Linked OXTR Variants Are Associated With Social Behavior Differences in Bonobos (Pan paniscus)

Single-nucleotide polymorphisms (SNPs) in forkhead box protein P2 (FOXP2), oxytocin receptor (OXTR), and arginine vasopressin receptor gene 1A (AVPR1A) have been associated with linguistic and social development in humans, as well as symptom severity in autism. Studying biobehavioral mechanisms in the species most closely related to humans can provide insights into the origins of human communication, and the impact of genetic variation on complex behavioral phenotypes. Here, we tested the hypothesis that similar genetic factors underlie social communication differences in both bonobos (Pan paniscus) and humans. We analyzed Sanger sequencing results to determine if bonobos exhibit individual variation at 10 loci across FOXP2, OXTR, and AVPR1A that have been implicated in human social development and behavior. We identified a novel variant in bonobo FOXP2, as well as three novel variants in bonobo OXTR that were 19-184 base pairs away from the target human SNPs. We also found a linked SNP combination (TGA) across the 3 novel bonobo OXTR sites at high frequency (65%) in the study population, including 6 homozygous bonobos. When comparing the combined OXTR genotypes, we found significant group differences in social behavior; bonobos with two copies of the TGA combination were more social than bonobos with one copy and bonobos with zero copies of the TGA combination. Taken together, our findings suggest that these OXTR variants may influence individual-level social behavior in bonobos and support the notion that linked genetic variants are promising biomarkers for differences in human social communication.