In order to resurrect the mammoth, they made the hairy rat?

Last week, a species of "hairy rat" was born, which attracted the attention of the world.

The reason for the attention is not only the cuteness of the "hairy mouse", but more importantly, the research team believes that this "hairy mouse" reproduces the hair characteristics of the long-haired mammoth, and its birth is an important step in the resurrection of the mammoth [1].

“长毛鼠”与正常的小鼠｜Colossal Biosciences

The "hairy rat" was created by an American biotechnology company called Colossal. One of the founders of the company is George Church, a geneticist and professor at Harvard University, and Ben Lamm, a serial entrepreneur. Colossal, who work to resurrect extinct animals such as mammoths and thylacines, has said they hope to create hybrid mammoth cubs by 2028 and reintroduce them to the Arctic permafrost.

This time, the "hairy rat" was developed to resurrect the mammoth. In a statement on the hairy rat, Ben Ram said: "By introducing multiple cold-tolerant traits from the mammoth's evolutionary pathway into existing animal models, we have demonstrated our ability to reconstruct the complex genetic combinations that nature has created over millions of years of evolution." ”

The long-haired mammoth (Mammuthus primigenius), a true mammoth, became extinct 4,000 years ago; The physique is similar to that of the African elephant, but the incisors are long and curved, the hairs are half a meter long, and the inner layer has short hairs, which can adapt to the cold environment. Pictured is a model of a hairy mammoth in the Royal Museum|Wikimedia Commons

But can the "hairy mouse" really bring the mammoth back to life?

Hairy rats are cute, but they have nothing to do with mammoths

Colossal's press release hinted at the similarity between the "hairy mouse" and the mammoth, as if the same maneuver could be applied to the elephant and the mammoth would be instantly resurrected in situ.

However, this implication is misleading. The cute "hairy rats" we see in the news have a very weak genetic connection to mammoths.

“长毛鼠”和猛犸其实关系非常微弱 | Colossal Biosciences

In this study, various combinations of gene edits were performed on experimental mice, involving a total of 10 genes[1]. Among them, 9 genes are responsible for regulating hair characteristics, some of them will change the length of hair, and some will change the texture of hair. The remaining one gene is involved in fat metabolism.

Of these 10 genes, 7 are actually unrelated to mammoths. They are just hair genes found in mouse studies, and no corresponding mutations can be found in mammoths. Editing these genes can certainly change the appearance of a mouse's hair, but no matter how similar it looks to a mammoth (and it doesn't), these are not really "mammoth traits."

The change in the appearance of this "hairy mouse" is due to 6 genetic modifications to its hair - however, none of these 6 genes are related to mammoths Rui Chen et al.

The remaining three genes are related to the mammoth genome, but it is difficult to say whether the editing actually caused the mice to have "mammoth characteristics". Although the researchers believe that their operation can improve the cold resistance of mice, this has not been tested in any way.

In short, current research has not been able to prove that mice have been genetically modified to look like mammoths – and even if they do, they are still far from being truly resurrected.

Resurrect Mammoth, how far is it technically?

According to Colossal, the "resurrection mammoth" is achieved through gene-editing of Asian elephants.

The Asian elephant is the closest living animal to the mammoth. Theoretically, if you compare the genomes of the two and then modify the differences one by one, you can end up with an organism with the same genetic material as a mammoth.

亚洲象（Elephas maximus）｜Wikimedia Commons

But in fact, such a "complete revision" is almost impossible to achieve. Despite being closely related, mammoths and elephants are still very different. There are about 1.4 million "letters" in the genomes of the two animals, and these differences alter more than 1,600 genes encoding proteins [2]. With so many differences, the amount of work to modify is too great and it is difficult to implement with existing technology.

Colossal's researchers are well aware of this. Therefore, their plan from the beginning was not to resurrect the mammoth in the true sense of the word, but to select only some key genes for editing to create a "hybrid" with mammoth characteristics. They called this "hybrid" of the elephant and the mammoth "mammophant".

According to the researchers' assumptions, the main body of the "mammoth" is still an elephant, but it will have mammoth characteristics such as small ears, long hair, and cold tolerance Yahoo Finance

Even if the goal is only to create a "mammoth", there are still many unsolved technical difficulties. Although biotechnologies such as gene editing are well established in mice, none of these experimental methods can be directly transferred to elephants because there are many physiological differences between the two. It is still unknown what technical adjustments will be required.

Even if elephant embryos are successfully edited, it can be difficult to raise them. Artificial embryos need to be implanted into the surrogate mother for development, but Asian elephants are scarce protected animals, and considering animal welfare, it is difficult to carry out large-scale surrogacy with mother elephants.

George Church, co-founder of Colossal, has mentioned that he wants to solve this problem with an "artificial womb" [3]. But now the artificial womb technology is also very immature, and the version that can cultivate the fetus from scratch has not yet been developed.

With this money, it is better to protect the elephants first

In addition to the technical difficulties, the "Resurrection Mammoth" project has also been questioned by many in terms of ecological impact.

According to Colossal, the ultimate goal of the project is to create large populations of "mammoths" and then release them into permafrost to "fill the ecological niche". They believe that this will improve the ecological environment and slow down global warming.

Restoration of Ice Age fauna. Is it realistic to release "artificial mammoths" to improve the environment? Wikimedia Commons

It may be a good idea, but no one can guarantee that it will work out. Mammoths have been extinct for more than 4,000 years, and the ecology and climate have changed so much that the habitat suitable for them may be long gone. Moreover, man-made "mammoths" are not the same as the mammoths of the past, and it is difficult to say how they will survive and change their environment.

Relying on the "resurrection mammoth" gimmick, Colossal has raised hundreds of millions of dollars. Critics argue that if the money is spent on elephant conservation, the benefits would be much greater than the creation of "mammoths".

It is much easier to reap the ecological benefits by protecting elephants than it is to resurrect mammoths Wikimedia Commons

It's hard to say whether resurrecting mammoths will improve the environment, but protecting elephants can help. For example, elephants have been found to adjust vegetation structure by eating fast-growing trees with lower carbon absorption capacity to make room for those with greater carbon absorption capacity. Therefore, protecting elephants can increase the ability of tropical rainforests to absorb carbon dioxide, thereby delaying climate warming [4].

If you really want to make the planet a better place, start by focusing on the wildlife that exists.

bibliography

[1]https://www.biorxiv.org/content/10.1101/2025.03.03.641227v1.full.pdf

[2]https://www.cell.com/cell-reports/fulltext/S2211-1247(15)00639-7

[3]https://www.nature.com/articles/d41586-024-00670-z

[4]https://www.slu.edu/news/2023/january/elephants-atmospheric-carbon-research.php

[5]https://theconversation.com/woolly-mice-are-a-first-step-to-resurrecting-mammoths-but-theres-a-very-long-way-to-go-251640

[6]https://www.nature.com/articles/d41586-025-00684-1

Author: Window knocking on the rain

Editor: Mai Mai

题图来源：Colossal Biosciences、Wikimedia Commons

本文来自果壳自然（ID：GuokrNature）

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