Like the movie "Jurassic Park," the path to restoring extinct large birds has moved closer. A U.S. bio corporations working on de-extinction said it has succeeded in hatching chicks from artificial eggs. Extinct large birds lay eggs so big that it has been hard to find surrogates among living birds, but now a laboratory route to restoration has opened.
Colossal Biosciences on the 19th (local time) released a photo of a researcher looking at an egg-shaped artificial egg and another of a chick just hatched from it. The company said it transferred the contents of freshly laid chicken eggs into the artificial eggs and raised them in an incubator for 18 days, resulting in 26 chicks. It did not disclose the hatching success rate.
Colossal Biosciences was founded in 2021 by George Church, a geneticist at Harvard Medical School, and billionaire entrepreneur Ben Lamm. The company's goal is to restore extinct animals like in "Jurassic Park." It has already succeeded in bringing back the dire wolf, a wolf that went extinct in the Americas 13,000 years ago. It also announced a result in which it restored mammoth hair genes in mice to make them shaggy.
◇ Removing roadblocks to restoring extinct birds
The artificial egg consists of a hard outer shell printed with a 3D printer and an inner transparent silicone membrane. The inner membrane allows oxygen to pass freely like a real egg. It traps moisture and blocks bacteria. The company said the transparent membrane also helps observe embryonic development.
Artificial eggs have been studied since the 1980s. The Roslin Institute at the University of Edinburgh hatched chicks by placing lab-grown embryos into other eggs. Researchers also grew embryos in plastic cups or kitchen wrap instead of eggshells. The problem was oxygen. Bird embryos need a lot of oxygen in late development, but supplying high-concentration oxygen without a shell damaged DNA. The new artificial egg allows atmospheric oxygen to pass through, so there is no need to supply oxygen artificially.
The artificial egg is a key technology in Colossal's project to restore the moa of New Zealand, which went extinct in the 15th century. In the dire wolf project, a similarly sized hunting dog served as a surrogate. Birds that lay eggs are different. The moa stood as tall as 3.6 meters, so there is no current bird that could serve as an egg-laying surrogate. A moa egg is 80 times the size of a chicken egg and is 4 and 8 times larger than the eggs of ostriches and emus, the two largest living birds. The company said artificial eggs can be scaled at will, eliminating that problem. Artificial eggs can be raised in existing incubators, so no surrogate needs to brood them.
Carles Lalueza-Fox, director of the Natural History Museum of Barcelona in Spain, said, "Colossal has succeeded in developing an unprecedented artificial egg," adding, "The most important breakthrough lies in the permeability of the membrane, which allows gases (oxygen and carbon dioxide) to pass." He said the device could be used to bring back other extinct birds such as the Carolina parakeet. The Carolina parakeet went extinct in North America in the early 20th century.
Megan Davey of the Roslin Institute said, "With only a press release and no paper, scientific verification is limited," but added, "Colossal's artificial egg is an important advance not only for birds but also for conserving other egg-laying endangered species such as reptiles and monotremes." Monotremes are egg-laying mammals like the platypus.
◇ Gene editing before the sperm and egg stage
Colossal plans to use artificial eggs to restore the moa, which went extinct in the 15th century, and the dodo, which went extinct on Mauritius in the Indian Ocean in the 17th century. Strictly speaking, it is not about finding and cloning the DNA of moas or dodos as in the movies. Instead, it is a method of changing today's birds to approximate moas or dodos.
Restoration proceeds in the following steps. First, DNA is extracted from moa and dodo remains to decode their genetic information. This is compared with the most closely related living birds to identify differences. Then the genes of the related birds are altered to the moa- or dodo-like form. That is gene editing. Colossal co-founder Church is the world's leading scientist in interspecies gene editing.
When restoring the dire wolf, gene editing was performed on embryos after sperm and egg fused, and then they were implanted into the uterus of a surrogate dog. Gene editing in birds is different. Hans Cheng of Michigan State University said, "Even a freshly laid egg already has as many as 50,000 cells, and that's too many cells to edit the genes."
Colossal adopted a method of changing primordial germ cells, stem cells that will develop into sperm and eggs, to be like those of moas or dodos. If the genes of primordial germ cells are edited and transplanted into emus or ostriches, they will produce moa or dodo sperm and eggs. Once these fertilize and an egg carrying moa or dodo genes forms, it can be removed before it gets bigger and transferred into an artificial egg for incubation.
For dodo restoration, Colossal is analyzing the genes of the Nicobar pigeon, whose genes are most similar. Last fall, it succeeded in culturing primordial germ cells from the rock pigeon, which has genes similar to the Nicobar pigeon. With the development of the artificial egg, most of the pieces of the puzzle for restoring extinct birds have now fallen into place.
Colossal said research on restoring extinct birds also helps save today's birds that are at risk of extinction. According to the company, 3 billion birds have disappeared in North America alone since 1970. More than half of bird species now have declining populations, and 1 in 8 species faces extinction. Raising such birds with artificial eggs could increase survival and boost their numbers, it said.
◇ "Restoring ecosystems should come first," critics say
Colossal is also conducting research to apply methods like the artificial egg to mammals. Co-founder Lamm said, "We can't subject endangered Asian elephants to in vitro fertilization a thousand times to restore mammoths," adding, "From the start, we planned artificial wombs to make thousands of mammoths."
The company chose the fat-tailed dunnart, a marsupial only 6–9 centimeters long, as the model for artificial womb research. Its 13-day gestation is the shortest among mammals, making it easy to assess the effectiveness of an artificial womb. It is already known to have completed a significant portion of gestation using an artificial womb.
An artificial womb could also help human preterm infants. But it could spark other debates. If a woman wants to end a pregnancy, she could transfer to an artificial womb instead of having an abortion. That could avoid ending a life, but it may raise concerns about infringing on a woman's right to choose. Legal disputes over the status of fetuses and newborns are also possible. Colossal said it would not apply artificial wombs to any primates, including humans, but noted it could transfer related technology to third parties.
Claims that artificial eggs can save birds at risk of extinction have also drawn criticism. Stuart Pimm, an ecologist at Duke University, said, "Whether or not Colossal's attempt is technically feasible, it will not address the biggest problems facing today's endangered birds," adding, "The most urgent solutions are to reduce habitat destruction, prevent building collision accidents, and stop predation by feral cats."
References
Colossal Biosciences (2026), https://colossal.com/colossal-biosciences-artificial-egg-dodo-moa/
Colossal Biosciences (2025), https://www.businesswire.com/news/home/20250407444322/en/Colossal-Announces-Worlds-First-De-Extinction-Birth-of-Dire-Wolves
bioRxiv (2025), DOI: https://doi.org/10.1101/2025.03.03.641227