Dolly the sheep was the first successfully cloned mammal twenty years ago. After living a short life of 6.5 years compared to the average of eleven years, Dolly passed due to Osteoarthritis. This progressive disease in Dolly brought up an important question: Does cloning animals make them age prematurely? At the time, no one had an answer.
Nine years ago, four sheep, Daisy, Diana, Debbie, and Denise, were cloned from the same cell line as Dolly. Today, those sheep are happy and healthy. Now another question arises: How have Dolly’s clones lived longer?
To understand how this can happen, you must first understand the procedure for cloning. To clone, scientists use a process called “somatic cell nuclear transfer.” This process involves clearing DNA from an existing egg and replacing it with the new DNA. However, it is always possible that not the entire original DNA from the egg is removed. These little bits left behind can alter an animal’s cells, tissues, and even their behavior. These cloned sheep are perfect examples of this happening. All four look exactly like Dolly. However, Debbie has stiff joints especially on a cold day. Also, scientists can tell which MRI’s are hers, due to differences in her tissues and bones.
The topic of cloning can be a touchy one; there are benefits and downfalls of it. On one hand, threatened species can increase their population numbers through this process. On the other hand, there are many questions on if it is safe and morally correct. At the end of the day, there is clearly a lot more to learn about cloning from these sheep. Scientists hope to study cellular and molecular differences in these sheep.