New Data Support Human Arrival In North America 22,000 Years Ago

Imprints of human footprints in light-colored rock
Fossilized footprints in White Sands National Park, New Mexico. Credit: USGS, NPS, Bournemouth University

In 2021, scientists uncovered ancient human footprints in White Sands, New Mexico. Dating of the footprints suggested that people arrived in North America thousands of years earlier than anthropologists had thought. It sparked fierce debate among researchers, some of whom raised concerns about the radiocarbon dating process used in the original study. Now, a new study provides additional data supporting humans’ arrival in North America 22,000 years ago.

Ira talks with Maggie Koerth, editorial lead at Carbon Plan about the latest in this debate about the peopling of North America and other top science news of the week including how solar storms affect bird migration, why ants are getting ensnared in plastic, and how climate change is improving Bordeaux wine.

Segment Guests

Maggie Koerth

Maggie Koerth is a science journalist based in Minneapolis, Minnesota.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow.

Later in the hour, we’re going to dig into a big philosophical question: Is math real? Really, we’ll do that. And we’ll be taking your calls about the math questions you’ve always been too scared to ask, but now no one knows who are so you can ask those questions.

But first, remember that study from a couple of years ago when scientists found human footprints in White Sands, New Mexico– the footprints suggesting that humans arrived in North America some 22,000 years ago– thousands of years earlier than anthropologists originally thought? Remember that?

Well, now there’s a new study that provides additional data supporting this earlier arrival of humans to North America. And in science, of course, we always welcome new data. And sometimes, though, interpreting it means not– well, not so straightforward to do that.

Joining me now to put this find in perspective, along with other science news of the week, is Maggie Koerth, editorial lead at Carbon Plan, based in Minneapolis, Minnesota.

Maggie, welcome back to Science Friday.

MAGGIE KOERTH: Hi, Ira. Thanks for having me.

IRA FLATOW: Nice to have you. OK. Can you parse this for us? What’s in this new study about when people arrived in North America?

MAGGIE KOERTH: Yeah. So this study is, like you say, a redo, meant to appease some critics and offer a little bit more context. And the key change is that they are doing a couple of new dating techniques for these footprints.

The first paper had done radiocarbon dating on seeds from an ancient plant that were found embedded in the footprints. But critics had pointed out that that technique could give you incorrect results if the lake that the plants once sat in had contained a lot of carbon that dissolved out of nearby rocks. The rocks could be really old, but the plants might not actually be.

So this new paper is trying to date the footprints with two completely different methods.

IRA FLATOW: Which are?

MAGGIE KOERTH: First, they are dating grains of pine pollen. Well, first they’re dating grains of pine pollen that were also found embedded in layers of soil in the footprints. And pines don’t go in water. So bada-bing, no carbon contamination.

Then the second thing they’re doing is taking these grains of quartz crystal from a layer of clay just above the footprints, and they’re using a dating technique that basically measures when the crystal structures were last exposed to sunlight.

IRA FLATOW: Wow. This is very creative. It’s interesting to hear. Is this going to end the debate about when humans arrived in North America?

MAGGIE KOERTH: Well, both of them got about the same kind of age range. They’re both in that 22,000 year age range. But it’s probably not actually going to end the debate.

What it does do, I think, is highlight where the debate stands. This is something that’s really been changing and growing in evidence over the last 30 or 40 years.

And you’re in a space now where you’ve got some people who already believe that humans were in North America a lot longer than previously thought. And you have some people who will never be convinced that humans were in America longer than previously thought. And you’ve got a lot of people in the middle, who are looking at this kind of evidence and seeing it build up.

IRA FLATOW: Yeah. Well, we’ll wait for some more evidence to come in. And until that time does happen, let’s move on to birds. Right now, we’re in the midst of fall bird migration. In the past, we’ve talked about some of the things birds are up against as they migrate south for the winter– like tall buildings. But there’s potentially another interesting obstacle in this bird’s way– solar storms. How does that fit in here?

MAGGIE KOERTH: Well, those birds are using the magnetic field of the Earth to guide them when they migrate. So when space weather disrupts Earth’s magnetic field, you end up with the birds getting messed with a little bit as well.

And the weather that we’re talking about here is, of course, metaphorical. It’s not wind and rain in space. It’s the movement of charged particles, radiation, plasma through the solar system. And Earth’s magnetic field is our interplanetary umbrella. The space weather hits that so it doesn’t hit us personally.

But when that weather is bad enough, it can distort the magnetic field in ways that people don’t notice. But now there’s some evidence that maybe birds do notice.

IRA FLATOW: Because they’re navigating by this magnetic field. And then the magnetic field is being influenced by the solar storm.

MAGGIE KOERTH: Yeah. Right. So these scientists were tracking 23 years of bird migrations in the spring and fall. And ironically, they did this using the actual Earth weather radar systems that pick up large amounts of birds flying into the air.

So they used that information and combined it with data about when big space weather was happening. And they found that when the night is dark and space stormy, the birds tend to just sit out and not fly.

IRA FLATOW: Well, that is cool. They’re smart enough to stay home.

MAGGIE KOERTH: Yeah. And we don’t exactly know what’s going on. This is just a correlation that’s been found at this point. We don’t know why space weather grounds the birds. And we don’t even actually know if it does. This could be a false correlation that we just haven’t figured out yet. But it looks like space weather maybe plays a role in what these birds decide to do and when they decide to fly.

IRA FLATOW: Really cool. That’s cool. Let’s go from the sky down into the dirt. And I’m talking about ants. Scientists recently discovered ants that were wrapped in plastic. And I’m not talking about something you buy in the museum shop. Tell me more about what they actually found.

MAGGIE KOERTH: Yeah. So obviously, scientists have known for a long time about the way that plastic can affect sea life and water birds. They get all tangled up. But this is the first documented evidence of terrestrial insects getting trapped in plastic, like a kind of sci-fi substitute for amber.

So these researchers were studying ants in the Canary Islands. And in the course of this other research, they found two that were tangled up in these red and black fibers that were woven around their legs and their bodies. And the fibers turned out to be plastic.

These ants are still alive. The paper says they are still somehow mobile. So unlike these other situations, where researchers have documented injuries or illness caused by plastic pollution in animals, it’s not clear that these ants are being harmed as much as they’re just being deeply inconvenienced.

IRA FLATOW: Ants that are being annoyed. Are they trying to lift up their legs like we would if we’re stuck in something and try to get out of it? I wonder if that’s happening.

MAGGIE KOERTH: I mean, I have to assume, right? I’m imagining a cat with tape on its paws high-stepping around. But this is still a really important finding because it’s documenting just how ubiquitous plastic has become in the environment. We’re talking about these ants in a remote pine forest on a mountain, and there’s plastic there.

IRA FLATOW: Yeah. Let’s stay in the animal kingdom for a bit longer because this next story is about how researchers successfully transplanted a pig kidney into a monkey. Now, they have done that before, but there’s something significantly new here, right?

MAGGIE KOERTH: Yes. Like you said, this is something that’s been done before. And it’s been done before because chronic kidney disease is on the rise. And Americans are seeking these new kidneys at a rate that donations just can’t match. You’ve got 104,000 Americans on the national transplant waiting list, and 86% of them are waiting for kidneys. So this idea of getting to cross-species organ transplants is a big deal.

And what they did in this case is gene editing pig kidneys. So they took these donor pig kidneys, and they stopped them from producing sugars that would normally tell the human body that the organ isn’t one of our kind. And then there was a bunch of other edits they did as well, including ones adding human genes that would prevent organ rejection.

These altered kidneys went into 15 monkeys. And eight of the monkeys lived more than five months. One of them made it past the two-year mark.


MAGGIE KOERTH: And in contrast, monkeys that got non-edited pig kidneys tended to die in less than a month.

IRA FLATOW: So that’s good news, then. I mean, making progress with that.

MAGGIE KOERTH: Yeah. Yeah, it’s definitely the longest that there has been a successful cross-species transplant like this. Like you say, it’s been done in the past, including with brain-dead human patients. But most of the time they haven’t lasted as long as this.

IRA FLATOW: Right. And speaking of genetic data, the company 23andMe, which provides that at-home genetic testing kit, it announced last week that they had been hacked. Have they been hacked? What happened here?

MAGGIE KOERTH: So the bad news is that someone got into a bunch of people’s 23andMe accounts. And they used that access to download information about hundreds of thousands of other users. And they’re now selling it online for $1 to $10 a pop.

But there is some good news here as well. Because it doesn’t look like 23andMe’s actual databases were hacked. The information being sold doesn’t include raw genetic data. And the hackers seem to be playing it up as a bigger, more professionally targeted deal than it actually is, according to an article from Wired.

So the basic gist is that “hacking” is a strong word for what happened. It’s more like these attackers guessed some account passwords based on credentials that had been compromised in attacks on other websites. And so once they were in there, then, they scraped data that 23andMe users had chosen to make visible to other 23andMe users. So it’s things like sex, age, and broad ancestry categories.

And these attackers were claiming that this was a targeted attack on people of Ashkenazi Jewish origin. But the data that’s for sale seems to include a lot of people of Chinese descent as well. And they also said they had celebrity profiles. But some of those celebrity profiles seem to be cut/pastes of each other.

So this was a lot more sloppy and a lot less, I guess, really impressive of a hack than they were trying to make it sound when they were telling people that they’d done it.

IRA FLATOW: I got about a minute left, but I want to end with some unexpectedly good news. Typical climate change stories aren’t really good news. But this one, the changing climate may be a boon for wine growers in Bordeaux, France. Tell me about that.

MAGGIE KOERTH: Turns out wet winters and hot dry summers are becoming increasingly common in southwest France. And that is the ideal kind of situation for making an award-winning Bordeaux wine.

IRA FLATOW: And there you go. Wow. I guess there is some good news. Maggie, always great to have you on the show.

MAGGIE KOERTH: We can toast to the future.

IRA FLATOW: [CHUCKLES] I’m opening a bottle–


IRA FLATOW: –right after the show is over.

Maggie Koerth, editorial lead at Carbon Plan, based in Minneapolis.

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