Introduction
This article will explore how cats experience taste compared to humans. We’ll look at the anatomy of cat and human tongues, differences in taste receptors, the impact of their strong sense of smell, taste preferences, genetic causes for varying taste capabilities, and the effects on diet. The goal is to understand why cats seem to taste food differently than humans, despite some similarities in our taste anatomy and receptors.
Anatomy of Cat Tongues
A cat’s tongue is made up of small, backward-facing spines called papillae that contain the cat’s taste buds (Robinson, 1990). Cats have fewer taste buds compared to humans, with only around 473 taste buds on their tongue (Hill’s Pet Nutrition, 2022). However, cats still respond to the basic taste groups that humans can detect – sweet, sour, bitter and salty.
Anatomy of Human Tongues
Humans have taste buds located on papillae throughout the surface of the tongue, soft palate, pharynx, and larynx. The tongue contains three types of papillae that house taste buds: fungiform, foliate, and circumvallate papillae. Fungiform papillae are present on the anterior two-thirds of the tongue and contain one to several taste buds each. Foliate papillae form parallel folds on the posterior lateral edge of the tongue and contain several hundred taste buds. Circumvallate papillae are present in a V-shape near the back of the tongue and contain thousands of taste buds.
According to research, humans have around 5,000 taste buds that are replaced every 10-14 days. The density of taste buds is highest on the tip and sides of the tongue. Each taste bud has 50 to 150 taste receptor cells that connect to nerves running to the brain. This complex structure with a high density of taste buds allows humans to perceive five primary taste qualities: sweet, salty, sour, bitter, and umami.
Taste Receptor Differences
Cats lack taste receptors for sweets and have an increased number of taste receptors for bitter tastes compared to humans. The key difference is in taste receptors called T1Rs which detect sweetness. While humans have functional T1R2 and T1R3 receptors to detect all types of sugars and sweeteners, cats lack a functional T1R2 receptor. This means cats perceive sweet foods differently than humans.
According to research cited on CatsonBroadwayHospital.com, humans have approximately 9,000 taste buds that distinguish sweet, sour, bitter, salty, and savory flavors. Cats only have around 470 taste buds and lack the T1R2 receptor to detect sweetness (Source).
In humans, the T1R2 and T1R3 couple together to bind to sugars and trigger sweet taste perception. Without T1R2, cats miss this complete sweet taste experience. However, they can still weakly detect some sugars using the T1R3 receptor alone.
While lacking in sweet perception, cats have more bitter taste receptors. Evidence shows domestic cats have positive selection for gene mutations that increase their sensitivity to bitter compounds, which allows them to better avoid toxins in plants and other foods (Source).
Sense of Smell Impact
Cats rely more on their sense of smell than their sense of taste. A cat’s sense of smell is 14 times better than humans, with over 200 million scent receptors compared to our 5 million [1]. This superior sense of smell allows cats to experience flavors in ways humans cannot. Scent contributes hugely to a cat’s perception of taste. Aromatic compounds from food travel to the olfactory epithelium in the cat’s nose as it eats. These scent clues, combined with the cat’s limited taste buds, create the overall flavor experience.
Because cats depend so much on smell to inform taste, their experience of food is very different from humans. They may enjoy flavors that seem bland to us, detecting savory notes imperceptible to our noses. On the other hand, they miss out on experiencing sweet flavors at all due to lacking the taste receptor gene responsible for sweetness perception [2]. Overall, cats live in a rich olfactory world, where smell and taste are inextricably linked.
Taste Preferences
Cats have taste preferences that are different from humans due to differences in their taste receptors. Research shows that cats are especially attracted to flavors from animal products and fat, while not having much preference for sweet or salty tastes.
Specifically, cats are drawn to meaty, fishy, and milky flavors, which would have appealed to their carnivorous ancestors (Umami taste perception and preferences of the domestic cat, 2022). The compound glutamate is associated with these savory umami tastes, and cats have a high number of glutamate taste receptors.
On the other hand, cats dislike overly sweet or bitter tastes. They have very few taste receptors for sweetness compared to humans, and do not show a preference for high sugar foods (Taste preferences and diet palatability in cats, 2020). Bitter flavors from plant compounds like tannins are also unappealing to cats’ taste buds.
Understanding cats’ unique taste preferences can help cat owners select foods and treats their cats will find irresistible based on their natural flavor affinities.
Genetic Cause of Taste Differences
The primary genetic cause of taste differences between cats and humans is a mutation in the Tas1r2 gene which encodes the T1R2 taste receptor protein. This mutation prevents cats from being able to detect sweet tastes (Bachmanov et al., 2014). Humans and many other mammals have an intact Tas1r2 gene and can perceive sweet flavors, however the mutated version in cats eliminates their ability to taste sweetness.
The evolutionary reason for cats’ altered sweet taste receptors relates to their obligate carnivore status. Since cats evolved to eat a strictly meat-based diet, they lost some of their taste receptor genes through neutral evolution over time, including Tas1r2 for sweet taste. This gave cats a taste perception more suited to their biology and natural prey diet, while humans maintained a more omnivorous palette (Carolina, 2022). The different taste receptors in each species evolved to match their nutritional needs.
Impact on Diet
Cats have very different dietary needs compared to humans due to their status as obligate carnivores. As obligate carnivores, cats require meat-based proteins in their diet and cannot synthesize certain essential amino acids like taurine on their own [1]. Taurine, in particular, is an amino acid that cats cannot produce enough of and must obtain from their food. Lack of taurine can cause severe health issues in cats, such as heart disease and vision loss.
On the other hand, humans are omnivores and can obtain complete nutrition from both plant and animal sources. While humans also require protein, we do not require nearly as much protein in our diets as cats, and we can synthesize taurine unlike cats. This fundamental difference in cats being obligate carnivores means they require a high protein, meat-focused diet, whereas humans have much more flexibility in food sources.
Interesting Facts
Cats have fewer taste buds than humans, with only around 473 compared to our 9,000.[1] Despite this, their sense of taste is still advanced in certain ways. For example, cats have an excellent sense of bitter tastes which helps them detect spoiled food and avoid eating it.
There’s a myth that cats can’t taste sweet things at all. In reality, they do have receptors for sweetness, but they evolved differences in a key taste gene called Tas1r2.[2] This means they are not as attracted to sugary or starchy foods as humans. However, some cats do show a fondness for sweet flavors in moderation.
Cats use their sense of smell to detect flavors more than their actual taste buds. Their sense of smell is around 14 times better than humans! That’s why smells that seem fine to us may put a cat off their food entirely.
Kittens have more active taste buds than adult cats. As they grow up, some of their taste buds fall idle. This explains why kittens are typically more explorative with food and flavors.
The feline taste system evolved to detect meats and proteins. Cats find the taste of amino acids like glycine highly palatable. Comparatively, they have a limited appetite for sweet or salty flavors.
Overall, while cat tasting abilities differ from our own, they are still complex and specialized. Cats enjoy a refined sense of taste tailored to their evolutionary niche as carnivores.
Conclusion
In summary, cats have a very different sense of taste compared to humans due to differences in their taste buds and genetics. Cats lack receptors to detect sweet flavors and instead have a heightened sensitivity to amino acids that make meat taste delicious to them. This results in cats perceiving flavors very differently than humans.
For cat owners and breeders, these differences mean cats enjoy a protein-rich diet focused on meat, fish, and poultry. Food with intense umami or savory flavors will be preferred over sweet flavors. Owners should avoid feeding sugar-filled human foods to cats. Understanding the feline sense of taste helps create cat food and treats optimized for cats to enjoy.