- Mail exchange between Reinhard Renneberg and George Church
- In German only: Wie wiederbelebte Mammuts die Arktis retten können. Online-Artikel. Last visit: 14.02.2023
- Colossal: https://colossal.com/mammoth/. Last visit: 14.02.2023
- In German only: Spiegel Online: https://www.spiegel.de/international/world/should-the-woolly-mammoth-be-brought-back-to-life-a-caeb7d13-c1f7-4372-a59b-c8fd085249a9. Last visit: 14.02.2023
- Pleistocene Park: https://pleistocenepark.de/en/publications/. Last visit: 14.02.2023
- engoo.com: https://engoo.com/app/daily-news/article/company-plans-to-bring-woolly-mammoths-back-to-the-arctic/HvYsaB1pEeyl2rNiRRCZeA. Last visit: 14.02.2023
- ResearchGate: https://www.researchgate.net/publication/345716347_Yunyugen_-the_Late_Pleistocene_locality_of_the_mammoth_fauna_in_the_basin_of_the_Yana_River_North-Eastern_Siberia. Last visit: 14.02.2023
Counteracting climate change: a "mammoth" task?
Can we counteract global warming and protect future life on earth? A research team is pinning its hopes on cloned mammoths.
Bringing back the woolly mammoth through CRISPR and modern genetic engineering?
Translated from the original German version.
An interesting new idea for tackling climate change is to reduce the thawing of the Siberian permafrost soil and the release of methane. Methane (CH4) is the second largest contributor to climate change after carbon dioxide (CO2). It is produced where organic material is decomposed in the absence of air, i.e. in swamps and on the seabed. Methane is 25 times more harmful to the climate than CO2, but it remains in the atmosphere for a much shorter time. And a daring plan links methane tackling with the return of the mammoth.
According to the plan of Prof. George Church of Harvard University (Cambridge, USA) the woolly mammoth, which has been extinct for a thousand years, could be brought back with the help of genetic engineering and the gene "scissors" of CRISPR. It is then to be reintroduced in huge herds in a protected area in Siberia. More about this in the interview with Prof. Church below.
The ambitious plan is to be executed in six years. €60 million in start-up funds have already been raised. And yet there are many sceptics to this plan, implemented by the US company Collossal.
About 50,000 years ago, Homo sapiens spread across the world and changed it for ever. We wonder today: What would the earth look like if mankind had never existed? How many species of animals and plants would still be on our planet? "We have the DNA, the technology and the leading experts in the field to bring them all back," Collossal optimistically states. Prof. Church has been promoting the idea of reviving extinct animal species, such as the giant bird Dodo, for years. So far, however, he has lacked the funds to do so.
2027: the first mammoth calf?
According to the current project status, the first calf is to be born in 2027. Strictly speaking, however, no woolly mammoth will be created as it existed before its extinction. According to Church and his team, the goal is to create a cold-resistant elephant that looks and behaves like a mammoth - a "mammufant", so to speak.
For example, the genes are supposed to ensure a dense coat and additional layers of fat, according to palaeontologist Victoria Herridge from the National History Museum in London. An extremely complex process.
According to Church, the available genetic material of a mammoth is not sufficient to clone it completely. The thawing permafrost soil repeatedly releases remains of the huge animals. Blood, tissue or DNA remains uncovered from tusks provide good insights into the evolution of the mammoth - but they have not yet really helped in the cloning process of a mammoth.
Can mammoth elephants slow the thawing of the permafrost?
Why should the animals roam through the Arctic again at all? According to Church, mammoth elephants could contribute to the permafrost melting less quickly. The release of climate-damaging greenhouse gases from the frozen ground could be prevented. According to the theory, the mammoth hybrids would tamp down and compact the snow and thus make it more difficult for the soils to thaw.
The mammoths could be released in a huge nature reserve in north-eastern Siberia, run by Russian scientists Sergei and Nikita Zimov - father and son. According to the two, however, exaggerated expectations should not be placed in the mammoth clones: The chances that everything will be perfect are slim. Mammoths cannot directly combat climate change, but they can make Arctic landscapes more diverse and resilient as pastures.
The permafrost soil of the northern hemisphere is known to store almost twice as much carbon as is currently contained in the atmosphere. When the ground thaws, microorganisms and bacteria begin to decompose the plant and animal remains that have been stored in the earth for thousands of years. In the process, they produce carbon dioxide and methane. So if the global temperature continues to rise, the permafrost could release more greenhouse gases, says Dr. Guido Grosse, permafrost researcher at the AWI Research Unit in Potsdam, Germany. However, the release would not be sudden, as is often feared in the media.
However, Grosse has doubts on whether the thawing of the frozen soils can be stopped, because many millions of square kilometres of permafrost region are at stake. They would have to be populated by an enormously high density of animals. It simply takes too long until there are enough animals to counteract the Arctic's warming. For him, the decisive factor is still: fossil emissions from coal, oil and natural gas must be stopped - as quickly as possible.
Other scientists are also sceptical: according to Prof. Gareth Phoenix from the University of Sheffield, UK, it would even be detrimental if only grass and no trees grew in the areas populated by mammoths. Trees and moss in the forested Arctic regions could be crucial for the protection of the permafrost.
Mammoths would also need an intact habitat
Even if Church succeeds in making a breakthrough, the question comes up: Can the animals survive at all over the long term in the wild? According to Russian scientist Lena Grigorieva, the entire ecosystem of the animals would have to be restored in order to produce offspring. This is not unproblematic at a time when polar bears are already having to go further and further south in search of food because the ice is no longer thick enough for them to hunt seals.
Zimow at least rules out the possibility that mammoths could be dangerous to humans. They would not harm anyone. Even in the modern world, the population could be kept under control. Problems would rather be caused by hunters who want to capture mammoth tusks.
Most importantly, there are 1,400 gigatonnes of carbon trapped in the soil that are released due to higher average temperatures. Much of this is methane, which is much more damaging to the climate than carbon dioxide. This is more important than anthropogenic sources of carbon, which is mainly carbon dioxide, which only accounts for ten gigatonnes per year.
An interview: George Church and the return of mammoths
How can the mammoths help?
Church: Some models suggest that a higher ratio of grass to trees, as was the case thousands of years ago, would help in three ways: first, by reflecting more solar radiation. Second, grazing herbivores that trample the snow allow the -40 degree Celcius temperature to better penetrate to the ground, preventing the methane-rich soil from thawing. A thick, fluffy layer of snow is like a down duvet, but if you compress the snow so that it becomes solid ice, it has very high thermal conductivity.
And the third benefit would be a better photosynthesis rate via the grass, because that means CO2 sequestration and not just a slowing down of carbon loss.
The first step is to develop a technology that can make dozens to thousands of changes to the germline. The second step would be to increase reproduction to the point where they can have an effect in a reasonable period of time. And the third is to place them in such a way that they migrate from nodes to regions with high carbon content and low human population density.
Do we have the technology for precise genetic modification?
Church: Yes. There have been 42 successful modifications performed on different strains of pigs for the purpose of subsequent organ transplantation. They are so healthy that they donate organs for preclinical and clinical trials in humans. For the mammoths, we have compiled a list of edits where the maternal and paternal gene variants of the cold-resistant ancestors were the same. In many cases, these will be targeted for cold resistance.
What else needs to be done to ensure that the animals are well adapted to the environment?
Church: Most of the cold-tolerance gene variants affect the thickness of the fat layer, hair and wool - all over the body. Also small ears, specialised fat deposits, skeletal structures, tusks. We want to produce both short and long tusks. Short tusks could also be a protection against ivory poaching. Or no tusks at all, because in the wild it has been shown that elephants can manage without tusks.
Do these genes come from mammoth DNA samples? Is the original genetic structure of the mammoths even known?
Church: Yes, there are many frozen mammoths. Mammoth genomes are among the best sequenced genomes in the world. Elephant genomes are also second only to human genomes. So we have a good mapping of the genes, because Asian elephants in particular are very similar to mammoths, with 99.6 per cent genome similarity. The changes we make in the blood, for example, in the haemoglobin, are maybe in the order of five. You can almost think of it as elephants and mammoths being mutants of each other.
How do you plan to build up a sufficiently large mammoth population, also to avoid inbreeding?
Church: The idea is to start with a herd of Asian elephants that has a few woollier members and is large enough to quickly grow into a diverse herd. There is a big overlap in temperatures - winter for the Asian elephants and summer for the mammoths is pretty similar. In the process, they will be genetically diverse from the start because they have the diversity of the elephant hosts plus the diversity that we introduce. We are also trying to make artificial reproduction possible, so that we can in principle create thousands of animals with different genetic compositions at the same time.
So you are planning to use artificial wombs for mammoths?
Church: Correct! Our two reasons are that, firstly, we do not want to interfere with the natural reproduction of the endangered elephant species in any way. The second reason is that we want to observe the entire development process. It is much easier to follow the development in a laboratory than when it takes place in a wild mother.
Our team is cooperating with the Pleistocene Park in Siberia, where Sergei and Nikita Zimov are studying the relationships of about ten reintroduced species. We can learn from this dynamic as it is very close to the environment we want to work in. It is also important to look for ways to guide their migrations. Maybe we can influence their movement by planting perennials selectively. But we will start their migrations far away from any population centres, at least 100 kilometres for the first animals. Can the plan work fast enough to curb climate change in time? We hope so.
How would you measure the success of the project?
Church: In masurements of carbon dioxide, methane and ground temperatures: The release of methane and carbon dioxide is to be reduced and the average summer and winter temperatures on the ground are to decrease.
Could you ellaborate on why an artificial womb will be used?
Church: In order not to further burden the highly endangered elephant species with breeding experiments. We believe that with artificial wombs we can scale up from the first few elephant calves to thousands in parallel. Thus, the scaling up does not depend on the slow breeding process. Normally it takes about nine years to reach sexual maturity, almost two years to get pregnant, and they only have one calf per pregnancy. So if we want it to be fast, many embryos have to grow at the same time - and without surrogate mothers.