The brilliant premise of Michael Crichton’s Jurassic Park and its sequel, The Lost World, I believe is so well-known that I needn’t put a spoiler alert here. In these science thriller novels, a dreamy, ambitious industrialist finances the work of molecular biologists who harvest dinosaur DNA from insects that fed on dinosaur blood before getting trapped in tree sap and ultimately fossilized in amber.
The scientists then sequence the DNA, and discover that the genomes are incomplete. They substitute the missing nucleotides with sequences from amphibians (frogs), and use the reconstructed genomes to grow dinosaur embryos, which of course grow up to become the fascinating “villains” of the story.
This scenario raises so many technical questions that I assigned some of my college senior molecular biology students to tackle some of them. Worthy of several Mythbusting Thriller Science posts!
Let’s begin with the dinosaur blood. Of course it’s true that some insects (such as the pesky mosquito) do feed on the blood of animals. During the age of the dinosaurs, there were plenty of insects around (some famously large compared to what we’re used to today). It’s quite likely some of them made a living biting dinosaurs and consuming their blood. But what about the DNA?
A mature human red blood cell, or erythrocyte, has a feature that makes it different from virtually every other cell type in the body: it has no nucleus. The nucleus is a special membrane-bound sac inside a cell where the DNA lives. In erythrocytes, which make up the vast majority of blood cells, there isn’t any genomic DNA. This is true not only of humans, but mammals in general. Reptiles, however, have nucleated red blood cells; so do birds, in case you’re remembering Crichton’s thesis that dinosaurs were ancestors of birds. The blood of these animals is a good source of genomic DNA.
So far, so plausible. But from here it gets dicey…