# Hair Curiosity **URL:** \ **Category:** Factual Questions\ **Created:** [January 10, 2000, 9:59pm UTC](https://boards.straightdope.com/t/hair-curiosity/5998 "2000-01-10T21:59:00Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Gazelle](https://avatars.discourse-cdn.com/v4/letter/g/b4bc9f/32.png) [@Gazelle](https://boards.straightdope.com/u/Gazelle)\ **Post date:** [January 11, 2000, 6:11am UTC](https://boards.straightdope.com/t/hair-curiosity/5998/1 "2000-01-11T06:11:00Z")
Has serious research been conducted on hair? I’m not talking about DNA research. These questions may sound stupid, but I’ve always wondered… My dog has hair that is black at the root, white in the middle and red at the end. She’s a shedder; I assume that her hair will grow to a genetically-specified length and hang on until it’s pulled out. So: If I pull out a hair that’s 1/3 black at the root, 1/3 white in the middle and 1/3 red at the end, will an identical hair grow in the same place? In other words, is a follicle programmed to produce one specific hair? * * * Canthearya, _Mearless_ ---
**Author:** ![Cheese\_Head](https://avatars.discourse-cdn.com/v4/letter/c/ad7895/32.png) [@Cheese\_Head](https://boards.straightdope.com/u/Cheese_Head)\ **Post date:** [January 10, 2000, 9:59pm UTC](https://boards.straightdope.com/t/hair-curiosity/5998/2 "2000-01-10T21:59:00Z")
I doubt hairs are exactly alike. Sort of like snowflakes, no two are the same. ---
**Author:** ![JoeyBlades](https://avatars.discourse-cdn.com/v4/letter/j/a87d85/32.png) [@JoeyBlades](https://boards.straightdope.com/u/JoeyBlades)\ **Post date:** [January 10, 2000, 10:28pm UTC](https://boards.straightdope.com/t/hair-curiosity/5998/3 "2000-01-10T22:28:00Z")
Cheese Head writes: > [@](#): > > I doubt hairs are exactly alike. True, but they do tend to have a common trend. I have noticed that on my dog, who had only dual color hairs, that they all look basically the same, light on the bottom and darker on the top. My assumption was that the color of the hair gets darker as the hair aged. This was supported by the fact that all of the shorter, newer hairs were all light. However, since Canthearya sees dark, then light, then dark again, this seems to punch a hole in my theory… Good question! ---
**Author:** ![scole](https://avatars.discourse-cdn.com/v4/letter/s/90ced4/32.png) [@scole](https://boards.straightdope.com/u/scole)\ **Post date:** [January 10, 2000, 10:44pm UTC](https://boards.straightdope.com/t/hair-curiosity/5998/4 "2000-01-10T22:44:00Z")
The pattern you refer to (dark/light/dark banding on a single hair) is called agouti. It results because the melanocytes in the hair follicles alternate between depositing eumelanin (black) and phaeomelanin (yellow). The mechanism that causes them to switch back and forth is not clearly understood at this time. In mice it’s known that the gene “agouti” (oh, those mouse geneticists and their clever names)is required for this switching. There are multiple known alleles at the agouti locus which can result in completely black or completely yellow hair (along with causing obesity and other weird, non-hair related stuff). Agouti hairs are the “normal” color for a wide variety of wild animals. So yes, if you pull out one of your dog’s hairs a similar one will grow in its place. ---
**Author:** ![beefymeg](https://avatars.discourse-cdn.com/v4/letter/b/e47c2d/32.png) [@beefymeg](https://boards.straightdope.com/u/beefymeg)\ **Post date:** [January 10, 2000, 10:46pm UTC](https://boards.straightdope.com/t/hair-curiosity/5998/5 "2000-01-10T22:46:00Z")
Are we only talking dog hair? If not, then I can tell you that I have one hair that keeps growing back in the same place. I can tell because it’s white and none of my other hairs are. Ok, actually, it grew back white about four or five times, but since the last time I yanked it out I haven’t seen it. I also have one coarse hair that always grows out of the same spot under my chin. Again, it hasn’t returned for several months since the last time I removed it. ALSO, the under-part of my hair (just behind my ears) always grows curly, while the rest of my hair is usually only wavy. And no matter what I do to my arm hair, it will never grow as long as my head hair. At least, I hope it won’t. It hasn’t yet. That would be weird. * * * Sucks to your assmar.