Mammal with four cell chromosomes

Mammals are diploid, that is, we have all chromosomes repeated twice in all cells. Otherwise, it is usually a harmful genetic mutation, such as polyploidia, the trisomy of the human chromosome 21. Researchers have discovered the exception of this genetic standard: Tympanoctomys Barrerae.

The small rodent of the Argentine desert is a tetraploid with four repetitions of chromosomes. The researchers do not know the causes of this peculiarity.