With Epigenetics, Your DNA Can Change Within Your Lifetime

An early competitor to Darwin's theory of evolution by natural selection was Lamarckism. Posed by French scientist Jean-Baptiste Lamarck, the theory said that organisms could pass on characteristics acquired within their lifetimes — giraffes, for example, might stretch their necks as they reach for leaves higher on a tree, then pass those longer necks on to their offspring. Science has since named Darwin the resounding winner of that theoretical battle, but new research suggests that although Lamarck didn't have the big picture right, he may have been onto something. That research deals with epigenetics: the way that outside influences like environment and nutrition can actually change the way your genes are expressed, and pass those changes to your kids.

DNA 'n' Friends

When you think about DNA, you probably imagine that classic double-helix structure that looks like a twisted ladder. What you may not imagine is how that structure exists in your body. Those "ladders" are wound around marshmallow-shaped complexes of proteins called histones, and how tightly they're wound affects how easily the genes in that portion of the DNA can be expressed. Epigenetic markers on the histones influence that winding, and therefore influence gene expression.

At its very basic level, epigenetics is how the exact same DNA that codes for a liver cell can also code for a brain, heart, or blood cell: it turns off a few genes here and turns on a few genes there, and all of a sudden you've got a fully functioning organism made from all sorts of different cells. But at a much more mysterious level, epigenetics may also be the cause of all sorts of changes throughout your life. The research into those effects is still new, but what scientists know so far is pretty intriguing. Exercise, for example, may change the epigenetic marks in muscle and fat cells. The plastic additive BPA may have disease-causing epigenetic effects. The same goes for childhood trauma, which could explain why abuse victims have a higher risk of disease as adults.

Leave Your Lamarck

But is that Lamarckism? Lamarck said that acquired characteristics could be inherited. Is that true of epigenetics? The answer is yes, within limits. Some of the most spine-tingling discoveries about epigenetics involve the effects they have on a person's offspring. The famous Överkalix study from 2002 looked at 300 people who had been exposed to famines in the early 1900s, and found that the amount of food a person had access to as a child influenced their grandchildren's cardiovascular risk. (Surprisingly, famine had a beneficial effect, giving later generations a lower risk of cardiovascular death). Likewise, a 2017 paper published in The FASEB Journal showed that famine could lead to smaller offspring two generations later. Other research suggests that risk of obesity, diabetes, and heart disease could be passed on through epigenetics.

But what's not clear is how long these changes last. One study in roundworms found that epigenetic changes in one generation could last for up to seven subsequent generations. But that's roundworms; an animal that one, lives for less than a year, and two, has genes we can mess with to see the exact mechanisms at work. Humans are much more complex, and when it comes to the changes scientists have seen, we can't rule out undetected DNA mutations or the effects of gut bacteria. Anyway, if Lamarck was right, generations of mice with their tails removed would produce tailless mice (they don't). And even if epigenetics can survive through hundreds of generations, there had to be a driving force behind it — and that force is natural selection.

Epigenetics 101

Key Facts In This Video

  1. The epigenome doesn't change your DNA, but it decides how much or whether different genes are expressed in different cells in your body. 02:02

  2. If your genome (DNA) is the hardware of the computer, the epigenome is the software. 03:24

  3. Some of your epigenetic information is passed from generation to generation. 04:56

Written by Ashley Hamer September 1, 2017

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