 Despite the successful creation of viable offspring via SCNT in various mammalian species, researchers still have limited understanding of how the technique works on the subcellular and molecular level. Although the overall efficiency and safety of reproductive cloning in mammals has significantly increased over the past fifteen years, it is not yet a safe process (Whitworth &amp; Prather 2010). For example, the rate of abortions, stillbirths and developmental abnormalities remains high. Another source of concern is the risk of premature ageing because of shortened telomeres. Telomeres are repetitive DNA sequences at the tip of chromosomes that get shorter as an animal gets older. When the telomeres of a cell get so short that they disappear, the cell dies. The concern is that cloned animals may inherit the shortened telomeres from their older progenitor, with possibly premature aging and a shortened lifespan as a result.