No stranger to the problem of radical Darwinism that presents man as nothing more than a “trousered ape,” GK Chesterton once quipped that “dogmatism of Darwinians has been too strong for the agnosticism of Darwin; and men have insensibly fallen into turning this entirely negative term into a positive image. They talk of searching for the habits and habitat of the Missing Link; as if one were to talk of being on friendly terms with the gap in a narrative or the hole in an argument, of taking a walk with a non-sequitur or dining with an undistributed middle.”  He condemned the Darwinian habit of looking at the history of prehistoric man (i.e. man before there was history) for the existence of a Missing Link.  What he probably could not have anticipated was that in some time in the future we might cease to look for the Missing Link in the past and begin to create it.

The NIH recently announced that it was in the process of making funding decisions for two areas of research in which:

1. human pluripotent cells are introduced into non-human vertebrate embryos, up through the end of gastrulation stage, with the exception of non-human primates, which would only be considered after the blastocyst stage, or
2. human cells are introduced into post-gastrulation non-human mammals (excluding rodents), where there could be either a substantial contribution or a substantial functional modification to the animal brain by the human cells.

Named for the Greek mythological fire-breathing female monster with a lion’s head and a serpent’s tail called a Chimera, the research is focused on creating an organism that is composed of cells derived from human and non-human species.   The name alone ought to give us pause as to whether this is an avenue we ought to be pursuing.

To be fair, it is not the mingling of the cells that is problematic—technically all humans are chimeras in that they have many bacterial cells mixed in their bodies, but it is the type of cells that are problematic.  It helps to see the problem by cutting through some of the scientific jargon.

What exactly is a pluripotent cell?  It is a cell that has the capacity to develop into every cell type in the human body.  There are two main sources for these types of cells—embryonic stem cells and adult stem cells.

Gastrulation is an early developmental stage of an animal embryo in which three germ layers are formed—the ectoderm (by which the skin, nerves and brain are formed), the mesoderm (bone, connective tissue and muscle), and the endoderm (out of which the lungs, liver and digestive system form).

Blatocyst represents the stage in which a ball of cells forms just before implantation.

With these definitions in place we can clarify what is being proposed.

1. Introducing human cells that have the potential to turn into any types of cells to an animal embryo at an early stage of development.

What researchers have discovered is that if they remove the nonhuman animal gene for the development of a specific body part in that animal and introduce pluripotent cells of another animal, then the animal will develop that body part.  A 2010 study in Japan showed that when researchers injected rat stem cells into embryos of mice that had been modified to not produce their own pancreas, the mice developed a healthy pancreas that was almost completely composed of rat cells.  The proposal is to do something similar with human stem cells that could develop body parts that would be composed of human cells.

2. At a later stage of development, human brain cells would be introduced into the                      animal brain.

This area of research would lead to “a substantial contribution or a substantial functional modification to the animal brain by the human cells.”

Even if we assume that the intention of the research is good, that is, therapeutic in nature, the creating of Chimeras is still morally problematic in ways that might not seem apparent at first.

Obviously the use of embryonic stem cells for research, because it is the result of the destruction of a child, creates a grave problem.  But even if adult stem cells are used, this still represents grossly unethical behavior.

First, the potential for the pluripotent cells to develop into any types of cells is a huge problem.  There is no way to know a priori which types of cells they might turn into.  Knocking out a particular gene may allow some control, but how do they keep them from developing into other types of cells?  In other words, the earlier the human stem cells are introduced during animal development the greater the chance for widespread integration. What would happen if some human cells made their way into the testes or ovaries and human sperm and eggs were grown?  Supposing two chimeric animals were to mate then it is possible that a human embryo could develop.

Likewise with the brain.  One experiment took brain cells of developing quail and put them into developing brains of chickens.  The result was that the chickens exhibited vocal trills and head bobs like quails.  Should we expect anything different with the mingling of human and non-human brains?  The animals would begin to exhibit human behaviors.

This sheds light on the bigger issue and one that our society especially is in no position to navigate.  What exactly makes a person a person?  Where do we draw the line between a human and non-human?  The most obvious place to draw the line would be when the offspring has two human parents (we even have trouble doing this!).  When would the animals that have been integrated with human cells cease to be mere animals and instead become human?

This is not a question merely for philosophers but has legal implications.  When do we decide that the creature is worthy of the respect given to all human beings?  Does a humanzee have the same rights as other humans?  What are our obligations towards the Chimera?  When the research is done, can we simply destroy the chimeras or are we obligated to allow them to live?

It is this blurring between human and nonhuman ultimately that makes this type of research so dangerous.  While the researchers may have the best of intentions, there are dangerous consequences.  Fr. Tad Pacholczyk from the National Catholic Bioethics Center proposed the following guidelines when determining the licitness of particular Chimeric research:

• The procedures must not involve the creation or destruction of human embryos.
• They must not involve the replication of major pillars of human identity in animals, such as the brain system.
• They must not involve the production of human gametes, meaning the basic building blocks of human reproduction.

One can easily see that what the NIH is proposing violates all three of these principles and therefore we have an obligation to oppose this.

We have been assuming good will on the part of those who are conducting the experiments, but the fact of the matter is that not all who embark on this work are looking for therapeutic applications.  In the 1920s, Josef Stalin tasked Russia’s top animal breeding scientist Ilya Ivanov to find a way to cross human beings with apes to create a super soldier.  Stalin may have died, but his dream did not die with him.  As CS Lewis said in his book Abolition of Man, “each new power won by man is a power over man as well.”  The power that man has to make himself what he pleases is really the power of some men to make other men what they please.

In conclusion, science offers great hope for the future of medicine.  However this requires a commitment to growth in our moral understanding as well in order to avoid the pitfall of confusing the technically possible with the morally permissible.  We would all be well advised to heed the warning of John Paul II when he said that once “the human body, considered apart from spirit and thought, comes to be used as raw material in the same way that the bodies of animals are used…we will inevitably arrive at a dreadful ethical defeat” (Letter to Families, 19).  We must stop the creation of the Missing Link.