The Little Lamb
That Made a Monkey of Us All
Can Humans Be Cloned Like Sheep?
Dr. Ray Bohlin
March 7, 1997
Like many others, I was caught totally flat-footed, astonished by
the announcement of the successful cloning of an adult sheep,
Dolly. Caught so unaware, in fact, that Probe is re-airing my
three-year-old program on human cloning the week of March 17-21,
1997, because so little had changed. When the announcement of a
successful sheep cloning was made, it was too late to pull the
program from the schedule; tapes had already been sent to all the
radio stations and there just wasn't time to replace it in only
three weeks. Consequently (and spurred by a number of phone calls
and e-mails from around the country), I have compiled a few thoughts
and comments regarding scientific and moral considerations about
this historic breakthrough to temporarily plug the gap.
- Normal mammary cells were intentionally starved of critical growth
nutrients in order to allow the cells to reach a dormant stage of the normal
cell cycle. This process of bringing the cells into dormancy
apparently allows the cell's DNA to be reprogrammed by the proteins
already in the egg cell for renewed cell division and new cell
functions. The cells were fused with an enucleated egg cell (a cell
that had its nucleus removed) and stimulated to begin cell division
by an electric pulse.
- The process was inefficient. Out of 277 cell fusions, 29
began growing in vitro. All 29 were implanted in receptive
ewes, 13 became pregnant, and only one lamb was born as a result.
This is a success rate of only 3.4%. In nature, somewhere between
33 and 50% of all fertilized eggs develop fully into newborns.
- The procedure was very non-technical, and no one is really
sure why it worked. It needs to be repeated. All attempts to clone
mouse cells from adults have failed. Some suggest that sheep
embryos do not employ the DNA in the nucleus until after 3-4 cell
divisions. This may give the egg cell sufficient time to reprogram
the DNA from mammary cell functions to egg cell functions. Human
and mouse cells employ the nuclear DNA after the second cell
division. Human and mouse cells may not be capable of being cloned
because of this difference.
- The purpose of these experiments was to find a more effective
way to reproduce genetically engineered sheep for the production of
pharmaceuticals. A sheep embryo can be engineered to produce a
certain human protein or hormone in its milk. The human protein can
then be harvested from the milk and sold on the market. Instead of
trusting the somewhat unpredictable and time-consuming methods of
normal animal husbandry to reproduce this genetic hybrid, cloning
it assures that the engineered gene product will not be lost.
- Genetic material is the same in all cells of an organism
(except the reproductive cells, sperm and egg, which have only half
the full complement), but differentiated cells are biochemically
programmed to perform limited functions, and all other functions
are turned off. Based on attempts in frogs and mice, most
scientists felt that the reprogramming was impossible.
- A critical question is the lifespan of Dolly. All cells have
a built-in senescence or death after so many cell divisions. Dolly
began from a cell that was already six years old. A normal lifespan
for a ewe is around 11 years. Will Dolly live to see her seventh
- It is also uncertain as to whether Dolly will be
reproductively fertile. Frog clones are usually sterile.
- Reprogramming the nucleus could lead to procedures to
stimulate degenerating nerve cells to be replaced by newly growing
nerve cells. Adults do not generate nerve cells normally.
- Will humans be cloned for spare parts? While this is
certainly possible, I consider it very unlikely that this would be
sanctioned by any government. That doesn't mean, however, that
someone won't try.
- Will humans be cloned to replace a dying infant or child?
This is certainly a possibility, but we need to ask if this is an
appropriate way to deal with loss. Might unrealistic expectations
be placed on a clone that would not be placed on a normally-produced
- Will humans be cloned to produce children for otherwise
childless couples? This is the most often-given reason for human
cloning. This argument is unpersuasive when there are currently so many
children that need adoption. Also, this further devalues children
to the level of a commodity. If in vitro fertilization is
expensive, cloning will be worse.
- Will humans be cloned for vanity? Someone will certainly
- Will human clones have a soul? In my mind, they will be no
different from an identical twin or a baby that results from in
vitro fertilization. How a single fertilized egg splits in two
to become two individuals is a similar mystery.
- Does cloning threaten genetic diversity? Excessive cloning
may indeed deplete the genetic diversity of an animal population,
leaving the population susceptible to disease and other disasters.
But most biologists are aware of these problems, and I would not
expect this to be a major concern unless cloning were the only
means available to continue a species.
- If the technique is perfected in animals first, will this
save the tragic loss of fetal life that resulted from the early
human experimentation with in vitro fertilization? In
vitro fertilization was perfected in humans before it was known
how effective a procedure it would be. This resulted in many wasted
human beings in the embryonic stages. The success rate is still
only 1 in 5 to 1 in 10; normal fertilization and implantation
success rates are 2-3 times that. While animal models will help,
there will be unique aspects to human development that can only be
known and overcome by direct human experimentation which
disrespects the sanctity of human life.
- This provides a means for lesbians to have a child. One
supplies the nucleus and the other provides the egg. The egg does
contain some unique genetic material in the mitochondria that are
not contributed by sperm or nucleus. One cell from each donor would
be fused together to create a new individual, though all the
nuclear genetic material comes from one cell. Sue Bohlin has an
upcoming program on homosexual myths including gay marriage. This
is no longer marriage as it is currently understood, and the
technological hoops that must be jumped through for any gay couple
to have children should be a clear warning that something is wrong
with the whole arrangement.
- Are human clones unique individuals? Even identical twins
manage to forge their own identity. The same would be true of
clones. In fact, this may argue strongly against the usefulness of
cloning since you can never reproduce all the life experiences that
have molded a particular personality. The genes will be the same,
but the environment and the spirit will not.
All together, I find the prospect of animal cloning potentially
useful. But I wonder if the procedure is as perfectible as some
hope, and may end up being an inefficient process to achieve the
desired result. Human cloning is fraught with too many possible
difficulties, from the waste of human fetal life during research
and development to the commercializing of human babies (see
my previous cloning article) with far
too little potential advantage to individuals and society.
What there is to learn about embryonic
development through cloning experiments can be learned through
animal experimentation. The cloning of adult human beings is an
unnecessary and unethical practice that should be strongly
discouraged if not banned altogether.