Overview
- Dolly, born in 1996–97 as the first mammal cloned from an adult cell, proved that an adult cell nucleus can restart development but required many attempts to succeed.
- Most animal cloning still uses somatic cell nuclear transfer, a process that inserts a donor cell nucleus into an enucleated egg and depends on the egg to reset epigenetic marks.
- The technique remains low-yield and error-prone — incomplete epigenetic reprogramming causes high embryo loss and developmental abnormalities, which made Dolly’s 277 attempts an emblem of the problem.
- Practical uses today are narrow: livestock with valued traits, commercial pet copies, and targeted conservation efforts such as the 2020 black-footed ferret clone, while a 2024 rhesus monkey cloning experiment drew sharp animal-welfare concerns.
- Research on cloning helped show adult cells can be reprogrammed and fed the rise of induced pluripotent stem cells, and policy choices now favor safer tools like iPSCs and gene editing while reproductive human cloning remains widely restricted.