Dr. Yonatan Sahle, leader of a team who found stone tools older than expected, stands in front of an outcrop where artifacts were found. Photos courtesy David Braun

Ancient stone-tipped javelins found in Ethiopia have scientists raising eyebrows thanks to an odd dating conundrum. The javelins were recently carbon-dated to around 280,000 years ago. Pretty old, right? There’s only one problem:​ The earliest fossils of modern Homo sapiens are from around 195,000 years ago. With an 80,000 year gap, you have to ask: Who made them?

The discovery could mean one of two things: that our species is much older than archaeologists once thought, or, more likely, that another species before us was intelligent enough to make and use these kind of projectile weapons.

The found remains are indeed from a tool that was thrown rather than thrust, a conclusion evident from telltale fracture marks on the spearheads. This is a key finding, because it suggests more advanced tool-making abilities. Projectiles have obvious advantages, too: those using them could hunt from a distance and thus hunt safer and more effectively, out of the reach of horned and hoofed predators.

John Shea, a paleoanthropologist from Stony Brook University in New York, told National Geographic that our ancestors moved towards more complex tools between 200,000 and 300,000 years ago, around the same time that a shift in their anatomical structure may have allowed us to develop language. This discovery could therefore be a further indication of the time when our ancestors first started exhibiting complex behaviours. “I think the advances seen here in tools have to do with the emergence of language,” he said.

An example of a pointed artifact from the Gademotta site, showing impact fractures in two locations. Via Sahle et. al

David Braun, a senior lecturer at the University of Cape Town and a member of the team that discovered the stone tips, which published its results in PLOS One, didn’t want to lay claim that it was necessarily contemporaneous to the birth of language. “Anatomically we might’ve been able to get there,” he explained when I spoke to him on the phone. “You could probably have the capabilities but not the cognitive structures to develop modern language.” 

He was enthusiastic about a possible link to developing consciousness. “I think these [the stone tips] are a reflection of the increases in transmission behaviours that happened through time,” he said. “When we get to the nitty-gritty, things are a lot less black and white and are much more grey. I’m reasonably sure that all of the hominins had some type of communication but whether it’s symbolic language or self-awareness, I don’t know. We only have broken rocks!”

As with all big discoveries in the sciences, the finding in Ethiopia has been met with some skepticism. Some consider the remains of a horse in Eartham Pit in Boxgrove, England, to be the very first evidence of a projectile tool, and that dates to around 500,000 years ago—much earlier than this spear. In that case, the projectile itself isn’t preserved, but a semi-circular hole in the horse’s shoulder-blade has been pointed to as evidence of the very first javelin tool since its discovery in 1989.

But Braun explained that his team’s discovery is different. “The real reason that Yonatan’s discovery is so important is that he calculated the speed at which the tool hit and broke,” he said, referring to his colleague Yonatan Sahle. The tool’s fracture velocity—the speed that the point cracked upon hitting an animal (perhaps)—was between 700 and 1100 metres per second.

“There’s no way you can thrust a spear into an animal and have it break at this speed,” he said. That proves that the tool was used as a projectile, not a thrusting weapon. Such calculations aren’t possible with other discoveries, as that kind of analysis can only be done on the type of volcanic glass the spear tips are made of.

The discovery of tools of any shape and size are imperative when it comes to understanding a world where humans didn’t dominate the planet. They’re also massively important in understanding how the human race evolved from an intuitive minority into the booming tour-de-force that it is today.

The incremental changes in behaviour over millennia, from early knife-like instruments to the explosion of tool use during the Neolithic Revolution, have been pieced together through the gradual trawling of soil and sand. But changes and innovations didn’t happen in a linear fashion; similar tools appeared separately in different regions, while some were invented, lost, and invented again.

“The behaviour that we associate with modern humans was probably a much slower process than once thought,” Braun said. “It’s two steps forwards, one step back. A lot of these innovations caught on, and some of them didn’t. It’s an accumulation over thousands of years that gets you to the full-blown modern culture that you see in Europe from 20,000 years ago onwards.”

“This discovery is so important because it means that the behaviours that we associate with humans might be disconnected with the appearance of our particular species,” he said.

But understanding the behavioural development of humans is more difficult than, say, tracking physiological changes because behaviours don’t leave fossilized skeletons behind. What changes may have happened have to be studied through the tools and other records left behind.

“There are huge changes in the biology of human ancestors from five million years ago until about one million years ago,” said Braun. “The changes after that are all behavioural. I think the exciting thing about finding stone tools is that we actually have a record of what those changes were, but by no means do we understand them.” 

Even so, finding tools can go a long way towards understand how humans—and our ancestors—developed.

“We are able to say a lot about changes in behaviour and that helps us understand how we changed from a very minimal part of the planet to populating every corner of the globe,” he said. “Tools are the only insight we have into the behaviour of our ancestors; the only thing we have is our archaeological record. It probably has a really big story to tell, we just haven’t figured it out yet.”