No disrespect but if NJs were ever a landrace they apparently WERE selectively engineered as the info below was taken from 3 different websites and is one reason we hesitated getting them. I need my birds to be happy staying inside the yard and NJ feedback was that they were flighty which was another reason for passing them up. I truly appreciate the wonderful feedback on their temperament and productivity But JMHO a small bird should not exhaust itself laying too-large an egg without going broody or its body doesn't get rest from being so productive. General sense is that nutrition will suffer either in the bird or its eggs but that's just my deduction - not that lifespan is shortened per se but nutritional defects cannot be overtly seen in areas like internal organs.
WEBSITE EXCERPTS confirming engineered breed
The Norwegian Jaerhon is a small breed
developed in Norway in the 1920's from a single pair of birds and imported to the U.S. in 1996. Hens weigh 3lbs and roosters weigh 5lbs
The only truly Norwegian breed, Jærhøns were
developed around 1920 near the town of Stavanger.
The Jærhøns was
selectively bred at the state-controlled breeding station at
Bryne in Jæren from its establishment in 1916 until it closed in 1973. Breeding stock was then transferred to the state agricultural college at
Hvam, Nes.
Following work done in the first half of the twentieth century, the Jærhøns is
auto-sexing.