And since it's never been observed that an animal's DNA has ever been inserted into a human ...
Wrong.
The first publicized case of animal-human hybrids took place in 1996 when Jose Cibelli, a scientist at the University of Massachusetts, took DNA from his white blood cells by swabbing the inside of his cheek. He then inserted the DNA sample into a hollowed-out cow egg.
If such an embryo (were allowed) develop, he said, the result would resemble a human being but carry bovine mitochondria, the energy-producing component of every cell.
http://www.mindfully.org/GE/GE3/Human-DNA-Cow-Egg.htm
Note: This is a 2001 article.
Definitely not half and half, but not half bad.
Last October (2001), Greenpeace Germany dug up a patent claim for a similar human-animal hybrid, only this time it involved a pig. U.S.-based Biotransplant and Australia-based Stem Cell Sciences grew a pig-human embryo to 32 cells before ending its life.
"If the embryo had lived, it would be 95% human."
http://www.mindfully.org/GE/GE3/Human-DNA-Cow-Egg.htm
Still not half and half, but not bad.
... a flock of about 50 smelly sheep, many of them possessing partially human livers, hearts, brains and other organs...(The researcher couldn't) wait to examine the effects of the human cells he had injected into the fetus’ brain about two months ago.
In the past two years, scientists have created pigs with human blood, fused rabbit eggs with human DNA and injected human stem cells to make paralyzed mice walk.
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Note: This is a 2005 article.
Still not half and half, but getting closer.
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