By Francesco Rivetti
Jurassic Park and its dinosaurs have shaped the childhood and fantasy of millions of kids and adults for the past decades. But is there any possibility for these theropods to come back?
The first question we need to ask ourselves is whether amber-preserved mosquitos actually contain preserved DNA like in the movies. For any biologist this will not be a surprise, but unfortunately it is impossible for DNA to remain intact in hardened resin. Penney et al. (2013) tried to recreate the experiments of the film series and so they extracted DNA from bees trapped in copal, a fossilized precursor of resin, but unfortunately yielded nothing. Unfortunately for the scientists of Jurassic Park, amber might not be the best place to look for ancient DNA, as it forms through exposure of tree-sap to high pressures and temperatures (Editor, 2020). These conditions certainly do not go hand in hand with DNA preservation (Could, 2020). Nevertheless, a group of scientists in 2013 found in Montana a fossil of a mosquito with red pigment in its abdomen (Editor, 2020). After mass-spectrometry, the pigment was confirmed to be blood due to the presence of porphyrin, a breakdown molecule of haemoglobin. But again, there was no presence of DNA (Greenwalt et al., 2013).
If there is no DNA in mosquito’s abdomens, can we find any soft tissues from which to extract DNA? Scientists have found remains of collagen and red blood cells in 75-million-year-old bone fossils, but unfortunately, these again showed no signs of DNA (Bertazzo et al., 2015). Something that should be noted is that finding DNA is not enough, as our aim is to recreate an entire genome: hence, we need billions of nucleotides. Furthermore, the most ancient genome ever found was from a 700,000-year-old horse from Yukon, nearly 100 times younger than any dinosaur (National Geographic, 2020). Disastrously for us, the only reason why the whole genome could be reconstructed was that the missing pieces were taken from modern horses; for obvious reasons, this approach would not be viable with dinosaur DNA (Editor, 2020). Sadly, other studies have hypothesized that even in optimal conditions a genome can only be preserved for 1.5 million years, after which the sequences become too fragmented for a genome to be reconstructed (National Geographic, 2020).
Maybe instead of finding DNA remains, we could potentially restore ancient DNA from living animals by “un-evolving” them but undoing 66 million years of evolution sounds like an immense challenge (Editor, 2020). Interestingly, similar research has been done right here at Imperial College London. Professor Arkhat Abzhanov compared modern birds to dinosaurs by looking at the DNA and skeletal structure of skulls, beaks, and snouts. The research team was able to identify small genes that if mutated significantly altered an embryo’s anatomy. For example, the professor was able to generate a chick-embryo with a snout and not a beak. Nevertheless, as the aim of the research was not dinosaur-genesis, the embryo was not allowed to develop and hatch (Reverse, 2020). Anyhow, even if scientists developed a dino-like bird, could it be classed as a dinosaur?
Lastly, we need to ask ourselves a very important question: is there any need? Personally, even if I find the idea of dinosaurs roaming Earth once again extremely fascinating, I do not see the point. We have no idea how they would react in our world, and given that nature has condemned them to extinction (for once we had nothing to do with it), why bring them back? (Editor, 2020) Experts have no idea how these dinosaurs would react to current temperatures and atmospheric composition, so we don’t even know if they could survive. Similarly, for a population to be genetically sustainable it requires a minimum of 5,000 specimens, and I am not sure if anyone would want so many T-Rexes at any given moment (Editor, 2020).
Nevertheless, before bringing back long-gone species back to life, should we not try to preserve the species that are about to go extinct? What is the point of re-creating a long-gone, naturally disappeared, ecosystem if we cannot even maintain ones that have been stable and prosperous on Earth for the past ten thousand years? Anyways, if we were extremely adamant about species-restoration, then, I would first look at all the species that we as a species drove to extinction just in the past thousands of years. Animals like the passenger pigeon, which was hunted to extinction in the 19th century, or the lesser stick-nest rat from Australia (Shultz, 2020). In this way we could potentially give back to nature some of the biodiversity that unfortunately we continuously keep taking away.
Bertazzo, S., Maidment, S., Kallepitis, C., Fearn, S., Stevens, M. and Xie, H. (2015) Fibres and cellular structures preserved in 75 million–year-old dinosaur specimens. Nature Communications, 6(1). Available from: https://www.nature.com/articles/ncomms8352 [Accessed 3rd November 2020]
Editor, L. (2020) Is It Possible To Clone A Dinosaur? Available from: https://www.livescience.com/54574-can-we-clone-dinosaurs.html#:~:text=Apologies%20to%20people%20keen%20on,bone%2C%20experts%20told%20Live%20Science.&text=It’s%20no%20surprise%20that%20dinosaur%20remains%20contain%20DNA%2C%20she%20said. [Accessed 3rd November 2020].
Freethink. (2020) Reverse Engineering Dinosaur DNA. Available from: https://www.freethink.com/videos/dinosaur-dna [Accessed 3rd November 2020].
Greenwalt, D., Goreva, Y., Siljestrom, S., Rose, T. & Harbach, R. (2013) Hemoglobin-derived porphyrins preserved in a Middle Eocene blood-engorged mosquito. Proceedings of the National Academy of Sciences, 110(46), 18496-18500. Available from: doi:10.1073/pnas.1310885110. National Geographic. (2020) World’s Oldest Genome Sequenced From 700,000-Year-Old Horse DNA. Available from: https://www.nationalgeographic.com/news/2013/6/130626-ancient-dna-oldest-sequenced-horse-paleontology-science/ [Accessed 3rd November 2020].
Natural History Museum. (2020) Could Scientists Bring Dinosaurs Back To Life? [online] Available from: https://www.nhm.ac.uk/discover/could-scientists-bring-dinosaurs-back.html [Accessed 3rd November 2020].
Penney, D., Wadsworth, C., Fox, G., Kennedy, S., Preziosi, R. & Brown, T. (2013) Absence of Ancient DNA in Sub-Fossil Insect Inclusions Preserved in ‘Anthropocene’ Colombian Copal. PLoS ONE, 8(9). Available from: doi:10.1371/journal.pone.0073150
Shultz, D. (2020) Should We Bring Extinct Species Back From The Dead? Science | AAAS. Available from: https://www.sciencemag.org/news/2016/09/should-we-bring-extinct-species-back-dead [Accessed 3rd November 2020].