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To get us thinking about creating new life forms, we tag along with a group of kids on a visit to the American Museum of Natural History exhibit on Mythic Creatures. Curator Laurel Kendall tells us that even figments of the human imagination deserve to be a part of natural history. But what do we mean when we say something is "natural?" Sometimes nature does things that might seem unnatural, at least at first glance. Karen Keegan and her doctor Lynne Uhl tell reporter Soren Wheeler a story of disputed motherhood that might throw your idea of natural for a loop. (Hint: Karen is more than one person, kind of.) Then we enter the world of bioengineering with scientist Lee Silver from Princeton University. Silver tells us about a strange creature created by scientists back in the 80s, called a "geep." And then he tells us about a very disturbing real-life incident that playwright Jeremy Kareken, in collaboration with Dr. Silver, turned into a play about the implications of combining humans and other animals.


Karen Keegan, Laurel Kendall, Lee Silver and Lynne Uhl

Produced by:

Soren Wheeler

Comments [30]

Bonnie Raymond from Maine

A human x chimp is NOT a chimera. It is a hybrid!!!

Mar. 05 2016 03:25 PM
Daniel Pryke from Minneapolis

The chimera was extremely interesting. Would it be that being a chimera would provide steps forward in evolution because of a greater variety of DNA, or would there be no extra variation to provide steps forward? How would a couple of chimeras' baby look? And is it partly a genetic thing to become a chimera, or is it purely chance?

Nov. 19 2015 09:08 AM
Lola CHamberlain

I get a knee jerk bad reaction to the human/chimp hybrid but it's really tough to explain why. I think that many people have the same reaction, and that it's super important to not just go off a gut instinct but really examine the causes of a fear. I'm sure that the benefits of researching things like this far outplay the risks.

Nov. 18 2015 10:52 PM
jamie from United States

"If you believe in evolution"


Hahha. Like saying, 'if you believe in change.'

You have several episodes that prove evolution. Silly that you would add that "if."

It's as silly as if you said, "if you believe the earth is round."

Catering to a religious audience?

-Jame (BA in Anthropology, MA in Education)

Dec. 08 2014 02:58 AM

Chimera Show: V. interesting. If the twin embryos had been male and female would the result have been a hermaphrodite?

Sep. 25 2013 07:22 PM
Peggy from Raleigh, NC

I could not have been more disappointed! This was the first time that I had ever heard of this program. I had to turn it off when my children were correcting the incorrect information being presented. If these folks got the simple information that is readily available wrong, I have to feel the rest of there information would also be suspect.

Oct. 11 2012 06:41 PM
John A

Morality? What's that? But seriously. People need to be looking out for a bio meltdown - that is, when a human created genome becomes more able to consume the planet than what has so carefully come to balance out over the centuries.

Oct. 06 2012 01:03 PM
Monique Russ

Please send me a transcript of this radio lab.

Nov. 12 2011 10:08 PM

I'm not sure I believe that a Princeton senior thought she would try and carry a chimp / human, or that she would think she could get that past the IRB or IACUC. Just creating the embryo would be a pretty good project.

Nov. 06 2011 08:35 AM
Mister Bear from Orange County, CA

This episode aired on KPCC on November 5, 2011.

The narrator said something to the effect that if one believes in evolution, one believes that humans evolved from chimpanzees. This is not what people that believe in evolution believe. Instead, it sounds more like what (some) people that don't believe in evolution believe that people-that-believe-in-evolution believe in. The audio from the scientist immediately afterwards states what people that believe in evolution really believe: that humans and chimpanzees had a common ancestor not very long ago.

Nov. 05 2011 07:11 PM
sean Nolan from Pittsburgh-Greensburg, PA

Yes, I loved the chimera show also, and it was just aired here in Pittsburgh area two nights ago, Feb 1 2011 I believe. I heard it in my car following a massage. I wanted to know more about the young bio-tech start-up CEO one of you spoke to who I think was based in New Haven if I recall correctly. Thanks if you have any help.

Feb. 03 2011 07:36 AM
Daniel Martin from Reno, NV

Marc Naimar had a good point, and it's why i hopped on here. The way it was worded in the program, it makes evolution sound like it's ridiculous. It's not a matter of "if you believe" in evolution, we evolved from chimps-- it's like saying we evolved "from" tigers and into humans, while they just stayed the same. Just as humans and chimps have a common ancestor, so do humans and tigers, or humans and whales, or humans and snakes if you just go back far enough down the evolutionary tree.

Jan. 22 2010 08:07 PM
Irvin Eisenberg from Montpelier, VT

I am a massage therapist and have become interested in tissue differentiation. I was wondering more about Chimerism. At what point do the two organisms form to become one and how are areas divided. Do whole organ systems have one set of DNA, or different tissue types have different DNA, or is it more on the lines of ectomorphic tissue is one DNA while endomorphic and Mesomorphic are another? Is there any place I can read more about Chimerism?


Dec. 30 2009 10:07 PM
Robert Kieronski from Newport, RI

Aaaa !

On 12/24/09 I heard "So-called Life" on WGBH. It was an outstanding program !!

It turns out that I will shortly be completing development of one of those hypothetical genetic "games" mentioned in the program. Completion is scheduled for around the end of January, so I was very excited to hear your show.

Stay tuned.


Dec. 24 2009 01:22 PM
Jeremy Kareken from Sunnyside, Queens

In re the chimp/human comments:
Absolutely correct about "common ancestor," not a human coming from a chimp. People seem to have a hard time talking about time when it comes to evolution. There was quite possibly a time where there were species between what we call a chimp and what we call a human today. Or, something that looked like neither.

And careful: we're not talking about a chimera human/chimp, but a hybrid human/chimp - the product of a mating of a human and a chimp. A chimera human with chimp cells or organs would still act like a human. And vice versa. 23 Chromosomes from the human, 24 from the chimp (because chimps have 48), or 23, if they could induce a turner-syndrome like dropping of the sex chromosome.

Apr. 26 2008 10:30 AM

I would like to second the request for geep pictures!

Apr. 23 2008 04:38 PM
Soren Wheeler

Marc and Jennifer (and all),

You are quite right. Unfortunate that I let this slip by. Lee Silver did try to correct Robert by noting that humans developed slowly over millions of years from a chimp-like ancestor, and at each step along the way the offsrping were similar to their parents ... but we cut him a bit short and Robert's comment was still off the mark.

Thanks for catching this and keeping us on our toes.

Marc, Re: Silver's talk with his students, I don't think he was actually asking them to predict the characteristics, just prompting them to think about the myriad possibilities and the consequences of those possibilities.

Thanks again, and sorry we slipped up on this one.


Apr. 18 2008 10:45 AM
Marc Naimark from Paris, France

Ooops. I missed Jennifer's comment saying the same thing as my 4:15 post. At least I'm not alone in finding this bit wrong.

Apr. 18 2008 04:21 AM
Marc Naimark from Paris, France

And about Lee Silver's comments: he said that he discussed with his students a possible human-chimp chimera, and which characteristics of the chimera would come from the human and which from the chimp. But in the earlier section on the geeps, it was clear that there is absolutely no way of predicting the characteristics of the chimera, and that each one was different, based on the development of the embryonic cells coming from either the sheep or the goat. Can you explain this apparent discrepancy?

Apr. 18 2008 04:20 AM
Marc Naimark from Paris, France

I love Radiolab, and regret that so few episodes can be produced each season. But this segment included a statement by Robert K. that was, as far as I know, totally unscientific, and even dangerous.

It concerned the discussion of creating a human-chimp chimera (at pproximately minute 16). Robert said that "if you believe in evolution, you believe that chimps eventually became humans. And so somewhere in history, there's someone who was 10% chimp and 90% human...".

This idea that evolution claims that humans descend from apes is one of the fallacies used by creationists in their attacks on Darwinism. I "believe" in evolution, and according to what I've been taught, humans and apes descend from a common ancestor; one does not descend from the other. That's a very big difference. Human evolution is not about becoming less ape-like, it's about becoming more human, just a chimp evolution is about becoming more chimp-like.

We need a correction!!!!!!

Apr. 18 2008 04:15 AM
Jennifer from Washington

Thank you for an interesting show. As a science teacher, I have a couple picky comments on one statement, from the human/chimp chimera discussion:

"Well there once was a creature like that, because if you believe in evolution you believe that chimps eventually became humans"

One big misconception about evolution is it claims that "humans evolved from monkeys." Humans and chimpanzees are genetically similar because they share a common ancestor. (PBS has a good evolution site with more info on this distinction:

I'm also leery of the phrase "believe in evolution." Evolution is a scientifically testable and supported theory, in contrast to faith-based fields of thinking that require belief. As with every other field of science, the study of evolution is not about belief. It is about evidence.

Perhaps these seem like small distinctions, but I hate to see a science show perpetuating misinformation about such an unnecessarily divisive issue.

Apr. 13 2008 11:01 PM

Great Show! I always look forward to the new episodes. I am a little confused about the link to the jewelry website.... Is that a mistake? Just curious - I wanted to see who was selling Pegasus wings.....
Snacky O

Apr. 11 2008 07:22 PM
pffft from Seattle

Another great Radio Lab episode. Keep up the good work. Radio Lab is up there with This American Life as one of my top shows.

The Karen Keegan segment was especially good and quite moving.

Apr. 10 2008 01:31 PM
Soren Wheeler

Unfortunately, there's a little time lag between the show going on the radio and being available on the website or through podcast. But it will be up in the next couple weeks and we'll post a blog when it's ready.
Sorry for the wait.

Mar. 24 2008 11:49 AM

I'd love to listen to this show, but I can't find the audio link anywhere, even though the show was a week ago. Could someone post it, or be so kind as to tell me how to find it? (Apologies in advance if it is obvious and I am somehow missing it.)

Mar. 23 2008 12:35 AM
James The Giant Peach from Park Slope

where can we see pictures of the Geep?

Mar. 14 2008 03:44 PM
Jeremy Kareken from New York

TGAlison: It's not likely but certainly possible. Chimerism includes a number of specific intersexual conditions and a simple DNA test will check. I'm curious: what parts do you think are those of your never-born fraternal sister? Or brother?

TG is even less specific than "chimerism," because it's not a medical diagnosis, but a social rubric, and rather a broad one at that. There are all sorts of medical conditions that can encourage gender identity issues - adrenal hyperplasia, androgen sensitivity, hermaphoditism. And there are people who just like to play dress-up who call themselves TG.

Now hermaphroditism can be a symptom of chimerism, but you can be certain through DNA testing. One generally sees skin abnormalities in cases of chimerism. They follow what are called "Blaschko's Lines." And certainly other intersexual components occur, like testes in some women, ovaries in men, or ovotestes, and the like...

Mar. 08 2008 02:38 PM
Alison from Minnesota

I'm transgendered. I wonder if anyone has explored the idea that perhaps transgendered people could be chimeras. Could I actually have the DNA of both a man and a woman in me? Has anyone heard of research into this?

Mar. 06 2008 04:05 PM
Soren Wheeler

The doctors did compare the son's DNA to Karen's mother and two brother, though unfortunately Karen's father had passed away by that time. And they did find that the sons were related to her larger family. To my knowledge, they never compared Karen's second set of DNA to the family, I believe beceause they felt the twin explanation was pretty clear and they didn't want to keep poking and prodding Karen.

Mar. 06 2008 10:34 AM
Scott McVicker from Half Moon Bay, California

Re: Karen Keegan. Two tests I would have liked to see - A comparison between Karen's two DNA samples with that of her parents, and the same test of her children relative to their grandparents.

Feb. 26 2008 01:44 PM

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