Warning: The following relates events that some might find disturbing.
In November of 1998, Advanced Cell Technology, Inc. (ACT) succeeded in manufacturing a human-cow hybrid for the purpose of proving that it was possible to derive stem cells from an animal-human hybrid, from which to grow various tissues and organs that could be human enough to be given to humans in need of replacement organs and tissues. Stem cells, which were and perhaps are still considered by many to be available only in embryos, are wonderful cells that can develop into any organ or tissue. The hybrid, which was aborted twelve days after conception, had been the result of the implantation of human DNA into a cow’s egg whose own DNA had been removed. A chemical had been added to spur meiosis. The scientists seemed to be using animal eggs instead of human eggs because animal eggs were easier to obtain. In contrast, the DNA inserted into the emptied egg could have been taken from anywhere within any part of the human donor’s body – in the case of this human-cow hybrid, the DNA had come from a man’s leg. (In a 2006 BBC report, I found a reference to how human such a hybrid would be: “The resulting embryo would be 99.9% human; the only bovine element would be DNA outside the nucleus of the cell.” However, a 2007 report by CBC News, the Canadian Broadcasting Corporation, wrote that it would be “99.5 per cent human.”)
It was revealed in October of the next year that BioTransplant, Inc., in the USA, and Stem Cell Sciences in Australia had been producing pig-human hybrids. Pigs’ organs, of course, are genetically and functionally very similar to those of humans, and so one can understand why they would have been selected. The resulting pig-humans had been aborted after “around a week.”
Fast-forward to 2003. Though they would not reveal it until 2005, scientists at the Shanghai Second Medical University in China produced human-animal hybrids consisting not of cows or pigs, but rabbits. “They were allowed to develop for several days in a laboratory dish before the scientists destroyed the embryos to harvest their stem cells.”
By 2004, things had become unspeakably bizarre. “In Minnesota,” wrote Rick Weiss for the Washington Post, “pigs are being born with human blood in their veins. In Nevada, there are sheep whose livers and hearts are largely human. In California, mice peer from their cages with human brain cells firing inside their skulls.” By now, such creatures had become known as chimeras (it might be best if you reread that word and imagine thunder rumbling ominously). Regarding the idea of endowing animals with human brain cells, such as the aforementioned mice, Reiss recalled:
The potential power of chimeras as research tools became clear about a decade ago in a series of dramatic experiments by Evan Balaban, now at McGill University in Montreal. Balaban took small sections of brain from developing quails and transplanted them into the developing brains of chickens.
The resulting chickens exhibited vocal trills and head bobs unique to quails, proving that the transplanted parts of the brain contained the neural circuitry for quail calls. It also offered astonishing proof that complex behaviors could be transferred across species.
Meanwhile, wrote Weiss, Dr. Irving Weissman of Stanford University’s Institute of Cancer/Stem Cell Biology and Medicine expressed interest in producing mice whose brains did not possess some human brain cells, but were composed entirely of them:
He proposes keeping tabs on the mice as they develop. If the brains look as if they are taking on a distinctly human architecture – a development that could hint at a glimmer of humanness – they could be killed, he said. If they look as if they are organizing themselves in a mouse brain architecture, they could be used for research.
Just a few months later, National Geographic News  described the ongoing research of Dr. Weissman, and quoted him in the context of whether the production of chimeras ought to be outlawed because of ethical concerns:
Irv Weissman, director of Stanford University’s Institute of Cancer/Stem Cell Biology and Medicine in California, is against a ban in the United States.
“Anybody who puts their own moral guidance in the way of this biomedical science, where they want to impose their will—not just be part of an argument—if that leads to a ban or moratorium. … they are stopping research that would save human lives,” he said.
Weissman has already created mice with brains that are about one percent human.
Later this year he may conduct another experiment where the mice have 100 percent human brains. This would be done, he said, by injecting human neurons into the brains of embryonic mice.
Before being born, the mice would be killed and dissected to see if the architecture of a human brain had formed. If it did, he’d look for traces of human cognitive behavior.
Weissman was soon granted permission to perform the experiment. Just before spring in 2005, scientists at Stanford University announced that they would, indeed, attempt to produce a mouse whose brain cells were entirely human. Wrote James Langton for the Telegraph, “Researchers at Stanford University have already succeeded in breeding mice with brains that are one per cent human cells. In the next stage they plan to use stem cells from aborted foetuses to create an animal whose brain cells are 100 per cent human.” Granting the team permission to carry out the experiment, Prof. Henry Greely, the head of the university’s ethics committee, said that “if the mouse shows human-like behaviours, like improved memory or problem-solving, it’s time to stop.” (A fear that began to grow among scientists, Langton mentioned, involved human cells spreading to the chimeras’ reproductive organs, potentially causing them to produce human eggs or sperm. If these chimeras then mated with each other, it could theoretically result in human embryos being conceived within the wombs of non-humans.) Mysteriously, MSNBC later reported this:
Weissman, who has already created mice with 1 percent human brain cells, said he has no immediate plans to make mostly human mouse brains, but wanted to get ethical clearance in any case. A formal Stanford committee that oversees research at the university would also need to authorize the experiment.
The MSNBC report also referred to bizarre goings-on at the University of Nevada-Reno. Dr. Jason Chamberlain had injected human brain cells into the brain of the fetus of a sheep two months earlier, and would soon euthanize its pregnant mother, extract the unborn chimera, and study it. “He can’t wait to examine the effects of the human cells,” it said.
By 2007, we were producing sheep that were only 85% sheep, their organs saturated with human cells, and the technique by which chimeras are produced by injecting human cells into animal fetuses was being ironed-out. The Roman Catholic Church had decided to publicly address the production of chimeras. Summarizing the proclamation of the bishops representing the Vatican, Jonathan Petre for the Telegraph wrote that the “bishops, who believe that life begins at conception, said that they opposed the creation of any embryo solely for research, but they were also anxious to limit the destruction of such life once it had been brought into existence.” He went on to quote their announcement, which said in part, “At the very least, embryos with a preponderance of human genes should be assumed to be embryonic human beings, and should be treated accordingly.”
The entire written statement by the bishops is available for reading.
Bovine humans were produced again by British scientists in 2008. Shortly thereafter, scientists at Newcastle University in Australia announced what was already pretty obvious: the process was easy. In fact, by this point, over 270 chimeras had been produced.
According to BBC News, things looked bleak in 2009 for endeavors in the UK to continue hybrid cloning. Although a push the previous May to outlaw the whole spectrum of animal-human hybrid experimentation had failed, researchers were nevertheless finding it difficult to secure funding and as a result no such experiments were known to be taking place in the UK. There were suspicions that moral convictions were behind this, but these were refuted. In addition, efforts to derive stem cells from adult human tissue were showing promise, potentially negating the necessity for the hybrids. Of note: the estimated humanity of the hybrids had been apparently been recalculated; the creatures were now “some 99% human and 0.1% animal” (this was likely a typo and ought to have read “99% human and 1% animal”).
Yet, behind closed doors, human determination was enabling the experiments to continue in Britain after all – cloaked in secrecy. Though it would not be revealed until 2011, these experiments produced over 150 hybrid embryos – all of which were aborted within two weeks of conception.
That revelation came on the heels of a dire warning from the UK’s Academy of Medical Sciences that experiments involving the placement of human brain cells into apes could produce speaking apes whose thought processes displayed traits idiosyncratic to humans. According to the Telegraph, the report published by the academy referred to such creatures as “monsters.” The academy described its new plans for a larger and more powerful oversight board and tighter restrictions on experiments that could lead to the production of such creatures. From the Telegraph:
Professor Thomas Baldwin, a member of the Academy of Medical Sciences working group that produced the report, said the possibility of humanised apes should be taken seriously.
He said: “The fear is that if you start putting very large numbers of human brain cells into the brains of primates suddenly you might transform the primate into something that has some of the capacities that we regard as distinctively human.. speech, or other ways of being able to manipulate or relate to us.
“These possibilities that are at the moment largely explored in fiction we need to start thinking about now.”
No such experiments are currently known to have been taking place at that time… in the UK, anyway.
Now, a word about apes: It has been demonstrated that some species of apes are capable of learning basic American Sign Language (ASL). The most celebrated case is a chimpanzee named Washoe (1965-2007), who over the course of her life as a research subject learned and used well over two hundred signs and also provided controversial evidence that she possessed traits such as self-awareness and empathy. (Evidence of such human traits among apes raised in ape nurseries tends to be controversial because of its implications and its origin: its implications question the ethics of subjecting apes to medical experimentation and the urbanization of their natural habitats; its origin is typically ape nurseries, which are often involved in campaigns against such things. Thus, those who advocate the use of apes in medical experiments, as well as those who intend to urbanize regions recognized as ape habitats, accuse those who provide such evidence as having fudged the evidence.)
Another relatively famous case is Koko, a gorilla born in 1971. According to BBC News, Koko, who has an I.Q. of at least 75, “uses a sign language of 1,000 gestures to communicate with humans and can understand 2,000 words of spoken English.”
A bonobo in Iowa named Kanzi is another nice example of the high intellectual capacity demonstrated by some apes. According to a 2006 article in the Smithsonian magazine by Paul Raffaele, he allegedly knows over three hundred illustrated symbols and three thousand spoken English words. He has also shown himself capable of building and lighting a campfire and then roasting marshmallows over it (this is a learned skill, of course).
In 2010, research revealed that at least some chimpanzees can conceptualize volume, strengthening suspicions that, while not geniuses, apes are remarkably intelligent. The fear expressed by the Academy of Medical Sciences in 2011 was that the lack of restrictions on and responsible and sensible oversight of human-animal hybrid experimentation could soon lead to situations wherein the brain of an ape, apparently intelligent enough already to learn basic English and contemplate volume, would be augmented and enhanced by the insertion of human neurons.
Again, it was in the UK that those ethical concerns were being expressed. The world is a big place, with lots of scientists involved in hybridization research in a number of countries. How difficult would it be, I wonder, for just one team somewhere in the world to unofficially “neglect” to abort just one embryo? How difficult would it be, I wonder, for just one team to unofficially allow one such embryo into a consenting womb? Such a thing could never be acknowledged, of course…
If you tell a human not to do something, and also tell that human that it is possible to do that thing, the human will naturally feel inclined to do it – with drooling eagerness if the consequence is feeling like a god. Such is fallen human nature. Yes, it will inevitably happen. Somewhere, someone will inject human neurons into the brain of an ape fetus, or someone will fail to abort and will then implant a hybrid embryo. And, that someone will know demi-godhood. How few are those humans who have rejected recognition as gods! Indeed, such recognition has throughout history proven to be intoxicating… and never enough. Besides, if one is crafty enough to produce one hybrid, and if the experience is intoxicating, why stop at just one?
 Details of hybrid clone revealed, BBC News, June 18, 1999. http://news.bbc.co.uk/2/hi/science/nature/371378.stm
 Fergus Walsh, “Plan to create human-cow embryos,” BBC News, November 6, 2006. http://news.bbc.co.uk/2/hi/health/6121280.stm
 Creation of human-animal embryos sparks debate in Britain, CBC News, January 5, 2007. http://www.cbc.ca/news/health/story/2007/01/05/chimeras.html
 Human-pig embryo accusation provokes debate, Australian Broadcasting Network, October 9, 2000. http://www.abc.net.au/science/articles/2000/10/09/196491.htm
 Maryann Mott, “Animal-Human Hybrids Spark Controversy,” National Geographic News, January 25, 2005. http://news.nationalgeographic.com/news/2005/01/0125_050125_chimeras.html
 Rick Weiss, “Of Mice, Men and In-Between: Scientists Debate Blending Of Human, Animal Forms,” Washington Post, November 20, 2004. http://www.washingtonpost.com/wp-dyn/articles/A63731-2004Nov19.html
 Maryann Mott, “Animal-Human Hybrids Spark Controversy,” National Geographic News, January 25, 2005. http://news.nationalgeographic.com/news/2005/01/0125_050125_chimeras.html
 James Langton, “Scientists to make ‘Stuart Little’ mouse with the brain of a human,” Telegraph, March 6, 2005. http://www.telegraph.co.uk/news/worldnews/northamerica/usa/1485070/Scientists-to-make-Stuart-Little-mouse-with-the-brain-of-a-human.html
 Scientists create animals that are part-human: Stem cell experiments leading to genetic mixing of species, MSNBC, April 29, 2005. http://www.msnbc.msn.com/id/7681252/ns/health-cloning_and_stem_cells
 Claudia Joseph, “Now Scientists Create a Sheep That’s 15% Human,” Daily Mail, March 27, 2007. http://www.dailymail.co.uk/news/article-444436/Now-scientists-create-sheep-thats-15-human.html
 Jonathan Petre, “Chimera embryos have right to life, say bishops,” Telegraph, June 26, 2007. http://www.telegraph.co.uk/news/uknews/1555639/Chimera-embryos-have-right-to-life-say-bishops.html
 Great Britain: Parliament: Joint Committee on the Human Tissue and Embryos (Draft) Bill, Evidence, vol. 2 of Human Tissue and Embryos (Draft) Bill (London: The Stationery Office, 2007), 294-97.
 Maggie Fox, “British Scientists Make Human-Cow Embryos,” Reuters, April 2, 2008. http://uk.reuters.com/article/2008/04/02/uk-cloning-cows-idUKN0242023320080402
 Clive Cookson, “Scientists Find Hybrid Embryos Easy to Make,” Financial Times, June 20, 2008. http://www.ft.com/cms/s/0/96d72196-3e62-11dd-b16d-0000779fd2ac.html
 Clare Murphy, “Uncertain future for hybrid research,” BBC News, January 13, 2009. http://news.bbc.co.uk/2/hi/health/7826331.stm
 Daniel Martin and Simon Caldwell, “150 human animal hybrids grown in UK labs: Embryos have been produced secretively for the past three years,” Daily Mail, July 22, 2011. http://www.dailymail.co.uk/sciencetech/article-2017818/Embryos-involving-genes-animals-mixed-humans-produced-secretively-past-years.html
 Nick Collins, “Ethical rules needed to curb ‘Frankenstein-like experiments’ on animals.” Telegraph, July 22, 2011. http://www.telegraph.co.uk/science/science-news/8652093/Ethical-rules-needed-to-curb-Frankenstein-like-experiments-on-animals.html
 Nick Perry, “’Signing’ Chimp Washoe Broke Language Barrier,” Seattle Times, November 1, 2007. http://seattletimes.com/html/localnews/2003986892_washoe01m.html (accessed October 3, 2012); Benedict Carey, “Washoe, a Chimp of Many Words, Dies at 42,” New York Times, November 1, 2007. http://www.nytimes.com/2007/11/01/science/01chimp.html?_r=1&ref=science&oref=slogin (accessed October 3, 2012).
 ‘Talking’ Gorilla Demands Dentist, BBC News, August 9, 2004. http://news.bbc.co.uk/2/hi/americas/3548246.stm (accessed October 3, 2012).
 Paul Raffaele, “Speaking Bonobo,” Smithsonian Magazine, November 2006, http://www.smithsonianmag.com/science-nature/10022981.html (accessed October 3, 2012); Laurentiu Garofeanu, “Amazing Photos of Kanzi the Bonobo Lighting a Fire and Cooking a Meal,” Telegraph. http://www.telegraph.co.uk/news/picturegalleries/howaboutthat/8985122/Amazing-photos-of-Kanzi-the-bonobo-lighting-a-fire-and-cooking-a-meal.html (accessed October 3, 2012).
 Matt Walker, “Chimps Are Intelligent Enough to Appreciate a Full Pint,” BBC News, February 23, 2010. http://news.bbc.co.uk/earth/hi/earth_news/newsid_8528000/8528534.stm (accessed October 3, 2012).