Why this Matters
We've been genetically engineering for over 10,000 years, taking advantage of random genetic mutations and exerting human selection in the animals and plants around us. Only in the last 50 years have we developed the tools to exert greater control and speed onto the process. 
With a technique discovered in the 1970s and reliably patented in 2012, we can now cut and paste DNA, albeit still with very high error rates. You definitely don’t want to try designing your next baby - at least not yet. 
Outside of science fiction and in the real world, the market is now making rapid advancements in gene therapies for cancer and diseases like cystic fibrosis .
Ancient Genetic Engineers: Puppies and Corn
Before we knew that genes were made of deoxyribose nucleic acid (DNA), ancient humans were already familiar with the concept of genes. As early as 12,000 years ago, humans culled aggressive Asian wolf pups and bred the docile human-friendly pups. Fast forward to today we have over 300 breeds of dog, ranging from Great Danes to chihuahuas. 
A little bit later, around 10,000 years ago, agriculture made it’s way to Mexico. Ancient pre-farmers discovered that if they planted the seeds of the most fruitful teosinte grain, a type of grass with barely more seed than the grass that grows in your lawn, over several growing cycles the grains would get larger - and larger - until the Aztec society was dependent on maize (corn). 
So What Are Genes, Anyway?
The code that makes us up are made of 4 molecules represented by the letters: G, A, T, and C. These molecules form a helical structure.
Imagine a set of spiral staircases long enough to wrap around the Earth 30 times, clustered into 46 chunks, all tied in knots around themselves. Each time a new cell is created, a new set of staircases are built. In the human body that comes out to over a thousand times more than the number of stars in our Milky Way Galaxy. 
In order to create the proteins that make life, imagine a man has to go step-by-step over 750,000 miles of staircase - each step being one letter of the 3 billion-letter long recipe that creates a human life. Some parts of the staircase are so treacherous and knotted that the man jumps off and skips to the next part; some parts just don’t make any sense, leaving many portions of the recipe unread.
In fact, all the proteins that make life are coded on less than 10% of this staircase. While the purpose of the rest is still a mystery to science, the seemingly meaningless repeating patterns of “junk code” gives us clues to our evolutionary history and make familial DNA tests possible .
Genetic Engineering Today: Gene Therapies
Over our lives, our DNA changes and mutates in the process of aging. Our bodies are very protective of our genes, and our immune system exists to detect and destroy any items that don't belong, like viruses or bacteria. 
Some people's genes cause disease though, like the BRCA1/2 genes that are highly linked to breast cancer. In many cases of cancer, there is a gene that either causes greater incidence of genetic mutations or allows mutated genes to replicate wildly and out of control into tumors. 
In order to bypass the body's natural defense and DNA-repair system, scientists use vectors, Trojan horses that sneak in therapeutic DNA past the defensive walls.
Viruses are common vectors (you'll hear the term viral vector a lot). Some therapies today use a modified version of the AIDS virus to inject genetic information, it's like a cellular needle. 
Another method is by extracting our own stem cells, the "blank slate" cells which can become almost anything . The problem with this therapy is that stem cells are hard to find in an adult human, found usually in the bone marrow or roots of your teeth - two places where we really don't want doctors to go!
Up Next: Research in Genetic Engineering
Those treacherous parts of the staircase? That’s gene regulation and epigenetics. Next week we will discuss the research behind gene regulation and Lamarckian evolution.