I’ve been reading a new book by Jack Horner and James Gorman, How to Build a Dinosaur: Extinction Doesn’t Have to Be Forever(amzn/b&n/abe/pwll), and I was pleasantly surprised. It’s a book that gives a taste of the joys of geology and paleontology, talks at some length about a recent scientific controversy, acknowledges the importance of evo-devo, and will easily tap into the vast mad scientist market.
It is a little scattered, in that it seems to be the loosely assembled concatenation of a couple of books, but that’s part of the appeal; read the chapters like you would a collection of short stories, and you’ll get into the groove.
The first part is about Horner’s life in Montana, the Hell Creek formation, and dinosaur collecting. Hand this to any kid and get him hooked on paleontology for life; I recall reading every book I could get my hands on that talked about Roy Chapman Andrews as a young’un, and it permanently twisted me…in a good way. This will have the same effect, and many people will think about heading out to Garfield County for a little dusty adventure. I know I am — all that stands in my way is South Dakota.
A good chunk of the book is about molecules and how they show the relatedness of dinosaurs to birds, and to the work of Horner’s former student, Mary Schweitzer, who discovered soft tissue in T. rex bones. Horner presents a good overview of the subject, but is also appropriately cautious. You’ll get a good feel for the difficulty of finding this material, and for interpreting it; he clearly believes that these are scraps of real T. rex tissue, but how intact it is, what kinds of changes have occurred in it, and how much information will be extractable from these rare bits of preserved collagen (or whatever) is left an open question.
Finally, the subject of the title…Horner was an advisor to the Jurassic Park movies, and right away he dismisses the idea of extracting 65 million year old DNA in enough quantity to reconstitute a dinosaur as clearly nothing but a fantasy. That’s simply not how it can be done. But he does have a grand, long-term plan for recreating a dinosaur.
What is it? Why, it’s developmental biology, of course. Development is the answer to everything.
Here’s his vision, and I found it believable and captivating: start with a modern dinosaur, a chicken, figure out the developmental pathways that make it different from an ancient dinosaur, and tweak them back to the ancestral condition. For instance, birds have lost the long bony tail of their ancestors, reducing it to a little stump called a pygostyle. In the embryo, they start to make a long tail, but then developmental switches put a kink in it and reduce it to a stub. If we could only figure out what specific molecules are signaling the tissue to take this modern reducing path and switch them off, then maybe we could produce a generation of chickens with the long noble tails of a velociraptor.
My first thought was skepticism — it can’t be that easy. There may be a simple network of genes that regulate this one early decision to form a pygostyle from a tail, but there have been tens of millions of years of adaptation by other genes to the modern condition; we’re dealing with a large network of interlinked genes here, and unraveling one step in development doesn’t mean that subsequent steps are still competent to respond in the ancient pattern. But then, thinking about it a little more, one of the properties of the genome is its plasticity and ability to respond in a coherent, integrated way to changes in one part of a gene network. That capacity might mean you could reconstitute a tail.
And then, once you’ve got a tailed chicken, you could work on adding teeth to the jaws. And foreclaws. And while you’re at it, find the little genomic slider that controls body size, and turn it up to 11. What he’s proposing is a step-by-step analysis of chicken-vs.-dinosaur decisions in the developmental pathways, and inserting intentional atavisms into them. This is all incredibly ambitious, and it might not work…but the only way to find out is try. I like that in a scientist. Turning a chicken into a T. rex is a true Mad Scientist project, and one that I must applaud.
One reservation I have about this section of the book is that too much time is spent dwelling over ethical concerns. Need I mention that real Mad Scientists do not fret over the footling trivia of the Institutional Review Board? These are chicken embryos, animals that your average member of the taxpaying public finds so inconsequential that they will pay to have them homogenized into spongy-textured slabs of yellow protein to be slapped onto their McMuffin. Please, people, get some perspective.
As for respecting the chickens themselves, what can be grander and more respectful than this project? I would whisper to my chickens, “With these experiments, I will take your children’s children’s children, and give them great ripping claws like scythes, and razor-sharp serrate fangs like daggers, and I will turn them into multi-story towers of muscle and bone that will be able to trample KFC restaurants as if they were matchboxes.” And their eyes would light up with a feral gleam of primeval ambition, and they would offer me their ovaries willingly. I’d be doing the chickens a favor. Maybe some chicken farmers would have cause to be fearful, but I wouldn’t be working on their embryos, so let them tremble.
Oh, all right. Horner is taking the responsible path and putting some serious thought into the ethics of this kind of experiment, which is the right thing to do. It’s also the kind of project that will generate serious and useful information about developmental networks, even if it fails in its ultimate aim.
But I have a dream, too. Of a day when biotechnology is ubiquitous, and middle-class kids everywhere will have a cheap DNA sequencer and synthesizer in their garages, and a freezer with handy vectors and enzymes for directed insertional mutagenesis. And one day, Mom will come home with a box of fresh guaranteed organic free range chicken eggs, and Junior’s eyes will glitter with a germ of a cunning plan, fed by a little book he found in the library…and 30-foot-tall fanged chickens will triumphantly stride the cul-de-sacs of suburbia, and the roar of the dinosaur will be heard once again.