Biologists discovered a hard biological limit to infinite cloning

Space · Published 23 October 2026 Swipe more like this →

In short: For decades, scientists wondered if a mammal could be cloned indefinitely. After 20 years of research and over 30,000 attempts, a team of Japanese researchers finally hit a wall. They discovered that cloning a clone eventually leads to a biological 'mutational meltdown' that makes life impossible.

In 2005, Teruhiko Wakayama and his team at the University of Yamanashi began a landmark experiment in Japan. Starting with a single female mouse, they began a process of serial re-cloning: cloning the clone, then cloning that clone, and so on. The goal was to see if this chain could theoretically continue forever. Using a technique called somatic cell nuclear transfer—where a cell's nucleus is injected into a denucleated egg—the team produced over 1,200 mice over two decades.

Initially, the process appeared to be improving. The success rate climbed from 7 percent at the start to a peak of 15.5 percent by the 26th generation. However, the team hit a 'critical turning point' at the 27th generation. From that point forward, the success rate plummeted. By the 57th generation, only 0.6 percent of the mice survived. Finally, in the 58th generation, every single mouse died shortly after birth, despite showing no visible abnormalities.

The reason for this failure is a phenomenon the researchers call 'mutational meltdown.' While previous studies suggested clones would be free of mutations, genome sequencing revealed that harmful genetic mutations were accumulating with each successive generation. The researchers found that these mice had three times more mutations than mice born through sexual reproduction. Wakayama compared the process to a photocopier: each copy loses quality, and eventually, the image becomes too blurry to be useful. A biological ceiling on this technology is defined by research proving that mammals lack the capacity for endless cloning.

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