Tag Archives: mammoths

Episode 320: More Elephants

Thanks to Connor and Pranav who suggested this week’s episode about elephants! It’s been too long since we had an elephant episode and there’s lots more to learn.

Further reading:

Asian elephants could be the maths kings of the jungle

Many wild animals ‘count’

A big difference between Asian and African elephants is diet

Study reveals ancient link between mammoth dung and pumpkin pie

The Asian elephant (left) and the African elephant (right):

The African bush elephant (left) and the African forest elephant (right) [photo taken from this page]:

The osage orange is not an orange and nothing wants to eat it these days:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

We haven’t talked about elephants since episode 200! It’s definitely time for some elephant updates, so thanks to Conner and Pranav for their suggestions!

Conner suggested we learn more about the Asian elephant, which was one we talked about way back in episode 200. The biggest Asian elephant ever reliably measured was a male who stood 11.3 feet tall, or 3.43 meters, although on average a male Asian elephant, also called a bull, stands about 9 feet tall, or 2.75 meters. Females, called cows, are smaller. For comparison, the official height of a basketball hoop is 10 feet, or 3 meters. An elephant could dunk the ball every single time, no problem.

The Asian elephant used to live throughout southern Asia but these days it’s endangered and its range is reduced to fragmented populations in southeast Asia. There are four living subspecies recognized today although there used to be more in ancient times.

Elephants are popular in zoos, but the sad fact is that zoo elephants often don’t live as long as wild elephants, even with the best care. The elephant is adapted to roam enormous areas in a family group, which isn’t possible in captivity. In the wild, though, the elephant is increasingly endangered due to habitat loss and poaching. Even though the Asian elephant is a protected species, people kill elephants because their tusks are valuable as ivory. Tusks are a modified form of really big tooth, and it’s valuable to some people because it can be carved into intricate pieces of art that can sell for a lot of money. That’s it. That’s the main reason why we may not have any elephants left in another hundred years at this rate, because rich people want carvings made in a dead animal’s tooth. People are weird, and not always the good kind of weird.

In happier Asian elephant news, though, a 2018 study conducted in Japan using zoo elephants replicated the results of previous studies that show Asian elephants have numeric competence that’s surprisingly similar to that in humans. That means they understand numbers at least up to ten, and can determine which group of items has more or less items than another group. That sounds simple because humans are really good at this, but most animals can only understand numbers up to three. It goes one, two, three, lots.

Many animals do have a good idea of numbers in a general way even if they can’t specifically count. Gray wolves, for instance, know how many wolves need to join the hunt to successfully bring down different prey animals. Even the humble frog will choose the larger group of food items when two groups are available. But the Asian elephant seems to have an actual grasp of numbers. I specify the Asian elephant because studies with African elephants haven’t found the same numeric ability.

Elephants make a lot of sounds, such as the iconic trumpeting that they make using the trunk. Way back in episode 8 we talked about the infrasonic sounds elephants also make with their vocal folds, sounds that are too low for humans to hear. But the Asian elephant also sometimes makes a high-pitched squeaking sound and until recently, no one was sure how it was produced. It turns out that the elephant makes this sound by buzzing its lips the same way a human does when playing a brass instrument. It’s the first time this particular method of sound production has been found outside of humans.

This is what a squeaking Asian elephant sounds like:

[elephant squeak]

Pranav suggested we learn more about the African forest and bush elephants. Those are the two species of African elephants that are still alive, and they’re also endangered due to habitat loss and poaching. The forest elephant is critically endangered. The forest elephant lives in forests, as you probably guessed, especially rainforests, while the bush elephant lives in grasslands and open forests. It’s sometimes called the savanna elephant since it’s well adapted to life on the savanna.

The forest elephant is only a little larger on average than the Asian elephant, while the bush elephant is much bigger on average. A big bull bush elephant can stand as much as 13 feet tall, or 4 meters, which means it might not dunk the basketball every time because the basketball hoop is awkwardly low.

The bush elephant lives in areas where it’s often extremely hot and dry. Since large animals retain heat, the bush elephant has many adaptations to stay cool. Its ears are really big, for instance, and have lots of blood vessels. This means the blood is close to the surface of the skin where it can shed heat into the air. In hot weather the elephant can flap its ears to help cool its blood faster. But one big adaptation has to do with its skin. The bush elephant’s skin is covered with what look like wrinkles but are actually crevices in the skin only a few micrometers wide. The crevices retain tiny amounts of water that help keep the elephant cool. Since elephants don’t have sweat glands the way people do, they have to bathe in water and mud to get moisture in the crevices in the first place.

Elephants are megaherbivores, meaning they eat mega amounts of plants. This has an impact on forest dynamics, but until recently the only studies on elephant diets and ecological effects were on African elephants. A 2017 study on Asian elephants in Malaysia found that instead of mostly eating sapling trees, the elephants preferred to eat bamboo, grasses, and especially palms.

In comparison, the African bush elephant eats plant parts that other animals can’t chew or digest, including tough stems, bark, and roots. It also eats grass, leaves, and fruit. The African forest elephant eats a lot more fruit and softer plant parts than the bush elephant, and in fact the forest elephant is incredibly important as a seed disperser. Seeds that pass through the forest elephant’s digestive system sprout a lot faster than seeds that don’t, and they also have the added benefit of sprouting in a pile of elephant dung. Instant fertilizer! At least 14 species of tree need the elephant to eat their fruit in order for the seeds to sprout at all. If the forest elephant goes extinct, the trees will too.

Around 11,000 years ago, when the North American mammoths went extinct, something similar happened. Mammoths and other megafauna co-evolved with many plants and trees to disperse their seeds, and in return the animals got to eat some yummy fruit. But when the mammoths went extinct, many plants seeds couldn’t germinate since there were no mammoths to eat the fruit and poop out the seeds. Some of these plants survive but have declined severely, like the osage orange. It produces giant yellowish-green fruits that look like round greenish brains, and although it’s related to the mulberry, you wouldn’t be able to guess that from the fruit. Nothing much eats the fruit these days, but mammoths and other megafauna loved it. The osage orange mostly survives today because the plant can clone itself by sending up fresh sprouts from old roots.

Another plant that nearly went extinct after the mammoth did is a surprising one. Wild ancestors of modern North American squash plants relied on mammoths to disperse their seeds and create the type of habitat where the plants thrived. Mammoths probably behaved a lot like modern elephants, pulling down tree limbs to eat and sometimes pushing entire trees over. This disturbed land is what wild squash plants loved, and if you’ve ever prepared a pumpkin or squash you’ll know that it’s full of seeds. The wild ancestors of these modern cultivated plants didn’t have delicious fruits, though, at least not to human taste buds. The fruit contained toxins that made them bitter, which kept small animals from eating them, because the small animals would chew up the seeds instead of swallowing them whole. But the mammoths weren’t bothered by the toxins and in fact probably couldn’t even taste the bitterness. They thought these wild squash were delicious and they ate a lot of them.

After the mammoth went extinct, the wild squash lost its main seed disperser. As forests grew thicker after mammoths weren’t around to keep the trees open, the squash also lost a lot of its preferred habitat. The main reason why we have pumpkins and summer squash is because of our ancient ancestors. They bred for squash that weren’t bitter, and they planted them and cared for the plants. So even though the main cause of the mammoth’s extinction was probably overhunting by ancient humans, at least we got pumpkin pies out of the whole situation. I mean, I personally would prefer to have both pumpkin pie AND mammoths, but no one asked me.

World Elephant Day is on August 12, and this episode is going live in late March. That means you have a little over four months to get your elephant celebration plans ready!

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 256: Mammoths and the End of the Ice Ages

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Further reading:

Million-year-old mammoth genomes shatter record for oldest ancient DNA

Mammoth Genome Project (with pictures of cave art and ancient carvings of mammoths)

The most famous cave painting of a mammoth, from a cave in France:


Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

It’s the last Monday of 2021, which means the very last extinction event episode. There’ve been way more extinction events in earth’s long history than the five we’ve covered this year, and not all of the extinction events I chose to highlight were even necessarily the biggest. This one, for instance.

You may have noticed a pattern when I talk about ice age megafauna. So many animals went extinct about 11,000 years ago. That’s this week’s topic, the end-Pleistocene extinction event.

The Pleistocene is often called the ice age, or ice ages since it consisted of multiple glaciation periods separated by warmer times when the glaciers would retreat for a while. It started roughly 2.6 million years ago and is considered to have ended 11,700 years ago. Keep in mind, as always, that these dates are just a shorthand to help scientists refer to changes in earth’s history. There was no one day where the sun rose and everything had abruptly changed from one era to another. The changes took place over a long time, hundreds of thousands of years, with different parts of the world changing more quickly or slowly than others depending on local conditions.

At the beginning of the Pleistocene, the world’s continents were roughly in their present positions. Two continental plates in what is now Central America collided very slowly over millions of years, which caused the land to buckle up and magma to erupt through the earth’s crust as volcanoes. The volcanoes created islands in the Central American Seaway, a section of ocean between North and South America that connected the Atlantic and Pacific Oceans. By around 5 to 10 million years ago, the volcanoes and land continued to be pushed up, and sediment from rivers filled in between them, until finally instead of islands there was actual land that connected North and South America. That land is called the Isthmus of Panama and it allowed the great American interchange where animals from North America could cross into South America, and vice versa, but that’s a topic for another episode.

Another result of the Isthmus of Panama’s formation is that the Atlantic and Pacific Oceans were more separated. Instead of ocean currents circulating between North and South America, they were cut off and new currents formed. Ocean currents help distribute warm water to colder areas and cold water to warmer areas, which affects air and land temperatures too. Around 2.5 million years ago, the ocean current changes had changed the entire overall temperature of the earth, making it much cooler overall. That wasn’t the only cause of the ice ages, but it was a major factor.

The earth gradually became cooler and dryer, a process that had already started due to other causes and was accelerated by the ocean current changes. As the global temperature dropped, more and more water was locked up in huge glaciers called ice sheets, at first around the poles and then farther south. This meant sea levels dropped a lot. North America was connected to Asia by a stretch of grassland steppe called Beringia that had formerly been submerged.

As the temperatures dropped and the climate changed, animals and plants had to adapt. The ancestors of modern elephants had lived in Africa for millions of years, but they started migrating to other parts of the world around 3 million years ago. Because they were already big, they were good at retaining heat in their bodies and became quite successful as the climate grew cooler and cooler. They evolved long hair to stay even warmer and spread throughout much of the world, including Europe, Asia, and North America. You may know them as mammoths, which were closely related to the modern Asian elephant. The first mammoth known was the South African mammoth that lived around 5 million years ago and stood about 12 feet tall at the shoulder, or 3.7 meters.

We actually know a lot about the various species of mammoth because we have so many remains. Our own distant ancestors left cave paintings and carvings of mammoths and other animals in many parts of the world, we’ve found lots of fossilized remains, and we have lots of subfossil remains too. Because the mammoth lived so recently and sometimes in places where the climate hasn’t changed all that much in the last 10,000 years, namely very cold parts of the world with deep layers of permafrost beneath the surface, sometimes mammoth remains are found that look extremely fresh.

Before people understood extinction and related natural concepts, some people who lived in areas where dead mammoths occasionally weathered out of the permafrost thought they’d only died recently. That’s how fresh the dead animals looked. The people didn’t know what the animals were, though, and assumed that since they were only ever seen partially buried, they must be underground animals. In parts of Siberia, people thought mammoths lived underground and if they accidentally came to the surface, they died.

In February of 2021, a genetic study of mammoth DNA found in teeth was published in Nature. Nature is one of the most important scientific journals in the world and they don’t just publish any old genetic study these days, now that DNA is so much easier to sequence than it used to be. In this case, though, the DNA came from three mammoth teeth that were more than one million years old and possibly around 1.5 million years old. The teeth were found in the 1970s in different places. Before DNA was successfully found in the teeth, the oldest DNA sequenced was from a horse bone that was about 780,000 years old at the most.

Genetic material breaks down relatively quickly once an animal dies, becoming more and more fragmented as the years pass by. That’s why we don’t have any dinosaur DNA—they just lived too long ago for any usable genetic material to remain. The mammoth genetic study is a big deal since it’s pushed back scientists’ ability to sequence ancient DNA, at least of some samples. In the case of both the mammoth teeth and the ancient horse bone, the remains were preserved in permafrost that slowed the fragmentation of the DNA.

The study found that one of the teeth belonged to an early woolly mammoth and the other two were from early steppe mammoths, but it’s not as simple as it sounds. The two steppe mammoth teeth looked alike but their genetic story was very different. One had genetic markers that identified it as an ancestor of woolly mammoths–but the other didn’t. The one that didn’t is called the Krestovka sample and was found in Russia. Researchers aren’t sure yet if it’s actually a new species or subspecies, but it was obviously part of a population isolated from other steppe mammoths.

But it gets even more complicated, because Columbian mammoths from North America do show that some of their ancestors were related to the Krestovka sample–and Columbian mammoths are also related to woolly mammoths. Researchers suspect that the Columbian mammoth was a species that developed from hybrids of the Krestovka steppe mammoths and woolly mammoths. Over half a million years ago, there were enough of these hybrid mammoths that they were actually numerous enough to form their own stable species. Hybrid speciation is still a relatively new concept but as genetic studies get more sophisticated, we’re getting more evidence of it happening.

Researchers are hopeful that even older genetic samples can eventually be sequenced, but there’s a hard limit to DNA found in permafrost. That limit is 2.6 million years, which is when the permafrost began forming. And that brings us back to the ice age.

Mammoths weren’t the only animals adapted to cold conditions, of course. They weren’t even the only elephant lineage that adapted to the cold. Mastodons aren’t actually that closely related to mammoths but they are an elephant relation.

The woolly rhinoceros was about the size of living rhinoceros species but was covered in thick fur. It had a massive hump on its shoulders that was made up of fat reserves and muscle, much like modern bison. It went extinct about 10,000 years ago.

A giraffe relation, Sivatherium, lived in Africa and parts of Asia during the Pleistocene. Its neck wasn’t as long as a modern giraffe’s but it was still tall, over 7 feet tall at the shoulder, or more than 2 meters, and almost 10 feet tall including the head and neck, or 3 meters. The males had two pairs of ossicones that resembled antlers, a large pair on its head and a smaller pair over its eyes. Ossicones are bony projections usually covered with skin and hair, and modern giraffes have ossicones too.

Mammals weren’t the only megafauna, though. Mega just means big, and fauna just means animal. There were megafauna birds and reptiles too, such as the Asian ostrich. It lived throughout much of Asia and the Middle East until around 8,000 years ago and was related to the modern ostrich. The wonambi was an Australian constrictor snake, not related to the snakes living in Australia now, that could grow up to 30 feet long, or 9 meters.

So what happened to cause the extinction of all these amazing animals? Surely we know more about this extinction event than we do about older ones since it happened so recently, right?

Actually, no. Although it feels significant to us now, the end-Pleistocene extinction event actually wasn’t very big compared to the others we’ve discussed this year. A lot of ice age megafauna are still around, including bears, wolves, moose, reindeer, horses, bison, elephants, giraffes, lions, tigers, camels, kangaroos, tapirs, ostriches, condors, and lots more. Even humans are ice age megafauna since we spread throughout the world during the Pleistocene.

We do have hints of what might have caused the end-Pleistocene extinction event, and one big hint comes from what happened in Australia. Like the rest of the world, Australia’s climate was cooler and dryer during the ice ages and animals that had adapted to the cold lived throughout the continent. This included diprotodon that we talked about in episode 224, along with kangaroos, wombats, koalas, and other marsupial mammals that were bigger than the ones living today. But extinctions in Australia started a lot earlier than they did in the rest of the world, around 45,000 years ago. There’s also no corresponding extinction event among marine animals. By about 40,000 years ago almost 90% of all species of Australian megafauna had gone extinct, while smaller animals and marine animals were mostly just fine.

One specific event that happened around 45,000 years ago was the colonization of Australia by humans. Humans had visited and even lived in Australia as far back as 70,000 years ago, but by 45,000 years ago they were really spreading throughout the land. The animals of Australia had never encountered smart, fast tool-users before and didn’t know what to do except try to avoid them. Humans had weapons like spears that could kill at long range, and humans worked together to kill animals that before then had no predators due to their size. Humans also drink a lot of water because we developed in a part of Africa where water is abundant. Fresh water isn’t nearly as abundant in Australia, so humans would stake out water sources and keep other animals away.

The Australian extinctions were probably a combination of climate change, humans hunting large animals that reproduced slowly, and humans outcompeting animals for water sources. The same causes probably led to extinctions in other parts of the world, but because humans took longer to spread to continents like the Americas that are far away from Africa, those extinctions mostly took place later than in Australia. It’s also important to note that Africa showed almost no extinctions at the end of the Pleistocene. Researchers think this is because the animals of Africa evolved alongside humans and knew how to deal with us.

Natural climate change was definitely a contributing cause to the extinctions, though. Ice sheets melted, glaciers retreated, and the world warmed over the course of just a few thousand years. Animals that were well adapted to the cold had to move to places where it was still cold, but those places didn’t always have the right foods or enough food. The sea levels rose too, cutting off access to parts of the world. Beringia became covered with ocean again, for instance, where it remains today, separating Asia from North America.

Humans probably finished off the mammoths by hunting the last ones to extinction, but some populations survived much later than the 10- to 12,000 years ago commonly given as their extinction date. There were still mammoths alive in the world only 4,000 years ago and maybe only 3,700 years ago—but only on an island where humans didn’t live.

Wrangel Island is located in the Arctic Ocean near western Siberia, more than 85 miles from the nearest coast, or 140 km. It has low mountains and sea cliffs and is cold and dry most of the year, which is the kind of climate mammoths preferred.

The woolly mammoths that lived on Wrangel Island were probably cut off from the mainland when sea levels rose and flooded Beringia. They lived on for thousands of years after their mainland relations had gone extinct. Gradually the mammoths became more and more inbred, leading to genetic defects at a much higher rate than in a healthy population. Even so, the mammoths might have managed to survive even longer except for one thing. Around 1700 BCE, humans arrived on the island. Shortly afterwards, the mammoth was extinct.

Wrangel Island is a nature sanctuary these days and home to lots of animals, including polar bears, walruses, Arctic foxes, seals, reindeer, musk ox, and wolves. All of these are considered ice age megafauna, so although the mammoths are gone, other megafauna remain.

While we don’t know for sure that humans played a big part in the end-Pleistocene extinction event, we sure didn’t help. We can’t blame our ancient ancestors for their actions but we can learn from their mistakes. We’re in the middle of another extinction event right now, often called the Holocene extinction or Anthropocene extinction, directly due to our actions. Habitat loss, pollution, overhunting, and human-caused climate change are driving more species of animal and plant to extinction every year.

It can feel overwhelming, but there are lots of small things you can do to help. Just picking up trash and putting it in the waste bin or remembering to take your reusable bags to the grocery store can make a difference. No one person can fix all the world’s problems, but if everyone does a little bit to help, the big problems get smaller and more manageable. If everyone pitches in, we can make the world a cleaner, better place for animals and for people.

Happy new year! Let’s make it a great one!

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!