How do scientists know they hooked up?

Summary

This video explores the intricate journey of modern humans, tracing their origins from Africa and highlighting interactions with other ancient species, such as Neanderthals and Denisovans. It reveals how genetics showcases a complex family tree, with modern humans carrying traces of these archaic relatives. The narrative emphasizes the evolving understanding of our ancestry and the research methods that shape these insights. Additionally, the video introduces Ground News, a platform designed to help users navigate diverse news coverage and uncover blind spots in their media consumption, fostering a more informed public dialogue.

Takeaways

• 🧬 Modern humans (Homo sapiens) share genetic material with Neanderthals, with many individuals having less than 2% Neanderthal DNA.
• 🔍 Early interpretations of Neanderthals as primitive ancestors have been challenged by recent research, revealing them as complex beings.
• 🧪 Svante Pääbo's work in extracting and sequencing ancient DNA has been pivotal in understanding human evolution.
• 🔗 Genetic studies indicate significant similarities between Neanderthal and modern human genomes, supporting the idea of interbreeding.
• 🌍 Evidence shows that Neanderthals and Homo sapiens coexisted and interacted in Europe, as suggested by archaeological finds.
• 🗺️ New discoveries, like a baby tooth in France, highlight direct evidence of Neanderthal and Homo sapiens interactions.
• 🔄 The Four-Population test reveals a genetic connection between Neanderthals and non-African modern humans, suggesting historical mixing.
• 🧑‍🤝‍🧑 The complexity of human ancestry includes other ancient humans, such as Denisovans, contributing to our genetic makeup.
• 📚 Ground News is introduced as a tool for comparing how different media outlets cover stories, emphasizing the importance of media literacy.
• 💡 The narrative of human ancestry is evolving, showcasing a messy and interconnected family tree rather than a linear progression.

Q & A

What does the script suggest about the complexity of human ancestry?

The script suggests that human ancestry is much more complex than a simple linear progression, with multiple waves of migration, mixing with different archaic human species, and a 'messy' family tree.

Who are the Denisovans and how do they relate to Homo sapiens?

Denisovans are another type of ancient human found in Siberia, and genetic evidence shows that they also interbred with Homo sapiens, indicating interactions among different human species.

What is the significance of Neanderthals in the context of human evolution?

Neanderthals are portrayed as both close relatives and ancestors of modern humans, representing a separate branch of the human family tree, contributing to our genetic heritage.

What are some outcomes of human migrations mentioned in the script?

Outcomes of human migrations include some groups dying off, others returning, some flourishing, and various populations mixing with unfamiliar groups.

How does the script address the idea of unknown archaic humans?

The script indicates that our genomes may contain traces of additional unknown archaic humans whose remains have not yet been discovered.

What does the term 'blind spot' refer to in the context of news consumption?

'Blind spot' refers to news stories that receive little or no reporting from specific political perspectives, highlighting areas where media coverage may be lacking.

What is Ground News and what features does it offer?

Ground News is a platform that aggregates news stories from various sources, allowing users to compare how different outlets cover the same story, including their political bias and factual accuracy.

How does the script emphasize the importance of research methods in understanding news?

The script emphasizes that there is a lot of nuance and uncertainty in research methods, and complexity is added when discoveries are reported in the news, affecting public perception.

What is the aim of the Howtown channel, as mentioned in the script?

The aim of the Howtown channel is to explore not just what we know about human history but also the various methods we use to discover and understand that information.

How does the script suggest supporting the channel?

The script suggests supporting the channel by signing up for Ground News, which not only helps the viewer navigate the news but also provides a way to support Howtown.

Outlines

00:00

🧬 Exploring Human Ancestry and Neanderthals

The narrator discusses the evolutionary relationship between modern humans and Neanderthals, suggesting that Neanderthals are both distant relatives and part of our ancestral lineage. This perspective emphasizes the complexity and messiness of the human family tree, challenging the conventional understanding of human ancestry. The narrator portrays this view as more realistic and compelling.

05:01

📰 Navigating News Coverage with Ground News

The narrator highlights the significance of understanding how scientific discoveries are reported in the media, particularly in relation to the human ancestry discussion. They introduce Ground News, an app and website developed by Harleen Kaur, which aggregates news from around 50,000 sources. Ground News allows users to compare different outlets' coverage, revealing political biases and factual reliability. An example is provided regarding a study on Neanderthals caring for a disabled child, showcasing how various news outlets interpret the story. The narrator appreciates the 'Blind Spot' feature, which identifies underreported stories from specific political perspectives, encouraging users to explore Ground News for better media understanding.

Keywords

💡Homo sapiens

Homo sapiens, or modern humans, are the species to which all contemporary human beings belong. The video discusses the genetic connections between Homo sapiens and other ancient human species, illustrating that our lineage is not straightforward. For instance, it notes that modern humans share DNA with Neanderthals and Denisovans, emphasizing the complexity of human evolution.

💡Neanderthals

Neanderthals are a distinct group of archaic humans that lived in Europe and parts of Asia until about 40,000 years ago. The video positions Neanderthals as not only our close relatives but also as part of the broader human family tree, stating that they are our 'great uncles' and that many modern humans carry traces of Neanderthal DNA. This inclusion highlights the intertwined nature of human evolution and challenges the notion of clear-cut species boundaries.

💡Denisovans

Denisovans are another ancient human group discovered from fossils found in a cave in Siberia. The video reveals that Denisovans interbred with Homo sapiens, contributing to the genetic diversity of modern humans. This concept supports the video’s theme of a more complex human ancestry, showcasing that multiple human species coexisted and interacted.

💡Genetic mixing

Genetic mixing refers to the interbreeding between different species or groups, leading to a shared genetic heritage. The video underscores this concept by stating that Homo sapiens mixed with both Neanderthals and Denisovans, thus enriching our genome. This notion challenges the traditional view of human evolution as a linear process, suggesting instead a more intricate tapestry of relationships.

💡Archaic humans

Archaic humans refer to early human species that existed before the emergence of modern Homo sapiens. The video discusses how our understanding of these archaic humans is evolving, with evidence suggesting that they may have contributed to the genetic make-up of contemporary humans. This reinforces the idea of human evolution as a shared journey rather than a solitary path.

💡Human family tree

The human family tree illustrates the evolutionary relationships among different human species. The video describes this tree as 'messy' and 'believable,' reflecting the reality that multiple waves of human migration and interbreeding occurred. This complexity challenges simpler narratives about human evolution and emphasizes our interconnectedness.

💡Research methods

Research methods refer to the systematic approaches scientists use to gather and analyze data. The video highlights the importance of understanding how discoveries about human ancestry are made, which can influence public perception and knowledge. This is crucial for comprehending the ongoing nature of scientific inquiry and its impact on our understanding of history.

💡Ground News

Ground News is a news aggregation platform designed to provide users with a comprehensive view of how different media outlets cover stories. The video introduces Ground News to illustrate the challenges of navigating biased media coverage and the importance of diverse perspectives in understanding current events. This tool helps viewers recognize their own media blind spots and promotes critical consumption of news.

💡Political bias

Political bias refers to the inclination of news outlets to favor a particular political perspective in their reporting. The video discusses how Ground News allows users to see the political bias of various sources, helping them to better understand the news landscape. This concept is essential for viewers to critically assess the information they consume and to become more informed citizens.

💡Blind Spot feature

The Blind Spot feature of Ground News identifies news stories that are underreported or overlooked by certain political perspectives. The video emphasizes this tool as a means for users to broaden their understanding of current events by exposing them to viewpoints they may not encounter in their usual media consumption. This encourages a more holistic view of news and fosters critical thinking.

Highlights

The fossil record has revealed multiple waves of human migration out of Africa, showcasing complex patterns of survival and intermixing.

Neanderthals are identified not just as separate species but as part of the human family tree, being our 'great uncles' and also ancestors.

Recent studies indicate that modern humans interbred with Neanderthals and Denisovans, adding layers to our genetic heritage.

Denisovans, a previously lesser-known group, also mixed with Homo sapiens, further complicating our understanding of human evolution.

Genetic analysis shows evidence of unknown archaic humans, indicating that our evolutionary history is still being uncovered.

The depiction of the human family tree is now recognized as much messier and more interconnected than previously thought.

Howtown channel focuses on not just knowledge but on the processes used to uncover and understand scientific discoveries.

Ground News, developed by a former NASA engineer, helps users navigate news stories by providing comparative analyses of coverage.

Ground News aggregates news from around 50,000 sources, highlighting different perspectives and biases in media reporting.

The platform provides a visual breakdown of news stories, including coverage spectrum and ownership, to enhance understanding.

The 'Blind Spot' feature in Ground News helps users identify areas of underreported news, broadening their media consumption.

Insights into how different media outlets spin stories illustrate the importance of understanding bias in reporting.

The discussion on Neanderthals caring for a disabled child showcases the complexity of social behaviors in ancient human relatives.

Highlighting compassion and altruism in Neanderthals suggests that these traits may have ancient origins.

The overall narrative emphasizes the significance of staying informed and aware of different media biases for comprehensive understanding.

Transcripts

There's a secret in my family history,

and I'm not talking about my childhood

teddy bear addiction.

The truth was revealed a few years ago

thanks to genetic testing.

I have Neanderthal ancestors.

So it looks like

I have less than 2% Neanderthal DNA.

Interesting. Okay, I want to look at mine.

Okay.

It says less than 2% of my DNA.

But it's more than 31% of other customers.

There's growing scientific consensus that Joss

and I and every human on earth

has a little bit of DNA

passed down from ancient liaisons with a creature

who was once considered

a completely separate species.

The amount of Neanderthal DNA

you have depends on where your roots are.

But as we ask in every Howtown episode,

how do they know?

How did they figure that out?

It's a remarkable story.

Scientists had to reach back in time

and read the genetic code of people who died

50,000 years ago,

and then decrypt secret messages

hidden inside our living cells.

And their discoveries have rewritten

the established history of our species.

In 1856, in the Neander Valley of Germany.

Some miners unearthed this partial skull

along with a few other bones.

Scholars took a look at the remains and announced

that this was a new type of human.

Other bits

and pieces turned up from Spain to Siberia

in caves, in pits, sometimes fused into walls.

One of the skeletons

inspired this artist reconstruction,

which was widely published in 1909.

It helped popularize

a very specific image of Neanderthals

that survives to this day.

That early illustration was labeled

one of our first ancestors.

It was easy for readers

to imagine that this Neanderthal,

who could not assume

the upright position of the superior races,

was the uncivilized progenitor of the clever

skater on the same page.

But almost all of this turned out to be wrong.

For one thing,

the illustration’s reference skeleton

belonged to an old Neanderthal

with terrible arthritis.

Most of them actually stood up straight.

Plus, Neanderthals

weren't even around 20,000 years ago.

They went extinct several

thousand years before that.

And scientists

started debating

whether Neanderthals

were our evolutionary grandparents

or more like our distant great uncles.

The second theory was supported by the location

and timing of the remains.

Neanderthal bones

were found across this area

and dated to this time period.

Meanwhile, bones that looked like modern humans,

Homo sapiens, were found in Africa.

The oldest was around 200,000 years old.

This doesn't look like Neanderthals

gave rise to Sapiens.

This looks like two distinct populations

evolving separately on their own continents.

At some point, a group of sapiens left Africa,

and around the same time

they were spreading across the globe.

The intervals disappeared where Homo

sapiens and Neanderthals

were found in the same site.

The Neanderthals were always buried deeper,

separated by soil and time.

It looked like Team

Great Uncle was winning the debate.

But to really prove this,

they had to get their hands

on some Neanderthal DNA.

If you wanted to send a message

50,000 years into the future,

you wouldn't write that message in DNA.

There's so many things that can rip it to shreds.

Heat and light and moisture

and bacteria and even our own enzymes.

Ancient DNA is really low quality

and very difficult to work with.

And so you can't just take your run of the mill

molecular biology techniques

that you would use with modern DNA

and apply them to ancient samples.

But geneticists have slowly developed

new techniques.

In the 1980s, they coaxed a little DNA

out of a taxidermied quagga

that had died 140 years earlier.

They sequenced just 229 base pairs,

the letters of the genetic code.

Two years later, an enthusiastic Swede named

Svante Pääbo

published a paper on the DNA

he had collected from the face of a 2500 year

old mummy.

Meanwhile, DNA sequencing was swiftly improving.

Researchers who claim to have extracted DNA

from ancient insects

trapped in amber.

Suddenly, anything seemed possible.

Welcome

to Jurassic P--

But those amber results couldn't be replicated.

They are most likely just sequenced

some modern DNA

that had made its way into their samples.

And this contamination is a huge problem

for anyone trying to work with ancient DNA.

So if I touch the bone

and I sweat, I can transfer some DNA from my hand

to the bone

and the amount of DNA

that that will transfer

and can be like a million times more

than the DNA that is preserved inside.

Even Pääbo’s mummy DNA was questioned,

so he set out to eliminate sources

of contamination

using careful protocols that are now standard.

I have a whole clean suit that covers my entire

self a mask, hairnet, double gloves,

the whole nine yards.

Most of the people,

when they see us walking in that room, it's like,

oh my God, something dangerous is happening.

But we are actually protecting the sample.

I take actually a dentistry drill,

and I first clean off the surface

to remove potentially any of that contamination.

And after removing that first layer,

I then start to collect

small amounts of bone powder.

By the 2000, a more experienced

and cautious

Pablo embarked on an ambitious new project

sequencing the entire Neanderthal genome all

3.2 billion base pairs.

His team collected DNA from these

three shards of Neanderthal bone

that had been tucked in a cool,

dark Croatian cave for millennia.

Now, bone doesn't contain much DNA, even in life,

but DNA from the decomposing body

can seep into the bone

matrix and get stuck there.

And so Pääbo’s team was able to extract

and sequence a bunch of ancient DNA,

but it wasn't in great shape.

Those molecules that I'm getting out of

my bones are highly degraded, fragmented.

The chromosome will be like

hundreds of millions of bases

of units of DNA.

I got like a 30 to 50

bases. If a chromosome were enlarged

the length of the Boston Marathon,

These fragments

would be the size of a single baked bean.

And I try to find where they actually match,

like a puzzle.

It seems like really hard to know

if you're dealing

with such small fragments of DNA,

to know

that they are actually coming from the organism

that you want it to be coming

from, versus from a human,

or a bug or a microbe or something

that was just around. Exactly.

And in fact,

they think that most of the DNA

that they're getting is from microbes.

Assembling the entire Neanderthal genome

would be like solving a 20 million piece

puzzle with a bunch of other puzzles mixed in.

And there's no picture on the box.

They didn't have a full Neanderthal genome

to reference.

But they did have two recently completed genomes.

Sapiens and chimpanzees both come from a common

ancestor, splitting into two groups

millions of years ago.

The bundles of DNA in our cells, chromosomes,

look very similar.

And if you zoom in,

there's a different base, a different letter,

every 80 positions on average.

If you looked at the two of us,

it would be about every thousand base pairs

we'd have something different.

So there's still a fair amount of variation

just between individuals.

Since the Neanderthal-Sapiens split

is much more recent than our split with chimps,

you'd expect them to be pretty similar to us.

And you could use both genomes

as a reference, seeing

where little bits of Neanderthal DNA best line up.

This puzzle,

lining up method is how they can tell that

we're at least talking about a hominid and not a

microbe, right?

So the microbe pieces

aren't going to line up and overlap nicely.

It's a tedious process,

but of course, computers speed up the busywork.

In 2010, they published the first draft

of three full Neanderthal sequences.

As expected,

they were similar to ours,

with just one difference

every 600 positions on average.

Okay, so that shows that we're

we're related to them,

which I guess probably wasn't really disputed.

We knew we were related to them, just like

we know we're related to chimpanzees.

But to say that our ancestors

interbred with them seems like a different thing

that requires

more proof than just kind of showing

these similarities on the genome.

Totally.

We're back to that big question, grandpa versus

great uncle.

How did they figure out that our ancestors

knocked boots with Neanderthals?

The initial evidence came from something

called the Four-Population test.

We've got chimps and Neanderthals,

and then we can split Homo sapiens

into two groups:

The ones who stayed in Africa,

and those who left relatively recently

to live in Neanderthal territory.

I'll just switch to a logarithmic scale

so it's easier to see.

In most spots in the genome,

all four populations will have the same base

inherited from our common ancestor.

If you have a mutation here before the split,

you'd expect all three of these groups

to have that same change.

But if there was a mutation here,

you'd see that change only in Neanderthals.

When they compared the genomes, though,

there were a surprising number of places

where Neanderthals and Non-africans

shared the exact same change.

And there were often

several of these matches

in the same stretch of DNA.

Though it's possible that two identical mutations

could arise by chance

in Neanderthals and Sapiens,

you would expect

to see the same number

of coincidences in both sapiens groups,

not much more frequently in the group

that happened to visit Neanderthal territory.

Let me make sure I understand the logic of this.

Yeah.

So they find these similarities between us

and Neanderthals.

If our similarities with Neanderthals

could be attributed

to our common ancestry with Neanderthals,

then we would see those traits kind

of equally distributed across modern humans.

But instead,

they see a difference

in the amount of relatedness based on

whether the people's ancestors stayed in Africa

versus left into the part of the world

where Neanderthals were.

And thus the most obvious explanation

is that they were interbreeding.

Yeah, it is very suspicious, to say the least.

The scientists who made this

discovery were, in their own words,

strongly biased against the possibility

of Neanderthal interbreeding.

So they were deeply suspicious of their own data.

But the more they tested their conclusions,

the more data they gathered, the stronger

the evidence became that

people of Eurasian descent have Neanderthal DNA.

I remember learning somewhere

that different species

usually can't produce offspring that are fertile.

Yeah.

Is there an explanation for why that wouldn't

be the case here?

Well, the explanation is sort of

that “species” is a made up idea.

It's a squishy category and especially

within this research,

they don't really like to talk about species.

We are not using the term species anymore.

Even population gets difficult

now. We are using like lineage,

different human lineage or different human group.

We don't know how to define a species.

We don't know

how many

difference in the genomes

would make you a different species.

We don't even want to try to do it.

There's a lot of evidence that,

there might have been

some fertility issues

when these groups interbred.

But obviously it wasn't enough

to stop the mixing entirely.

They must have tried really hard.

They tried

really hard or enough times that it worked out.

But yeah, I mean,

all of these researchers

call Neanderthals “humans.”

The term “human” is a broader

term than just Homo Sapiens.

A few years ago,

a new paper offered evidence that all modern

human populations have Neanderthal DNA,

including Africans.

Instead of relying on a comparison of DNA

from different populations,

this study looked at the length of stretches

of DNA that matched Neanderthals.

Why would length be significant?

While chromosomes tend to get mixed up over time,

the child of a Neanderthal and a Sapien

would have one set of chromosomes

from each parent.

But in that child,

those chromosomes get slightly scrambled.

And with each generation that passes,

like the pulses of a food processor,

the continuous blocks of Neanderthal DNA

get smaller and smaller.

So longer length means more recent

influence.

So you can look through modern genomes

for stretches of Neanderthal flavored DNA

that aren't too short, which suggests

that they entered

the genome more recently through interbreeding.

Scientists

use this logic

in a more recently sequenced genome

that was higher quality to find shared DNA

between Africans and Neanderthals.

Part of the explanation

is that some sapiens must have picked up

some Neanderthal DNA in Eurasia,

and then migrated back into Africa.

That all leaves us with a new mystery.

Genetics strongly

suggests that interbreeding happened.

But we don't have any evidence from archeology

that Neanderthals and Sapiens ever

interacted until now.

A recent discovery, for the very first time,

gave us a glimpse of a specific moment

when and where these two groups crossed paths.

It all hinges on three clues: a single baby tooth,

a pile of stone blades,

and the smoke of ancient campfires

trapped in stone.

And like many mystery stories,

this one starts

with an enigmatic European detective.

The skull is an empty box.

It won't tell you anything of what

is in the brain of this population

and who they were.

If you want to understand the Neanderthal,

well you have to read the Naked Neanderthal.

Or you have to do, like me,

to spend 50 years in caves

trying to understand this incredible creature.

Since the 1990s, Ludovic has been excavating

a rock shelter in the Rhone valley of France.

When you're working in the cave,

you are entering it and living in a time capsule.

Several time capsules

release several distinct layers of Earth.

The top layer is relatively recent and contains

remnants of Stone age sapiens.

Further down, Ludovic found a set of teeth.

It's the most complete series of teeth

we ever found on Neanderthals.

So far, we're following that familiar pattern

a Sapien layer above, Neanderthals below.

In most of the layers,

they found Neanderthal teeth.

But in this layer, layer E, was a single

baby tooth that looked Homo sapien.

And it just looks like a human tooth.

Or do they have any molecular way

to confirm that it's a human tooth? Right.

So unfortunately, this exposed,

you know, rock shelter

wasn't the best place to preserve DNA.

So they had

previously tried to get DNA out of animal bones

that were in the same layer,

and they weren't able to get the DNA out of it.

It was too degraded.

And so they were like,

it's not worth it to destroy this tooth,

just to see if we can get DNA

when we probably won't be able to.

But they also know the exact measurements

and proportions

of features of Neanderthal and Sapien teeth.

The baby tooth

definitely fell into the Sapien category,

but it was in rough shape.

When this baby tooth discovery was made

some people were a little suspicious.

They're like, what can we say for sure?

It looks like a human tooth,

but is there so much damage

that maybe it's hard to tell.

But Ludovic didn't

just find teeth in these layers.

We have millions of objects.

The bones they left from the animals

they were hunting, the flint

they were making their tools with that.

If you study these tools, and Ludovic

has literally

looked at millions of them in his career,

you start to notice a key difference

between Homo sapiens and Neanderthals.

Some of these Neanderthal craft

can be really impressive

in terms of technologies,

but each of them is unique.

You have an incredible creativity,

and on the other side,

among Homo sapiens population,

you have an incredible efficiency,

an incredible standardization.

It's very boring.

We don't like any kind of transgression.

We must be all together doing the same thing.

In layers D and F.

Ludovic found lots of varied Neanderthal tools

in layer E, the baby tooth layer,

there was something different.

Careful measurements

revealed those boring standardized points.

They looked just like the tools found in Sapiens

settlements all the way over in Lebanon.

Together with the tooth

that's compelling evidence that the people from

layer E were Homo sapiens.

Okay. But even if it's there

and it's sandwiched

between two Neanderthal layers,

that could just mean that, you know, different

people visit

this place at different times in history, right?

And they could be separated

by hundreds, if not thousands of years.

The tools they use to date,

these things aren't very precise.

If you find, like a skeleton in your backyard

and you want to know how old it is, radiocarbon

dating would be great at telling you

if it's 20,000 years old or 20 years old.

But when you get specific, if you found

a Neanderthal skeleton and a human skeleton

that had lived a thousand years

apart from each other,

they might still look like

they had the same age using this technique.

It's like if yesterday

you were eating with Caesar

on your left and Charlemagne on your right.

And so this is what I mean “contemporary.”

It's contemporary at the scale of 2000 years.

It's good

for getting a general picture of things.

But when you want to say,

hey, did these two people meet?

It's pretty much impossible to use that tool.

So researchers turned to this new method,

one that I think is so ingenious.

Right next to the stone tools and bones,

they found lots of little rocks

that had chipped off the ceiling,

and they had bits of soot from ancient

campfires trapped inside.

When you cut them and when you polish them,

it can sometimes smell of burnt wood.

And sometimes it smells like

like a barbecue, like meat.

Whoa, whoa.

Ooh. Just that smell is preserved.

Yeah. in this rock.

And then you cut it open and you could smell it.

Exactly.

So the smell can be preserved.

The soot had drifted up to the ceiling

and then was sealed in place as calcium

crystals formed new rock over it.

During the rainy season,

more water

seeps through the rock, carrying more dissolved

calcium, and bigger crystals form.

In the dry season, smaller crystals.

So you can actually see this annual cycle

and count the years in these layers of rock.

A little bit like tree rings.

And when you look at it under the microscope,

you're just like,

oh my God, there's 20 different layers.

And each one of these soot traces

represents an occupation event.

And so you have a kind of a barcode.

Collecting all the ceiling fragments

in one layer gives you a bunch of these barcodes.

It's pieces of a puzzle.

And we have to build the puzzle.

And just like the DNA puzzle, computers can help

line up all these barcodes

to create a continuous history.

Here's that history for layer F, a Neanderthal

layer, and here's

the one for the baby tooth layer, Layer E.

Incredibly, they overlap.

Between the last Neanderthal fire

and the first Sapiens fire,

the rock recorded just one seasonal cycle.

That was really surprising.

It wasn't just less than a human generation,

it was estimated to a year.

There on that specific territory,

we have the two populations, not more or less

a thousand years,

Not with Charlemagne

and Julius Caesar,

but in terms of the true life of a person.

These two groups

must have known about each other.

Maybe they even watched each other

from this rock shelter.

Wow.

What must of that have been like?

It's just a hint of an encounter,

one without any suggestion of interbreeding,

and one that we'll need more evidence

to convince the skeptics.

But our genomes tell us that moments like this

must have happened many times.

There's a new sort of picture forming.

Instead of this pure line of Homo

sapiens marching out of Africa,

we now have a much more chaotic family

story, with multiple waves of humans

leaving the continent,

sometimes to die off, sometimes to return,

sometimes to flourish,

and sometimes to mix with strangers.

And not just with Neanderthals.

Scientists found the remains of another type

of ancient human in a Siberian cave,

and genetics showed

that these Denisovans also mixed with sapiens.

And there's growing evidence that our genomes

contain traces of even more unknown archaic

humans, ones

whose remains we haven't even found yet.

And the Neanderthals?

They are our great uncles

from a different branch.

But they're also among our great,

great, 2000-times-great grandparents.

This picture of the human family

tree is much messier,

and I think much more believable.

Howtown is a channel that's not

just about what we know,

but the different ways we figure stuff out.

And if you like that,

you can support us by signing up for our Patreon.

There's a lot of nuance and uncertainty

when it comes to research methods,

and there's a whole other level of complexity

that gets added

when those discoveries are reported in the news.

That's where the sponsor for this video comes in.

Ground news. Ground news.

What is that?

So Ground

News is a website and app developed by a former

NASA engineer named Harleen Kaur.

It gathers

news stories from like 50,000 different sources,

so you can compare how different outlets

cover the news.

So I feel like as a news consumer, it's very hard

to navigate all of the different stories.

How would something like this

make that easier for me?

It gives you some more metadata basically.

For every story you've got

this visual breakdown of who covered the story,

where they land

on this spectrum of political bias.

You can see how factual those outlets tend to be.

And who owns them.

And all that info is coming from these three

independent news-monitoring organizations.

I see.

But let me just show you what it looks like.

Neanderthals in Spain care for a disabled child

with Down Syndrome, study finds.

I never saw that headline.

This is, I guess two months ago

this news came out.

This allows you

to see how the different outlets

sort of put their spin on the news.

So a lot of the--

The abortion angle.

So the National Review has an abortion angle.

The left-of-center news

outlets are talking a lot

about how compassion and altruism

are this ancient thing. I think

the thing that I like the most about Ground News

is they have this Blind Spot feature.

You know,

it's very easy

for us to be in our little media bubbles.

On the top, it says “for the left.”

So that means for the people on the left,

this is where you would go to see

what your blind spots are?

Exactly. News stories that had little

to no reporting on the left.

I think this is a good tool

for understanding the news,

which is of course one of our goals.

So if you want access to this tool,

you go to ground.news/howtown

to get 40% off their Vantage plan,

which is the one that I have access to.

If you support them, it's a way of supporting us.