 |
| Click to enlarge. |
Dogs have the widest range of body sizes among mammals.
The size differential between the largest dog, the Great Dane, and the smallest, the Chihuahua, appears to be due to a single gene which suppresses IGF-1, an "insulin-like growth factor 1" hormone.
This single-gene hormone-suppression appears only in domestic dogs, and only in the smaller dogs such as the Jack Russell Terrier.
Suppression of the IGF-1 appears to be associated with a longer life span. Conversely, animals across a wide variety of species have been shown to have an increased risk of death from age-related diseases such as cancer and heart disease if higher levels of IGF-1 are present.
.
No comments:
Post a Comment