Fat sand rat
Psammomys obesus
— Where the name comes from
Psammomys is “sand mouse”, from psámmos and mŷs. Obesus, “fat”, is a judgement the animal in the wild does not deserve: in the desert it is lean and highly strung, and becomes obese only when it eats what we give it. Few species have an epithet describing not the animal but what happens to it in captivity.
— Facts
- Group
- Mammals · Mammalia
- Order
- Rodents
- Habitat
- Salt desert, wadis, expanses of halophyte succulents
- Range
- North Africa and the Middle East, from Algeria to Arabia
- Size
- 12–19 cm of body, tail 11–15 cm, 90–200 g
- Diet
- The fleshy leaves of glasswort and other salt plants
- Lifespan
- 3 years
— Characteristics
- 01
It is diurnal, unusual for a desert rodent.
- 02
It eats plants so salty that it must void the salt through very powerful kidneys.
- 03
It stacks cut stems outside its burrow to dry them in the sun.
— What sets it apart
In its world nothing is sweet, and that has made it the model for type 2 diabetes. Fed on standard laboratory chow — starch-rich compared with glasswort — it develops obesity, hyperglycaemia and insulin resistance within weeks, exactly as a human population does on moving from a traditional diet to an industrial one. It was on this animal that people understood how far diabetes is not a disease of the body but of a mismatch between an ancient metabolism and a new food.
