Here is a metaphorical query for everyone — Wall Street traders, venture capitalists, writers, politicians, farmers, mechanics, and editors. Are you a T. rex or a chicken?
Turns out we may be a bit of both — as I discovered during a recent trip to Bozeman, Montana, where I had come to find out if I share a genetic sequence with a tyrannosaurus rex that died 68 million years ago in Hell Creek, an isolated spot near the Canadian border.
In the basement of Bozeman's Museum of the Rockies, I'm running my fingertips over a stump of the T. rex's cool, hard femur bone, or what's left after scientists sliced up and pulverized most of it in search of microspecks of soft tissue that should have decayed eons ago.
Instead, paleontologists discovered fragments of a protein with apparent similarity to Type I collagen, a building block of both skin and bone. In bone, it both holds the bone together and keeps it flexible. In human skin, collagen is the single largest component (after water). Collagen is found in most creatures with bones — including humans.
In a basement lab at the museum, dinosaur hunter Jack Horner is showing me the truncated femur. All around him teams of paleontologists study heaps of bones using everything from tiny brushes and magnifying glasses to C.T. scanners and an electron microscope.
Horner is the real-life scientist on which Michael Crichton based the central character in his novel Jurassic Park. Horner also advised Steven Spielberg on the Jurassic Park films.
He disagrees, however, with the central scientific conceit of both book and movie: that dinosaurs could be reborn using dinosaur DNA in the bellies of Jurassic-era mosquitoes that had bitten dinosaurs and then been trapped in amber. "It's unlikely that could happen," he says.
But Horner — a genial man whose unruly gray beard makes him more of a rustic Santa Claus than an Indiana Jones — says it could be possible to re-create dinosaurs another way. So anyone out there with an interest in starting a theme park with real dinosaurs and potentially raking in the cash, listen up!
As Horner explains, dinosaurs are still with us. They're now called birds. As pretty much any nine-year-old fascinated with terrible lizards can also tell you, many dinosaurs shared bone structures and other features — including, on some species, feathers — with modern avians. This strongly suggests that dinosaurs, including the ferocious T. rex, evolved into birds.
The short protein fragments recovered from the T. rex bone found in Hell Creek confirms this, matching most closely to chicken collagen. (This analysis was organized by a former student of Horner's, Mary Schweitzer of North Carolina State University, and was written up in Science magazine last year.
In fact, Horner will tell you that chickens retain dormant sequences of DNA that would, if activated by bioengineering, cause a chicken to grow teeth and a dino-tail, and to grow little T. rex arms instead of wings.
This has led the whimsical Horner to propose that a real Jurassic Park (are you entrepreneurs listening?) might feature a "chickenosaurus" as an attraction.
This might not equal the punch of a real T. rex running amok and eating lawyers and threatening children, or packs of viciously intelligent velociraptors scrambling between the legs of majestic brontosauruses, but those sharp little chicken teeth might hurt like heck if they grabbed onto a finger.
Actual T. rex DNA did not survive the eons, though since DNA is what provides the instructions for making proteins, scientists can make educated suppositions of what the DNA sequence might have looked like.
My own investigation into my inner T. rex/chicken is an offshoot of the book I'm writing, Experimental Man: The Ultimate High-Tech Exam, in which I'm having scientists run extensive tests on my genes (and other parts of my body).
It is a writer-as-guinea-pig effort that allows me a personal perspective from which to describe and assess the latest science and technologies that are striving to tell us more about our health and our bodies past, present, and future.
Horner and others are helping me tell the story of evolution contained in our genes. Certain genes and other DNA sequences have been passed down to humans and other modern organisms from the age of the dinosaurs, and beyond.
As part of my "exam" into genes inside us, I asked molecular biologist Nathaniel David to compare the T. rex protein fragments to the human Type I collagen protein. David is chief science officer of Kythera Biopharmaceuticals, a Los Angeles biotech company developing drugs based on, among other things, manipulating collagen.
David was disappointed by the smallness of the fragments but was impressed by their similarity to human sequences in collagen.
"The recovered dinosaur-protein fragments were short (less than 20 amino acids in length) while the human-collagen protein is over 1,000 amino acids in length," he wrote in an email. Amino acids are what proteins are made of. "But those we had were either perfect matches or different at only one amino acid position."
Below is a comparison of one of the 68-million-year-old T. rex fragments to the human collagen sequence; each letter below represents an amino acid:
The only difference is a single amino acid, T (bolded), meaning that the T. rex-derived fragment contained a threonine amino acid at that position, while humans have a proline.
However, as David said, these 18 amino acids tell an incomplete story about the evolutionary similarity of human and T. rex Type I collagen, a protein over 1,000 amino acids in length in humans, and in chickens — and presumably in T-rexes.
"We would need more of the protein to compare to the human to see how this protein has changed in evolution," said David, "or even better, the DNA. But DNA just isn't chemically stable enough for a Jurassic Park-style comparison."
The next step in my dino-quest is to compare this mini-stretch of T. rex protein — and its possible genetic code — to my own collagen protein. This may differ from the reference human protein used by David, which is posted online.
I already know that, like most humans, I share 60 percent of my genes with the modern version of a T. rex — a chicken. I'll soon be finding out how I personally came out on the T. rex-and-chicken question.