Dolly the sheep comes to mind when we think of cloned animals. She was made famous as the "cloned sheep" made in the 1990s. But Dolly was a century late when it came to cloning. The first animal ever cloned was in the 1800s. Hear a tale of cloned animals, scientific discovery, and baby hair.
When the media went nuts for Dolly the sheep in the 1990s, she was often billed as the first cloned animal. This was not technically correct. Dolly was justifiably famous for being the first animal cloned from an adult somatic cell. A somatic cell is a cell that is not formed as part of the fertilization process. Dolly's original cell was taken from adult mammary tissue of an already-grown sheep. That was a great scientific achievement built on a longer history of animal cloning than most people are aware of. The first successfully cloned animal lived over a century before Dolly was created.
The first animal to be cloned was a sea urchin in 1885. It had a two-fold scientific value; it was both a clone and a refutation of a then-current theory of cell biology. Scientists posited that the first combination of sperm and egg to make a creature had a complete amount of genetic information. When the cell divided, the amount of genetic information in each cell halved. When the two cells divided again, each of the four cells got one fourth the genetic information of the original cell. This was the best explanation at the time for why cells that developed from the original eventually became different tissues. No one understood how a cell that contained all the genetic information to make a human being could just become a skin cell. The theory was backed up when a scientist took a hot needle to the first division of cells in a frog embryo, destroying one of the two cells. The remaining cells developed into half an embryo.
When Hans Dreisch came up with a variant of the experiment with a newly divided sea urchin cell, he expected to get two halves of a sea urchin. He hadn't destroyed either of the two embryonic cells. He had simply shaken them apart and let them develop from there. To his astonishment, he got the very first pair of animal clones; two complete sea urchins. Was it a fluke? Or some quirk of sea urchin biology?
Confirmation came in 1902, with a charmingly down-home experiment. Biologist Han Spemann started experimenting with dividing salamander cells. Dreisch's shake 'n bake system wasn't working on the salamander cells. They had to be forcibly separated, but of course no equipment existed at the time to separate them. Spemann cast around, looking for a very fine apparatus to use, and finally settled on strands of hair combed from the head of his own baby. (Some say the baby was a son. Others a daughter.) My making a little loop, Spemann divided the cells at different stages of development. He found that at first they all developed into identical clones of each other, but at a certain point, dubbed determination by Spemann, only half-embryos grew from the cells. He announced that any cells after that point could never grow into full creatures.
Dolly, of course, proved him wrong. It just took more than baby hair.
Top Image: Toni Barros
Via Thinkquest twice and BCS.