Epigenetics: Why Inheritance Is Weirder Than We Thought
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Epigenetics: Why Inheritance Is Weirder Than We Thought

The sweet smell of fruit doesn’t normally
send rats running. But when researchers paired the orange-cherry-almondy scent of the chemical
acetophenone with a painful electric shock, lab rats quickly learned to fear it. Along
the way, extra neurons sprouted in their noses and in the smell-processing center of their
brains, making them super-sensitive to the scent. This result isn’t shocking. What is surprising
is that the rats’ pups – and their pups’ pups – were also startled by the smell of
acetophenone and had the same extra neurons as their fathers, despite never having been
introduced to either their dads or the fruity scent before. But how could the pups have inherited something
their fathers learned? Basic genetics tells us that only DNA gets passed along to offspring;
characteristics like memories, scars, or giant muscles, can’t get passed on since acquiring
them doesn’t alter the genetic code. But it turns out that instilling fear in the rats
did trigger genetic changes – not in the DNA sequence itself, but instead, in how that
code was read and used in the rats’ bodies. In every cell, biological machinery constantly
translates DNA into the proteins needed to carry out vital processes. Chemical switches
attached to the DNA turn genes on and off or up and down, telling the machinery which
proteins to produce and in what quantities. These switches, called “epigenetic tags,”
are why a kidney cell looks and acts differently than a skin or nerve cell, even though the
two cells’ DNA is identical. But the switches in any one cell aren’t
set in stone: teaching those rats to fear that fruity smell switched one of their smell-sensing
gene into overdrive. Researchers don’t know all the places in the rats’ bodies where
this switch got flipped, but they know it happened in one key set of cells: the rats’
sperm cells, which would one day pass along this tweaked genetic material, making the
next generation of rats super-sensitive to acetophenone. Rodents aren’t the only creatures demonstrating
this weird type of inheritance. In Överkalix, Sweden, boys who suffered through tough winter
famines went onto have super-healthy sons, with extremely low risks of heart disease
and diabetes. And their sons’ sons had the same excellent health, living an unbelievable
32 years longer, on average, than the grandsons of boys who hadn’t gone hungry. To be clear, this does not mean we should
start starving our kids for the benefit of future generations – scientists don’t
even know yet exactly which switches the Swedish famines flipped. While we have been able to
connect specific epigenetic changes to health effects in mice, we’re a long way off from
being able to make those connections in humans. That may sound like a bummer, but it’s mostly
because we humans don’t live in the well-controlled environment of a laboratory. And for that,
we should be grateful.

100 thoughts on “Epigenetics: Why Inheritance Is Weirder Than We Thought

  1. I thought epigenetic markers could not be turned off once turned on. Unless you are a type of jellyfish that can do transdifferentiation. That's why stem cells are so special.

  2. Copperheads have a distinct smell (a snake) theirs a ton of them in my area but I dont get fear when I smell it unlike my brother and all my grand fathers

    (I think its because I cant smell well so my brain never learned that the smells a threat

  3. Anyone remember the old days of dank memes like fire building and not eating random berries on bushes? Those aren't memes? Yes they are! You people clearly don't know the dank memes of the old days.

  4. Some humans did live like lab rats — under Nazi doctors like Josef Mengele. What human biochemical discoveries did they make (if any) ?

  5. 2:22
    What I see is a pregnant rat or mouse, not a fat one. Then the human version is a fat human… Wait, what?

  6. to bugs animals are gods to animals humans are gods to us the people we look up to is our God cause we love them

  7. Stop testing on animals! ;-; i feel bad for them, test on humans instead, not only are we the ones that we want to use the information on, but we're pretty overpopulated too.

  8. uuuuh. did they bother to track females?
    males get more genes from their mother than their fathers – Due to how X/Y works
    this experiment seems kinda flawed and bias.

  9. That might explain phobias and fears that can't be explained.  Especially if your parents didn't have them but your grandparents did.  It might skip one generation and then settle in on the next one.  Very, very interesting and food for thought.

  10. I found this video interesting, but I know I wouldn't if my science teacher stretched it out for 2 class periods, instead of 3 minutes. Good job!

  11. There is one mistake in this video.All cells have different DNA,not same.For example,each neuron has 1000 mutations that are not present in neighbouring neurons.

  12. This is why its stupid to reply with "you were never a slave" when African American talk about how the history affects them.

  13. Why would you shock a rat?! You don't need to hurt the poor thing to learn from it! Sorry… But I hope the rat isn't dead, poor thing…

  14. funny story about epigenetics and famine, the dutch honger winter (lit. hunger winter) or winter of hunger in the last winter of WW2 was and is still used for epigenetics research, as it remains the only real winter famine (it has a human cause, but functionally the same) in a relatively well developed (at that time, its much more developed now) country to date

  15. Epigenetics is also why universally, humans typically at the very least turn their nose at the smell of sulfur or excrement. We are alive today because our ancestors knew better than to rummage around and eat things contaminated with those smells, especially in the time before modern medicine.

  16. Scientific dogma, with absolutely zero proof…..where's the proof….With the millions of environmental conditions, or stimuli, that could contain negative consequences, or promote fear, a rat would have to pass half the world on through it's sperm….I suspect something completely different is at play here…..

  17. 0:14 that is like telling an kiddo on a idle_sniper_war to type 'bind e explode' in console 1:07 (incoming another tf2 joke): Achievement get: doc, stock and barrel

  18. Wrong about the building muscle. If family works out through generation it is easier for descendants to gain muscle

  19. I actually have a scar on my forehead that my mom got from chickenpox. I never injured my forehead. I just got that scar from my mom.

  20. Good ol' biology, just as you start thinking you have things figured out, there's an exception or things get more complicated. On the upside, biochemistry is probably the fastest progressing branch of science right now because there is just so much to work with.

  21. Probably why there are so many people afraid of snakes and spiders.  After people saw so many they knew die from just a bite they probably became deathly terrified of those animals and passed down that fear.

  22. Is it safe to say that in human applications, what my grand parents feared that hindered them in their full potential and happiness is also passed down 6 generations later? Reasons why some (Sad to say most) are unhappy with the current situation of their lives and got stuck with no purpose.

  23. Don't starve ur kids for future generations but if u urself want to do ot i think is ok if there is a chance, for thousands of years people have fasted for religion purposes (religious leader made them fast during famine and winter time because there wasn't enough food and they didn't want a revolt against who ever was incharge…) ut fasting at least has benefits plus u get ur body used to spending energy while u have an empty stomach might come in handy…

  24. Does this mean epigenetics is only executed through the male's DNA (though sperm DNA changes), since females are born with all their eggs already?

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