Answer
The five primary taste sensations are salty, sweet, sour, bitter, and umami. Their adaptive significance are listed below:
Salty - Salts are electrolytes. Electrolyte deficiencies cause a craving for salt which triggers the individual to seek out salty food to correct this imbalance.
Sweet - Sweet is associated with carbohydrates and foods of high caloric value. Evolutionarily speaking, foods high in calories are very important in sustaining life.
Sour - Sour foods are usually associated with acids. Sour taste may signal humans to avoid the food.
Bitter - Bitter taste is usually associated with spoiled foods and alkaloids. From an evolutionarily standpoint, humans want to avoid spoiled foods.
Umami - Umami is the "meaty" taste produced by amino acids. Humans want to eat enough meat to maintain protein levels.
Work Step by Step
Humans need to live and grow. The five taste sensations-salty, sweet, sour, bitter, and umami-are vital for optimal human growth. Humans tend to crave salty, sweet, and umami tastes. Humans need the electrolytes found in salty foods, the carbohydrates found in sweet foods, and the amino acids found in umami foods to live and grow. On the other hand, foods that are sour and bitter are usually best avoided. Sour foods may upset the stomach and not taste pleasant while the unpleasant taste of bitter foods may signal that a food is spoiled. In fact, the threshold for bitterness is much lower than the other taste sensations indicating that avoiding spoiled foods is pretty important from an evolutionary standpoint. (pg 589).
