The answer is: An air conditioner that turns on if the temperature gets too hot.
Even though they hurt you emotionally, Negative feedbacks serve their own important function. They keep your feet on the ground and prevent you from getting too arrogant.
This function is similar as a cooling air conditioner. Hot temperature in the comparison above represent your arrogance and the air conditioner represent the negative feedback.
The gene which is produced once or twice in a lifetime is the milk producing hormone after childbirth. This is because it is produced only after the birth of the child. The growth of the mammary glands takes place during pregnancy. The breast continue to increase in size after giving birth to a child. After delivery only copious milk is produced which is generally done with the help of milk hormone. During pregnancy the secretion of the milk is inhibited by the estrogen and progesterone which circulates in the blood stream which in turn inhibits the release of prolactin from the pituitary gland thus making the mammary glands unresponsive. Where as insulin is a hormone which helps the body to utilise the sugar or glucose from different sources like carbohydrates that we get while we eat food and adrenaline is secreted when we are scared or when we feel that we are in danger. Therefore, milk producing hormone is the gene that are turned once or twice in a lifetime.
It's where Charles wrote his book
Commensalism. The fish is benefited and the sea urchin is not affected.
