Bees do it. Lizards and snakes do it. Turkeys and Komodo Dragons can do it. Have babies without daddies, that is. It’s called Parthenogenesis. And it’s sort of when a clone isn’t a clone.
Parthenogenesis a form of asexual reproduction in which growth of the embryo occurs without fertilization. The growth of the embryo begins due to a change in temperature, a mechanical action, or a chemical action. The term applies only to animals. (Botanical asexual reproduction is called something else.) And since the offspring are clones of the mother, they are usually female.
This phenomenon was first observed in aphids and recorded by Charles Bonnet in the 18th century.
In 1899, Jacques Loeb reported artificial parthenogenesis in sea urchins. Gregory Pincus used temperature and chemicals to induce embryonic development in rabbit eggs in 1936. Today, some sources say about 70 vertebrates can reproduce this way and if you include all organisms that number will top 2000 species.
Some species are obligatory parthenogenic, in other words, they cannot reproduce sexually at all. Other species are facultatively parthenogenic, meaning they have the ability to switch between sexual and parthenogenic reproduction.
There have been no known natural parthenogenic offspring in mammals. There are a number of different theories as to why that is, but it was reported in 2004 that one laboratory created parthenogenic mice. It was a lengthy, complicated, and inefficient process.
Not a Clone?
Cloning is different from parthenogenesis. According to The American Heritage Medical Dictionary cloning is “the transplantation of a nucleus from a somatic cell (a body cell, not a gamete) into an ovum, which then develops into an embryo.” Mosby’s Medical Dictionary goes a little farther in its definition, “a procedure for producing multiple copies of genetically identical organisms or of cells or of individual genes. . . .”
The offspring in cloning can be not identical to the parent organism if either somatic cell or the ovum is not from the parent organism.
In parthenogenesis, the process of fertilization does not happen. Thus the offspring is identical since no new DNA is required.
Then there are the different types of cloning: recombinant DNA, Reproductive Cloning, and Therapeutic Cloning. Each could be topics of their own, so I won’t get into the details here. If you’re curious, I’ve listed my online resources below.
Do You Know a Clone?
Since there has been no confirmed, recorded human clones born, many of you will answer this question in the negative. Or perhaps you will remember Dolly the Sheep (1996-2003), the first cloned mammal. Yet, I’ll bet you know at least one set of identical twins. Identical twins have identical DNA, they come from a single cell. And it appears that nearly every species on Earth can bear twins.
Will the True Clone Please Stand?
So which process creates a true clone? Is it okay to take the parthenogenic or cloning process just so far as to make stem cells and not allow the cells to develop into an organism? Why do we need this research, you ask?
Stem cell research has already shown us that it has terrific potential to cure deadly diseases such as cancer and diabetes. It’s just a tantalizing glimpse of what may be possible. Think of the many millions of people who may be helped by this process.
And what about invitro fertilization? Most of us accept that this is one way for couples unable to conceive naturally to be able to have children. Is this cloning? What if, only one partner was able to contribute the cells to create the offspring due to genetic or other diseases?
If we could repopulate endangered species through cloning, would that be an acceptable use of the process?
If we outlaw cloning, do we outlaw the cloning and the parthenogenesis that nature affords us? Would you get rid of those cute identical twins everyone likes to ooh and ahh at?
What’s in a Word?
Does the difference in semantics affect the ethics of this situation? For many people, the answer is no. And I respect their concerns. There are reasons to be concerned. As with most scientific discoveries, there is the potential for both an immense amount of good and terrible wrongs.
Not to make light of anyone’s particular beliefs, there is no easy answer.
As a science fiction author and a nurse, I find this topic is a gold mine of information and emotional reactions. I’m having fun using parthenogenesis as a springboard to explore a little of the controversies involved.
Do you read fiction that takes on controversial issues? Has a book or article about such a controversial issue ever changed your mind?
Your responses to this topic are important to me. In fact, some of your answers may fuel development in my novel. I only ask that you respect others who may reply with differing opinions. Thank you so much.
If you’d like to learn more, here are some of my online resources:
- Thinkquest.org
- Human Genome Project
- How Stuff Works
- Fact Monster
- Nova – alternative to cloning:
- What Mom and Dad Never told you about the Birds and the Bees
- Ohio State The Tremendous Turkey (link no longer available)
- Fatherless Mouse