GMOs Part 3: What are genes and how are they modified?

In Part 2, I showed you that it’s almost inevitable that we dislike GMOs considering our food fears and the entities that profit from them.

The good news, however, is that this appears to be correctable. Teaching people about GMOs seems to reduce their fears. (This is not the case with other controversial topics in science where correcting misinformation can sometimes lead to a backfire effect.) In this series, you and I will be putting this to the test. How will you adjust your beliefs after learning about GMOs? Let's see...

The major obstacle to learning any science is unnecessary complexity and technobabble. My goal here, therefore, is to make GMOs as understandable as possible. All you need is a basic definition of a gene, and how genes are modified. That's it.

Basic definition of a gene

1. A gene is a strand of chemicals in a cell. It carries instructions to make a protein.

2. Proteins are responsible for traits, like eye color or height.

3. Every organism has tens of thousands of genes. A full copy resides in every cell.

4. Genes are passed down to the next generation.

How genes are modified

Now that you know what a gene is, you need to know how they are modified. To explain, I will focus in on a single food, the tomato, and follow it through its 10,000 year history. Try to answer the following questions:

Q: What part of the world do tomatoes originally come from?

A: Although it's tempting to think Italy or the Mediterranean, this is the wrong answer. Tomatoes are actually a plant from the New World, native to the region around present-day Peru and Ecuador. They were only brought to Europe about 500 years ago, after Columbus.

Q: What did "wild" tomatoes look like?

A: Wild tomatoes were small (half an inch in diameter), purple, with a thick skin, yielding few calories, and tasted horrible. (See below)

However, well before they were introduced to Europe, neolithic South American farmers were able to breed it into the tomato pictured below.

Which leads to the next question...

Q: How did they do this?

A: About 10,000 years ago, South Americans switched from a nomadic life of hunting and gathering to a life of farming. Instead of waiting for nature to grow tomatoes, they could grow many more by planting the seeds. Occasionally, they’d notice one of those tomatoes was bigger, or juicier, or more pest resistant than its neighbors (see picture below). The next season, only those seeds were planted. And so on, and so on, until they bread the big, tasty, calorie-yielding tomato we know today. This process is called plant breeding. Which leads to the next question...

Q: How does plant breeding work? How does the occasional tomato in the field become different from its neighbors?

A: Random genetic mutation. Genetic mutations happen ALL the time in nature. In fact, every time a cell divides, it must copy all its genes - billions of bits of information. On average, a single copy error is made. Not bad, but considering the billions of cells in billions of organisms, that's a lot of genetic mutation, and a lot of genetic variation.

Sexual reproduction is another source of genetic variation. Unlike bacteria, who reproduce by cloning themselves, most plants and animals have a male sex and a female sex. These genetic variants combine to create offspring with even more genetic variation. You, for example, are a genetic variant of your parents, and a genetic variant of your siblings.

Natural selection

Mutation and genetic variation are not a mistake. In fact, they are essential to all life on earth. When environments change, as they always do, some variants are bad for survival, some are good for survival, and some do nothing. The ones good for survival are passed on. They are “selected" by nature. This "natural selection" of genetic variation is the basis of evolution. In deed, every species, all life on earth, is just one long chain of naturally selected genetic variants.

Breeding = artificial selection

Breeding also takes advantage of mutation and genetic variation, however, instead of nature doing the selecting, the farmer is doing the selecting. They "artificially" select the variants best suited for farming and human consumption. Traits like, crop yield, taste, or resilience to pests.

Plant and animal breeding began all over the planet ten thousand years ago. We call it the Agricultural Revolution.

It’s all genetic modification

Regardless of whether it's natural selection or artificial selection, it’s all genetic modification. Thousand of genes were changed to breed the wild tomato. Well before scientists got their hands on it.

Which begs the next question: were these "genetically modified" foods tested for safety by our ancestors? I will address this in the next post.