All Cracked Up Over Dinosaur Genes
It had to occur at some point. Just the possibility of accomplishing a Jurassic Park-style resurrection of dinosaurs from DNA fragments was too tempting. And, sure enough, that is the direction some scientists are heading. But they are not using DNA trapped in pieces of amber. No, these scientists plan on bringing dinosaurs back through ordinary bird eggs. That’s right, bird eggs! Can’t you just picture an old mother hen roosting on a clutch of eggs, only to look down and see scale-covered dinosaurs emerge? But don’t fret too much; the techniques and knowledge needed to make this scenario a reality don’t even exist yet. This is just the latest attempt to perpetuate the dinosaurs-to-birds theory.
“Bring out the T. rex in your chicken and the ape in your aunt. The past is coming back to life with a roar as we discover the power of evolution’s sleeping genes,” speculates Philip Cohen (2001, p. 31). That’s a truly bold statement, considering we do not yet possess the knowledge or techniques to begin working on such a project. The idea sounds relatively easy—take bird DNA, tweak the genes in order to allow evolution to “work in reverse,” and the result, according to Cohen, is the blueprints for dinosaurs. However, this idea makes some extraordinary assumptions. First and foremost, it assumes birds did evolve from dinosaurs. However, as we have pointed out before, the evidence for this simply does not exist (see Harrub and Thompson, 2001a and 2001b). Second, this scenario assumes that scientists will be able to magically get evolution to work in reverse. Yet experience and time already have demonstrated that researchers are unable to artificially make things “evolve forward” in the lab, much less go in reverse!
The cover of the July 21, 2001 issue of New Scientist has an eye-catching picture of six plastic dinosaurs crawling out of six broken chicken eggs. This picture is positioned just below a cover banner that reads: “Rewinding Evolution—How to Turn a Chicken into a Dinosaur.” The author of this paper describes two hot new fields that he believes will make it possible to go from chickens to dinosaurs: the evolution of development (what they now term evo-devo), and comparative genomics. However, both of these fields are far from building a roaring dinosaur from pieces of chicken DNA. Human chromosomes range in length from 50 million to 263 million bases. With few exceptions (e.g., red blood cells), each of the trillions of cells in the human body contains a complete set of chromosomes—known as the genome. If all the bases in the human genome were spread out 1 millimeter apart, they would extend from Memphis to Los Angeles. Each single human cell contains over 30,625 genes hidden amongst our 22 pairs of chromosomes (excluding the X and Y sex chromosomes). Of the 30,625 genes identified thus far, all are located on material smaller than a grain of salt—and yet, according to Cohen, researchers intend to “reach in there” and rewind evolution (2001). This will be no easy task, because while humans possess 46 chromosomes, chickens possess almost twice that number (78), which will only make their task that much more difficult.
The author makes genetic manipulation appear as easy as walking into a room and turning on a light switch, when, in reality, this could not be farther from the truth. We are just now finishing up the massive human genome project that was carried out to map the genetic material in human chromosomes (see Thompson, 2000a; 2000b). However we still do not know what all of these genes do yet. It’s one thing to map out the base pairs that compose all of our genes, but it is quite another to know the function and regulatory switches of each of those 30,625 genes. Combine that with the fact that many genes have multiple functions and occasionally require signaling from neighboring genes, and you can see very quickly that mapping the human genome was only a small part of the overall big picture.
Additionally, we do not currently possess the ability to just “jump in” and cut genes in any fashion that we want—hoping to somehow rewind the genes. Through genetic engineering, we have gained the ability to break DNA chains using restriction enzymes, but even this technology is limited as to where the cuts actually take place. Now comes the additional problem of not having the genome of birds mapped. Then, add to that the insurmountable problem of not knowing the dinosaurs’ genomes. Oftentimes, the DNA segments that make up our genes are composed of areas referred to as “junk” DNA, which is supposed to indicate that they lack any apparent function. However, researchers have found that many of these areas regulate genes and thus, the genes’ on and off switches, if you will, are located in these “junk” regions. Currently, biologists have a hard enough time finding these regions, let alone deciphering their effects. Plus, this information comes from experiments utilizing living animals that can be manipulated in an effort to record specific changes. Constructing the regulatory region of extinct dinosaur genes will be a gargantuan task, especially given the fact that many genes have more than one function. The author even admitted that the task will be “much tougher finding all the various sequences that turn them on and off at the right times and places in the developing sequences” (p. 32). Genetic engineers currently do not possess the ability to microscopically correct genetic diseases in humans, and yet these same individuals are proposing to make dinosaurs from bird DNA?!
While this article contained some interesting pictures of chicken-dinosaur hybrids, and a great deal of speculation, data from scientific observations were obviously lacking. The author stated that “most of the genes that build a chicken would be interchangeable with those found in a dinosaur” (p. 32). But which bird DNA would researchers use? Pelican, or canary? Toucan, or ostrich? And from the DNA they selected, what type of dinosaur would be possible? Does canary DNA most closely resemble Triceratops, while ostrich DNA matches Tyrannosaurus rex? And what will these individuals do in order to assure themselves of the two different sexes needed for reproduction. Also, while we do have fossilized dinosaurs eggs to use as models for size, we still lack the knowledge of the conditions in which such eggs should be incubated. It appears to me that, from the available evidence, the idea of “rewinding evolution” to produce dinosaurs from bird DNA is not quite all it’s cracked up to be!
Cohen, Philip, (2001), “Monsters in our Midst,” New Scientist, 171:30-33, July 21.
Harrub, Brad and Bert Thompson (2001a), “Archaeopteryx, Archaeoraptor, and The ‘Dinosaur-to-Birds’ Theory—[Part I],” Reason & Revelation, 21:25-32, April.
Harrub, Brad and Bert Thompson (2001b), “Archaeopteryx, Archaeoraptor, and The ‘Dinosaur-to-Birds’ Theory—[Part II],” Reason & Revelation, 21:33-40, May.
Thompson, Bert (2000a),“Cracking the Code—The Human Genome Project in Perspective [Part I],” Reason & Revelation, 20:57-64, August.
Thompson, Bert (2000b), “Cracking the Code—The Human Genome Project in Perspective [Part II],” Reason & Revelation, 20:65-72, September.