Zoe has managed to conceal her Cylonic identity to her father Daniel, until now. It actually has been pretty easy. Daniel had no way of knowing that the special chip that infuses soul into the Cylon, whatever exactly that might mean in these circumstances, was infusing Zoe's. The Cylon, after all, looks nothing like Zoe.
But apparently the family dog can see - sense, feel, perceive - through this. In a fine final scene, Caesar the dog (possibly the great-great-grandfather of Jake the dog we met in the New Caprica insurgency in Battlestar Galactica's third season) clearly recognizes Zoe in the Cylon. Exactly how is not clear. Surely the Cylon, in addition to not looking like Zoe, neither moves nor smells like Zoe either. So how does the dog know it's Zoe? Assuming it's not some sort of super dog, a different variety of dog on Caprica unknown on our Earth, the only answer is that the dog can sense Zoe's presence in the Cylon, through the non-organic packaging. Dogs are sensitive to the characteristics of personhood that are shared by both humans and Cylons.
This provides a profound connection between humans and Cylons that was not fully apparent even in Battlestar Galactica. In philosophic mind-body terms, it says that mind (psyche, personality, soul: who were are) is not dependent upon the flesh. It can live in completely artificial housing. Even more so than BSG, Caprica is staking itself out as important philosophic science fiction.
Meanwhile, in terms of the plot, Daniel now knows Zoe is in the Cylon - at least, he says her name, after the dog jumps happily around her. And in V-world, Zoe and Philomel realize that every Cylon, like every genome, can be subtly different, showing us how it came to be that the Six's had significant differences in personality in BSG, as did the Sharons and the other models.
Caprica continues as one of most thoughtful science fiction series in years.
See also: Battlestar Galactica Caprica: Exquisite, Flawed Copies ... 1.2: Dawn of a Different Machine ... 1.3: Daughters, Missing and Present ... 1.5: Adama's Daughter ... 1.6: The Chip and its Roots
The Plot to Save Socrates
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