Does eyebrow hair grow back?
Most human hairs grow at about 0.44 mm per day. Hair is ‘programmed’ to be of a specific length depending on exactly where it is on the body. This works by the individual hair growing for a period of time depending on where it is on the body, then the individual hair falls out and a new hair starts to grow in the same place to replace it. In humans this ‘falling out’ is not synchronized and so at any point in time, at a part of your body, you will have the same distribution of hairs of different lengths and it looks like nothing is changing. In reality, all the time, new hairs are appearing to replace some of the old ones, everywhere that you have hair. (In cats on the other hand, this falling out is synchronized, all the ‘programmed length’ hair in a region will fall out at the same time – this is an example of moulting and its really noticeable.) If a hair is removed by force, that hair’s follicle realizes that it has a complete hair to replace and it will immediately start to grow o
