Episode 348: Australopithecus and Gigantopithecus

Thanks to Anbo for suggesting Australopithecus! We'll also learn about Gigantopithecus and Bigfoot! Further reading: Ancient human relative, Australopithecus sediba, 'walked like a human, but climbed like an ape' Human shoulders and elbows first evolved as brakes for climbing apes You Won't Believe What Porcupines Eat Past tropical forest changes drove megafauna and hominin extinctions An Australopithecus skeleton [photo by Emőke Dénes - kindly granted by the author, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=78612761]: Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. It’s officially monster month, also known as October, so let’s jump right in with a topic suggested by Anbo! Anbo wanted to learn about Australopithecus, and while we’re at it we’re going to talk about Gigantopithecus and Bigfoot. On our spookiness rating scale of one to five bats, where one bat means it’s not a very spooky episode and five bats means it’s really spooky, this one is going to fall at about two bats, and only because we talk a little bit about the Yeti and Bigfoot at the end. In 1924 in South Africa, the partial skull of a young primate was discovered. Primates include monkeys and apes along with humans, our very own family tree. This particular fossil was over a million years old and had features that suggested it was an early human ancestor, or otherwise very closely related to humans. The fossil was named Australopithecus, which means “southern ape.” Since 1924 we’ve discovered more remains, enough that currently, seven species of Australopithecus are recognized. The oldest dates to a bit over 4 million years old and was discovered in eastern Africa. Australopithecus was probably pretty short compared to most modern humans, although they were probably about the size of modern chimpanzees. A big male might have stood about 4 ½ feet tall, or 1.5 meters. They were bipedal, meaning they would have stood and walked upright all the time. That’s the biggest hint that they were closely related to humans. Other great apes can walk upright if they want, but only humans and our closest ancestors are fully bipedal. In 2008 a palaeoanthropologist named Lee Rogers Berger took his nine-year-old son Matthew to Malapa Cave in South Africa. Dr. Berger was leading an excavation of the cave and Matthew wanted to see it. While he was there, Matthew noticed something that even his father had overlooked. It turned out to be a collarbone belonging to an Australopithecus boy who lived almost 2 million years ago. Later, Dr Berger’s team uncovered more of the skeleton and determined that the remains belonged to a new species of Australopithecus, which they named Australopithecus sediba. More remains of this species were discovered later, including a beautifully preserved lower back. That discovery was important because it allowed scientists to determine that this species of Australopithecus had already evolved the inward curve in the lower back that humans still have, which helps us walk on two legs more easily. That was a surprise, since A. sediba also still shows features that indicate they could still climb trees like a great ape. It’s possible that Australopithecus, along with other species of early humans, climbed trees at night to stay safe from predators. In the morning, they climbed down to spend the day mostly on the ground. One study published only a few weeks ago as this episode goes live suggests that the flexible shoulders and elbows that humans share with our great ape cousins originally evolved to help apes climb down from trees safely. Monkeys don’t share our flexible shoulder and elbow joints because they’re much lighter weight than a human or ape, and don’t need as much flexibility to keep from falling while climbing down. Apes and hominins like humans can raise our arms straight up over our heads, and we can straighten our arms out completely flat. Australopithecus could do the same. The study suggests that when another human ancestor, Homo erectus, figured out how to use fire, they stopped needing to climb trees so often. They evolved broader shoulders that allowed them to throw spears and other weapons much more accurately. Australopithecus probably mostly ate fruit and other plant materials like vegetables and nuts, along with small animals that they could catch fairly easily. This is similar to the diet of many great apes today. The big controversy, though, is whether Australopithecus made and used tools. Their hands would have been more like the hands of a bonobo or chimpanzee, which have a lot of dexterity, but not the really high-level dexterity of modern humans and our closest ancestors. Stone tools have been found in the same areas where Australopithecus fossils have been found, but we don’t have any definitive proof that they made or used the tools. There were other early hominins living in the area who might have made the tools instead. We also don’t really know what Australopithecus looked like. Some scientists think they had a lot of body hair that would have made them look more like apes than early humans, while some scientists think they had already started losing a lot of body hair and would have looked more human-like as a result. There’s no question these days that Australopithecus was an early human ancestor. We don’t have very many remains, but we do have several skulls and some nearly complete skeletons, which tells us a lot about how our distant ancestor lived. But we know a lot less about a fossil ape that lived as recently as 350,000 years ago, and it’s become confused with modern stories of Bigfoot. Gigantopithecus first appears in the fossil record about 2 million years ago. It lived in what is now southern China, although it was probably also present in other parts of Asia. It was first discovered in 1935 when an anthropologist identified two teeth as belonging to an unknown species of ape, and since then scientists have found over a thousand teeth and four jawbones, more properly called mandibles. The problem is that we don’t have any other Gigantopithecus bones. We don’t have a skull or any parts of the body. All we have are a few mandibles and lots and lots of teeth. The reason we have so many teeth is because Gigantopithecus had massive molars, the biggest of any known species of ape, with a protective layer of enamel that was as much as 6 mm thick. Some of the teeth were almost an inch across, or 22 mm. A lot of the remaining bones were probably eaten by porcupines, and in fact the mandibles discovered show evidence of being gnawed on. This sounds bizarre, but porcupines are well-known to eat old bones along with the shed antlers of deer, which supplies them with important nutrients. The teeth were too hard for the porcupines to eat. We know that Gigantopithecus was a big ape just from the size of its mandible, but without any other bones we can only guess at how big it really was. It was potentially much bigger and taller than even the biggest gorilla, but maybe it had a great big jaw but short legs and it just sat around and ate plants all the time. We just don’t know. What we do know is that its massive jaw and teeth were adapted for eating fibrous plant material, not meat. The thick enamel would help protect the teeth from grit and dirt, which suggested it ate tubers and roots that would have had a lot of dirt on them, although its diet was probably more varied. Scientists have even discovered traces of seeds from fruits belonging to the fig family stuck in some of the fossilized teeth, and evidence of tooth cavities that would have resulted from eating a lot of fruit long before toothpaste was invented. Many scientists thought at first that Gigantopithecus was a human ancestor, but one that grew to gigantic size. It was even thought to be a close relation to Australopithecus. Other scientists argued that Gigantopithecus was more closely related to modern great apes like the orangutan. The debate on where Gigantopithecus should be classified in the ape and human family tree happened to overlap with another debate about a giant ape-like creature, the Yeti of Asia and the Bigfoot of North America. We talked about the Yeti way back in episode 35, our very first monster month episode in 2017. Expeditions by European explorers to summit Mount Everest, which is on the border between China and Nepal, started in 1921. That first expedition found tracks in the snow resembling a bare human foot at an elevation of 20,000 feet, or 6,100 meters. They realized the tracks were probably made by wolves, with the front and rear tracks overlapping, which only looked human-like after the snow melted enough to obscure the paw pads. Expedition leader Charles Howard-Bury wrote in a London Times article that the expedition’s Sherpa guides claimed the tracks were made by a wild hairy man, but he also made it clear that this was just a superstition. But journalists loved the idea of a mysterious wild man living on Mount Everest. One journalist in particular, Henry Newman, interviewed the guides and specifically asked them about the creature. He wrote a sensational account of the wild man, but he mistranslated their term for it as the abominable snowman. The word Yeti comes from a Sherpa term yeh-teh, meaning “animal of rocky places,” although it may be related to the term meh-teh, which means man-bear. But the peoples who live in and around the Himalayas belong to different cultures and speak a lot of different languages. There are lots of stories about the hairy wild man of the mountains, and lots of different words to describe the creature of those stories. And the idea of the Yeti that has become popular in Europe and North America doesn’t match up with the local stories. Locals describe the Yeti as brown, black, or even reddish in color, not white, and it doesn’t always have human-like characteri