Small, scarce, and shy, the white-bellied pangolin has one of the highest number of chromosomes among all mammals: a total of 114 chromosomes. However, this is just the beginning of these animals\u2019 bizarre genetic quirks.\u00a0<\/p>\n
Pangolins are a family of small, scale-covered mammals that includes eight species, four of which live in Asia and four in Africa.\u00a0<\/p>\n
In 2023, scientists from UCLA studied the genomes<\/a> of three of these species \u2013 white-bellied, Chinese, and Sunda pangolins \u2013 and stumbled across what they called a true \u201cscientific surprise\u201d.<\/p>\n They found the white-bellied pangolin had 114 chromosomes, significantly more than any mammal except the Bolivian bamboo rat<\/a>, which has 118.<\/p>\n However, it was only the females that had 114 chromosomes. The males have just 113 chromosomes, which is really strange since in almost all species, both sexes carry the same number.<\/p>\n \u201cThere\u2019s nothing else like them on the planet,\u201d Jen Tinsman, an evolutionary biologist at UCLA and co-author of the 2023 study, said in a statement<\/a>.<\/p>\n Chromosomes<\/a> are thread-like structures within a cell\u2019s nucleus that package DNA. Coming in pairs, they compact the genome so it fits inside the cell while safeguarding the genetic instructions that are passed from one generation to the next.<\/p>\n Different species have different numbers of chromosomes: Homo\u00a0sapiens typically have 23 pairs, chimpanzees have 24 pairs, dogs have 39 pairs, fruit flies have four pairs, and Tasmanian devils have seven pairs. The highest chromosome count<\/a> of any animal is the Atlas blue butterfly, which has 229 pairs.<\/p>\n The number of chromosomes isn\u2019t necessarily linked to a species’ size, intelligence, or complexity. Over evolutionary time, chromosomes can split or merge. Many of these fissions and fusions don\u2019t affect survival; they just persist in the population by chance.<\/p>\n It isn\u2019t quite clear why the white-bellied pangolin has such an unusual genome assembly, but a greater understanding of it could be very useful.<\/p>\n