones always evolve prior to their receptors.

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Receptors often evolve before their specific ligands, as seen in the case of the mineralocorticoid and glucocorticoid receptors. The evolution of these receptors before the appearance of their specific hormones (glucocorticoids and aldosterone) in vertebrates suggests a more complex evolutionary pathway where receptors might initially have had different ligands or functions.

Based on Phylogenetic Analyses of the Mineralcorticoid and Glucocorticoid Receptors