Is this a perfect morning for you, going out
and looking for elephants? It is. Yeah. This is very recent. No? Well, we got a tree in the middle of the road. Elephant pushed it over looking for palm fruits. Dominique, you think this is elephant damage? Elephant maintenance? Yeah. Elephant maintenance. I like that. Gorongosa National Park in Mozambique is one
of the jewels of southern Africa. If you’re lucky enough to visit, you might
even spot some elephants, although Gorongosa’s elephants have a reputation for being hard
to find. And that’s not the only thing that makes
these elephants different: A lot of Gorongosa’s elephants are tuskless. I’m evolutionary biologist Shane Campbell-Staton,
and my research brought me here in 2017 to try and understand why – and now, years
later, we’re starting to unravel the mystery behind the unexpected and rapid evolution
of these elephants. In this show, we’ll discover how ONE species
– humans – is reshaping the world and determining the future of every other form
of life. And it’s more than just our basic needs
– even our whims have a global impact. We can destroy – and create – at a scale
our world has never seen. So what will be the legacy that defines our
species’ history? This is Human Footprint. This is my friend DOMINIQUE Gonçalves. She runs the elephant ecology project here. Knowing where the park's elephants are is
a big part of her job. But they don't make it easy. Incredible to me that an animal that big can
be so cryptic. And ambush you. Yeah. Can you see it from there? Yeah. I see her. You can hear it. Ma’Ca’Pu You can hear something off in the palms. We have arrived. Welcome to Paradise. When you see them up close, the tuskless elephants
are hard to miss. Female African elephants normally have tusks,
just like the males. But more than a third of Gorongosa’s females
have no tusks at all. To understand what happened, you need to know
a little about Mozambique’s history. Well, you have to remember, Gorongosa was
one of the battlefields. MmmHmm. And a lot of bad things happened in this place
during the war. Dominique is talking about the Mozambican
civil war: a bloody conflict that raged from 1977 to 1992. You can still see the scars of war all over
the park. The driving force of conservation is people. If people are poor, you are not going to succeed. This is Pedro Muagura. Gorongosa’s Park Warden. When he's not managing the park's million-plus
acres of forest, wetland and savanna, he's getting his hands dirty planting trees…and
singing for anyone who will listen. The Gorongosa I'm seeing today is very different
from what existed here before the war. Before civil war, this park was very rich. When we talk about top two in Africa, we're
talking about Serengeti, Gorongosa, Kruger National Park. Pedro’s first experience of Gorongosa was
in 1992 – right after the Civil War. I was teaching forestry and wildlife management,
and I used to come with the students to do animal identification. The problem was, there weren't many animals
left to identify. In terms of mammals. We used to spend 2 to 3 days to view one baboon. To view baboon. I'm not talking about lion. I’m not talking about elephant. The war had devastated the park’s wildlife. When you have war, the first area to be destroyed
is Nature. Protected areas. Forestry. Wild animals here were used like bank. They used to exchange these wild animals’
products with ammunitions, firearms, uniforms. Many species were hunted to provision the
armies with meat. But elephants – with their ivory tusks – were
an even more valuable commodity. Gorongosa’s elephant population crashed
from 2500 to less than 200… a loss of more than 90% in just 16 years. And half the female survivors were tuskless
– nearly three times as many as before the war. Researchers began to think that the intense
ivory poaching during the war had literally changed the face of Gorongosa’s elephant
population. It wouldn’t be unprecedented for hunting
to drive evolution. In fact, one of the earliest measurements
of natural selection in the wild comes from foxes hunted for their furs in Canada. Some foxes carried a genetic mutation, giving
them a silver coat instead of red, making their pelts more valuable. But after a century of hunters targeting these
silver foxes, that mutation became rare. But elephants aren’t foxes. They live for decades and reproduce slowly. Could poaching cause elephants to evolve in
just 16 years? When I arrived in Gorongosa, we knew that
tuskless females, once a rarity, had become more common. Thanks to researchers like Dominique, we'd
also learned that tuskless females often have tuskless female offspring. But no one knew which genes encoded tusklessness,
or whether those genes had undergone natural selection during the war. So we needed elephant DNA. We’re looking for genes that are consistently
different… There it is. Between elephants with and without tusks. And in Gorongosa’s elephants, we found two. One is a gene called AMELx. In humans, mutations in this gene cause a
condition called amelogenesis imperfecta. Women with this condition often don’t develop
their upper lateral incisors, which are the teeth right next to your two front teeth… And in elephants, they’re exactly the teeth
that develop into tusks! Since AMELX differed between tusked and tuskless
females, and it has this known effect in humans, we feel pretty confident that this gene is
part of the reason so many Gorongosa elephants don’t have tusks. After the civil war, tuskless females were
among the last elephants standing And they passed that trait on to their female
offspring, who now live in a population very different from the one their mothers grew
up in. Human hunting really did drive the evolution
of the world's largest land animal. Okay. Are we ready? Let’s rock. Awww yeah. You’ll see once we hit the Urema River. We’ll go up, hopefully get around to the
floodplain. Awesome. That sounds awesome. Also, looking for some elephants, we saw on
the way in earlier. It’s a nice hot day, and these guys love
water. Look at all those ele[phant]s crossing. Oh my God. That’s incredible. They got some little ones with ‘em. Yeah Yeah. There’s some tuskless ladies. Yeah, you can see the one on the right is
tuskless. Yeah. And the one leading up front now. Elephants can't decide whether or not to grow
tusks. But here in Gorongosa, we decided for them. It’s incredible to think that an entire
ecosystem that’s been going for millions of years. And we've come along in 15 years – 15 years
– and fundamentally changed aspects of this ecosystem, it’s absolutely incredible. I think it speaks to the power of who we are
as a species. Seeing the park from above is also a good
reminder that this story isn't just about elephants. Elephants are connected to everything else
here, too. They have an oversized role to play in this
ecosystem, and their tusks are part of that role. The elephants use them to, you know, the tusks
to debark trees, and dig holes and fight the males. And if an elephant can't knock down a tree
or eat properly, how does that have this domino effect all the way to the ecosystem, and then
to us? So there's many, many questions. Questions that Gorongosa’s elephants can
help us answer someday, now that they’re better protected from poaching. Today, at more than a thousand strong, this
population is bouncing back. For me, it’s like how, it shows a lot of
how resilient they are. They carry this past, heavy past, this trauma,
which, you know, makes them extremely aggressive or less tolerant to people. Yeah. To us. But maybe these elephants can sense that they
aren’t being hunted anymore. Okay, everyone, stay quiet. That’s him. You can’t yet prove it, but you can see
that some of them are becoming more tolerant. I don't think they forget. Yeah. An elephant never forgets. But maybe they can be on the road to forgiveness? Yeah, forgiveness, exactly. It's not forgetting, but might be forgiveness. This will never not be incredible. In today's Gorongosa, researchers like Dominique
think that tusks are probably an asset for elephants rather than a liability. So with time… maybe these herds will start
to look like other elephants again. For now, Gorongosa’s tuskless elephants
are a living testament to the power of our species to re-shape nature and even drive
the evolution of the world’s largest land animal. Thanks for watching! If you want more Human Footprint, you can
tune in to the full length series on the PBS App or on your local PBS station. Check out the link in the description to watch
a full episode and to find out more about the show.
