The Animal With No Males for 80 Million Years (And How It Still Evolves)

[00:00:00]Imagine there are no males. Not extinct, never existed for 80 million years.

[00:00:05]That's bdelloid rotifers. They're microscopic animals, smaller than a grain of sand, and every single one is female. Always has been. No males have ever been found. Not one.

[00:00:19]In most species, that's a death sentence. Without sexual reproduction, you can't shuffle genes. Mutations stack up, evolution stalls. Biologists even have a name for it, Muller's ratchet.

[00:00:32]The math says they should have gone extinct millions of years ago. They didn't. Here's how. Bdelloid rotifers steal DNA, not metaphorically, literally. When they dry out, and they can survive complete desiccation, their cell membranes become temporarily permeable. Foreign DNA from bacteria, fungi, plants, even other animals slips in, and the rotifer just incorporates it. Up to 10% of their active genome is borrowed from other species. They use horizontal gene transfer, a trick usually reserved for bacteria, to stay genetically diverse without ever having sex. Scientists have found plant genes, fungal genes, and bacterial genes all functioning inside a single rotifer. It has no males. It has no need for them.

[00:01:20]Follow for the next one, because octopuses rewrite their own RNA in real time instead of mutating DNA, and that's even harder to believe. Everything you thought you knew about how genes work is about to get weird.