Heredity determines not only how fast hair grows; it determines the life of a hair, which affects length as well. Using a human example, let say two people each have hair growing at the rate of ½ inch each a month. In one year's time, this would be 6 inches, however on one person, the life of the hair, meaning from the time it spouts, to the time it falls out is 4 years, while the other person's life hair is 10 years. The person with a 10-year life will have hair that grows a total of 5 ft. before it dies of a natural death, while the person with a 4-year hair life, maximum hair length would only be 2 feet. This doesn't take into account any trimmings or damage. This is why some people can grow waist length hair so easily, and others rely on extensions. Humans have been found to vary from 2 years to over 10 years on hair life. There is more variation in hair life than there is on how fast the hair grows each month, but both affect overall length. This same thing would apply to dogs as well, and with shorter hair breeds, hair life is very short. There is great variation among the Yorkie breed, and some will never attain floor length hair. Don't forget though, to keep that hair from being damaged and breaking off, show breeders wrap their hair. |