Probe Ministries
Can Humans Be Cloned Like Sheep?
Dr. Ray Bohlin
Why Is Cloning So Difficult and How Did They Do It?
Like so many others I was caught totally flat-footed and
astonished by the announcement of the successful cloning of an
adult sheep, Dolly. A few years ago I aired a radio program on the
prospects of human cloning and considerably downplayed the
possibilities. Earlier this year, we here at Probe had decided to
rebroadcast this program because little had changed. When the
announcement about Dolly was made, it was too late to pull the
program from the schedule as tapes had already been sent to all the
radio stations, and there just wasn't time to replace or update it.
Consequently, I compiled a few thoughts and comments on this
historic breakthrough and quickly made it available on our web site
to temporarily plug the gap.
Subsequently, the article was featured on Christian Leadership's
web site, Leadership
University (www.leaderu.com), and I started
receiving numerous phone calls and e-mails as a result. This essay
is now an updated and expanded version of that article to help us
think through both the scientific and moral implications of this
stunning achievement.
The 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 of chromosomes). However, differentiated cells
(liver cells, stomach cells, muscle cells, etc.) are biochemically
programmed to perform limited functions and all other functions are
turned off. Most scientists felt that the reprogramming was next to
impossible based on cloning attempts in frogs and mice.
So what did the scientists in Scotland do that was successful?
Well, they took normal mammary cells from an adult ewe and starved
them (i.e., denied them certain critical growth nutrients) in order
to allow the cells to reach a dormant stage. This process of
bringing the cells into dormancy apparently allows the cells' DNA
to be deprogrammed. Apparently most if not all of the programming
for specific functions of the mammary cells were turned off and the
DNA made available for reprogramming. The starved mammary cells
were then fused with an egg cell that had its nucleus removed. The
egg cell was then stimulated to begin cell division by an electric
pulse. Proteins already in the egg cell somehow altered the DNA
from the mammary cell to be renewed for cell division and
embryological functions.
As might be expected, the process was inefficient. Out of 277 cell
fusions, 29 began growing as embryos in vitro or in the
petri dish. All 29 were implanted into 13 receptive ewes, yet only
one became pregnant. As a result of these efforts, one lamb was
born. This translates to a success rate of only 3.4%, and the
success rate is even less (.36%), when you calculate using the 277
initial cell fusions attempted. In nature, on the other hand,
somewhere between 33 and 50% of all fertilized eggs develop fully
into newborns.
Altogether the procedure was rather non-technical, and no one is
really sure why it worked. The experiments still need to be
repeated. Previously, all attempts to clone mice from adult cells
have failed. But clearly, an astounding breakthrough has been made.
You can be sure that numerous labs around the world will be
attempting to repeat these experiments and trying the technique on
other mammalian species. Can this procedure be done with humans?
Should we try it with humans? I'll be dealing with these questions
later in this discussion.
Why Clone Anything?
Before proceeding to deal with the question of human cloning,
a more basic concern needs to be addressed. Some, for example, may
be asking, "Why would anyone want to clone anything in the first
place, but especially sheep?"
The purpose of these experiments was to find a more effective way
to reproduce already genetically engineered sheep for production of
pharmaceuticals. Sheep can be genetically 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. This is
accomplished by taking the human gene for the production of this
protein or hormone and inserting it into an early sheep embryo.
Hopefully the embryo will grow into a sheep that will produce the
protein.
This is not a certainty, and while the process may improve, it will
never be perfect. Mating the engineered sheep is also not foolproof
because even mating with another genetically engineered sheep may
result in lambs that have lost the inserted human gene and cannot
produce the desired protein. Therefore, instead of trusting the
somewhat unpredictable and time-consuming methods of normal animal
husbandry to reproduce this genetic hybrid, cloning more directly
assures that the engineered gene product will not be lost.
There may be other benefits to cloning technology. Reprogramming
the nucleus of other cells, such as nerve cells, could lead to
procedures to stimulate degenerating nerve cells to be replaced by
newly growing nerve cells. Nerve cells in adults do not ordinarily
regenerate or reproduce. This could have important implications for
those suffering from Parkinson's and Alzheimer's.
If the process can actually be perfected to the extent that
production costs are reduced and the quality of the eventual
product is improved, then this would be a legitimate research goal.
The simplicity of the technique, though still inefficient, makes
this plausible. But there are still questions that need to be
answered.
One critical question concerns the lifespan of Dolly. All cells
have a built in senescence or death after so many cell divisions.
Dolly began with a cell from a ewe that was already six years old.
A normal lifespan for a ewe is around 11 years. Will Dolly live to
see her seventh birthday? Actually most cell divisions are used up
during embryological development. Dolly's cells may peter out even
earlier. This is critical because a 10-year-old sheep is considered
elderly, and lambing and wool production decline in sheep after
their seventh year. My guess though is that since Dolly's genes
were reprogrammed from mammary cell functions to embryological
functions, that the senescence clock was also reset back to the
beginning. I expect Dolly to live a normal lifespan.
It is also uncertain as to whether Dolly will be reproductively
fertile. Frogs cloned from tadpole cells are usually sterile. It is
possible that while Dolly is normal anatomically, the cloning
process may somehow interfere with the proper development of the
reproductive cells. If this were the case, there may be other
problems not immediately detectable. This will be answered this
summer when Dolly reaches sexual maturity.
Can We Clone Humans?
While we have established that animal cloning may be
permissible and even scientifically useful, what about cloning
humans? First of all, is it feasible? Secondly, just because we can
do it, should we? Should we even try?
At this point it is reasonable to assume that because the procedure
works with sheep and possibly with cattle (the experiments with
cattle are already underway), it should be perfectible with humans.
This does not mean, however, that there may not be unique barriers
to cloning humans as opposed to cloning sheep.
Some suggest that by using the particular procedure developed by
the researchers in Scotland, sheep may be easier to clone. The
reason is that sheep embryos do not employ the DNA in the nucleus
until after 3 to 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 only the second cell division. This may be why similar
experiments have not worked in mice. Therefore, human cells and
mouse cells may not be capable of being cloned because of this
difference.
If this barrier does indeed exist, it is not necessarily
insurmountable. The news of a cloned sheep was surprising enough
that no one, including me, is now going to step out on the same
sawed-off limb and predict that it can't eventually work
with humans. I mentioned earlier that the procedure is so
startlingly non-technical that there are numerous laboratories
around the world that could immediately begin their own cloning
research program with a minimum of investment and expertise. While
I fully expect that many labs will begin studies on cloning other
mammalian species besides sheep, I'm not so sure about humans.
In 1993, researchers here in the United States employed well known
techniques to artificially twin human embryos. They immediately
became embroiled in a firestorm of public scrutiny that they did
not anticipate nor enjoy (see my earlier article, "Human Cloning: Have Human
Beings Been Cloned?"). They were even criticized by other
researchers in the field for jumping ahead without scrutinizing the
ethical ramifications. The public reaction was no doubt very
sobering to the rest of the scientific community. Many countries
have already either completely banned experimentation in human
cloning or at least imposed a temporary moratorium so that the
ethical questions can be properly investigated before stepping
ahead. Even the researchers in Scotland responsible for Dolly have
plainly stated that they see no reason to pursue human cloning and
are personally repulsed by the idea.
There are some in the scientific community, however, who feel that
the ability to do something is reason enough to do it. But in this
case, I believe that they are the minority. For example, molecular
biologists imposed a moratorium of their own in the 70s when
genetic technology was first being developed until critical
questions could be answered. Also, while nuclear weapons have been
produced for over 50 years, only two have been used and that was 52
years ago. Many are now being dismantled. These cases show us that
human restraint, though rare, is possible.
So while it is reasonable to believe that humans can be cloned, and
that someone, somewhere may try, the overall climate is so against
it that I don't think we will see it announced anytime soon.
Why Clone Humans?
Overall, the public reaction has been negative toward cloning
human beings, and this is rather curious in a culture that is
admittedly post-Christian in orientation. Nevertheless, many people
still want to draw a distinction between animals and humans.
As Christians we understand this desire because we assert that
humans are made in the image of God and that animals are not. There
is, therefore, a clear demarcation between animals and humans. But
in an evolutionary view, humans are nothing special--just another
animal species. The expected reaction was offered by an editorial
in the Dallas Morning News (Monday, 3 March 1997, 9D) by Tom
Siegfried which he titled: "It's hard to see a reason why a human
Dolly is evil." He summarized his perspective when he said, "The
ability to clone is part of gaining deeper knowledge of life
itself. So Dolly should not be seen as scary, but as a signal that
life still conceals many miracles for humans to discover." To the
naturalist, any knowledge is valuable, and the means to obtain it
is justified essentially by its benefit to society.
With this in mind, let's explore some of the reasons why people
have suggested that human cloning is a worthwhile proposition and
deal with some of the questions people are asking.
Concerns About Human Cloning
There is much that can be learned about human embryonic
development by researching human cloning. While this is true,
this is precisely the reasoning used by Nazi Germany to justify
experimentation on Jews. Experiments were performed on exposure to
cold, water, and other extreme conditions with human subjects,
frequently to the point of death, because data on human subjects
was deemed indispensable. Of course, we know now that animal models
work just as well; consequently, there is no need to use human
models to gain this type of data.
Will humans be cloned for spare parts? A few writers have
suggested that some individuals may want to establish an embryonic
clone to be frozen and put away. Then, in the event of a childhood
disease requiring a transplant, the embryo can be thawed, implanted
in a surrogate, and raised to a sufficient age for the spare organ
to be harvested and transplanted. While this is certainly possible,
I consider it very unlikely that these practices would be
sanctioned by any government because it completely tosses aside the
uniqueness of humanity and trashes the concept of human dignity.
That doesn't mean, however, that someone won't try.
Will human cloning be used to replace a dying infant or
child? This is certainly a possibility, but we need to ask if
taking such a course of action is an appropriate way to deal with
loss. Unrealistic expectations may be placed on a clone that would
not be placed on a normally produced child. The cloned child may be
the same genetically, but different in other respects. This could
create more frustration than comfort.
Will humans be cloned to provide children for otherwise
childless couples? This is the reason most often given for
human cloning, yet the argument is unpersuasive when there are so
many children that need adoption. Also, this devalues children to
the level of a commodity. Also, if in vitro fertilization
seems expensive at $5,000-8,000 a try, cloning will be more so.
Will human clones have souls? In my mind, they will be no
different than 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, but it happens.
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 10 to 20%. The success rate of normal fertilization and
implantation is around 33 to 50%. 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 does not
respect the sanctity of human life.
Cloning provides a means for lesbians to have children as a
couple. 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 partner is fused together to create a new individual,
though all the nuclear genetic material comes from only one cell.
The real question is whether this is the proper environment for any
child to grow up in. (For more information on this topic, see Sue
Bohlin's essay, "Homosexual Myths.")
Homosexual "marriages" are not really marriages in the normal
understanding of the term, 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 we 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. It 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 Human Cloning radio script) 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.
© 1997 Probe Ministries International
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About the Author
Raymond G. Bohlin is executive director of Probe Ministries.
He is a graduate of the University of Illinois (B.S., zoology),
North Texas State University (M.S., population genetics), and the
University of Texas at Dallas (M.S., Ph.D., molecular biology). He
is the co-author of the book The Natural Limits to Biological
Change, served as general editor of Creation, Evolution and Modern
Science, and has published numerous journal articles. Dr. Bohlin
was named a 1997-98 and 2000 Research Fellow of the Discovery
Institute's Center for the Renewal of Science and Culture. He can
be reached via e-mail at rbohlin@probe.org.
Copyright © 2002 Probe Ministries.
All rights reserved.
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