How to Build a Dinosaur, by Jack Horner

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I met Jack Horner a few weeks ago, at Adventures of the Mind, and completely enjoyed my time talking with him. He’s best known as the dino-tech-advisor expert for the Jurassic Park movies, but his day job is as a professor at Montana State University and as head of the Museum of the Rockies — his focus, of course, is paleontology.

I got to hear him talk with a big group of high schoolers — and to get them to think through in a reasoned way how we could tell how social & smart certain dinosaurs were from the fossil record — a line of thinking that he pioneered decades ago, and which ultimately lent credibility to the idea that birds are essentially avian dinosaurs.

The really fun thing when you talk with Dr. Horner, other than the fact that he’s extremely iconoclastic, is that within a couple of minutes, you can tell that he can actually see the dinosaurs in his mind’s eye — that for him, they’re very alive and active. He’d like that to be true for everyone and he’d like to see that vision made more real:

Well, paleontologists may deal with the long dead. But at the heart of all the digging and preparation of skeletons and museum displays is the attempt to reconstruct the past, to re-create moments in the history of life. What we would really love to do, if we could, is bring ’em back alive.

Anyway, the book starts out by explaining some basics of the archaeological timeline, and some specifics about the geography that Horner works in — Montana. It talks about his first finds of giant T. Rex fossils, and then an accidental discovery — once when they had to break a T. Rex femur in order to transport it, they found remnants of blood cells inside the bone — and then they started pulling on the thread.

That led them to the main story in this book, the shift from paleontology as mostly digging & reconstruction to including sophisticated genetic analysis:

It became clear to some of us in paleontology that it was time for a change in the way we did our work. We didn’t need to give up the satisfying summer fieldwork, the digging up of the past, but we did need to add new tools. And we needed to go beyond the dissecting microscope, through which we could see fine details of bone structure. We needed to get down to the level of molecules in fossils—and in living things. By the 1980s molecular biologists were already using differences in genes in living creatures to calculate rates of evolution and to date events in evolution. They had developed a new stream of evidence to compete with or supplement the fossils weathering out of the earth.

That, of course, changes everything. Much of the book is about the parallels between how fetuses develop and how evolution happens — because it’s often genetic markers turning on and off that determine whether things like tails develop.

And the big insight of that type of analysis is that if you can change how embryos develop, you can, in a way, turn back the evolutionary clock — you can do things like grow chickens with teeth (which has been done). Horner wants to do a few more things, including growing a chicken with a tail — because it harkens back to what non-avian dinosaurs must have developed like. He says this:

What I like about the idea of using a chicken that developed into a dinosaur as evidence of the reality of evolution is that it is more than an idea. It is an experimental result. And it calls out for questions. What is it? How did you do it? Is it a circus freak or a trick? What does it mean? Without staking out a position or starting a war of words, the animal would prompt a discussion that would have to end up with the mechanisms of evolution and its footprint in the genes of living animals. Even more than a fossil, it would cry out for explanation.

It’s an amazing idea, and one that we seem to be heading towards. I’ll leave the ethical & scientific discussion to Horner — there’s much of that in the book and you can decide for yourself — and just say that the whole idea is incredible. It seems clear to me that we’ll see this sort of work in our lifetimes, and it will undoubtedly raise a whole raft of new questions. Here’s how Horner ends (which is more of a beginning, really):

That would be the most satisfying lecture I could possible give. I don’t like providing answers. I never have. I like questions. I like asking them, trying to figure out answers, trying to figure out what we are really asking, and what new questions come up. For this event I won’t have to prepare any speech at all. My entire prepared text will consist of one simple question, from which everything else will follow. I’ll walk to the edge of the stage, point to the creature on the leash, look at the audience, and say, “Can anyone here tell me what this is? ”

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