Siberian permafrost. It's sort of like the huge old chest-type freezer in your grandmother's utility room. It's so big and so full of ancient stuff that every once in a while, digging through the layers, you find a frozen treasure that's been buried so long no one knew it was there.
In Siberia, those frozen finds occasionally include intact woolly mammoths from the last Ice Age. Several have been found in such good shape that they could have been cooked and eaten, except that doing so would be serious scientific sacrilege.
Around 30,000 years ago, during the last Ice Age, Siberia was one of the areas that was not covered by glaciers. That's why so many mammoths lived there, along with fearsome predators like huge short-faced bears and giant saber-toothed cats.
Not to mention less fearsome ground squirrels. These little critters buried caches of seeds underground for the winter. Every so often, someone discovers one of these caches.
Some scientists from the Russian Academy of Sciences got excited about trying to get some of these seeds to sprout. First they tried it the old-fashioned way—simply planting some. Nothing happened. Then they got serious about it. They took tissue from some immature fruit, found intact reproductive cells in it, and cultured those cells in some sort of goop that was mostly sugar. The cells grew into seedlings, which grew into plants that eventually bloomed and produced viable seeds of their own.
The plants are an older incarnation of a current Siberian flower called narrow-leafed campion, or Silene stenophylla if you want to be formal. They have white flowers with five long petals. If you saw one in your yard, you'd probably consider it a weed. It's pretty ordinary looking for being 30,000 years old.
As a haphazard amateur gardener, I found this story both inspiring and discouraging. In my kitchen right now, spread out on a tray with a thin covering of potting soil overlaid with paper towels, are a couple of dozen tomato seeds. They've been sitting there for two weeks now. I've kept them damp. I've kept them warm. I've even talked to them—though it's possible that, "Sprout, damn you, you dried-up little spaghetti sauce wannabes!" isn't working as motivation.
So far, nothing. Not a single sprout. Heck, I can't even see the seeds in there.
I've been trying to persuade myself that this isn't my fault. After all, the seeds are from last year. The expiration date on their packets was October of 2011. They must be too old to sprout.
That theory was working just fine, thank you, until I heard about the 30,000-year-old Siberian flower. Now, the truth has become painfully clear. An extinct Siberian ground squirrel has a greener thumb than I do.
Or maybe I just need to be patient. Maybe these seeds will sprout after all, if I just give them another 30,000 years to mature.
Practical Prairie Woman 
I posted a comment on your Facebook entry, about my experience with an avocado seed this winter. I have sprouted many of them in a glass of water before, but this year, all I got was a glass of stinky water. So your project had company, in it’s aborted attempt.
I have found that the way to get tomato[or any other kind of seed]to sprout and grow is to scatter them where you DON’T want them to be. That way they take off and flourish marvelously, and you can transplant them to the place where you DO want them and they can react accordingly…in most cases, in my experience, with a quick and final wilt. ginny
I really like the “where you don’t want them” approach. I have a theory that the best way to get rid of dandelions would be to find a use for them so they’d be considered a cash crop. They’d immediately become hard to grow.
By the way, the day after I published this, my tomato seeds started to sprout. Apparently public shaming works well, too!