Grannies rule! Even for orcas
26 January 2017 Last updated at 06:58 GMT
Just like humans, orcas stop having babies part way through their lives.
Most mammals have babies until they die, but orcas and humans don't - and now scientists think they might know why.
It's all to do with helping young orcas to grow up safely and keep the family together.
Watch the video to get all the details!