Do our choices really change our DNA?
A prize-winning molecular biologist explains epigenetics to us like a kindergarten teacher.
If you’re interested in science, you may have heard rumors
that genes aren’t as set in stone as our high school teachers seemed to think
they were. Instead, people’s environments may actually change their DNA, or at
least how DNA is expressed.
This field, called epigenetics, is pretty exciting, but it’s hard to tell what’s true and what’s wishful thinking. Can trauma really be passed down through generations? And if I stretch my neck enough, will my ancestors start to resemble giraffes?
So we sat down with Howard Cedar to figure out what the real deal is. He's an Israeli-American molecular biologist from Hebrew University in Jerusalem who just won Columbia University's prestigious Horwitz Prize for epigenetics.
“We all get from parents what I like to call a book,” explained Cedar. “DNA has a language. It has letters and words and sentences and paragraphs. Each gene is an instruction for one component of the body.”
In other words, DNA is like a book about how to build a person, and genes are like sentences.
So can these sentences be changed? According to Cedar, these letters are written in ink. You can’t add or modify them. But “it turns out that this text can be annotated,” he said.
The secret to this change is “methyl groups.” These chemicals “tell the cells what should be read and what should not be read,” Cedar told us. They’re sort of like a black marker that you can use to cross out sentences, a process unsurprisingly called “methylation.”
DNA may be unchangeable, but methyl groups are different. “Methylation can be changed.” This means your body-making instructions can change too.
“The basic characteristics of man are determined by the text of his genes, but the fine tuning of those properties is probably affected by environment,” said Cedar. “I think that’s the general picture."
Still confused? Here's a colorful video about it.
This is where all the exciting gene-changing stuff comes in: it seems like methyl groups can be turned on and off during people's lives, which can change their DNA, and maybe even the DNA of their children.
According to Cedar, there’s a lot of weird phenomena that can best be explained by methyl groups, some of it pretty mind-blowing. For instance, some people who go through trauma recover, but their bodies change a decade later.
“A change in methylation is the only thing that’s stable enough to explain this,” said Cedar. “There’s nothing else we know of that’s so stable. The trauma changed the genes that are expressed. And that will become permanent. And it’ll affect this person.”
There’s even evidence that these chemicals could affect a person’s children. Sometimes, pregnant women temporarily develop diabetes while they’re pregnant (one more reason you should be really nice to pregnant women), and the diabetes goes away when they give birth.
Here's where it gets weird: when those children grow up and get to be around 50 years old, 90% of them get diabetes (good thing there's a lot of creative ways to cut out sugar).
“There’s a good possibility that the fetus undergoes some changes in methylation so that its expression pattern is different, and that expresses itself many years down the line,” Cedar told us. “There are a lot of examples like this.”
Methylation could also explain why only one twin develops schizophrenia or how our food affects our genes.
“I think that diet may have a big effect on the liver, the pancreas, the brain,” he said. So eating healthy isn't just good for you; it's good for your future children.
As new as all this research is, the idea behind it has been around for more than 100 years.
“This whole concept of environment affecting genes is a very old idea,” pointed out Cedar. Back in the 19 th century, before anybody knew about genes, Charles Darwin argued that an animal’s attributes are unchangeable, created by random mutations and evolution.
Another biologist at the time, Jean-Baptiste Lamarck, disagreed. Lamarck thought animals make choices, and those choices lead to physical changes in their children. A giraffe may have started as an animal with a short neck. But after straining to reach high leaves, the animal’s children slowly developed longer and longer necks.
For a long time, we all thought Darwin was right, and Lamarck was wrong. But over last 40 years, epigenetics has started teaching us that the truth may be somewhere in the middle.
“Genes don’t change as a result of the environment,” Cedar told From The Grapevine. “But maybe the environment can affect not the gene, but the methylation.”
Much like DNA, these theories aren’t set in stone. Scientists like Cedar still don’t know for sure how methylation works, and they’re only beginning to understand how it can change DNA. But Cedar maintains the evidence is pretty strong, and that these chemicals plays a big role in our development. When we figure out how all this works, we might be able to cure a variety of diseases.
“Presumably someday, we’ll be able to control something like post trauma,” explained Cedar.
Cedar said if he takes a newborn mouse that’s genetically predisposed to getting cancer and give it a drug to change its methyl groups, then the mouse won’t get cancer.
“Cancer is basically an epigenetic disease,” he said. The stakes are, apparently, pretty high.
“If you think about it, it’s our whole lives,” said Cedar. “How much of what happens to us throughout our life brings about permanent changes that cause disease? We just don’t know.”
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