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Your Extinct Cousin LOVED Eating Grass
Your Extinct Cousin LOVED Eating Grass
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0:00
In 1959, researchers unearthed a skull of one
0:03
of our ancestors that was… pretty baffling.
0:05
Not only was this head very hefty for its body size,
0:08
but the skull had a big ridge along the top,
0:11
and its dramatic cheekbones flared out from the sides of its face.
0:14
On top of that, this guy had a big jaw that housed some
0:17
exceptionally large molars, larger than any other hominin.
0:21
It was this mouthful of jumbo-sized chompers
0:24
that earned the skull its nickname: Nutcracker Man.
0:27
And the more we dug up on this archaic ape,
0:29
the more questions we seemed to have about it.
0:31
So we really had to take a long hard look at some
0:33
big hard teeth to unravel at least some of the mystery.
0:37
Here is the full story of our mysterious nut-cracking cousin.
0:42
[♪INTRO]
0:44
Let’s not get too far ahead of ourselves.
0:46
The first weird member of this branch of the family tree
0:49
was found decades before Nutcracker Man hit the scene.
0:52
The first skull in the group was described in 1938 by a famed,
0:56
and famously racist, paleontologist Robert Broom.
1:00
And a couple of decades later, Louis and Mary Leakey found
1:03
the similar, but even more extreme Nutcracker Man skull,
1:07
which was eventually lumped together with the
1:09
first skull into a genus called Paranthropus.
1:12
Broom’s skull is from the species Paranthropus robustus,
1:15
and Nutcracker Man is from Paranthropus boisei.
1:18
They both appeared on the scene over 2 million years ago,
1:22
but in different places. Robustus has only been found in
1:25
Southern Africa while Boisei called Eastern Africa home.
1:28
They have another cousin called Paranthropus aethiopicus,
1:32
which hung out in the same region as Boisei.
1:35
But we don’t have as much fossil evidence of that one,
1:37
so it doesn’t get as much attention.
1:39
There are a few features that we know unite all
1:41
the Paranthropus species together in their weird group.
1:44
They each sport a big sagittal crest, which is
1:47
the ridge that runs along the top of the skull.
1:49
They also all have huge flared zygomatic arches,
1:52
meaning really big cheekbones.
1:54
These two areas of the skull are where the chewing-and-chomping
1:57
related muscles called the masseter and temporalis muscles attach.
2:01
And theirs were far beefier than ours. Let me show you.
2:05
Put your fingers on your temples, like this.
2:07
Now clench your teeth together a few times, like this.
2:09
Feel those muscles? That's the temporalis at work.
2:12
It connects from the side of your head down into your jaw.
2:15
Feel along with your fingers as you clench to the side of your face,
2:19
and now you're on the masseter. Working together,
2:21
these muscles pull your jaw up and back with force enough to chew.
2:25
Because these muscles touch so many areas of the skull,
2:28
the size and shape of the bones can reveal a lot
2:30
about a particular specimen’s facial muscles,
2:33
even when the muscles themselves are long gone.
2:35
The bigger the muscle attachment zones,
2:37
the stronger the maximum bite force would be.
2:40
Which brings us to Paranthropus and its signature mohawk.
2:43
Not only did Paranthropus have chewing muscles that went
2:46
all the way to the top of the skull, they needed this ridge of bone
2:49
to anchor them, which means they had massive jaw muscles.
2:54
On top of a muscle-y face, these Paranthropus skulls
2:57
had robust jaws that held some gigantic molars.
3:01
P. boisei’s teeth were especially dramatic,
3:04
not only in their giant size but also in how thick the enamel was.
3:08
Boisei first earned the nickname Nutcracker Man after
3:11
the classic Christmas decor because, well, look at it.
3:15
But it wasn’t just a superficial comparison.
3:18
Researchers initially thought that these guys must have eaten
3:20
hard foods like nuts, using their oversized and extremely strong
3:24
molars combined with all that muscle power to crack hard shells.
3:28
That said, their diet has been puzzled over for quite some time,
3:32
since not everyone was sold on this dietary direction.
3:35
The cracks really began to appear in this nutcrunching hypothesis
3:38
once researchers took a deep dive into the surface damage on
3:41
their teeth, which can indicate what texture of foods were eaten.
3:45
For example, you’d expect to see pits in their enamel if they spent
3:48
a lot of time crunching down on hard objects, like in a nut-based diet.
3:52
Researchers didn’t just want to look at tooth texture though.
3:55
They also analyzed the stable isotopes in the tooth enamel.
3:58
Isotopes are essentially different forms of the same chemical element.
4:02
The isotopes in our food, and the food of our food,
4:05
get incorporated into our own bodies,
4:07
making their way into our tooth enamel during childhood.
4:10
And this can reveal a lot about diet.
4:12
Grasses use a type of photosynthesis called C4, and woody plants
4:16
like trees and shrubs use a different pathway called C3.
4:20
Each pathway has a specific isotope signature.
4:23
Since nuts grow on trees, you’d expect a species
4:25
that ate a lot of trail mix to have a strong C3 signature.
4:29
But after a deeper dive into Nutcracker Man's mouth,
4:31
the results ended up, well, not particularly nutty!
4:34
Instead of pits they found long parallel grooves in the teeth of P. Boisei,
4:40
indicating that they chewed softer plant matter,
4:42
and not hard stuff like nuts and seeds.
4:45
Not only that, but their tooth enamel showed
4:46
that the majority of their plant-based diet was made up of C4 plants,
4:51
meaning they appeared to spend most of
4:52
their time browsing on grasses and reeds!
4:54
More puzzling still, they uncovered some significant
4:57
dietary differences between P. boisei and P. robustus.
5:00
Robustus had a lot more of the C3 isotope signature,
5:04
which meant they likely dined on a wider range of vegetables,
5:08
and weren’t so focused on grass grazing.
5:10
They also found differences in their dental damage.
5:12
Tooth chipping was really only showing up in robustus.
5:16
This provided more evidence that they likely had a little
5:18
more diversity in their diet than boisei, including harder foods.
5:22
So robustus really did eat crunchy stuff like
5:25
seeds, nuts, and roots, at least some of the time.
5:27
So even though boisei had bigger molars than robustus,
5:31
they didn’t appear to use them to chew down on hard foods.
5:34
Which means we’re still left with a lot of questions about what they ate.
5:37
Some think their nutcracker setup simply
5:39
allowed them to eat what’s called fallback foods.
5:42
Basically, they might have only needed to eat nuts
5:44
when they couldn’t find their favorite staples.
5:46
In those situations, they needed the chewing equipment so they
5:49
were always prepared for a crack-in-case-of-emergency situation.
5:53
Which could be the case, but we just don’t
5:54
have enough evidence to back that up.
5:57
But diet isn’t the only mystery left to solve about this ancient ape.
6:00
As bizarre as this big toothed primate might appear,
6:03
we knew it was still essentially an evolutionary cousin of ours.
6:07
And even if we have a rough idea of where they fit on our family tree,
6:10
it’s taken a lot more work to figure out how they
6:13
measured up to the rest of their contemporary cousins.
6:15
We humans are in the great ape group Hominini,
6:18
which includes today’s chimpanzees and bonobos.
6:21
And despite an extreme lack of fossils from their past,
6:24
we know the split from our modern ape relatives
6:26
happened sometime between 9.3 million and 6.5 million years ago,
6:31
thanks to DNA evidence.
6:32
But the hominin family tree is really more like a bush with a lot of
6:36
side branches and offshoots that didn’t make it to the modern day.
6:38
Which means that the hominin club
6:40
also includes a lot of extinct species,
6:42
like those in the genus Australopithecus,
6:45
as well all the early human species in the Homo genus.
6:48
And even though our early homo ancestors also
6:51
differed a lot from Paranthropus, especially dentally,
6:54
they’re still a close branch off in terms of our ancestry.
6:57
So as it currently stands, we’re pretty sure Paranthropus also falls
7:00
directly into our tribe, even if we couldn’t ever share hats, or dentures.
7:06
We know that some species of Homo, Paranthropus,
7:08
and Australopithecus were all alive and well at the same time,
7:12
around 2 million years ago.
7:13
Which isn’t all that long ago in the grand scheme of things.
7:16
And while we may not have figured out
7:17
complex dentistry yet at that point in history,
7:20
we do know that early Homo species were already tool-makers.
7:23
But it's hard to know if Paranthropus
7:25
also had that particular skillset, too.
7:27
That’s largely because, even when we have
7:29
found hand fossils from this time period,
7:31
we’ve never been able to confirm exactly
7:33
who those hand bones belonged to.
7:36
There were some sites where both tools and Paranthropus fossils
7:39
were found in close proximity, but that doesn’t necessarily
7:42
mean our big-toothed cousins were the artists behind the tools.
7:45
So while some suspected that they were making and using tools
7:48
alongside their relatives, there just wasn’t enough to go on.
7:51
But in 2025, literally while we were making this video,
7:54
a paper came out that described foot and hand bones from a
7:58
single specimen found alongside boisei teeth and skull fragments
8:02
that add some new evidence pointing in the tool-use direction.
8:05
This discovery revealed that boisei had very strong,
8:07
and very human-like hands, complete with long
8:11
and dextrous thumbs and fingers.
8:12
And yes, a powerful and accurate grip is also associated with
8:16
climbing abilities and not necessarily specific to tool use.
8:19
But the accompanying foot fossils tell us these guys were likely
8:22
spending much of their time with their feet firmly planted on the ground.
8:26
So if they weren’t using their strong grippers for climbing,
8:29
the next best option would be tool-making… right?
8:32
Well, maybe.
8:33
See, we know gorillas use their strong hands to break and
8:37
tear the outer layers of tough plants to get to the juicy interior,
8:41
so this could be why boisei needed strong hands too.
8:44
So perhaps the diet that gave them tough teeth,
8:47
also went hand in hand with, well, tough hands.
8:50
Which brings us to some of the other
8:52
lingering questions about Paranthropus.
8:54
Like, researchers have been pretty divided on who’s
8:57
really who in this genus, and how each of them should be split.
9:01
When it comes to figuring out who’s who in the fossil record,
9:04
it can be really hard to tell whether a bunch of
9:06
fossils all belonged to the same species, or multiple.
9:09
And with something like Paranthropus, where skulls can look really
9:12
different from one another, that question gets even more spicy.
9:15
This is a lot trickier than you might think thanks
9:17
to something called sexual dimorphism,
9:19
where the males and females of a species
9:21
look different from one another.
9:22
In some species like gorillas, this can be a massive size difference.
9:26
Now, assuming that a fossil ancestor of ours is a bit dimorphic
9:29
isn’t that far-fetched, because sexual dimorphism
9:32
is definitely common in a lot of apes, living and long gone.
9:35
Sexes often differ most dramatically in their size,
9:38
with males typically having a larger body size overall.
9:40
Males typically also have bigger teeth,
9:42
and have noticeably large canines.
9:44
In a species with canine size dimorphism,
9:47
one look at the canines is usually all you
9:49
need to tell what sex the individual was.
9:51
This dimorphism isn’t a hard and fast rule for all apes though,
9:55
and we’re a great example of that, since humans
9:57
lost some of that dimorphism over millions of years.
10:00
Trouble is, we don’t know when that trend kicked off,
10:03
so there’s no way to know if Paranthropus
10:06
would have been like us, or more like other apes
10:08
Plus, it’s not always easy to tell whether
10:10
your fossil was a Fred or a Freda.
10:12
And to make an argument about sexual dimorphism,
10:15
knowing what sex you’re looking at is a big deal.
10:18
So if we wanted to confirm that the variation within
10:20
Paranthropus is truly dimorphism, we need a way to actually
10:23
make a strong argument about what sex the different fossils were.
10:27
And while that’s a tricky task, there are ways to do it.
10:30
A big one starts in the mouth.
10:31
See, there’s evidence that even when our ancestors lost
10:34
the differences in canine tooth size,
10:36
the size of the root may still be dimorphic,
10:39
meaning males have longer canine roots than females do.
10:42
So looking at canine root size can help estimate the sex of individuals,
10:46
at least when they’re at the extreme ends of the scale.
10:49
This even works for modern humans.
10:51
But you also need a big sample size
10:52
to get the most accurate estimates.
10:54
And even with a lot of teeth to pull from,
10:57
it’s still only really helpful to infer things about the outliers both big
11:01
and small. When there’s size overlap in the middle, it’s much harder.
11:05
Luckily, researchers are now able to use a new technique
11:08
called paleoproteomics to solve this particular puzzle,
11:11
by recreating the DNA of a fossil whose DNA is completely decayed.
11:16
Basically, when you find a protein in a fossil,
11:18
you can reverse engineer what the
11:20
DNA code that made that protein was.
11:23
A 2025 paper published in Science used
11:25
paleoproteomics to look in Robustus’s dental enamel
11:29
for something called AMELY-specific peptides.
11:33
This type of protein signature comes from
11:35
a gene that only exists on the Y chromosome.
11:38
AMELY- specific peptides have a correlate on the
11:42
X chromosome called, surprisingly, AMELX-specific peptides.
11:46
But since everybody has at least one X chromosome,
11:49
finding AMELX alone can’t prove that the tooth came from a female.
11:53
It’s always possible that there were AMELY-specific peptides,
11:57
but that the sample didn’t pick them up for some reason.
12:00
The paper found that two of the four teeth they looked at had
12:03
AMELY-specific peptides, meaning that they came from males.
12:06
The other two teeth from this study didn’t have any AMELY,
12:10
but they did have more AMELX than the other teeth did.
12:14
The researchers argue that these teeth came from females,
12:17
though this conclusion isn’t as rock-solid as it is for the male teeth.
12:20
Interestingly, the two male teeth were on the small side for what
12:24
you might expect from that sex, and one had even previously
12:27
been thought to be female, based on its measurements alone.
12:30
The researchers even suggest that this little male tooth is such an
12:33
outlier that it could represent a new sub-population of Robustus,
12:37
or even a different species.
12:39
So it’s kind of the perfect case study for that “different sexes
12:43
or different species” question that we’ve been exploring.
12:45
All that said, this study was only looking at a very small set of proteins,
12:48
so it’s not enough for us to go back
12:50
to the drawing board on Paranthropus species.
12:52
So when it comes to Nutcracker Man and the rest of the Panthropus,
12:56
we now know a lot more about them than we did even just a decade
12:59
or two ago, but the jury’s still out on a lot of details of their lives.
13:02
Were they capable of making tools like the early members
13:05
of the genus Homo that they crossed paths with?
13:08
How closely related were these Paranthrops
13:10
to our past relatives, and even to each other?
13:12
And if not for cracking nuts,
13:14
what is really up with their big ol’ chompers?
13:16
In other words, how many nuts would Nutcracker Man crack,
13:20
if Nutcracker Man cracked nuts?
13:21
There are definitely a lot of questions still swirling
13:23
around these generously jawed marvels,
13:25
but now you know at least a little more
13:27
about one of your oddest-looking relatives.
13:34
[♪OUTRO]
