MALE NARRATOR: It was a typical autumn day in 2018 when two fishermen set off into the waters of Lough Neagh in Northern Ireland.

As they pulled up their net, they noticed something different among all their freshly caught fish-- something very large and very strange.

It was a catch of epic and ancient proportions, one that had not been seen by human eyes for thousands of years.

They had dragged up a beautifully preserved skull and antlers of megaloceros giganteus, an extinct beast more commonly known as the Irish elk.

Now, those two fishermen certainly weren't the first people to encounter megaloceros.

The fact is the archeological record is full of evidence that our ancestors lived alongside and interacted with these giant mammals for millennia.

But what happened when they did interact, when humans met this megafauna?

Did we perhaps love them to death, or is it possible that the megaloceros simply lived too large?

[MUSIC PLAYING] Megaloceros was one of the largest members of the deer family ever to walk the earth.

Despite being called the Irish elk, it's actually not very closely related to either of the two species known as elk today.

Instead, it's closest living relatives seem to be either the red deer or the fallow deer.

But we actually know a great deal about what megaloceros probably looked like in life because it inspired our human ancestors to immortalize it in art.

It often appears in cave paintings dating to the late Pleistocene epoch, most famously in Lascaux and Cougnac caves of France.

We know these figures represent megaloceros because of the one detail that the Ice Age artists took pains to capture-- the animal's enormous antlers.

Thanks to these depictions, we know a lot of other details about megaloceros that otherwise we'd never would've known.

Like, that it had dark stripes that contrasted with its pale head and neck, and attached to its shoulders was a distinctive hump probably made of fat because it's not on that skeleton.

And of course, there were the antlers.

At their largest, the antlers of megaloceros giganteus could reach 3.7 meters wide and way up to 45 kilograms.

Even today, it holds the record for having the largest antlers of any deer species.

Most experts believe that those giant features were used as a signal fire during mating season, which resulted in natural selection pressures for larger antlers.

But the antlers weren't just prized by females.

They may have also been important for humans in many parts of the world because these giant deer weren't only found in Ireland.

Megaloceros actually lived throughout Europe, northern Asia, and northern Africa and was used by different people in different ways.

Many archeological sites have been found with fragments of antlers that were modified by humans for their use.

Take, for example, the site known as Wulanmulun in Nei Mongol China.

The site dates back somewhere between 30,000 and 70,000 years ago.

And there, tools have been found that were made from the antlers of megaloceros, including things like a hammer.

Meanwhile, at sites in Spain and France from just over 30,000 years ago, we found more antler fragments that were modified by humans.

And interestingly enough, these fragments appear to have been made from antlers that have been shed, having fallen off before regrowing again the next summer.

This implies that humans may have scavenged and collected the antlers, rather than just hunting the deer for them.

And one of the most unique and frankly coolest artifacts made from megaloceros material is an intricately carved dagger from around 7,000 years ago recovered from a peat bog in Russia.

But along with providing material for tools, megaloceros may also have had a special less tangible significance for humans.

Some experts think that their frequent appearance of megaloceros in cave art and in unusual archeological contexts, like deep within caves, suggests that his antlers and bones could have been used in shamanistic religious rituals.

So if these animals were so valuable to our species, then what happened to them?

What went so wrong for megaloceros?

Well, as is the case with many extinctions, the precise cause or causes are still up for debate.

The most popular hypothesis is known as the antler theory and it places the blame on the very thing that made megaloceros so fascinating and memorable.

This idea was first suggested in 1830 by an Irish physician named John Hart, who thought that the massive size of the antlers must have required an equally massive amount of blood to grow and maintain.

Once the antlers were shed, he thought there would have been such a rush of blood back into the brain that males may have suffered seizures or strokes.

Another idea from the same period was that the antlers were so big that megaloceros would have constantly gotten tangled up in trees or bodies of water, causing them to either starve or drown.

But most of these theories predate the publication of Darwin's On the Origin of Species in 1859, so they don't take into account the concepts of natural selection and adaptation.

So by the 1930s, most of these early hypotheses were challenged using allometry, the study of the relationship between body size, shape, and growth rate.

And these studies found that the antlers of megaloceros grew in proportion with the rest of their bodies, so it's not like the headgear got too big to handle.

But that doesn't mean that those huge features still weren't a big problem.

In the 1990s, a new version of the antler theory emerged, and it's one that scientists actually agreed with.

This model suggested that megaloceros required a lot more nutrients than other megafauna and that might have contributed to their downfall.

Because of their antlers, megaloceros would need a consistent supply of both calcium and phosphorus in order to restore the nutrients that they lost during growth and shedding.

So any slight decline in their food supply would have enormously impacted their ability to survive.

In addition, the amazing size of the antlers may have made sexual selection very exclusive.

If only the males with the very largest antlers were being selected, then the species as a whole might have suffered a fatal drop in genetic diversity.

But if megaloceros had been so successful for thousands of years, then why would its antlers suddenly have become such a drag?

As with so many things, the demise of the megaloceros seems to be ultimately about timing.

During their heyday in the Pleistocene epoch, they thrived in extremely cold environments, often living through periods of glaciation, followed by a slight warming.

But in the late Pleistocene, as the climate started to change, megaloceros populations became increasingly restricted to modern-day Russia.

This is likely because the open grazing lands that had once sustained them were now turning into dense forests that the species struggled to survive in.

And that brings the antler theory back into play.

As the Pleistocene faded, megaloceros, which was mainly a grazing species, lost its ideal environment for feeding.

Populations began to dwindle, especially given that males needed a lot of nutrients to support their oversized headgear.

And to make matters worse, the newly forested environment may have made it difficult for deer with larger antlers to get around, which may have also displaced some of the population.

So perhaps, because of the combination of high sexual selection and the dwindling population of large antlered males, birthrates began to drop.

But the death blow might have been the hunting habits of our own human ancestors who likely had a taste for megaloceros.

For example, remains of megaloceros from an early Holocene site in Russia show clear evidence of having been butchered.

According to recent radio carbon data from other remains found in Russia, megaloceros had completely disappeared around 7,600 years ago.

But since then, many more specimens have been discovered, including many that were fished out of Irish peat bogs where the oxygen-poor environment kept the bones well preserved.

And it's not just the remains that have been preserved for all of these years.

Depictions of megaloceros in art and folklore throughout history have kept their memory alive as well.

For example, Irish poet Seamus Heaney used the imagery of a megaloceros skeleton being recovered from a bog as part of a series of poems about the famous bog bodies of Ireland.

And megaloceros also graces the Northern Irish coat of arms to this day, representing the natural environment of the country.

Whether in body or spirit, the so-called Irish elk continues to capture our imaginations.

And like our ancestors thousands of years ago, we continue to keep them alive through stories and art, reminders of the time when we met this majestic megafauna.

Thank you for joining me in this Konstantin Haase studio.

If megafauna are your thing, then check out our episode Life, Sex, and Death Among the Dire Wolves.

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