Most of us have an almost innate fascination with extinct animals. Pick a kid in your life and there's a good chance they'll happily spend an hour telling you all about their favorite dinosaurs. There's something enticing and a little frustrating in the idea that there were once fantastic creatures roaming the earth that disappeared — either due to environmental factors or human interference — before you arrived on the scene.
The notion of reviving extinct species was popularized by Michael Crichton's 1990 novel, and subsequent film adaptation, Jurassic Park. In that apocryphal tale, John Hammond acquires dinosaur DNA from the guts of mosquitoes trapped for millions of years in amber. Using modern species to fill in the genetic gaps, Hammond's scientists revive a number of extinct dinosaur and pterosaur species in an effort to build a theme park.
We all know how well that effort panned out. It's a hallmark of Crichton's work for cutting-edge fictional technologies to clash with human error, ignorance, and hubris to catastrophic ends. Such it is with Jurassic Park.
At the time, the technologies posited in Crichton's novel were complete fantasy. Genetics was still a burgeoning field of biology, just getting its feet on the ground. There were promises of what the field might be able to accomplish in the future with new tools, but none of that had materialized yet.
The Human Genome Project launched the same year as Crichton's novel and was completed in 2003, 13 years later. Since then, technology in the field has improved dramatically, with genome sequencing time frames now being measured in days rather than years.
While our ability to read DNA has improved, so too has our ability to write it. Technologies like CRISPR (as exaggerated in Rampage) have provided laboratory scientists with a way to edit DNA at will. While we still have a long way to go before we're creating animals from scratch, Crichton's ideas are no longer purely in the realm of fiction.
Crichton got a lot right when writing his most popular story. Of course, he took some creative liberties in the name of telling an entertaining tale, but there was some truth in the lie. One of the major challenges in resurrecting an extinct species is the degradation of DNA over time. Soft tissues just don't hold up very well, and hard tissues, like bone, tend to take on minerals and become fossilized. The process doesn't leave a lot to work with outside of structural anatomy.
However, soft tissues were reportedly isolated from a T-rex specimen in the early 2000s. Fragments of a broken rex leg bone were dissolved in an acid that slowly erodes bone but leaves soft tissues behind. Paleontologist Mary Schweitzer isolated blood vessels and what appear to be red blood cells from a 68 million-year-old dinosaur.
After this discovery, other samples dating back to the Jurassic Period were analyzed, and roughly half of them were found to also contain soft tissues. Schweitzer believes she's found an explanation for the unexpected preservation: iron.
According to subsequent research on the specimens, as well as more modern animals, iron in the blood works as a preservative preventing the expected decay of some soft tissues. They've even found preliminary evidence suggesting the existence of preserved DNA in some samples, though that has yet to be confirmed. If any DNA were confirmed to exist, it would likely be incredibly fragmented and incomplete.
There isn't much chance of our acquiring something even close to a complete dinosaur genome from fossils. And Crichton's solution of insects trapped in amber isn't much better. Dr. David Penney, and colleagues, at Manchester University attempted to retrieve genetic samples from insects preserved in copal, a precursor to fully fossilized amber, and came up empty-handed.
They used samples dating to roughly 10,600 years ago and, despite using modern technologies (much improved since the fictional InGen of the '90s), weren't able to locate anything.
"Intuitively, one might imagine that the complete and rapid engulfment in resin, resulting in almost instantaneous demise, might promote the preservation of DNA in a resin-entombed insect," said Dr. Penney, "but this appears not to be the case. So, unfortunately, the Jurassic Park scenario must remain in the realms of fiction."
If DNA retrieval from copal or amber deposits fail after only ten thousand years, the likelihood of gathering anything usable from deposits many millions of years old is even less likely.
But if Schweitzer taught us anything with her dinosaur soft tissues, it's that what's intuitive isn't always the case.
The case for modern mammoths
It may not be likely that we'll be flying off to an island resort to rub tails with prehistoric dinos anytime soon, but that doesn't mean the pursuit of de-extinction is, itself, dead. We just need to set our sights a little closer to home on the biological timescale.
Promising progress has been made in a furrier undertaking. Scientists from several teams on several continents are working toward the resurrection of the woolly mammoth.
Well-preserved mammoth specimens are popping up all the time, preserved in the permafrost of the Russian tundra. Mammoths, most closely related to Asian elephants, went extinct about 4,000 years ago, which makes the probability of obtaining workable DNA much more likely. In fact, the sequencing of the mammoth genome has already been completed, at least to the best of our ability.
The Woolly Mammoth Project hopes to resurrect the species, or at least what they call proxy species. This would be accomplished by modifying an Asian elephant embryo, using CRISPR or similar technology, to give it mammoth traits. Directly cloning an animal using DNA obtained from a frozen individual isn't possible as, even after only 4,000 years, the DNA has suffered some degradation. But breeding an animal functionally similar is, probably, within our grasp.
The scientific community is, however, divided on whether such a project should go forward. Unlike the scientists of InGen, modern researchers heed the call of the fictional Ian Malcolm in asking whether we should.
Some scientists believe resurrecting extinct species would be a detriment to conservation efforts. They fear the ability to bring a species back from the dead would give an excuse to the destruction of habitats and put currently endangered species at increased risk.
These fears haven't stopped the work from going forward. In fact, the first resurrection of an extinct species is already in the books.
The Pyrenean ibex, a subspecies of wild goat, went extinct in 2000. Three years later, scientists used a frozen tissue sample to clone a dead individual. The baby was born successfully but, sadly, died after only seven minutes.
While biology and genetics have experienced incredible breakthroughs since Crichton imagined his theme park nightmare, we've still got a lot of kinks to work out before we can make it a reality. Plenty of time to consider the ethical questions and improve our electric fences in preparation for Pleistocene Park.
The fifth installment in the Jurassic Park franchise, Jurassic World: Fallen Kingdom, hits theaters June 22.