On February 13, about 30 kilometres out into the Gulf of Aden, four Yemeni fishermen discovered a lifeless sperm whale. Working with other local seamen, they hauled the bloated carcass to a local beach. What happened next would make for a great film. This motley crew of mariners gutted the whale and discovered a motherlode of ambergris, a waxy blob of whale excrement, weighing around 127 kilograms. Highly valued by the perfume industry, ambergris fetches up to $20,000/kg. These mariners could become millionaires. Why would anyone pay so much for whale excrement, though? Firstly, ambergris is incredibly rare. Only an estimated one per cent of sperm whales (declared an endangered species in 1970) produce this waxy substance. Secondly, and more importantly, in the hands of artisanal perfumers, ambergris is transformed into a prized fragrance. Humanity has a longstanding love affair with all things fragrant. We have always been happy to exchange silver and gold for colourless scents that vanish in the wind. For example, Pliny the Younger, the Roman politician and prolific letter writer, ranted about how much perfumes (especially Yemeni frankincense) were costing Rome. "By the lowest reckoning India, China, and the Arabian Peninsula take from our empire 100 million sesterces [a Roman currency] every year – that is the sum our luxuries and our women cost us," he wrote. The great North African explorer, Ibn Battuta, makes similar observations about the Gulf Arabs of the 14th century, writing: "they will spend the night hungry in order to buy perfumes with the price of their food… When one of these women goes away, the odour of the perfume clings to the place after she has gone.” Our love of perfume remains as strong as ever, and in few places is this more apparent than in the UAE. Google Trends, which tracks the popularity of online search terms, has found that over the past five years, no place on the planet has searched the term "perfume" more than the UAE. What lies at the heart of our fondness for fine fragrances? Perhaps it is related to the close connection between our sense of smell and our emotions. Scents go straight to a part of the brain called the olfactory bulb. The nose literally has a direct line to the brain – no middleman. In turn, the olfactory bulb connects to the amygdala and the hippocampus, bits of wetware (i.e. brain) involved in emotional responses and memories. Scents, sights and sounds can trigger equally accurate memories, but fragrances give rise to the most emotional ones. Rediscovering the smell of a lost loved one on a hairbrush can provoke far more emotion than an old photograph. Given the link between scents and emotion, it is hardly surprising that scent marketing has become such a powerful tool in recent years. Emotions move us, and they can nudge us towards buying things. Scent can be a real deal-sealer. Alan Hirsch, the Smell & Taste Treatment & Research Foundation's neurological director, argues that "smell has a greater impact on purchasing than everything else combined". In a move that acknowledges this link, the new Mercedes S class car now has its own signature scent. Its air filtering system uses an ioniser to improve overall air quality before infusing the cabin with the unique S-Class fragrance – mood management on the move. This relationship between scents and sentiment is further illustrated by the high rates of depression and anxiety among people with an impaired sense of smell, also known as anosmia (complete loss) and hyposmia (partial loss). More common than blindness and profound deafness, anosmia can have severe emotional implications. A UK study, published in the journal <em>Chemical Senses</em> in 2014, reported elevated rates of depression (43 per cent) and anxiety (45 per cent) among people experiencing various forms of anosmia. This, by the way, makes it all the more alarming that anosmia has been reported as a symptom of Covid-19. Scents give us pleasure, and a reduced ability to smell them deprives us of this. But why are certain fragrances pleasurable in the first place? Here we have to look to our personal history and perhaps the evolutionary past. Many of the smells we universally dislike, such as spoiled food, are associated with illness risk; there is an obvious survival value in detesting such odours. Similarly, the fragrances we widely find pleasurable, such as fruits and plants, can be associated with nutrition, shelter and survival. Our culture and personal life experiences, however, will further refine our odour preferences. Certain cultural groups might prize certain odours that others find objectionable – smelly cheese, for example. We may even come to identify specific groups with a particular scent. When the Japanese encountered the Europeans after more than a century of seclusion, they called the Europeans bata-kusai: "smells like butter". On a personal level, we also learn to love or hate smells associated with emotional memories, such as that hospital smell or the aroma of fresh-cut grass. Like the emotions they evoke, fragrances can be hard to put into words. Those who describe the scent of ambergris, however, frequently refer to the sea. The author Katy Kelleher describes it as "sweet, yet rather marine, like vanilla and unrefined sugar mixed with seawater". I can see how such a fragrance might evoke happy childhood memories of trips to the seaside. For the Yemeni fishermen who discovered 127kg of floating gold, eau de ambergris is likely to create a whole new set of happy memories. <em>Justin Thomas is a professor of psychology at Zayed University and a columnist for The National</em>