My idea of the woolly mammoth is limited to the voice of Ray Romano and the unusual pairing with a sloth and sabre-tooth tiger in the Ice Age movie franchise. But in reality, the woolly mammoth was alive 5 million years ago, with species existing across Africa, Europe, Asia and North America. Unfortunately, like many animals, mammoths became extinct roughly 10,000 years ago due to a warming climate and widespread human hunting. The natural rate of extinction is around one to five species per year. Yet, scientists estimate that we are now losing species at up to 10,000 times that background rate.
Diversity within our ecosystem is not only beautiful, but from an evolutionary perspective it enables us to adapt and survive. Human activities are a major contributor to harmful changes to biodiversity and ecosystem function. Humans are considered one of the world’s greatest evolutionary forces, frequently driving rapid evolutionary events. They achieve this through relocation, domestication, hunting and the creation of novel ecosystems. It is also likely that emerging technologies, such as GMOs and de-extinction projects, will eventually provide additional mechanisms.
Nonetheless, with these advanced technologies comes great opportunity. Scientists are now harnessing these technologies to bring back extinct species, or to prevent extinction of vulnerable species, in so-called de-extinction projects. One of the animals at the forefront of this discussion is the woolly mammoth. Experts working on this project hope that bringing back the woolly mammoth could help convert the tundra back into grasslands. In this blog, we delve into the Woolly Mammoth Revival Project, exploring why and how these researchers aim to bring back these giants, and the associated social and ethical considerations surrounding their revival!
The woolly mammoth
Characteristics
The woolly, Northern or Siberian mammoth, species name Mammuthus primigenius, is a species of mammoth that lived during the Pleistocene epoch. While no modern human was alive to tell the tale of the woolly mammoth, extensive studies of fossil bone or tooth anatomy has yielded great information about the physical characteristics of these giants. They are among the best studied of any prehistoric animal due to the discovery of frozen carcasses in Siberia and Alaska. In addition, prehistoric cave paintings have also depicted the life of these animals, giving us an idea of their appearance.
Woolly mammoths were roughly the same size as modern African elephants. Males reached shoulder heights between 8.9-11.2ft, weighing up to 6 metric tons. Females reached 8.5-9.5ft in shoulder height and weighed up to 4 metric tons. These mammoths were well adapted to the cold environment. They were covered in fur, with long guard hairs on their outer covering and shorter hairs on their undercoat. The colour of their coat varied from dark to light. Both their ears and tails were short to minimise frostbite and prevent heat loss. One of their prominent features was their tusks, which could reach up to 15ft long. They also had four functional molar teeth. These animals were herbivores, eating a variety of grasses, leaves, fruits, berries, nuts and twigs.
Ecosystem
During the Pleistocene era, large numbers of woolly mammoths roamed the forests and tundra of Siberia. When the Ice Age hit, many woolly mammoths fell into icy pools of water where they were entombed in permafrost. The tundra, and much of the taiga, were once a grassland ecosystem referred to as the mammoth steppe. In Siberia, these mammoths would graze on steppe grasses along with bison and other large herbivores. At the end of the Pleistocene era, these herds vanished, transforming this ecosystem from abundant grasses to a more shrub dominated community.
Now, this tundra ecosystem, in the absence of these large grazing species, is affected by and contributing to human-driven climate change. These large animals would compact and scrape away thick insulating layers of winter snow. Their absence, alongside warmer summers, has accelerated the melting of permafrost and the release of greenhouse gases. The carbon release from the melting of the world’s permafrost is estimated to be equivalent to burning all the world’s forests two and a half times.
Extinction
To this day, scientists are still divided over whether hunting or climate change was the main factor that contributed to extinction, or whether it was a combination of the two. Nonetheless, unlike smaller animals, larger mammals are typically more vulnerable due to their smaller population sizes and lower reproduction rates.
The woolly mammoth coexisted with early humans, who hunted the species for food and used their bones and tusks for making art, tools and dwellings. Most woolly mammoths became extinct in the Holocene epoch around 10,000 years ago at the end of the last ice age. However, isolated populations managed to survive for thousands of years after that on St. Paul Island in the Bering Sea and Wrangel Island in the Arctic Ocean. T
he Wrangel Island population were isolated by rising post-ice-age sea levels and were the last mammoths to go extinct, disappearing roughly 4,000 years ago. By comparing the Wrangel Island mammoth’s DNA to that of two older mammoths, as well three Asian elephants, researchers recently found a collection of deleterious genetic mutations in the Wrangel Island mammoth. The population was so small and isolated that it led to inbreeding and ultimately the loss of genetic diversity. This resulted in the accumulation of harmful genetic mutations that had different effects, such as reduced fertility, that ultimately led to their demise.
The Woolly Mammoth Revival Project
The goal
In 2015, with a mission to enhance biodiversity, Revive & Restore launched the Woolly Mammoth Revival Project. The goal of the project, led by Harvard geneticist George Church, is to bring back this extinct species and re-populate the vast tundra and forest in Eurasia and North America. The team will use advanced technologies to re-engineer a creature with the genes from the woolly mammoth. The team emphasise that the intent is to not make exact copies of extinct woolly mammoths, but to use mammoth adaptations needed for Asian elephants to thrive in cold climates.
There are several reasons why the group consider revival of the woolly mammoth to be important, including:
- Confronting climate change: Research by Dr. Sergey Zimov shows promise that the tundra can be converted back to grassland with the introduction of grazers. Zimov founded the Pleistocene Park in 1996, a fifty square mile wide nature reserve in the Siberian Arctic, where he hopes woolly mammoths will roam again. Artic grasslands not only support higher biodiversity and abundance, but there is growing evidence to suggest that grazing, compaction and disturbance effects caused by these large herbivores enables deeper freezing of permafrost. The grasses insulate the permafrost from melting and thus prevents the release of greenhouse gases.
- Insights into modern biology and medicine: There is a wealth of information to be gained from ancient DNA. Genomes hold historic information about adaptation to survive across extreme conditions. Unlocking this information and discovering its functional effects within living cells can provide insights that could be useful to treat human diseases or for future space exploration.
- Conservation: The technologies and tools used to pursue this project will enhance our understanding and ability to conserve elephant species. For example, the team are hoping to apply bioengineering approaches to combat herpes for Asian Elephants.
The research
In 2015, Swedish scientists published the first complete genome of the woolly mammoth. Since then, other projects have compared the genomes of mammoths with that of the African and Asian elephants. Church’s team are focussing on manipulating the genome of the Asian elephant, which is the mammoth’s closest living evolutionary relative. There are roughly ~1.4 million differences between these two species, meaning that an Asian elephant is already 99.96% woolly mammoth.
The team have been using CRISPR genome engineering tools to insert DNA from the mammoth genome into living elephant cell cultures. So far, the team have rewritten a number of genes into Asian elephant cell lines, including mutations for mammoth haemoglobin, extra hair growth, fat production and cold resistance. These experiments have generated increasingly mammoth-like cells.
The group are also interested in exploring the non-protein coding mutations and how they are important for adaptation to cold climates. Once these traits appear sufficiently in stem cell derived tissues, the Church Lab will begin experiments to generate embryos, possibly through stem cell embryogenesis to avoid using elephants as surrogate mothers. If any method becomes successful, a suggestion has been made to introduce these elephant-mammoth hybrids (‘elemoths’) to the Pleistocene Park in Siberia.
Considerations of revival
Although de-extinction projects have positive intentions, they are ultimately subject to a host of debate. Revive & Restore, alongside the woolly mammoth project, has a range of other projects working on both extinct species, such as the carrier pigeon, and other vulnerable species, like the Black-footed ferret. While there are concerns that we may not be able to control the spread of genes, one of the biggest concerns is that people will no longer fear extinction. These types of projects could potentially undermine conservation efforts, with the public feeling less responsible for their behaviour and actions that ultimately contribute to global warming and biodiversity loss. Most importantly, some conservationists argue that efforts like the Woolly Mammoth Revival Project could divert important funds dedicated to protecting many endangered species and ecosystems that are still around today.
Others have also raised concerns that these hybrids may not be able survive in the Arctic because they are genetically different from extinct mammoths. We also do not fully understand the dynamics of the ecosystem back then – particularly the microbes that may have existed at the time. In addition, these animals often roamed in herds to learn survival skills. All together, these factors could lead to the ‘elemoths’ behaving unpredictably in their environment. Revive & Restore has expressed that they plan to raise these hybrids with captive Asian elephant families in zoos to teach them survival and herding behaviours.
Regardless, as our tools improve every day, de-extinction is becoming an increasing reality. Eriona Hysolli, Postdoctoral Researcher at Harvard Medical School, expressed:
“I feel like it’s only beneficial to try to keep our Earth as biodiverse as possible, and if we have to use some of the artificial tools to do so, so be it!”
We are entering a time where these futuristic and so-called ‘mad scientist’ ideas are becoming tangible. As a result, we can no longer avoid these important conversations and we must start thinking what we will do once these technologies become successful and applicable. However, like with all genomics technologies, we must remember, as Uncle Ben said to Peter Parker: “with great power comes great responsibility”.
Check out our interview with Eriona Hysolli as she delves into the detail of the Woolly Mammoth Revival Project headed by George Church.
References
- Bull J.W. and Maron M. How humans drive speciation as well as extinction. Proceedings of the Royal Society B: Biological Sciences. 2016 Jun 29;283(1833):20160600.
- Hysolli E. An American-Russian collaboration to repopulate Siberia with woolly mammoths … or something similar. Medium, 2019 Jan 1. Access: https://medium.com/@eriona.hysolli/an-american-russian-collaboration-to-repopulate-siberia-with-woolly-mammoths-or-something-similar-9cbac4e985cb
- Shultz D. Should we bring extinct species back from the dead. Science. 2016.
- Schnebly, R. Revive & Restore’s Woolly Mammoth Revival Project. Embryo Project Encyclopedia. 2021 Jan 19. (2021-01-19). Access: https://embryo.asu.edu/handle/10776/13209
Image credit: By Hailshadow – canva
