A clone is a biological entity, such as a segment of DNA, a single cell, or a complete organism, that possesses the same genetic makeup as the original from which it was copied. This copied material is produced through processes that result in genetically identical individuals. The concept applies across the biological spectrum, from microorganisms to complex animals and plants, encompassing both natural phenomena and laboratory techniques.
Cloning in the Natural World
Cloning is a widespread process in nature, serving as a primary method of reproduction for many forms of life. This form of asexual reproduction allows an organism to generate offspring that are genetically identical to the single parent. This process occurs across various branches of the tree of life, including in plants and even mammals.
A familiar example of natural cloning in humans is the formation of identical twins. This occurs when a single fertilized egg spontaneously splits into two separate embryos. Because both individuals originate from the same egg and sperm, they share nearly identical DNA, making them natural clones of each other.
Many plants have evolved methods for cloning themselves, a process known as vegetative propagation. Strawberry plants, for instance, send out horizontal stems called runners that can grow roots and develop into new, independent plants. Plants like onions and daffodils reproduce using bulbs, which are underground storage organs that can sprout new, identical plants. Taking a cutting from a plant and allowing it to root is also a direct form of cloning.
In the microbial world, cloning is the standard mode of reproduction. Single-celled organisms like bacteria and yeast replicate by splitting into two identical daughter cells. This process, often called binary fission in bacteria, ensures that each new cell is a genetic copy of the parent cell. This method allows for rapid population growth and demonstrates cloning as a basic biological mechanism.
How Artificial Cloning Works
Artificial cloning refers to laboratory techniques used to create a copy of an organism. The most known method for cloning a whole animal is somatic cell nuclear transfer (SCNT), which gained attention with the birth of Dolly the sheep in 1996. This process showed that genetic material from a specialized adult cell could be used to create an entire new animal.
The procedure for SCNT begins with two donors. Researchers take a somatic cell—any body cell other than a sperm or egg cell—from the animal they intend to clone. Simultaneously, they obtain an unfertilized egg cell from a female donor of the same species and remove its nucleus, which contains the genetic material.
The nucleus from the somatic cell is then transferred into the enucleated egg. Scientists can accomplish this transfer either by injecting the nucleus directly into the egg or by using an electrical current to fuse the entire somatic cell with it. This hybrid cell is then stimulated, often with an electric shock, to begin dividing as if it were a fertilized embryo.
Once the cloned embryo reaches an early stage, known as a blastocyst, it is implanted into the uterus of a surrogate mother. The surrogate then carries the embryo through a normal gestation period, giving birth to an animal that is genetically identical to the individual that provided the somatic cell. Dolly was the first mammal successfully born using this technique, which involved 277 attempts to produce one live lamb.
Clones and Identity
A common misconception is that a clone is an instantaneous, identical copy of the original, including its age and memories. In reality, a clone of a person would be born as a baby and would need to grow up, just like any other individual. The clone is simply a much younger, genetically identical twin.
While a clone shares the same DNA as the original, it would not be the same person. An individual’s identity, personality, and memories are not determined by genes alone. Life experiences, the environment in which one is raised, relationships, and personal choices all play a large part in shaping who a person becomes.
The case of identical twins provides real-world evidence for this principle. Though they share the same genes, identical twins are distinct individuals with their own personalities and life paths. Studies of twins separated at birth and raised in different environments show that while they may have striking similarities, they are also unique people shaped by their different upbringings.
A clone would develop its own consciousness and set of experiences from birth. It would have different memories and a unique perspective on the world, forged through its own journey through life. While genetics provides the biological blueprint, the tapestry of life’s experiences is what defines an individual’s personal identity.