Con gái nói không là không

-----

Giant African pouched rats are as clever as they are cute. Trained to wear little backpacks, they can rescue people from disaster areas in return for a treat.

They can also find landmines (mìn) that need disarming, sniff out tuberculosis (bệnh lao), and have even been recruited in the fight against wildlife poaching.

So handy are these intelligent mammals, we can't seem to breed enough of them. It's not just a problem with demand – the supply is also mysteriously limited.

Around a meter (3 feet) long from whiskers to tail-tip, the animals are more closely related to a genus of Madagascan rodents called antsangy, than true rats. Their life-span is also a relatively lengthy eight years, with some females holding off on breeding until they're four years old. Some will stop breeding again after a successful pregnancy.

Baffled, researchers took a closer look and found to everyone's astonishment many of the female rats hadn't merely sworn off more kids, they'd closed shop, sealing off their vaginas.

In this morphological state the females had a smaller uterus and a fused vaginal opening. What's more, their urine featured a profoundly different chemical composition than their nestmates with normal vaginal openings who were actively breeding.

Bài trước: Sao lâu vậy?