Scientists Tried to Clone Clones Forever. It Didn’t End Well

Key Points:

• Japanese biologists have identified a potential limit to how many viable clones can be produced from successive generations of cloned mice, based on 20 years of serial cloning research using the additive trichostatin A.
• Trichostatin A, an epigenetic modification reagent, helped suppress harmful genetic mutations during cloning, allowing the team to produce over 1,200 healthy cloned mice across many generations with normal lifespans and reproductive capabilities.
• Despite initial success, cloning efficiency and viability sharply declined by the 58th generation, with mice surviving less than a day, indicating an accumulation of harmful genetic mutations that cloning alone could not overcome.
• The study showed that natural sexual reproduction could partially reverse some genetic abnormalities, such as placental defects, suggesting that recombination during sexual reproduction helps filter out detrimental mutations that build up in clones.
• These findings highlight both the potential and biological constraints of indefinite serial cloning, with trichostatin A improving cloning success but not preventing long-term genetic degradation across many generations.