Life has existed for billions of years, but our world is still bursting with it. If cellular aging was truly inevitable then this would be impossibleWhat does an immortal germ line mean? In simple terms, it means that individuals are mortal, but a species is immortal. Your child has a mixture of two sets of genes, but the actual cells come from people who’ve already outlived many animals. These same cells are the product of millions of years of countless cell division – tracing back to life’s origin. While the rest of your body starts to degrade, germ cells are somehow shielded from this process so that offspring can expect to live to adulthood and repeat the process. If they didn’t receive this protection and children didn’t start life with a (mostly) blank slate, we’d find each generation was born with progressively worse health. This would be extremely bad news for any species. Understanding exactly what goes on in each embryo is therefore extremely important, and could help us learn how to protect against or even rewind cellular aging. Once we know what’s really going on inside an embryo, we’ll also be able to perfect stem cell technology and learn how to regenerate any region of the body. Can studying our beginning lead to breakthroughs that can delay our end?