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30 November 2023

Therapeutic and Reproductive Cloning of Human Beings

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Ethics, esthetics and genetic censorship

Genetic modification of human embryos is possibly the most momentous decision facing us since the origin of humankind. But the scientific community does not know where it stands; the political community remains irresponsibly on the sidelines; and the general public, to adopt a metaphor drawn from livestock farming, seems to have given up its status as a political animal and surrendered itself to Juvenal’s “bread and circuses.”

Throwing a spanner in the works of science and progress is nonsense. No censor has emerged from the judgment of history unscathed. Yet an attack on the dignity of humankind would be an unforgivable mistake and would take an exorbitant toll on our civilization.

BBVA-OpenMind-Laira Maganuco Pie de foto: Baby and creatures by Maganuco laira Fuente: Laira Maganuco
“Baby and creatures” by Maganuco Laira. Source: Laira Maganuco

The question is: Does it make sense to continue to ban research into gastrulation, the critical stage of our biological existence? Where do we place the uncrossable red line, aware as we are that, if we take the step of gene-editing the germ line[1], the change will be irreversible and will change the evolutionary course of our hereditary tree?

Jennifer Doudna (Nobel Laureate in Chemistry 2020, alongside Emmanuelle Charpentier), had more than a premonition: “From the moment I learned that scientists had used CRISPR in primate embryos to create the first gene-edited monkeys, I was already wondering how long it would take for some unorthodox scientist to do the same in humans.”


Jennifer Doudna, Premio Nobel de Medicina y Fisiología
Jennifer Doudna, Nobel Laureate in Chemistry. Source: Wikipedia

If it can be done, and it can, because we are already in a position to modify the genetic code that defines any species, including our own, it will be done, if it hasn’t already. Someone, somewhere on planet Earth (or in interstellar space), has most likely already changed the genetic makeup of homo sapiens.

Sooner than we can imagine, reality will overtake movie fiction, captured in films such as Splice (2009), starring two scientists who decide to ignore the ban on research with human embryos and end up creating a hybrid, overcome by the “vanity of vanities” of Ecclesiastes.

BAK_Nayman_JUN10_ART_570-Fuente: Warner Bross
Still from the film Splice, 2009. Source: Warner Bross


Extreme caution is essential in such a crucial matter. But an unfounded fear of the unknown is often the ideal breeding ground for disaster mongering from doomsayers who distort the actual facts and wave a banner of panic about experimentation with human embryos, which has nothing to do with the crux of the matter: the crucial difference between reproductive cloning and therapeutic cloning.

If we had left the world in the hands of dogmatists, we would still be living in the Stone Age. And surely, Professor Sinya Yamanaka (Nobel Laureate in Medicine and Physiology 2012) would have been pilloried for proving it is possible to reprogram cells that are already differentiated and return them to a state typical of pluripotent stem cells (cells that can be ‘reconverted’ into several different types of cells or tissues in the body).

Shinya Yamanaka, Nobel Laureate in Physiology and Medicine 2012
and winner of the BBVA Foundation Frontiers of Knowledge Award. Source: BBVA Foundation

If the first and ultimate purpose of ethics is the Good, as Aristotle wrote in his Nicomachean Ethics, what argument is available to those who insist on imposing moral dilemmas by appealing to religious, ideological or overtly fundamentalist convictions? Where is the problem if adult human pluripotent cells (i.e. stem cells, not cells from a human embryo) are inserted, for example, into an animal chimera? What principle of Natural Law is violated if adult cells are reprogrammed in the lab, returned to their primordial state, and converted into any other type of cell? To what extent is the sinister legacy of Nazi eugenics shaping a discussion that can no longer be postponed?

As absurd as it may seem, there are still many countries that have chosen to keep in place a stagnant legal framework in the field of fertility treatments. For many governments still stuck in the Precambrian, which are doctrinaire to the point of exasperation, the ban on generating human embryos for purposes of research brooks no exception whatsoever.

Fortunately, nature does not tolerate stasis or prior censorship. Scientific breakthroughs continue their inexorable course, oblivious to any obstacles and the inflexible attitude of prohibitionists.

Many countries still question therapeutic cloning or cell replacement therapy by nuclear transfer, which is capable of generating embryonic stem cells that are genetically identical to the patient. Conversely, there is still a minority of countries that accept and support research based on therapeutic cloning. Nuclear transplantation is permitted in the United Kingdom, Belgium, Sweden, India, China, Japan, Singapore, Israel, South Korea and a few other countries.

It is striking that many of those who cling to ‘No!’ seem to have deliberately forgotten that thanks to the nuclear transfer technique it was possible to clone Dolly the sheep. Few remember what the late Professor Sir Ian Wilmut had to endure, vilified to the point of humiliation.

Miembros del equipo de investigación que clonó a la oveja Dolly. Crédito: University of Edinburgh/ Maverick Photo Agency
he late Professor Sir Ian Wilmut with other members of the research team that cloned Dolly the sheep. Credit: University of Edinburgh/ Maverick Photo Agency

In essence, the process consists of introducing the nucleus of a differentiated adult cell into an unfertilized egg cell (which has previously been stripped of its nucleus) for reprogramming. This results in a cloned blastocyst, from which genetically identical stem cells are derived. The risk of immunological rejection is thus avoided.

The nuclear transplantation technique continues to meet expectations and to show that, although its therapeutic uses will not be available overnight, it has great potential to provide a reliable cure for many diseases.


The second after Dolly’s birth was made public, the scientific community was well aware that the cloning of the sheep opened the floodgates to stormy waters that were impossible to contain: the cloning of humans.

The reasoning is overwhelmingly logical: if the evidence shows that it is possible to clone animals, what are we waiting for to do the same with people?

There are still a majority of authoritative voices who argue that we would be committing an outrage with unpredictable consequences if we were to approve the reproductive cloning of human beings.

But everyone knows that, regardless of widespread appeals to responsibility and fundamental ethical principles, if it can be done (and it can be done, no matter how monstrous the results may be), it will be done.

For the time being, the only thing that the repeated failed attempts to apply nuclear transfer to humans (both publicly acknowledged and those performed in secret, clandestine laboratories) seem to have achieved is to feed groundless fears about therapeutic cloning and to encourage the malicious intentions of those who self-interestedly try to conflate it with reproductive cloning, in order to discredit it.

Células progenitoras neuronales diferenciadas de células SCNT-ESC. Crédito: Center for Embryonic Cell & Gene Therapy
Neural progenitor cells differentiated from SCNT-ESC cells. Credit: Center for Embryonic Cell & Gene Therapy

They have nothing to do with each other. While reproductive cloning seeks to create a being genetically identical to another, therapeutic cloning seeks to obtain genetically identical stem cells in order to use them for treatment without triggering rejection.

To conflate both types of cloning, out of ignorance or deliberately (to maliciously feed the confusion in an unmanageable turmoil), is nonsense, especially in the latter case. It is therefore appropriate to make very clear the widespread rejection (albeit with exceptions) by the scientific community of reproductive cloning, and its approval of therapeutic cloning, which opens the way to curing diseases.

In early 2001, the United Kingdom took the farsighted decision to decriminalize the use of human embryos for stem cell research, while at the same time taking steps to promote it. Since then, the world has not crumbled, as predicted by the doomsayers who did their utmost to prevent it by appealing to Nostradamus’ Les Prophéties.

Today, it is only from a position of ignorance or self-interested confusion that a moratorium on the use of human embryos for stem cell research can be proposed; just as it is only from cosmic misunderstanding or from the maledictions of an inquisitor that the (inevitable) destruction of human embryos for research can be condemned from a moral point of view.

What would become of parents who resort to fertility treatment, where many more embryos are created than are eventually implanted?


To conclude: nuclear transplantation meets all the necessary conditions to gain a foothold as a therapeutic tool. There is nothing to fear if human dignity is safeguarded to the highest degree.

It is not a question of giving scientists a blank check to do research with human embryos free of any qualms, but of providing them with the regulatory framework for them to do their work, in a transparent and unambiguous manner and under the oversight of independent authorities and bodies that safeguard human dignity, the backbone that lends meaning to bioethics and, perhaps, to our very existence.

History has taken its course, because fortunately there have always been women and men chosen by fate to question it, to challenge the status quo and to counter doctrinaire approaches, while accepting the consequences of the challenge. To me, unquestionable opinions have always given me a rash.

One day long ago, back in the Devonian, a bony fish with lobed fins lost its mind, ventured out of the water, abandoned its own kind, and became the first tetrapod (from the Greek tetra, “four”, and podo, “feet”), the first land vertebrate. If it weren’t for that creature (blissful bout of insanity!), we humans would not exist.

Only great individuals dare to tear down walls, even when aware of the risk of ending up bruised under the rubble. As Sir Karl Popper, probably the most influential philosopher of science of the 20th century (and also the most skeptical), founder of falsificationism or critical rationalism, wrote in his Logik der Forschung (The Logic of Scientific Discovery, 1934), all great achievements have defied common sense.

Fue la doctrina teológica de Servet la que motivó su persecución, principalmente por su negación de la Trinidad y su rechazo al bautismo infantil. Crédito: Alamy Stock Photo
It was Servetus’ theological doctrine that sparked his persecution, mainly because of his denial of the Trinity and his rejection of infant baptism. Credit: Alamy Stock Photo

Some paid for their heresy by being brought to account before the Holy Office, such as Galileo Galilei,sentenced to life imprisonment and ordered to abjure his ideas for mocking Ptolemy’s geocentrism and declaring his public support for Copernicus. Others, like Servet, were thrown onto the bonfire of the vanities (echoed by Tom Wolfe in the title of his novel, The Bonfire of the Vanities) for daring to think and disagree on the basis of reason.

Despite the years that have gone by since 1978, the lynching campaign that the pioneers of fertility treatment were subjected to, as if they were heretics deserving of excommunication, when they announced the birth of Louise Brown, the first “test-tube baby,” still resonates on the shelves of the newspaper archives.

As in many other facets of life, time and facts always win out, regardless of opinions for or against. This is the case, for example, with “reproductive tourism:” a factual reality that has become part of everyday life, with utmost simplicity, irrespective of the shows of support or disapproval that at the time ignited the fuse of controversy.


Biology is undergoing a pivotal revolutionary moment. It is only a matter of time before we humans become the only species capable of directing the destiny of our own evolution.

Questions about our species swirl in a sea of doubts and the horizon allows no glimpse of the future with the clarity and sense of foresight that we would like.

Despite progress, the past is still full of issues that the present has not yet been able to address. Even the laws that underpin our current certainties are faltering.

In ‘El Último Sapiens’ (‘The Last Sapiens’), I quote the sincere reflection of Professor Juan Carlos Izpisua: “I admit that I feel apprehensive every day when I cross the threshold of the lab. I am not ashamed to acknowledge that I even feel fear, a thrilling fear, in the face of the unstoppable stream of scientific discoveries.”

Juan Carlos Izpisua Belmonte, científico fundador de ALTOS LABS y director del Instituto de Ciencias de San Diego, California Fuente: ALTOS LABS Juan Carlos Izpisua Belmonte, founding scientist of ALTOS LABS
and director of the San Diego Institute of Science, California. Source: ALTOS LABS


We are living a momentous time for the future of humanity. The day will come when we–society as a whole, not just scientists–will have to decide whether or not to act on the immortal cells (the sperm and the egg), knowing as we do that, if we finally take that step, the decision can never be reversed, because the change will be forever, since we will have altered the natural course of evolution.

That is why it is vital for people to know what is happening, and for the authorities and governments to understand that scientists can and should participate in the discussion, but that it is not up to them to set the rules of the game.

One day we will be in a position not only to successfully confront currently incurable diseases, or to eradicate them completely, but also to improve the human species or even to create species beyond ‘homo sapiens.’ But the question is, should we?

Today we speak only of possibilities; tomorrow, we will speak of certainties. Society as we know it today will soon cease to be, because the day we least expect it, a surprise will be waiting just around the corner. And when this happens, which it will, we should know what to expect as soon as we manage to recover from the state of shock.

We are in a position to alter evolution, instead of patiently waiting for nature to take its course and let chance act accordingly. We need to be acutely aware of what this means or could entail for human life.

One day we will even be in a position to create superhumans or, conversely, underskilled beings, by altering, for example, human cognitive capacity. But the question is, should we?

For this reason and many others, it is vital and urgent for society to know what scientists are researching and to know it in the proper way. Furthermore, governments should act appropriately, but based on knowledge and ethical debate. Only in this way will we be in a position to begin to glimpse what will become of the human species tomorrow, and above all what we want it to be within the leeway that still remains to us.

We are now at a turning point in the evolution of the species; of life on our planet. It is not easy to foresee where we are headed, but it is common sense to realize that what we do now can change the human species, all organisms, all forms of life on Earth.

José Antonio Ruiz

Former professor at the University of Nebrija, Madrid, Spain


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[1] Definition of germline from the National Human Genome Research Institute: Germ line refers to the sex cells (eggs and sperm) that sexually reproducing organisms use to pass on their genomes from one generation to the next (parents to offspring). Egg and sperm cells are called germ cells, in contrast to the other cells of the body, which are called somatic cells.

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