On the computer screen, little pieces of genetic code are being slotted together like a giant jigsaw puzzle. Slowly but surely, the genetic whakapapa of an extinct creature from the distant past is being stitched together in front of your eyes.
Far from being Frankenstein’s monster risen from the dead, these genetic blueprints offer a unique opportunity to push through the mists of time to examine lost worlds and vanished lives in unprecedented detail…any maybe learn a thing or two in the process.
With the release of the latest trailer for Jurassic World: Dominion, palaeogenomics, the sequencing of the complete genetic blueprint of historical and ancient creatures, is back in the spotlight. And with that, the inevitable question of can we bring back extinct animals, let them run amok and eat lawyers. Scenes from Jasper Fforde’s fantastic Thursday Next series spring to mind with herds of mammoths roaming the UK and trampling country gardens, and Neanderthals running the public transport system.
To address the mammoth in the room, any technological developments on the de-extinction front should be used to conserve what precious biodiversity we have left, rather than trying to assuage the guilt humanity may feel for causing the next mass extinction event.
Take the extinct moa for example. Which one of the nine species would you bring back? Does its habitat still exist? A lot of Aotearoa New Zealand has undergone widespread environmental modification since human arrival. Remember in Jurassic Park scientists had to bring back an entire ecosystem and even then, the Triceratops ate the wrong plant and got sick. You can’t just bring one moa back from the dead. You need to create a self-sustaining population with a healthy level of genetic variation otherwise you are going to end up with serious complications…just think of kākāpō. Cute, yes, but kākāpō have about as much genetic variation as the English royal family and that’s being polite. Bringing back that many moa is a huge cash and time investment that could be better spent on conservation, even if you got over the technological issues like the whole moa and the egg thing. If you don’t believe me about the folly of de-extinction, I’ll just leave this helpful YouTube clip right here:
The science of ancient DNA has come a long way since its early days when short fragments of genetic code were isolated from an extinct quagga. Now scientists can sequence complete ancient genomes from animals up to 1.3 million years old, though this is still around 65 million years younger than dinosaurs. While we can’t bring back dinosaurs and let them run amok (just think of the lawsuits), we can delve into the distant past to answer some pretty interesting questions. Reconstructing these ancient genetic jigsaws has shed light on human and cultural evolution (being a Viking was more of a job description than anything genetic), domestication, how the ancestors of moa lost the ability to fly, ancient global pandemics, and natural history.
For nearly all of the history of life on earth, our only knowledge comes from the fossil and archaeological record. This vast geological library is, however, inherently biased and patchy, with the words clouded by convergent evolution (think ichthyosaurs and dolphins), functional constraints (there are only so many body forms seabirds can take, making distinguishing some species based on bones a complete nightmare) and a lack of morphological differentiation (i.e. bumps on bones) in recently evolved species. This is where the power of palaeogenomics comes into play. It allows us to test the fossil record, cross-examining these geological and archaeological witnesses to get at the real story.
Classifying the fossil record into different forms requires working out species boundaries, complicated by the fact that many animals are now extinct, or have lost a lot of morphological diversity through human impact. Palaeogenomics has shown that there are three times as many males than females in museum collections of bison, bears, and mammoths. Could this be males are more risker than females and find themselves part of the fossil record more often, or was there a bias in collecting larger flashier bones, ignoring the smaller ones, and what impact does this have on taxonomy, the science of naming biodiversity? In contrast, palaeogenomics has shown that some species like the dire wolf, of Games of Thrones fame, is only distantly related to the morphologically similar grey wolf.
Scientists used to think hybridization was rare in the fossil record compared to what you can observe in nature today like pārera grey duck and mallards, or kakī black stilt and pouaka pied stilt. Palaeogenomic analysis of the fossil record has blown the door wide open with the genetic fingerprints of hybridization all across it in hominins, bison, bears, horses, and cats, oh my. I distinctly remember in high school learning about the very tree-like evolution of our own genus Homo. Rather, it’s now distinctly looking a lot like a dense and intertwined divaricating bush you might see on a tramping trip. Tibetans for example can survive at high altitudes due to a gene gained from Denisovans.
As well as looking at species boundaries, palaeogenomics has been used to look at how animals responded to dynamic climatic and human influences through time. The mammoths that were marooned on Wrangel Island in northern Siberia long after the extinction of their kin on the mainland, died out only ~4000 years ago due to inbreeding (the same affliction affecting kākāpō) and genetic defects through genomic meltdown that contributed to the breakdown of mammoth social norms. On the flip side, there was no deleterious genetic load in the extinct South Island kōkako and huia, supporting the idea they were driven to extinction through human impact and predation from exotic predators.
It’s not just the genomes of animals that scientists can sequence but their diseases too, often with surprising results. Waves of human and animal migration around the world have resulted in novel interactions and zoonotic disease transfer – it’s even possible kurī Polynesian dogs bought diseases with them when Polynesians colonized New Zealand. The palaeogenomes of tuberculosis strains specific to pinnipeds (seals and sea lions) were sequenced from ancient human skeletons from coastal South America. Butchering marine mammals is a messy business, which is why scientists dissecting whales dress in biohazard suits to stop disease transfer (and is why my wife couldn’t stand roast portobello mushrooms for dinner after she’d dissected whales that day). Even hundreds of years after the fact, excavating archaeological sites full of seal and sea lion remains can be an oily exercise.
While most of these examples are from overseas, the future of palaeogenomics is looking bright, especially in New Zealand. With the development of new genetic techniques, we are unlocking the secret whakapapa of our taonga biodiversity, much of which has been previously intractable to analysis. By adding new pages to the biological heritage of New Zealand we can learn how our dynamic geological, climatic and human history has shaped the evolution of our unique wildlife, and how we can conserve what we have left.