Loneliness, or perceived social isolation, may be evident in any group-living species, although its assessment in nonhumans provides some measurement challenges. It is well-known that loneliness in humans confers significant risk for morbidity and mortality, although mechanisms remain unclear. The authors describe a naturally-occurring model of loneliness in adult male rhesus monkeys that shows many parallels with the phenomenon in humans. Lonely monkeys (those that display high frequencies of social initiations but low frequencies of complex interaction) show elevated sympathetic nervous system activity and down regulated Type I interferon responses. Analysis of data from simian immunodeficiency virus-infected monkeys indicates that these physiological changes have functional consequences. Use of this animal model can help identify mechanisms by which loneliness impacts health.
Conflict of interest statement
Declarations of interest: none
A behavioral taxonomy of loneliness in humans and rhesus monkeys (Macaca mulatta).PLoS One. 2014 Oct 29;9(10):e110307. doi: 10.1371/journal.pone.0110307. eCollection 2014. PLoS One. 2014. PMID: 25354040 Free PMC article.
Loneliness, Social Isolation, and Cardiovascular Health.Antioxid Redox Signal. 2018 Mar 20;28(9):837-851. doi: 10.1089/ars.2017.7312. Epub 2017 Oct 23. Antioxid Redox Signal. 2018. PMID: 28903579 Free PMC article. Review.
Loneliness, HPA stress reactivity and social threat sensitivity: Analyzing naturalistic social challenges.Scand J Psychol. 2018 Oct;59(5):540-546. doi: 10.1111/sjop.12461. Epub 2018 Jul 4. Scand J Psychol. 2018. PMID: 29972603
Toward a neurology of loneliness.Psychol Bull. 2014 Nov;140(6):1464-504. doi: 10.1037/a0037618. Epub 2014 Sep 15. Psychol Bull. 2014. PMID: 25222636 Free PMC article. Review.
An env gene derived from a primary human immunodeficiency virus type 1 isolate confers high in vivo replicative capacity to a chimeric simian/human immunodeficiency virus in rhesus monkeys.J Virol. 1996 May;70(5):3198-206. J Virol. 1996. PMID: 8627800 Free PMC article.