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.