In the preface to the 2nd edition of The fragility of goodness, Martha Nussbaum writes:
In order to be adequate, the Stoic theory needs three major sorts of modifications. First it needs a plausible accountof the relationship between adult emotions and the emotions of children and non-human animals. (The stoics implausibly denied that children and animals had emotions.
What were the reasons that Stoics denied that children had emotions? In the face of it this seems like an incredible claim. That animals don't have emotions seem a rather less incredible claim, as we have no direct social sympathy with them as we do with our own kind. But can one not appeal to the continuity of life? Of course that is perhaps more possible now, when we are aware of the evolution of life. It would seem implausible that there was a sudden transition from a species having no emotions to one that does. A continuum surely seems more likely. Did the Stoics then deny also any continuity of life too?
Greek myth, centaurs and satyrs for example, appear to at least support a mythos where human world appeared out of the animal world.