{"id":244,"date":"2026-03-04T12:16:33","date_gmt":"2026-03-04T17:16:33","guid":{"rendered":"https:\/\/blogs.bu.edu\/the-nerve\/?p=244"},"modified":"2026-08-24T21:33:09","modified_gmt":"2026-08-25T01:33:09","slug":"love-in-bloom-the-science-of-butterflies","status":"publish","type":"post","link":"https:\/\/blogs.bu.edu\/the-nerve\/2026\/03\/04\/love-in-bloom-the-science-of-butterflies\/","title":{"rendered":"Love in Bloom: The Science of Butterflies"},"content":{"rendered":"
\n

\u201cA life without love is like a year without spring.\u201d- Octavius Paler\u00a0<\/span><\/i><\/h3>\n<\/blockquote>\n
By Diya Dronavadhyala<\/h6>\n

As the short days on our snowy winter campus are replaced with cherry blossoms and sunny afternoons, it feels like love is wafting through the air. For some, spring represents a season of fresher produce, fruity drinks, and flowery pastries. For others, it represents a new season of hope and romance. In the wake of Valentine\u2019s day, grocery aisles are brimming with candy hearts and chocolate. Our society, for better or worse, inextricably links love with food; as the saying goes, \u201cthe way to one\u2019s heart is through their stomach,\u201d and of course, every rom-com viewer will tell you to \u201ctrust your gut when it comes to love.\u201d But are these proverbs rooted in any truth? In other words, how important is our gut in shaping our social interactions? From first-date stress to social bonding and affection, we can turn to neuroscience to examine whether the fluttering sensations we associate with love this season begin, at least in part, somewhere lower than the heart.\u00a0<\/span><\/p>\n

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I<\/span>n order to understand how our guts impact our social behaviors, we first have to delve into the science behind love and identify a few important players. Cognitive neuroscience\u2019s understanding of love is still pretty vague and speculative, but a widely accepted scientific framework to characterize love, coined by anthropologist Helen Fisher, boils down to three big aspects; she proposes that mammalian love is really \u201c<\/span>(1) the sex drive, or lust […]; (2) attraction, characterized by increased energy and focused attention on one or more potential mates[…] and the craving for emotional union with this mate or potential mate; and (3) attachment, characterized by the maintenance of close social contact in mammals […]\u201d <\/span>\u00a0(1998). <\/span>A key neurotransmitter implicated in our perception of love, mainly Fisher\u2019s attraction phase, is dopamine. Dopamine is responsible for activity in the reward pathway, modulating important areas including our ventral tegmental area and caudate nucleus (Edwards, 2015). <\/span>Functional MRI studies show that when subjects view images of a romantic partner these dopamine-rich regions become active. These same circuits are involved in reinforcement learning and goal-directed behavior, helping explain the exhilaration and intense focus often associated with early-stage love. <\/span>A few other main neurotransmitters and neuromodulators involved in love include oxytocin and serotonin. Oxytocin, the \u201ccuddle hormone,\u201d is associated with trust, emotional closeness, and stress buffering during social connection. It\u2019s often released during moments of intimacy to promote bonding or reduce anxious feelings. Serotonin, the \u201cfeel-good\u201d hormone, plays an important role in mood stability and sleep. All of these molecules contribute to love in the brain, from the excitement of the initial lust and attraction phases to longer-term attachment. However, our perception of love is deeply linked with peripheral systems beyond the brain and spinal cord.\u00a0<\/span><\/p>\n

As it turns out, there is a legitimate foundation for the connection between our gut and our social perception. The gut and the brain are linked through an intricate communication network known as the gut\u2013brain axis, a bidirectional system involving neural pathways, immune signaling, hormones, and trillions of microbes that reside in the digestive tract. Emerging evidence suggests that these microbes can influence stress responses, neurotransmitter systems, and possibly even social behavior.<\/span> The gut is home to the enteric nervous system, sometimes called our \u201csecond brain,\u201d as it harbors a shocking 100 million neurons that operate independently of the brain. Interestingly, the enteric nervous system produces around 90% of the body\u2019s serotonin, although this serotonin is typically associated with local functions like appetite regulation and digestion (Goyal, 1996). The presence of these neurons are why antidepressants are often prescribed to treat IBS or persistent gut conditions (Clouse, 2003). The significance of gut health in memory, mood and cognition remains an area of active research in neuroscience.\u00a0\u00a0<\/span><\/p>\n

If the gut does modulate love, it does so through an active role in the emotions associated with romantic experience, and, as evidenced by any number of teen dramas and soap operas, you can\u2019t have love without stress. The feeling of \u201cbutterflies\u201d in the stomach associated with first-date jitters and the \u201cwill-they won\u2019t theys\u201d of relationships are signs of excitement and anxiety. There have been some fascinating inquiries into the relationship between gut microbiota and our stress axes, which, while not directly correlated to romance and attraction, play a major role in our social experience of love. The hypothalamic\u2013pituitary\u2013adrenal (HPA) axis is the body\u2019s central stress response system, coordinating the release of steroid hormones known as glucocorticoids that, among other functions, regulate glucose metabolism and modulate immune response, such as cortisol.<\/span><\/p>\n

\u00a0A 2004 paper by Sudo et. al reveals the role of the gut microbiome in stress modulation. In the study, they examined the development of the HPA axis in germ-free mice, or mice raised in completely sterile environments, without any exposure to microorganisms. The researchers found that mice raised without any gut microbiota exhibited an exaggerated stress response when exposed to being placed in restraint stress, a confined space where the animal\u2019s locomotion is limited, showing significantly elevated levels of stress hormones, specifically corticosterone and ACTH, compared to conventionally colonized controls. When researchers introduced regular gut microbes early in life, they were able to prevent the animal from exhibiting this stress response, whereas introducing the bacteria in adulthood could not fully reverse the negative effects of early-life deprivation. These findings suggest that the gut microbiome plays a significant role in calibrating the HPA axis, and, especially in development, can be crucial to shaping how reactive one is to stress.\u00a0<\/span><\/p>\n

The vagus nerve, which originates in the brainstem and innervates the heart, lungs, and (of course) digestive tract, is another major facilitator of bilateral communication. The vagus nerve acts as a biological \u201chighway\u201d between the gut and the brain, allowing stress-related signals to travel in both directions. Signals originating in the gut can modulate central stress pathways via the vagus nerve, while stress-induced neural activity can feed back to alter gut motility, permeability, and microbial composition, These phenomena might explain why sometimes you get too nervous to eat before a date, or feel your stomach drop with anticipation (Lai, 2023). It\u2019s likely that those butterflies before dinner actually represent your brain and gut trying to re-allocate resources away from digestion towards more pressing situations. Evolutionarily, this makes sense; animals that were able to dedicate heightened attention and social vigilance would have had an advantage in finding a mate. Because early attraction is so often linked to stress and heightened arousal, it is plausible that the HPA axis and gut-modulated signalling would be involved in mediating the feelings and intensity of our initial experiences with love.\u00a0<\/span><\/p>\n

Beyond stress, the gut might also play a more direct role in shaping neurochemical systems implicated in love-associated feelings. Recent literature has begun to explore whether the gut microbiome may influence love-associated emotions through endocrine and neurotransmitter signaling, though this remains a highly speculative area of research. A recent review entitled <\/span>Does a microbial-endocrine interplay shape love-associated emotions in humans? <\/span><\/i>proposes that aspects of love like attachment and attraction can be partially attributed to microbial modulation of neurotransmission systems like the dopaminergic reward system (Robinson, 2025). Dopamine is produced by the conversion of a molecule called L-tyrosine to L-DOPA, and the subsequent conversion of L-DOPA to dopamine. There is emerging evidence suggesting that certain bacteria are implicated in the production of dopamine. For example, strains like <\/span>Bacteroides<\/span><\/i>, <\/span>Clostridium<\/span><\/i>, and <\/span>Enterococcus<\/span><\/i> have been shown to boost dopamine production by acting on AADC, a catalyst of the L-DOPA to dopamine conversion (Albani, 2025). Conversely, gut micro-bact<\/span>eria can also consume or metabolize dopamine or its precursors, limiting its availability to the host (Albani, 2025)<\/span>. Robinson references a landmark <\/span>Drosophila<\/span><\/i> (fruit fly) study that linked commensal bacteria, harmless microbes that live on or inside a host, to changes in mating preferences (Sharon, 2010). In this work, flies raised on different diets developed different mating behaviors that were abolished by antibiotic treatment and restored by microbial recolonization, implying that gut bacteria serves as a causal factor in mating preferences. The authors identify <\/span>Lactobacillus <\/span><\/i>as inducing these changes, likely due to its generation of pheromonal changes in the flies. It is important to note that these findings do not directly translate to mammalian models, where pheromones play a much less significant role in mating behaviors, but they serve to illustrate the larger point that gut microbiota can affect our social behaviors via sensory\/signalling systems. This study supports the biological plausibility that the microbiome-mediated modulation of neuroendocrine or sensory pathways could influence components of attraction or social bonding.\u00a0<\/span><\/p>\n

Robinson goes on to discuss the role of oxytocin and vasopressin, two neuropeptides widely recognized as central to attachment and long-term bonding. Importantly, emerging animal research suggests that the gut microbiome may influence oxytocin signaling through immune pathways and vagal nerve communication between the gut and brain. For example, a 2016 study on mice models investigated whether changes in the gut microbiome could influence social behavior in mice by studying offspring born to mothers fed a high-fat diet, which led to social deficits and altered gut microbial composition (Buffington, 2016). More excitingly, they found that reintroducing a specific bacterium, <\/span>Lactobacillus reuteri<\/span><\/i>, restored normal social interaction, normalized oxytocin levels in the hypothalamus, and improved reward-circuit function in the brain. (Buffington, 2016). This study presents compelling evidence that the gut microbiome can influence aspects of social interactions and bonding, although further research is necessary to determine exactly how these findings translate to human love-associated behaviors.\u00a0<\/span><\/p>\n

It should be noted that Robinson\u2019s hypothesis has been critiqued as overly optimistic about the role of the gut in love. In his October response entitled <\/span>The science of love is not quite there\u2026<\/span><\/i>, Dr. Adam Bode, an interdisciplinary researcher who specializes in the study of romantic and familial love, argues that \u201c<\/span>The article\u2019s assertion that \u2018we have a good understanding of the hormone systems that play important roles in forming emotions relating to love\u2019 […] is inconsistent with the state of knowledge surrounding the mechanisms of romantic love\u201d (2025). Bode emphasizes that, among neurotransmitters and neurohormones, only dopamine, oxytocin, and opioids have consistent empirical support in romantic love research, and evidence for roles of serotonin, testosterone, cortisol, vasopressin, and norepinephrine is limited or inconsistent, pointing out that Robinson\u2019s take is speculative at best. While the response article correctly cautions that the characterization of the neurobiology of romantic love remains incomplete, this limitation does not invalidate investigation into upstream biological systems that influence stress regulation, reward processing, and social bonding. Our uncertainty about the connection of the gut and social and emotional behaviors is a strong reason to continue researching the currently largely undercharacterized impact peripheral processes have on our social and psychological behaviors.\u00a0<\/span><\/p>\n

It has been established time and again that our emotional worldviews are fundamentally tied to the processes in our periphery; the systems underlying social bonding are deeply integrated with stress regulation and metabolic health. Maybe downing a yogurt drink isn\u2019t going to help you find your soulmate, but it appears that love is supported by unseen systems that regulate stress, reward, and emotional stability. Love is a complex phenomenon, and it cannot be reduced to any single molecule or body part. As we examine the intricate processes that go into mediating what at the surface seems like one of the most natural, innate experiences in human nature, it begins to become clear just how mind-blowing our physiology really is. It\u2019s crazy to think that something so abstract and profound as love, whether found in romantic attraction or connections with family and friends, is the product of the integration of so many immensely complicated, invisible processes. So, in the midst of this busy spring semester, it might be worthwhile to step back, smell the roses, and say those three little words to someone who gives you butterflies in your stomach.\u00a0\u00a0<\/span><\/p>\n

References<\/b><\/h4>\n

Albani, G., Vasuki Ranjani Chellamuthu, Morlacchi, L., Federica Zirone, Youssefi, M., Giardini, M., Chao, Y.-X., Tan, E.-K., & Albani, S. (2025). Gut Microbiota and Dopamine: Producers, Consumers, Enzymatic Mechanisms, and In Vivo Insights. <\/span>Bioengineering<\/span><\/i>, <\/span>13<\/span><\/i>(1), 55\u201355. https:\/\/doi.org\/10.3390\/bioengineering13010055<\/span><\/p>\n

Bode, A. (2025). The science of love is not quite there\u2026. <\/span>MSystems<\/span><\/i>, <\/span>10<\/span><\/i>(11). https:\/\/doi.org\/10.1128\/msystems.01189-25<\/span><\/p>\n

Buffington, S. A., Di Prisco, G. V., Auchtung, T. A., Ajami, N. J., Petrosino, J. F., & Costa-Mattioli, M. (2016). Microbial Reconstitution Reverses Maternal Diet-Induced Social and Synaptic Deficits in Offspring. <\/span>Cell<\/span><\/i>, <\/span>165<\/span><\/i>(7), 1762\u20131775. https:\/\/doi.org\/10.1016\/j.cell.2016.06.001<\/span><\/p>\n

Clouse, R. E. (2003). Antidepressants for irritable bowel syndrome. <\/span>Gut<\/span><\/i>, <\/span>52<\/span><\/i>(4), 598\u2013599. https:\/\/doi.org\/10.1136\/gut.52.4.598<\/span><\/p>\n

Edwards, S. (2015). <\/span>Love and the Brain<\/span><\/i>. Harvard Medical School; The President and Fellows of Harvard College. https:\/\/hms.harvard.edu\/news-events\/publications-archive\/brain\/love-brain<\/span><\/p>\n

Fisher, H. E. (1998). Lust, attraction, and attachment in mammalian reproduction. <\/span>Human Nature<\/span><\/i>, <\/span>9<\/span><\/i>(1), 23\u201352. https:\/\/doi.org\/10.1007\/s12110-998-1010-5<\/span><\/p>\n

Goyal, R. K., & Hirano, I. (1996). The Enteric Nervous System. <\/span>New England Journal of Medicine<\/span><\/i>, <\/span>334<\/span><\/i>(17), 1106\u20131115. https:\/\/doi.org\/10.1056\/nejm199604253341707<\/span><\/p>\n

Lai, T.-T., Liou, C., Tsai, Y., Lin, Y., & Wan Chi Wu. (2023). Butterflies in the gut: the interplay between intestinal microbiota and stress. <\/span>Journal of Biomedical Science<\/span><\/i>, <\/span>30<\/span><\/i>(1). https:\/\/doi.org\/10.1186\/s12929-023-00984-6<\/span><\/p>\n

Robinson, J. M., Crino, O. L., Camargo, A., & Breed, M. F. (2025). Does a microbial-endocrine interplay shape love-associated emotions in humans? A hypothesis. <\/span>MSystems<\/span><\/i>, <\/span>30<\/span><\/i>, 92. https:\/\/doi.org\/10.1128\/msystems.00415-25<\/span><\/p>\n

Sharon, G., Segal, D., Ringo, J. M., Hefetz, A., Zilber-Rosenberg, I., & Rosenberg, E. (2010). Commensal bacteria play a role in mating preference of Drosophila melanogaster. <\/span>Proceedings of the National Academy of Sciences<\/span><\/i>, <\/span>107<\/span><\/i>(46), 20051\u201320056. https:\/\/doi.org\/10.1073\/pnas.1009906107<\/span><\/p>\n

Sudo, N., Chida, Y., Aiba, Y., Sonoda, J., Oyama, N., Yu, X.-N., Kubo, C., & Koga, Y. (2004). Postnatal microbial colonization programs the hypothalamic-pituitary-adrenal system for stress response in mice. <\/span>The Journal of Physiology<\/span><\/i>, <\/span>558<\/span><\/i>(1), 263\u2013275. https:\/\/doi.org\/10.1113\/jphysiol.2004.06338<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

\u201cA life without love is like a year without spring.\u201d- Octavius Paler\u00a0 By Diya Dronavadhyala As the short days on our snowy winter campus are replaced with cherry blossoms and sunny afternoons, it feels like love is wafting through the air. For some, spring represents a season of fresher produce, fruity drinks, and flowery pastries. […]<\/p>\n","protected":false},"author":9591,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[12,1],"tags":[],"_links":{"self":[{"href":"https:\/\/blogs.bu.edu\/the-nerve\/wp-json\/wp\/v2\/posts\/244"}],"collection":[{"href":"https:\/\/blogs.bu.edu\/the-nerve\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.bu.edu\/the-nerve\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.bu.edu\/the-nerve\/wp-json\/wp\/v2\/users\/9591"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.bu.edu\/the-nerve\/wp-json\/wp\/v2\/comments?post=244"}],"version-history":[{"count":3,"href":"https:\/\/blogs.bu.edu\/the-nerve\/wp-json\/wp\/v2\/posts\/244\/revisions"}],"predecessor-version":[{"id":294,"href":"https:\/\/blogs.bu.edu\/the-nerve\/wp-json\/wp\/v2\/posts\/244\/revisions\/294"}],"wp:attachment":[{"href":"https:\/\/blogs.bu.edu\/the-nerve\/wp-json\/wp\/v2\/media?parent=244"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.bu.edu\/the-nerve\/wp-json\/wp\/v2\/categories?post=244"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.bu.edu\/the-nerve\/wp-json\/wp\/v2\/tags?post=244"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}