A human clone is an artificially created human being with DNA identical to the DNA of another human being.  Identical twins (monozygotic twins) have identical DNA but are naturally created and are, therefore, not considered clones.  Numerous species of animals, originally and most notably, Dolly the sheep, have been artificially cloned.  Human clones have yet to be created.

There are two possible reasons for creating human clones.  The first reason is for the fame and possibly the fortune of simply being the first to do it.  The second reason is to create tissue compatible cell-based cures for human ailments.  Tissue incompatibility is a major limitation for organ transplants and is primarily attributable to mismatched DNA.

The artificial creation of a clone is done by a process called Somatic Cell Nuclear Transfer (SCNT).  It consists of removing the nucleus of an ovum (a female egg) from one animal and replacing that nucleus with a nucleus removed from a somatic cell (a fully matured cell) from another animal.  At the successful completion of that step the resulting one cell animal is a clone of the animal which contributed the somatic cell.  The actual cloning process is now over.

The next step is to stimulate the clone, that now fertilized egg, to start growing, that is dividing by mitosis into two cells, four cells, and so on.  At this point it is an embryo.  A cloned embryo.

The SCNT process is exquisitely delicate and complex.  The ovum, while it is one of the largest of animal cells, is the size of a grain of sand.  The nucleus of that ovum, and of the somatic cell, is a much smaller element within that cell.  The process is accomplished with the eggs in a Petri dish, observed under a high power microscope, and manipulated by high precision mechanical instruments. The failure rate of this process is very high.  The creation of Dolly was successful after 227 tries.

After the cloned embryo starts to grow it can be used in two ways.  One way is to grow it to about 8 to 16 cells and then transfer it to the uterus of a female animal and allow it to gestate for the normal time period and be born naturally.  This is how Dolly was created.

The other way is to grow it to about 100 cells and then take it apart to remove the inner cell mass which consists of embryonic stem cells (ESCs).  These ESCs can, theoretically, be grown further to become a wide variety of animal tissues and be used to cure or alleviate diseases or injuries.  Since these ESCs came from a cloned embryo they can be used on the original somatic cell donor without fear of rejection.

Some scientists make the deceptive claim that these two uses of cloned embryos are two different forms of cloning.  As cloning is applied to humans these scientists term the first use, that of creating a cloned human being to be born, reproductive cloning, and is a form of cloning that they would never, ever, do.  They label the second use, that of creating a cloned human being to be dissected for its parts, therapeutic cloning, and a form of cloning which will alleviate a wide range of human suffering.

There are two major flaws to this deceptive labeling.  First of all the cloning process is complete when that SCNT process is successfully completed.  That one cell being is a clone.  The remaining steps are growing and using that clone.  Different uses of that clone do not constitute different forms of cloning.

Secondly if the original ovum and somatic cells were human cells the resulting one cell being is a human being and labeling its use in different ways does not make it something else. 

Dissecting, and thereby killing, that human being brings us back to the basic argument about embryonic stem cells.  Fortunately this argument, that is the inherent immorality of killing a human being regardless of the resulting benefits, has been largely rendered moot by scientists recent discoveries of a new way to create embryonic stem cells without killing human embryos.  This new technology would enable the creation of embryonic stem cells with the DNA of a somatic cell donor and therefore the same potentially valuable end result as that of a clone-originated ESC.

In summary

• Animal clones have been created artificially, starting with Dolly in 1997           
• Identical  twins are naturally occurring clones
• A human clone is a human being
• No human clones have yet been successfully created.
• Human clones are almost certain to be created within the next few years, probably in countries with less respect for human life than most western countries
• ‘Walking around’ human clones are possible but probably many years in the future.
• Stem cells, both adult (multi-potent) and embryonic (pluri-potent), are undeniably very valuable sources of medical treatments
• Stem cells with tissue compatibility (matching DNA), the kind intended to be created through cloning, will be even more valuable.
• Technology is finding ways to create stem cells of all kinds without killing human embryos