As Valentine’s Day approaches, and before we delve into the customary expressions of affection such as exchanging cards, red roses, or confessing your feelings to a crush, have you ever wondered how love works from a biological perspective?
Establishing love: hormones in action
Your experience of love, it turns out, is largely due to the work of hormones – the unsung heroes in this romantic tale.
Hormones, put simply, are chemical messengers that circulate around the body, each with its own unique task to fulfil. The pituitary gland, situated in the brain, plays the role of the conductor, releasing master hormones that prompt glands in different body parts to manufacture specific hormones. These hormones, in turn, instigate certain physiological effects, including the control of social behaviour.
According to Dr Helen Fisher, an anthropologist, love can be distilled into three stages – lust, attraction, and attachment – each fuelled by a distinct blend of hormones.
The first stage sees an amplification in testosterone and oestrogen, released by the gonads (testes or ovaries) in both sexes. Together, they mediate sexual excitation, with testosterone having a more pronounced effect.
Then comes the attraction phase. Ever wondered why encountering your crush causes your heart to beat faster, your palms to sweat, and gives you that “butterflies in your stomach” feeling? This can be attributed to a surge in dopamine and norepinephrine, hormones intricately associated with feelings of pleasure, euphoria, and arousal. Serotonin levels dwindle, leading to exasperating preoccupying thoughts of your potential partner. These hormonal changes parallel patterns often observed in obsessive-compulsive disorder – in essence, love can feel like an obsession.
Lastly comes the attachment phase, where the initial passion fades but culminates in a lasting relationship. Hormones oxytocin and vasopressin are at play, mediating social bonding – i.e., feelings of calmness, security, and comfort – as well as parental probity, which forms the cornerstone of long-term commitment.
The roles of appearance and genetics
Fundamentally, we are subconsciously programmed to be romantically attracted to compatible mates using our sense organs, which can provide us subtle pieces of information about them. From an evolutionary standpoint, this is critical because it underlies sexual selection, which posits that we select our mates based on certain traits that may contribute favourably to healthy offspring, maximising our population fitness.
Physical traits, such as having a symmetrical face, have some association with ‘good’ genes and health, subconsciously increasing attractiveness when searching for a potential mate. A healthy body-mass index and having certain waist-to-hip ratios likewise provide cues to health and reproductive potential.
Vocalisation also plays a part in attraction; high-pitched vocalisation in females is subconsciously perceived as a consequence of high oestrogen levels, which signals fecundity, making this a typically attractive trait to males. Meanwhile, resonant (low) vocalisation in males is attractive as it subconsciously indicates high testosterone levels, masculinity and improved reproductive fitness.
Information perceived from the airborne molecules released from potential mates is also used to select mates with dissimilar gene patterns through our olfactory system, allowing for increased diversification of the gene pool. The phenomenon underlying this is known as ‘molecular histocompatibility complex (MHC) disassortative mating’. MHC molecules are highly heterogeneous, inherited and presented on the surfaces of all nucleated cells. They help to present foreign invaders that are devoured into smaller pieces – known as peptides – to our immune system for recognition, and they also give rise to different body odours. Choosing someone with dissimilar MHC patterns has two implications: first, it expands the repertoire of recognised peptides, equipping us to better survive pathogenic infection; second, it limits inbreeding and increases genetic variability, increasing survivability.
Final thoughts
In the poetic words of William Shakespeare, “Love looks not with the eyes, but with the mind, And therefore is winged Cupid painted blind”. Evolution has indeed shaped us to identify compatible mates through visual, auditory, or olfactory cues. However, despite lacking expertise in the matters of love, I contend that evolution merely influences our initial impressions. Traits like personality and intelligence, I would argue, play a more critical role in sustaining an enduring relationship. Love, ultimately, remains an enigmatic and mysterious emotion – a sentiment echoed by the ongoing endeavours of scientists who have dedicated decades to studying the complexities of this exasperating, yet thrilling, emotion.