This article explains ‘gustation’ or ‘sense of taste’.
Introduction
The ability to distinguish between different tastes has been crucial to the survival of Homo sapiens.
Well developed ‘gustation’ allowed our hunter gatherer ancestors to distinguish between nutritional and toxic foods. We have evolved to enjoy the taste of food that is good for us and avoid food that harms us.
What tastes are good for us?
Our brains have evolved in such a way that if we think food tastes good we want to eat more. We enjoy foods that are good for our health.
We like the taste of fish, vegetables, bread and milk. These foods are often full of proteins, fibre and carbohydrates and have a pleasant, savory taste. We call savory tastes ‘umami’ (うま味) – a word of Japanese origin.
We enjoy foods that taste sweet; it is the sweet foods that are full of the sugars that give us energy.
We have a craving for food that tastes salty; among other things salt ensure that our muscles work properly and stops us dehydrating.
Recent research has shown that we may also gain pleasure from the taste of fats in foods; amongst other things dietary fats are essential to help keep our bodies warm and support cell growth.
When we eat something ‘hot’ such as chillis we often describe this as as ‘taste’. The ability to taste ‘heat’ on our tongues has nothing to do with taste and is just a pain signal sent by our oral nerves to the brain.
- What tastes could harm us?
We have evolved to dislike foods that are bitter or sour; it is the harmful toxins in plants that have a bitter or sour taste. The ability to detect bitter and sour tastes gives us a natural defense against eating these harmful toxins.
We do not like foods that taste acidic; it is the acidic foods that have gone bad and could poison us.
In total, Homo sapiens can detect combinations of five difference tastes. These different tastes include detecting foods that are bitter, sour, salty, sweet and savory (umami). Some scientists think we can detect the taste of ‘fat’ in our food; that would make ‘fat’ our sixth taste.
- How are we able to detect different tastes?
Gustation (sense of taste) explained
A human tongue has up to 4,500 visible bumps and grooves called papillae.
Four different types of papilla are located on different parts of the human tongue.
If you examine the cross section below you will notice how ‘taste buds’ are located in the side walls of the papillae.
Look closely and you will see that one type of papilla, the ‘filiform’ papilla, has no taste buds in its side walls.
Another difference is that the filiform papillae have microscopic ‘hair-like’ extensions called microvilli at their apex. The microvilli increase the tongue’s friction to help move food toward the throat after it has been eaten.
Whereas the microvilli of human filiform papillae can only be seen using a microscope, those of cats are easily visible to the naked eye.
but no taste buds on their tongues!
With ineffective eyesight and living in muddy water, it is the taste buds on their bodies that allows catfish to identify if food is safe to eat. Catfish do not have scales; they are covered with tissue that is more like skin.