Fun with pig clones

Every porker is different, even if it shares the same genes with a litter of siblings. So forget about ordering a copy of your favorite faithful companion.

Published January 9, 2003 8:30PM (EST)

In the early weeks of 2003, apparitions of Raelian-cloned babies have haunted headlines.

But the Raelian cult, whose members believe that the human race is descended from aliens, has failed to offer any proof that it has in fact bred the first human clone.

Until the cult comes up with some proof, nine red pigs in Texas have more to teach us about cloning than all the Raelian press conferences combined.

In an article forthcoming in the scientific journal Applied Animal Behaviour Science, Greg Archer, a graduate student in the animal science department at Texas A&M University, and Ted Friend, a professor there, detail the results of their behavioral study on the cloned pigs, born in two different litters.

Although all the pigs were cloned from the same fetal pig's cells, studies found that the pigs have distinct personalities, much like any other litter. The finding goes against the sci-fi conceit that cloned droids would not only look alike, but behave like carbon copies of each other.

Ted Friend, Ph.D., an expert in animal behavior, spoke with Salon by phone from his office in College Station, Texas.

What was the purpose of your cloned pig experiment?

It was to look at the variation among cloned animals to see how similar they are to each other from a behavioral standpoint. The issue was: Do they have individual personalities or not? Do they act like little Homer Simpsons?

Homer Simpsons? What do you mean?

I just saw the episode of "The Simpsons" where Homer got himself cloned about 30 million times.

And all the Homers were identical?

Yes, of course, and they all had a craving for jelly doughnuts. That's how they got rid of all the clones that were running over Springfield. They took a bunch of jelly doughnuts and tied them on the bottom of a helicopter and flew out over a cliff, and all the clones ran off the cliff looking for the doughnuts.

[But] most people in biology would suspect that they're not going to be identical at all.


Environmental influences. When you clone, you're starting off with a very young animal. So, it won't have the experiences that an adult had.

It won't have the formative jelly-doughnut experience?


Plus, there may be other things going on in the genetics. Scientists working in cloning call this the "epigenetic effect." When some of these genes are expressed, there's a lot of variation.

Even amid clones of the same organism, their genes are going to be expressed differently?

They might be. Right. Everything that we see from these pigs says yes.

How did you study the cloned pigs?

We looked at their behavior. We ran a bunch of tests used to assess temperament in animals. One series tested how they respond to restraint.

People do something like this very often when they're at a shelter adopting a dog, and they want to get a guess what the dog is like. They hold the animal on its back, and see if it struggles a lot. We did that with these pigs. Also, hold them down. Pick them up to see how many times they'd fight or argue or oink. Measure that.

Also, putting a blanket on their heads, which is a standard one. Put a blanket over a dog's head, and see if takes it off right away or if it sort of stands there. There was a lot of variation within a litter of cloned pigs. One pig would shake the blanket off immediately, and do that repeatedly. And another pig would just sort of sit there with the blanket on its head.

So, one pig was feisty, and one was complacent?

There were very different personalities in all the pigs, which is typical of pigs. One liked to play with people, and one didn't. One clone really liked to play with my 11-year-old son, just romp all over the pasture with him, and chase him like a little dog would. And the other pigs didn't want anything to do with him.

We did other trials, too -- food preference. That showed a lot of variation. Some would eat one particular type of food that some others wouldn't want anything to do with, and it was all fairly similar to what you'd see in a typical population of pigs.

So, even though they are genetically identical they behave as if they were just litter mates?


So, this suggests that the hope that people have that if their dog dies, and then they have it cloned, it's going to be their same dog, is just a fantasy.

There's no basis for that all. If I clone Elvis, will he come back and sing? Probably not. He probably won't even have Elvis' hips.

How did you structure the study?

It was run with two litters, one litter of five, and one litter of four cloned pigs. These were durocs, which is a red breed of pig.

All the pigs were genetically identical. They were all from the same cell, originally. They were born in the fall of 2001.

Why did you decide to clone durocs in particular?

The surrogate mothers who would carry them are white pigs. If the white sow had anything that was red, you'd know it was a clone. You couldn't possibly get it mixed up with something else.

Why did you need two different litters? You wanted more pigs?

A litter offers you a very useful kind of comparison, because you have multiple clones from the same animal. If someone was cloning sheep, you'd usually have one clone from each ewe, from each mother, and that meant you'd have five different mothers.

And then you get into the issue of how much effect does the mother have, whether the mother is flighty or nuts. The environment not only includes after the animal is born, but also the environment in utero when the embryo is developing, and the factors when the embryo is developing can have a profound effect on their behavior as well, as adults or on their personalities later on. Because neural circuits and hormonal patternings are being established as an embryo.

What do you think that the implications of this are for the nature vs. nurture debate? Doesn't it imply that a lot of personality is environmental?

Well, environmental, but there's more than just what the animal experiences. A lot of this is epigenetics, which is different things influencing how these genes are expressed. There's very little known about it at this time.

It's not so much necessarily environment. I think a lot of the individual pig's personality is set when he's born, like a lot of people. Certainly environment influences it, but if you're going to be aggressive or outgoing or whatever, a lot of that is kind of set.

Can you say more about this issue of the same genes being expressed differently?

There is a lot of variation, things going on that we don't know about. How they're replicated can make a difference, and there are some manipulations going on in the genes, while they're doing the transfer. We see some things that imply that there's normal variation in the genes as they're replicated.

It's different from identical twins. It's a very different situation than when you're dealing with identical twins.

How so?

Well, with identical twins you're splitting an embryo, you have one original embryo, and it's sort of split into two. And here you're dealing with individual embryos, each one separate at the initial stage of replication.

There's another issue, too, if you're trying to clone your dog. When you talk about identical twins, you have two people who look the same and behave fairly similarly, well, those two people grew up together, too. And they developed from a young cell vs. an old cell, and in cloning, if you're trying to clone your dog, then you'd be using old cells or mature cells.

Oh, I see. The identical twins grew up together, whereas the clone of your dog didn't grow up in the same environment as your dog.

They may have a different mother, but still there's a lot of manipulations done to the genes, and that can influence how they're expressed. But this is something that everyone is just looking into now, so there's very little known about it at this point.

What are the cloned pigs doing now? Are you still studying them?

Not much. Most of them farrowed. They were all females. They've been re-bred. They've had babies of their own.

Have the pigs had any health problems? You know, people often talk about how Dolly, the sheep, and other cloned animals have health problems.

Well, she was an old cell, and we're dealing with young cells, since these pigs were cloned from fetal cells. Fetal cells are usually easier to work with and you usually have fewer problems than if you're dealing with adult cells from the mature animal.

Because you've taken the old cell, and you're trying to "reprogram" it, is the term, to get it start growing as a baby again. That's difficult.

Like in the case of somebody trying to clone their pet.

Right. And that's where you get a lot more problems. When you're dealing with a fetal cell already, that's programmed to say: "Hey, I'm a baby. Let's grow." You have fewer problems, usually no problems. Our cloned pigs have had no problems that I'm aware of that we've ever seen that's different from normal pigs.

What did you make of the Raelians' announcement that they'd cloned a human?

As a researcher, I guess I'd have to say that I don't know. They gave no evidence, no nothing. It's just one person up there. Maybe it's a shame the press and the media made as much out of as they did without more information.

Why are you laughing?

Oh, let's not go there.

By Katharine Mieszkowski

Katharine Mieszkowski is a senior writer for Salon.

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