Table of Contents
o Stem cell research and cloning
o Cloning whole organisms
o Asexual reproduction in single-celled organisms
o Gene cloning
o Reproductive cloning
o Therapeutic cloning
o Pros and Cons of cloning animals
o How Dolly was Cloned
o Cloning endangered animals
o Cloning can bring back extinct species
o Is it possible to clone your pet?
While cloning is something that only exists in science-fiction in the minds of many people, the reality is that we have had cloning technology for decades. Not only have we cracked several types of cloning technology, but there is also exciting potential for cloning to yield beneficial innovations for the future generations of mankind.
We’re going to go through all this and more in today’s guide. Where we can, we have also linked away to resources to support or provide even more in-depth information on some of the subjects that we’ve brought up. Here’s a rundown of each section of this guide and which questions you can expect to be answered within:
What is Cloning?
As you can see, we have a lot to establish before we can get to the future of cloning and how it can benefit us in the future, so let’s get right into it!
What is Cloning?
Before we get into any specifics, it’s best we explain what cloning is. There are multiple working definitions of cloning, so let’s go to the root. The origin of the words for cloning comes from the plant biology field and was used to describe a similar process by which live animal cloning is facilitated.
We can thank plant physiologist Herbert J. Webber for coming up with the term “clone.” It comes from an Ancient Greek word for twig and was intended to refer to the process of burying a plant’s twig to grow a whole new plant.
This is still something that happens today in botanical and horticultural fields, even if the term clone has a whole new meaning in popular culture. If you know how cloning works, you can probably see already how this word can be used for animal cloning too. If not, don’t worry, we have explained everything below.
So how can we sum cloning up in a way that isn’t referring to a specific context? Perhaps the best way is this – cloning is the process of replicating a biological entity by using cells from that entity.
The result is genetically identical to the original. Cambridge Dictionary sums up cloning in a very similar way. Put simply, whether it’s a plant or an animal, cloning is where a part of one thing is used to make an identical genetic copy of that thing.
Is Cloning Possible?
If you couldn’t tell by how we’ve talked about cloning so far, yes! Cloning is absolutely possible.
Ignoring that plant cloning exists, and was the origin of the word, the animal cloning that comes to mind when most people hear the word is also possible.
Not only is it possible, but it has also happened, and happens in a wide variety of scientific fields. You see, when many people hear the word cloning, they think of the cloning of whole, living organisms.
While that is cloning taken to its logical end-goal, cloning can also refer to the replication of individual cells and tissues.
If you take just one cell of a being and use it to create just one more cell that is identical, that’s also cloning. In fact, that’s exactly what happens with stem cell research.
Stem cell research has often led to groundbreaking developments in the field of medicine, however, there are ethical concerns that come with the territory. To minimize these concerns, they often clone genetic material and make clones of those clones so that they can avoid many of the ethical concerns in the field.
It’s also easy to do so since stem cells can grow into many different cell types, but that’s a whole different topic. The short answer is yes, cloning is very possible because we have done so with plants, individual cells and organs, and even whole organisms, as we explain later below.
Do Clones Ever Occur Naturally?
A common misconception is that cloning is something to be done in white, sterilized labs, with complicated test tubes and expensive equipment.
That’s not wrong, of course, we only just mentioned stem cell research above. That said, yes, cloning is a natural process.
When we use science to clone, we are only following the example set before us in the natural world. Single-celled organisms, once the origin of all life on this planet, reproduce asexually.
Bacteria is probably the most popular example of a single-celled organism, and they also replicate through asexual reproduction.
This means they only use their own genetic information to create another single-celled organism, which then has the same information.
That fits our definition of cloning! Not only that, but you don’t even need to break out a microscope to see examples of cloned life. You may have heard that invertebrates can be cloned, and this is true.
If you cut a flatworm in two, the two halves will regenerate so that there are now two distinct but genetically identical worms. The same cannot be said for earthworms, however, that’s a myth. Instead, it’s common that the head half survives and regenerates while the other dies.
Human identical twins are also natural clones and the process that makes identical twins can occur in other mammals, too. That would be where a fertilized egg splits so that two or more embryos are created with the same DNA signature. Maybe don’t go around calling twins clones though, that can appear rude.
Some plants asexually reproduce too. It’s hard to find a mate when you’re rooted in the ground all day, so some plant species have adapted to reproduce using their own genetic information.
This is most common with bulbs and tubers, like onions, ginger roots, and sweet potatoes. That’s right, you’ve probably eaten plants that could be described as clones by the popular definitions of the word. This just demonstrates how natural the process is when it is found in the wild.
If you were hoping for a pretty flower, the dahlia is a popular example of a flower that reproduces through its bulb, a process called vegetative propagation. This is what onion and ginger do too, making the dahlia an example of a flower that reproduces through natural cloning.
What Are The Types of Artificial Cloning?
You’re probably not here to talk about plant life, however, so let’s look at the different types of artificial cloning that are available to us.
Artificial cloning is cloning that is done by humans, outside of nature, so this is where the people in lab coats come in.
There are three main types of artificial cloning that work right now. There may be more in the future, who knows?
For now, though, we have these three to work with:
- Gene Cloning
- Reproductive Cloning
- Therapeutic Cloning
Let’s tackle these, one by one.
First, gene cloning is also called molecular cloning in some fields. Don’t get confused, gene cloning and molecular cloning methods are one and the same. Both refer to the process of cloning a piece of genetic information instead of the whole organism.
To clone a gene, people much smarter than we isolate the gene that they wish to copy and place that gene into a vector. A vector is just something that spreads its genetic information, in this case, bacteria is a good example.
By placing the gene into bacteria or similar asexually-reproducing material, that gene is also cloned when the bacteria replicates itself. By piggybacking on this natural asexual process, scientists can copy genes to their heart’s content.
Reproductive cloning is how whole organisms, like living animals, are best cloned. Alongside reproductive cloning and animal cloning, this process is also referred to as adult cell cloning. As the dominant form of animal cloning today, reproductive cloning is the main focus of much of this guide, so we go into much more detail below.
For now, let’s move on and explain what therapeutic cloning is. We have technically mentioned therapeutic cloning already when we talked about stem cell research. That’s because therapeutic cloning is used to make a cloned embryo that creates stem cells.
By creating these embryos, it becomes possible to farm embryonic stem cells for further research. This is done during the first five days where the embryo’s stem cells have started to divide, after which the embryo is destroyed.
How Are Animals Cloned?
Animals are cloned via reproductive cloning, so let’s go into more detail on that. For reproductive cloning, a mature somatic cell is required. What’s a somatic cell?
Literally any cell that isn’t a sperm, egg, germ, or stem cell, that simple! Skin cells are an easy example of a somatic cell that is used for animal cloning.
Once they have this cell, they transfer its DNA into an egg cell, which has had its own nucleus, where the genetic information is, removed.
This can be done via injection or an electrical fusing process, either way, the end result is the same.
After developing an embryo from this combination, it’s moved into the womb of an adult female animal so that it can be carried to term.
When the female gives birth, the resulting animal has the same genetic information as the animal that the skin cell was taken from, making it a clone! This was how some of the most famous examples of cloned animals were created, like a certain sheep that the second half of this guide explores.
What Animals Have Been Cloned?
With the mention of animal cloning, we should at least give some information about which animals we have successfully cloned.
We have spent over half a century conducting experiments that involve cloning or attempts to clone that didn’t go so well. Naturally, that includes animal cloning too.
In 1952, the first-ever artificial cloning occurred with a tadpole. Not the most exciting animal to clone, we know, but everybody starts somewhere.
Similarly, carp cloning was developed in 1963, establishing the world’s first cloned fish. As with so many scientific experiments, the big experiments started with lab rats.
Well, mice, but you know what we mean.
In 1979, mouse embryos were created and split when they were in the test tube, then implanted into the wombs of female mice. This had limited success, enough that they then started experimenting with larger creatures, from chickens to sheep, and then cows, all using variations of the tadpole cloning technique.
Dolly the Sheep came from somatic cell transfer experiments conducted in Scotland and solidified herself as the first cloned animal through that process in 1996, though not without many, many failed attempts.
Cows were also cloned in Japan but the cloned litters had a roughly 50% survival rate at the time. Back to mice for a moment, there was also Cumulina, a mouse clone produced in 1997 that was the first cloned animal to reach adulthood.
Granted, that wasn’t very long, as she died of old age three years later, but it was still old for a mouse and an important historical moment when looking over the timeline of cloned animals.
Since Dolly and Cumulina proved definitively that cloned mammals could reach adulthood, many other cloning experiments have taken place and are taking place at this very moment. Name a mammal, any mammal, and it has probably been cloned or attempted to have been cloned. Here’s a shortlist:
- Tasmanian Tigers – 1999
- Mira the Goat – 1999
- Tetra the Rhesus Macaque – 1999
- Xena the Pig – 2000
- CC (for CopyCat) – 2002
- Snuppy the Dog – 2005
- Macaque Monkeys – 2018
Let’s stop at that last one, as it was a huge and controversial milestone in the scientific community. We all know monkeys as being closer to human beings than most other animals, and capable of higher levels of cognition when compared to other mammals, so this breakthrough was especially significant.
Tetra was created in 1999 through embryo splitting, meaning that there was always an asterisk next to her title as the first cloned monkey. With this new development, however, monkeys have been cloned using the same method that cloned Dolly in 1996.
Pros and Cons of Cloning Animals
Since we’ve stumbled into an ethical uproar, let’s talk more about the pros and cons of cloning animals.
Why do we want to clone animals?
Curiosity and scientific innovation is a good answer, sure, but there are agricultural and medicinal benefits that make cloning worth the time and effort involved.
Here’s a handy breakdown of the pros and cons of animal cloning in an easily digestible table format:
|Cloned animals are useful for testing drugs. |
Being genetically identical, they are more predictable and cost-effective to test on.
|Reproductive cloning is very inefficient at the moment and many resulting animals don’t reach adulthood.|
|Meat and milk from cloned cattle were ruled safe for consumption by the FDA in 2008. |
While cloned food products are too expensive to hit markets yet, this will allow positive traits of cattle to be replicated easier.
|Mammals, even if they hit adulthood, have struggled with some adverse health effects. These effects mainly target the brain, heart, and liver, and they can even age prematurely.|
|Cloning can be used to build up the populations of endangered or even fully extinct animals if we have sufficient DNA.|
Animals with personal significance, like pets, can also be cloned with animal cloning.
|Like with some other cloning types, there’s an ethical debate around cloning animals. |
Whether it’s bringing back dead animals or replicating your pet, the question of “should we do it” is always one that looms over these scientific advancements.
Have Humans Been Cloned?
Now let’s get into the real controversial stuff to end this first half of our cloning guide. Has a human ever been cloned? There is currently no scientific evidence that a human being has been cloned yet.
Take that answer as you will. After all, there’s a lot that we didn’t have scientific evidence for in the past, that was still happening.
The reason for this ambiguity is because many people and organizations have claimed to clone humans in the past. As far back as 1998, South Korean scientists claimed they successfully cloned a human embryo.
That’s the first step to creating a fully-fledged clone, so it’s a big boast, as you can imagine. The experiment was interrupted and canned not long after, however, with only four cells being made in total.
In more zany territory, a religious group that believes mankind was originally made by aliens called Clonaid tried announcing the birth of the first cloned human in 2002.
Given the extremely imaginative name Eve, this cloned human was never verified by the news or any affiliated research communities due to Clonaid not providing sufficient evidence.
They even cloned twelve more people, if they’re to be believed, but every claim requires evidence and they had none. Then, in 2004, we’re back to South Korea for Woo-Suk Hwang, who led a group in creating a human embryo out of a test tube.
Working from Seoul National University, the group made the claims in a journal simply called Science.
Fast forward to January 2006, Science announces that Hwang’s paper has been retracted due to lack of supporting proof. So, why hasn’t it happened yet? Cloning humans and primates is a much more difficult task than other mammals, hence why the cloning of macaques was such an event.
This is because humans have a more sophisticated protein makeup, with our spindle proteins causing an issue. These proteins are close to the chromosomes used for primate eggs, so getting to the eggs without removing the spindle proteins is difficult.
Removing the spindle proteins, however, interferes with cell division, making cloning impossible without them. Other animals have spindle proteins but they’re spread through the egg and don’t get in the way.
So no, we don’t think humans have ever been cloned. To be frank, if a viable human clone has been created anywhere, it’s much more likely that we would not be told about it. There’s a reason we approach the topic with such awe and that is because it is something that many people see as being clandestine and unnatural.
Coming out with the announcement of a human clone comes with a lot of ethical and legal baggage that needs to be dealt with, so on the slight chance that somebody has been cloned out there, they are much more likely to keep quiet and publish their research later instead of now, where they’d face negative consequences.
Who Was Dolly The Sheep?
Now that we’ve talked about everything else that you’d want to know about cloning, it’s high time we talk about Dolly the Sheep. Who was Dolly the Sheep? If you’re anything like us, you’ve heard of Dolly the Sheep before you properly understood cloning or what made them so special.
Dolly was a Finn Dorset sheep that, as we had mentioned above, was born in 1996. What makes her so special is that she was the first clone of an adult mammal using adult cell cloning methods, paving the way for many of the other examples we have given above.
To this day, somatic cell reproductive cloning is the foremost method of producing animal clones, and Dolly was the first. She was created by Ian Wilmut, a developmental biologist who worked with a group from the Roslin Institute. In the animal research world, that’s quite an esteemed name.
They’re a world leader in animal biology, so it makes sense that such a prestigious development had the help of these smart minds. This all happened near Edinburgh, in Scotland, the HQ of the Roslin Institute. Dolly’s birth was officially announced in February of 1997.
How Was Dolly Cloned?
How was Dolly cloned? With much difficulty, that’s how. Let’s start with the team at the Roslin Institute. It’s easy to imagine lab coats again but the team actually consisted of a wide variety of job roles to get the project off the ground.
Think about it, you don’t just need scientists who are qualified as embryologists, you also needed surgeons and veterinarians to gather genetic material and ensure that ethical concerns were being met, along with farm staff to keep the cattle happy.
A cell from a Finn Dorset sheep’s mammary gland was taken from the mother, so to speak, and then mixed with the egg cell of Scottish Blackface sheep. Now it should be mentioned that Dolly was not the first attempt. She also wasn’t the second, or the twentieth, or two-hundredth. Dolly was the result of 276 attempts at creating a sheep clone.
Maybe now you can see why animal cloning hasn’t caught on much since 1996, because there’s still a lot that needs tweaking and perfecting. Once the experiment got off the ground, there were enough established embryos to transfer into thirteen ewes. Only one of them would take and form a viable pregnancy, becoming Dolly 148 days later.
That was near the average expected gestation period, so no issues there, but there are other concerns that may have impacted Dolly later in her life.
Let’s learn all about what telomeres are. It’s really simple, telomeres are the tips of an organism’s chromosomes and they shrink over time. After a certain amount of time, they become so short that they can’t shrink anymore, the cell cannot divide and so dies, and this is what we call aging.
Since the age of an animal directly correlates to the quality and length of these telomeres and the chromosomes attached to them, a cloned animal can have difficulty living a full life.
So yes, while Dolly was born as a fresh-faced lamb, her origin DNA came from a sheep that was already six years old, and her chromosomes and telomeres developed in such a way that they’d already had six years of use because it’s the same genetic information.
It’s generally agreed that this shortened Dolly’s lifespan as she died in 2003 at the age of six.
As if the numbers couldn’t get any clearer, the average lifespan of Dolly’s sheep species was actually twelve, and so many believe that her life was directly halved because those six years of aging were represented in her chromosomes because they are copies of Dolly’s six-year-old mother.
There’s a lot of unknowns here, however. In 2016, a follow-up study by Kevin Sinclair muddied the waters by introducing four cloned Finn Dorset sheep.
These were Daisy, Debbie, Denise, and Dianna, and each of them outlived Dolly. Why is that important? They were cloned from her. If the telomere theory is fully correct, it should have been expected that they’d have even shorter lifespans than Dolly did, but this was not the case.
Whether it is the apparent telomere problem or the unpredictability of this technology, both are barriers to further advancement in the field.
If the chromosomes of a replicated being are also replicated via current cloning methods, a set of chromosomes would theoretically get you so far before they’re not worth cloning in the first place. Otherwise, the process is unreliable for the money required to get cloning projects to bear fruit.
The Future of Cloning
As we make our way towards the end of our guide on cloning, it’s time to think about how cloning innovations may shape the world of the future. In mentioning the benefits of cloning technology, we’ve talked about some of these already, but here we can go into even more detail.
Here are just some of the expected benefits of cloning that we can see for the future and, if we’re lucky, within our lifetimes:
- The ability to clone endangered animals
- The ability to bring back extinct animals
- The ability to clone your pet
There are some others, of course. We’ve already mentioned how gene and therapeutic cloning have exciting applications going into the future, but let’s focus on the future of animal cloning and how it could affect you in the next few decades.
Cloning Endangered Animals
Let’s start with cloning endangered animals. Conservation efforts all over the world expend time, money, and resources to make sure that the most at-risk species on our blue Earth are protected.
There are many reasons for this, from ecosystem sustainability concerns to the simple pleasure of making sure our children can grow up in a similar world that we did.
Cloning these endangered animals seems like an obvious conversation solution, and it is, don’t get us wrong.
As we discussed, it’s incredibly unreliable and expensive at the moment, so it’s not something we can roll out right now.
That said, we should be able to in the future if we can make cloning feasible. You’re not here for a lot of “can” and “should,” are you?
You want an example of how we have done this in the past. That’s where Elizabeth Ann comes in. This regally-named animal is a black-footed ferret and, you guessed it, they’re an endangered species. They’re ferrets, they’re roughly mink-sized and have an attitude, that’s all you need to know about them for now.
Recently, and we mean very recently, scientists cloned this first black-footed ferret using cells from a frosty ferret body that has been on ice since the 80s. Elizabeth Ann was born via a C-section on December 10th, 2020.
A Californian non-profit called Revive & Restore led the charge to bring these ferrets back in the name of biodiversity. As for Elizabeth Ann, she’s going to be housed in Colorado where she can hopefully grow old while being researched in the name of science.
As long as we can make reproductive cloning more reliable as a means of replicating living organisms, we can find and use cells to make more members of these endangered species. This would revolutionize animal conservation efforts.
Cloning Can Bring Back Extinct Species
That’s right, even if the species is extinct there’s the possibility that we can use cloning to bring them back.
And no, we’re not talking ferrets that haven’t been spotted for thirty years, we’re talking about the long-extinct animals that nobody is expecting to see anytime soon.
So how do you resurrect a species? Two ways are available to us so far. Let’s talk about the newest one first.
As with stem cell research, that’s a whole different topic that would need its own guide.
CRISPR is being used by Ben Novak and the team at Revive & Restore, the guys who led the effort to clone Elizabeth Ann, so these guys have credentials. This time, they’re targeting passenger pigeons.
There’s a lot of reasons why passenger pigeons are important, here’s a primer. The point is that this team isn’t using reproductive cloning. Instead, they are using CRISPR for a find-and-replace method. This means taking similar pigeon genes and altering them, through selective breeding, until they are as close to passenger pigeons as possible.
The next method is the old and unreliable reproductive cloning. But how do we get the genetic information from extinct animals? A lot of the things we’ve covered in this guide have already resembled the plot of Jurassic Park, but we can do you one better.
The best hope for getting a hold of usable genetic information for cloning a perfect replication of an extinct species would be the discovery of a frozen and mummified body. That would be our ideal mosquito-in-amber situation here.
If that sounds a little far-fetched for you, it’s already happened! Yuka was the best-preserved carcass of a woolly mammoth that had been found as of the writing of this guide, having been unearthed in 2010 and turned over to scientific experts in 2012.
Ice Age Park isn’t a thing yet, so what happened? While the body was invaluable for carbon dating and physiological research into mammoths, progress on the cloning front has been slow. It hasn’t halted, however, and a major breakthrough was made in 2019.
Following from the example set from passenger pigeons and Yuka the woolly mammoth, and the methods that are being used, the possibility that we see the partial return of extinct species is an exciting prospect for mankind.
It Is Also Possible To Clone Your Pet
Perhaps the most personal stake in cloning technology for a lot of us, it’s possible to have your pet cloned with the cloning technology that exists right now.
Before you get too excited, there are a few caveats:
- They may not look exactly like the original animal.
- They will not act like the original animal.
- It is very expensive.
Barbra Streisand famously made headlines for cloning her pet dog Sammie twice, and that set her back $50,000, not that she can’t afford it.
As a side note – yes, cloning her dog is exactly the kind of zany celebrity behavior that we’d expect from a superstar like Barbra Streisand, but there may have been a good reason.
While it was motivated by personal grief, Streisand did mention that the species is rare. This is true. The charming little Coton de Tulear dog breed may have originated from a shipwreck off the Madagascan coast, where they swam ashore and integrated, breeding with another dog breed and creating the unique Cotons that exist today.
Anyway, shipwrecked dogs aside, the look and behavior of a pet animal can often be tied to its environment. Depending on the species, a dog or a cat can have a different coat just from a genetic roll of the dice, even if all other genetic information present is identical.
It’ll also be notoriously difficult to replicate the upbringing of your clones so that they feel like the genuine article. Maybe this will change going into the future but for now, it seems that cloned pets just amount to very, very expensive replacements, where an adopted puppy or kitten would have the same effect.
With that, we have come to the end of our guide on cloning. We hope you’ve learned a lot from this guide without it being too much of a chore to get educated on this fascinating topic. Cloning methods, and gene editing in general, are going to become one of the most significant scientific advancements in the next century if the field continues at its current rate.
So, what have we learned? Not only have we gone through the definition of cloning and how each type of cloning happens, in both nature and the laboratories, but we’ve covered several of the animals whose names will be remembered by history books forever.
From Dolly and Cumulina to Elizabeth Ann and Yuka, following the stories of these animals is a fun, beginner-friendly way to track the advancement of cloning technology over the years. To make sure that you’ve got everything, check back with the contents at the top of this guide and see if you can answer the questions there.
Maybe you scan-read one section or struggled to understand something that will make sense on the second reading, in which case we’d advise you to brush up your knowledge by reading that section again and consulting any linked materials to get a better idea of the concepts being explained.