The ancient ice bird
Meet the ice bird, a treasure found under the Siberian permafrost. Love Dalén from Stockholm University told Phil Sansom the story…
Love - Back in 2018 I was part of a research expedition to a place called Belaya Gora in Northeastern Siberia, to go alongside Russian tusk hunters that were searching for mammoth tusks, going into these permafrost tunnels. And while we were there, one of the local Russians came out from one of the tunnels holding something very small in his hand. And it turned out to be a very small bird that looked extremely well preserved.
Phil - What did it look like?
Love - It was a bit dirty and wet, but otherwise it basically looked like a bird that had died just a few days ago.
Phil - Just like an ordinary brown bird?
Love - Yeah. I mean, given that it was partially covered in melted permafrost, which is muddy, it gave a quite sad impression initially, given that it was wet and so on; but it was pretty clear when we cleaned it up that all the feathers were preserved, and the overall shape, and you could see a small injury to its stomach where you could see some of the intestines and stuff like that. So it really looked like something had died only a few days ago.
Phil - Did you give the bird a name?
Love - Initially we had been calling the bird Ice Bird.
Phil - And you didn't know what kind of bird it was?
Love - We didn't know what kind of bird it was, what species it was...
Phil - What did you do to try and figure that out?
Love - We used the feathers to send for radiocarbon dating. This is a method that you can use to very accurately determine the age of an old specimen. It turns out that this part was 46,000 years old.
Phil - That so old!
Love - It is exceptionally old. It's very close to the actual limit of radiocarbon dating.
Phil - Did you figure out what kind of bird it was?
Love - Yep. We then extracted DNA from the bird and sequenced it, and this bird was from a species called horned lark.
Phil - Horned lark...
Love - Which is a small passerine bird that inhabits a large distribution in the Northern hemisphere.
Phil - What was the state of the DNA after 46,000 years in the Siberian ice?
Love - The DNA is in quite poor state. Normally DNA molecules are extremely long, and over time they fragment into smaller and smaller pieces, and this is how the DNA looked in this specimen as well. On top of that, the DNA was also contaminated by DNA from the environment - plants in the sediments, and bacteria that had probably been infesting the bird right after it died, and so on. By sequencing a lot of the DNA in there, we could pick out the few DNA sequences that actually came from the bird itself, and then we could puzzle together the whole mitochondrial genome - the small genome that exists inside the mitochondria, which are the small powerhouses inside all animal cells.
Phil - Did the mitochondria look like the mitochondria of a horned lark today? Or was it like, "clearly this is old mitochondria here"?
Love - This bird is clearly old because it doesn't look exactly like the modern horned larks. Today, horned larks are divided into a large number of different subspecies. And what we could show was that this particular bird actually seems to have belonged to a population that was a common ancestor of two subspecies that exist today.
Phil - So this is before the two species were two; this is the original one?
Love - Yes. Before the two subspecies evolved.
Phil - Does that tell you something about how these two subspecies evolved, or when they evolved?
Love - We think it does. So these two subspecies, one of them lives in Northernmost Russia today, and the other one inhabits the steppe in Mongolia. And so what we think happens is that back during the last Ice Age, the environment was comprised of a bit of a mosaic of different habitat types. And what happened at the end of the last Ice Age was that this mosaic stratified into the big biomes that we know today. So we do think that when the environment itself stratified into these large scale biomes, so did the horned larks, to the North and also to the South.
Phil - How incredible is it that this bird got injured, flew into the ice or something, and then 46,000 years later it's telling you all about how two different subspecies formed?
Love - It's quite amazing, isn't it? That something that old is preserved in such a perfect state. It's a bit like using a time machine where we can travel back in time and look at evolutionary change.
Phil - Maybe it's because I watched Jurassic Park last night, but it feels a bit like that. You know, they found the fly in the amber with the DNA from the dinosaur, and it's just this unbelievable event that tells you a million things.
Love - It really is. Actually one of our colleagues who was with us in Siberia, inside these tunnels, he kept whistling the theme song from Jurassic Park while we were there! Which was quite fitting.