Romantic love as regulatory co-option of maternal-bonding circuitry: a testable genetic account.

Romantic love lacks a mechanistic, testable evolutionary account. Prior work notes parallels with mother-infant bonding but leaves the genetic architecture and falsifiable predictions unspecified. We argue that romantic love evolved not through the evolution of new "love genes," but by altering the regulation of existing genes: changing when, where, and under what physiological conditions these genes are active. This regulatory co-option framework generates several falsifiable predictions: (1) a shared genetic basis between maternal bonding and romantic love, (2) the involvement of non-coding, regulatory DNA regions in the brain, (3) a largely shared genetic architecture between the sexes, with differences in gene expression, and (4) genetic signals localized to specific brain circuits. We outline specific genomic and statistical methods to test these predictions, establishing clear criteria that would support or refute our hypothesis. This work shifts the study of romantic love's evolution from analogy to a program of empirical inquiry and hopes to shed light on how social monogamy entered the Homo sapiens lineage. Key challenges include the lack of high quality meta-analytic fMRI evidence of romantic love and the scarcity of detailed data from relevant human brain circuits.