A crack team of scientists has made an extraordinary discovery among the small molecules of a giant creature: the genome structure is perfectly preserved in the remains of a 52,000-year-old woolly mammoth. The dry skin was so well preserved that it contained an intact mammoth chromosome, giving researchers unprecedented insight into the ancient animal’s biology.
The last mammoths became extinct 4,000 years ago, and some pyramids have been built in Egypt since then. However, in this study, the team examined mammoth samples dating back to 52,000 years ago and 39,000 years ago, a time when anatomically modern humans were still sharing the Earth with Neanderthals.
The remains of mammoths have been found in the grasslands where they once roamed. The remains of hairy proboscis animals are typically preserved in permafrost, the permanently frozen topsoil, although the stages of thawing and refreezing can damage the microstructure of the animals’ soft tissues. Sometimes, the preservation is stunning. For example, in 2022, a well-preserved mammoth-like calf was discovered in a Yukon gold mine. But recent discoveries reveal preservation at an entirely different scale: the molecular scale. The team’s research is published today in cell.
“We looked around and dug down, and when we finally zoomed in, we could see that there were A new type of fossil.
How do chromosomes survive for so long?
The 52,000-year-old remains investigated by the team still retain millimeter-scale hair, suggesting the mammoth was flash-frozen. The team says this preservation suggests it was frozen about 10,000 years before the Neanderthals went extinct, because the intact hair means the skin sample hasn’t experienced any thawing since then. Thus, animals retain hair, hair follicles, intact cells, and, of course, folded chromosomes within cellular regions. The team could actually see the genetic loops that control whether a certain gene is expressed or not.
“The sample was freeze-dried, forming a kind of beef jerky,” Lieberman-Eden said. Beef jerky is glass-transformed meat, making it durable. When it was freeze-dried, the mammoth skin became a molecular traffic jam at a microscopic level, preventing chromosomes from spreading. The skin samples become time capsules of ancient molecules, and the research team calls this rapidly frozen genetic material “color-changing glass.”
Gif: Vinicius Contessoto, Antonio Oliveira Jr., José Onuchic
Researchers say the quality of the remains makes possible the first genome assembly of an extinct species. Mammoths had 28 chromosomes, just like elephants (unlike us humans, who have 23). The team reconstructed the mammoth chromosome in 3D; it looked like a knotty knot to us. But for researchers, it’s an astonishingly precise glimpse into microscopic structures that map out the blueprints of Ice Age steppe giants.
“The differences captured through the mammoth genome open a window for comparisons between species,” Cynthia Pérez Estrada, a researcher at Baylor College of Medicine and co-author of the paper, said in a news release. Opening new doors “Just having a footprint of chromatin organization in three dimensions is incredible. “
Mammoth “beef jerky” keeps the molecular structure of chromosomes intact
The team went to great lengths to try and eliminate the molecular structure of the color-changing glass. In their tests, they swapped dried mammoth hide for dehydrated boar head bologna, which for all intents and purposes has the same structure at a molecular level. Researchers soaked color-changing glass beef in water, acid and liquid nitrogen; they heated it in microwaves and hit it with baseballs and mallets; they ran it over with cars and verbally bullied it (they joked at a press conference, ” “mentally hurt it”) and shot it with a shotgun (see photo below). Although the material became fragmented, its chromosomal structure remained intact at the microscopic scale.
“They are number one [preserved chromosomes]”We suspect many more will be discovered in the coming years,” Olga Dudchenko, a genomics researcher at Rice University and Baylor College of Medicine and co-author of the study, said in a news release. “
New findings reveal unprecedented molecular preservation in ancient ruins. While much older DNA has been discovered – in fact, several of the authors of the new paper were part of a team that published a study of the oldest preserved DNA at the time, which existed millions of years ago of mammoth tusks—but the newly described remains make it possible to study how the mammoth’s genes were expressed and its genome assembled. The current record holder for the oldest sequenced DNA belongs to a collection of environmental DNA recovered from northern Greenland, from which the research team was able to reconstruct the ancient environment of the Early Pleistocene.
What can scientists do with flash-frozen chromosomes?
The perfect preservation of this delicate molecular material could have implications for “resurrection,” a process through which some scientific teams and companies try to generate proxy species that represent recently extinct animals. Specifically, tracking genes that regulate cold tolerance and promote hair growth could be useful to companies trying to breed mammoths for the 21st century. Earlier this year, one such company – Colossal Biosciences – successfully created elephant stem cells, the first cells to be engineered into an embryonic state. Still, the team stresses that de-extinction is a difficult process and not the goal of their study.
“We are a very powerful species on a very small planet, and in situations like climate change, we make important decisions about the future of our species and the future of life on this planet,” Leibman-Eden said. “This It’s about our ability to learn from the past.“
Artificial intelligence could help unlock the tree of life
The closest living relative to the mammoth is the Asian elephant. Scientists can use mammoth chromosomes to better understand elephant genetics. But elephant genetics can also help scientists understand mammoths. Scientists could feed an AI model a piece of genetic code and ask the AI where proteins in a mammoth might bind, or how the genome might fold.
“Even feeding small amounts of data from mammoths into these AIs can yield a huge amount of information,” Lieberman Aiden told Gizmodo. In addition to Asian elephants, AI tools can also compile mammoth genomes Placed on the tree of life. “The power of artificial intelligence is its ability to take insights from all these species and combine them to give you a good guess,” Leibman-Eden added.
A combination of new technology, creative approaches and good luck are revealing the ancient world on an unprecedented scale. Understanding giant mammoths at the molecular scale helps us understand our ancient past and also contributes to conversations about the future of living animals.
