Australasian Science: Australia's authority on science since 1938

Reflection on the Discovery of a New Fossil Human Species

By John Long

The discovery of a new ancient human is a reminder about how much we’ve modified the planet.

Henry Fairfield Osborn, the former President of the American Museum of Natural History (1908–33) is well-known as the scientist who first studied and named Tyrannosaurus rex in 1905. He was also passionate about human evolution. In his book published in 1916, Men of the Old Stone Age, he wrote: “I am perhaps more proud of having helped to redeem the character of the cave-man than of any other single achievement of mine in the field of anthropology”.

Following the announcement of the faked fossil of Piltdown Man, made up of a lower jaw of an orangutan fitted to a modern human skull, Osborn developed his own theory that all apes had evolved entirely parallel to the ancestors of humans. This indeed is more or less how we regard our own evolution today.

The last common ancestor of the split between modern apes (gorillas chimps and orangutans) has now been dated using molecular methods and fossils to an event 5–7 million years ago.

Humans have a long evolutionary history dating back to a series of ape-like hominids called australopithecines that lived between 4 and 2 million years ago in Africa. The first fossils attributed to the genus Homo, in which we belong as Homo sapiens sapiens, is Homo habilis dated between 2.8–1.5 million years ago. This is based on various features but principally its larger cranial capacity of 550–687 cc, which is much larger than the australopithecines but notably smaller than modern humans (1350–1450 cc).

The recent discovery of a new species of fossil human by Dr Lee Berger of Witwatersrand University in South Africa created a lot of international media interest. The discovery of close to 1500 bones of around 15 individuals, named Homo naledi, meaning human “star” after the Rising Star cave system where it was found, came from the deepest recesses of the caves. This implied that perhaps they were ritually laid to rest here by their tribe. The skulls indicate they are very primitive, at the base of modern human radiations, but the site has not yet been precisely dated. Whatever age they turn out to be will be scientifically very informative.

This new species sits at a level similar to the previously oldest known members of our genus (H. habilis, H. erectus and H. rudolfensis) yet appears to have more human-like manipulatory ability of the hand and wrist, and a more modern human-like foot and lower limb. The paper is freely available from the new journal eLife (http://elifesciences.org/content/4/e09560).

It’s very exciting for palaeontologists to find another new ancient human species. It helps us think philosophically about where we have come from as a species, and what we went through before emerging as the dominant mammalian species today. Our early modern human ancestors survived the many rigorous Pleistocene ice ages, and managed to spread out to inhabit every continent on Earth.

But today we are the one species that is changing our planet more than any other species. Since leaving Africa between 125,000 and 60,000 years ago we have conquered every environment on Earth from polar ice fields to tropical jungles. Yet today we are wiping out habitats on Earth faster than ever before as our demand for resources increases with a rapidly rising global population (from 1 billion in 1800 to 7 billion today).

It’s important to reflect that the Earth inhabited by our early kin, like Homo naledi, was a dangerous place for a small ape-like person, but it was intact ecologically, unlike the world we now inhabit. No matter how far we have evolved since Homo naledi, we still have an inherent responsibility to look after our planet and devise a long-term political plan so we can all live sustainably.

It’s a hard problem to solve when comfortable modern humans, living outside the life-and-death existence of the African plains, tend to focus on economic growth over sustainability. The 1450 cc brain size of Homo sapiens sapiens certainly needs to be used more often.

John Long is Strategic Professor in Palaeontology at Flinders University, and current President of the Society of Vertebrate Paleontology.