For decades, the idea of human cloning has captivated imaginations, often appearing in science fiction as a harbinger of scientific marvel or ethical dilemma. Beyond the realm of speculative fiction, scientific endeavors have explored creating genetically identical copies of organisms. This naturally leads to a central question: how close has science come to achieving human cloning? The journey reveals a complex interplay of breakthroughs, controversies, and strict ethical boundaries.
Reproductive Versus Therapeutic Cloning
Understanding human cloning requires distinguishing between its two primary objectives: reproductive cloning and therapeutic cloning. Reproductive cloning aims to create an entire new organism that is genetically identical to a donor organism. This process would theoretically result in the birth of a baby that shares the same genetic blueprint as an existing individual, much like an identical twin born at a later date.
Therapeutic cloning pursues a different, more limited objective. This approach involves creating cloned embryos not for implantation into a womb, but solely for the purpose of deriving embryonic stem cells. These stem cells are then used in laboratory settings to study diseases, understand developmental processes, or develop potential treatments. The cloned embryos in therapeutic applications are typically developed only to a very early stage, usually a few days old, before the stem cells are harvested.
Notable Claims and Controversies
The history of human cloning has been marked by several high-profile claims that generated public attention but ultimately lacked scientific validation. In 2002, Clonaid, a company associated with the Raëlian religious movement, announced the birth of “Eve,” purportedly the first cloned human baby. This sensational claim was met with widespread skepticism from the scientific community, as no verifiable evidence or independent peer review was ever provided to substantiate the assertion. Despite the global media frenzy, the claim faded without any proof emerging, leaving it as a footnote in the history of cloning controversies.
A more damaging controversy emerged from South Korea involving scientist Hwang Woo-suk. In 2004, Hwang and his team published a paper in Science claiming to have successfully created the first cloned human embryos and derived stem cell lines from them. This announcement was initially hailed as a groundbreaking achievement, positioning South Korea at the forefront of stem cell research.
However, the triumph quickly turned into scandal. Investigations revealed that Hwang’s research was based on fabricated data, including the manipulation of images and the false claim of deriving 11 distinct stem cell lines. It was also discovered that his team had engaged in unethical practices, such as obtaining egg donations from junior researchers. The revelation of this scientific fraud in 2006 led to the retraction of his papers, the dismantling of his research lab, and a severe blow to the credibility of human cloning research worldwide.
The First Cloned Human Embryos for Stem Cells
Despite the controversies, genuine scientific progress in human cloning for therapeutic purposes eventually occurred. In 2013, a team led by Dr. Shoukhrat Mitalipov at Oregon Health & Science University successfully created human cloned embryos and derived embryonic stem cells from them. This achievement marked the first time that human cells were cloned using the same technique that produced Dolly the sheep, a process known as Somatic Cell Nuclear Transfer (SCNT). This method involves taking a somatic cell, such as a skin cell, from a donor and removing its nucleus, which contains the genetic material.
The nucleus from the donor cell is then inserted into an unfertilized egg cell from which its own nucleus has been removed. This reconstructed egg is subsequently stimulated to begin dividing, developing as if it had been fertilized. Mitalipov’s team demonstrated that these cloned human embryos could develop to the blastocyst stage, which is a very early developmental stage consisting of approximately 100 to 150 cells, typically reached after about five to six days of development.
At this blastocyst stage, the inner cell mass, which is the source of embryonic stem cells, was carefully isolated. These stem cells were then cultured in the laboratory, demonstrating their ability to differentiate into various cell types, a hallmark of true embryonic stem cells. These cloned embryos were developed only for the explicit purpose of harvesting these stem cells for research, with no intention to implant them into a uterus or allow them to develop further into a full-term pregnancy.
The Current Scientific and Ethical Landscape
The prospect of creating a full-term human clone remains largely unrealized and is not a focus of mainstream scientific pursuit. One major reason is the technical and safety hurdles associated with reproductive cloning. Animal cloning studies have consistently shown very low success rates, with only a small percentage of cloned embryos developing to term. Furthermore, cloned animals often exhibit severe health problems, including developmental abnormalities, organ malfunctions, and premature aging, a phenomenon sometimes referred to as “Large Offspring Syndrome.” These issues underscore the risks and unpredictable outcomes associated with attempting to clone a human being.
Beyond technical challenges, ethical objections and widespread legal prohibitions have largely halted any attempts at human reproductive cloning. Most countries around the world, along with major international scientific and medical organizations, have implemented bans or moratoria on human reproductive cloning. These prohibitions are rooted in moral concerns regarding human dignity, potential for exploitation, and the unknown long-term health consequences for a cloned individual. While therapeutic cloning research continues to hold promise for regenerative medicine and disease modeling, the creation of a cloned human baby remains a scientifically unfeasible and globally condemned endeavor.