Dave, it's amazing how prescient our early science fiction writers were. Fahrenheit 451 foretold of a world deluged by media and flat-screen TVs. A little known short story by Mark Twain predicted the internet. There are so many more including the Island of Dr. Moreau by HG Wells. If you've read that you're probably asking, 'Really?'

So, the story is about a doctor who lived on an island, creating part human, part animal beings. Are scientists now doing the same thing? Well... technically, yes. But thankfully, these animals are not anywhere close to grappling with their humanity like the characters in the book.

In August 2016, federal rules cleared the way for research introducing human stem cells into animal embryos. Since human stem cells have the ability to evolve into any cell and any tissue, growing them in animals to create life-saving organs is an obvious benefit for us, but what about the animals? An animal embryo injected with human stem cells could produce an animal with a human kidney or lung. But how about animals where the human stem cells become part of the brain?

Are we really ready to produce animal hybrids that have some ability for human thought? Then the question follows whether we'd be ready to sacrifice them after we harvest what we need. That would be disturbing. But some of this can be controlled by timing the introduction of the human stems cells into an animal embryo so scientists can better determine what tissues are humanized and their effects in the animal.

We have a lot to learn about this phenomenal horizon in biomedical research. Scientists will need guidance from ethicists and the public as they go down this road.