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A strange genetic mutation is responsible for the small size of some dogs

Currently, there are several small dog breeds like chihuahuas. Previously, researchers assumed that the genetic mutation related to this small size was due to their domestication. However, a recent study discovered that the appearance of the gene responsible for this characteristic in dogs goes back to long before this period. Scientists have even found the change in question in the DNA of old wolves of several tens of thousands of years.

The lead author of the study is Elaine A. Ostrander. Nevertheless, she was assisted by several scientists. The group published the results of their work in the journal Current Biology the Thursday January 27. The team discovered the genetic mutation in the dogs during a data analysis collected during the Dog Genome Project from the National Institutes of Health (NIH).

Dog Genome is a science project bringing together dog owners who help to take DNA samples of their pets. Through this program, scientists were able to locate the mutation genetics responsible for short stature in canids.

A mutation dating back 54,000 years ago

The genetic mutation is actually in DNA regulating expression of a particular gene. This is the gene for insulin-like growth factor 1 (IGF1 in English). After this discovery, the group responsible for the study consulted scientists in England and Germany.

Subsequently, the team discovered that the genetic mutation was already present in the DNA of fossils of Canis lupus campestris. In other words, these are siberian wolves who lived about 54,000 years ago. Currently, any species of canidae exhibits this mutation.

“It’s as if nature kept it in its back pocket for tens of thousands of years until it was needed. »
Elaine Ostrander, NIH geneticist specializing in dogs

An important gene in determining the size of the dog

If the IGF1 gene influences a dog’s height, it is not not the only gene responsible for this trait. At least 20 known genes determine their body size. Nevertheless, the IGF1 gene has a particular influence: it cause about 15% of the variance size between dog breeds. According to Ostrander, this percentage is not negligible for a single gene.

By comparison, Elaine Ostrander claimed that men have hundreds of genes who are responsible for their size. However, the fact that dogs have fewer genes linked to this characteristic is hardly surprising. The reason is that the majority of dog breeds have only been around for a short timea few hundred years.

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