The following is an extract from Our Human Story, a newsletter about human evolution.  in your inbox every month.
Some plot threads in the human story are fairly settled while others are still being worked out. One story that’s still being written is the settlement of the Americas.
We know from genetic data that the first Americans came from east Asia. This also makes geographical sense, because the gap between the north-eastern point of Russia and the north-western tip of Alaska is only a few tens of kilometres.
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But everything else is up for grabs: the exact timing of the initial settlement, whether there were previous incursions that didn’t leave any living descendants, the route or routes taken from north to south and how long it took people to spread throughout both continents.
These arguments tend to focus on North America, because that’s presumably the continent that was settled first: what we now call Alaska was relatively easy to reach from Asia, whereas a direct journey from Asia to what’s now Ecuador would have meant crossing the entire Pacific. At that time, people could only get to South America after they or their ancestors first reached North America.
This means South America has an unusual status: it was the last continent that our species inhabited. (Well, unless you count Antarctica, and I don’t, because even now nobody lives on Antarctica in a self-sustaining way.) And South American prehistory is unique.
Early entrance
Let’s briefly consider when people might have , just to put everything into context. The most likely window is between 20,000 and 10,000 years ago: there’s indisputable physical evidence of humans in South America 10,000 years ago, and genetics indicate they were there a bit before.
However, there are claims of older sites. Monte Verde in Chile has been claimed to be 18,500 years old, but this is contentious. More dramatically, there’s a rock shelter in north-east Brazil called Pedra Furada that is claimed to be triple that age. Excavated in the 1970s and 80s, it held charcoal from fires and what appear to be flaked stone tools. Carbon dating gave ages between 7000 and 60,000 years ago.
Very few archaeologists believe that humans were living at Pedra Furada 60,000 years ago. The dating itself seems fine – the issue is whether the tools are genuinely human-made. Some monkeys also use stone tools, often for cracking nuts – and this includes South American species. It may be that the artefacts at Pedra Furada were made by capuchins, not humans. (Horses can also make similar tool-like flakes of stone, but there were no horses in Brazil at the time.)
The monkey possibility is tackled in a review of Pedra Furada by one of its original excavators: Fabio Parenti, now at the Federal University of Paraná in Brazil. Parenti argues that some of the artefacts show signs of careful manipulation, beyond anything monkeys are known to do. There was also no sign of rocks used as hammerstones or anvils, which monkeys employ when cracking nuts.
I’m hesitant about this. Parenti’s argument focuses on a fraction of the artefacts at the site, and I wonder if those might be the result of accidents. I’d be more convinced if the majority of the artefacts looked human-made. Maybe people shared the site with monkeys – or maybe some of the monkeys mucked around with the stones.
What we know for sure, however, is that once people did reach South America, they were wonderfully creative – as people always are, given half a chance. Just in the last couple of months there have been some startling discoveries that shed light on our ancestors’ ability to express themselves.
Creative types
We’ll start with the oldest and come towards the present day. Since January 2020, researchers led by Ciprian Ardelean at the Autonomous University of Zacatecas in Mexico have been excavating at Sima de las Golondrinas (“Chasm of Swallows”), a cavern in north-central Mexico. In a May study, they described a great many bones. One was part of the pelvis of a human baby. Others belonged to animals like white-tailed deer, mountain bighorn sheep and American pronghorn.
Four of the bones have cut marks. Some could be due to butchery, but others look symbolic. In particular, one toe bone from a pronghorn has a set of four parallel lines carefully scratched into one end. Another bone, from a sheep, had been sculpted into an “unfinished figurine” at one end. Two of the bones were found in a layer of sediment known to be more than 16,000 years old – making them potentially the oldest works of art in the Americas.
Now let’s come a few thousand kilometres south to the Peruvian Andes. Researchers led by Christian Mader at the University of Bonn in Germany have excavated on a mountain called Cerro Llamocca. It seems to have been inhabited on and off for thousands of years. The oldest site they’ve come across is a rock shelter on the south-eastern slopes, where they found stone artefacts such as projectile points. Radiocarbon dating suggests it was occupied around 10,000 years ago, and possibly even earlier.
In more recent millennia, Cerro Llamocca became a sacred mountain or apu, used for funerary rites and other rituals. It was most heavily used between AD 600 and 1000. At that time a society called the Wari dominated the area, and the leaders may have incorporated local mountain gods into their pantheon to keep local people cooperative.
Writing with symbols
Still in Peru, many archaeological sites have yielded ceramic vessels. Their surfaces hold a hitherto unrecognised form of writing, according to Michelle Young at Vanderbilt University in Tennessee and Anita Cook at the Catholic University of America in Washington DC. Young and Cook took a close look at ceramic vessels from two sites, Atalla and Huari, and reviewed those known from other sites.
Many of the ceramics had symbols scratched into their surfaces after being fired. There were 142 examples from Atalla, though only five were intact. The most common markings were rather crude, including “a curved line or one or more straight lines, either parallel and/or perpendicular to one another”. Perhaps that’s not surprising: Atalla is the older of the two sites, in use from 1150 to 400 BC.
In contrast, Huari was in use from AD 600 to 1000. The symbols were far more diverse and complex, including “crossing lines, crosses, khipus, grid, composite curvilinear, and figurative forms”. A khipu, if like me you felt the need to look this up, is “a straight line with several parallel lines spaced at regular intervals that radiate away from it”. It may help to think of a child’s drawing of a comb or centipede. The figurative forms mentioned include birds and flowers.
Young and Cook show that similar sets of symbols can be found scratched into ceramics from a huge area of Peru. They argue the symbols are “semasiographic writing”, meaning writing that doesn’t use an alphabet where letters represent sounds, but instead uses symbols that represent concepts. Less ABC, more emoji.
Traditionally, archaeologists thought there were no writing systems in South America. That is now changing with the growing recognition that the Inca wrote using knots on strings. If Young and Cook are correct, writing was practised widely across the continent and for many centuries.
Stomp
I’m going to finish with the most recent site, which is also my favourite. This one, for reasons that will become clear, I really want to visit.
We’re still in Peru, but now we’re at Viejo Sangayaico in the central Andes, on the upper reaches of the Ica River. Around AD 1000 to 1400 it was home to people called the Chocorvos. They kept animals and grew crops. They held animist religious beliefs centred on phenomena like thunder, lightning and earthquakes.
At Viejo Sangayaico, Kevin Lane at the University of Buenos Aires in Argentina has described an open-air platform. In the centre, there is an area about 10 metres across that makes a deep sound, like an acoustic drum, when someone steps on it. When four people did so, the thumps were as loud as 80 decibels, on par with a noisy restaurant.
Lane excavated a small pit and found a series of alternating layers: tiny spherical rocks and a mix of bone and charcoal. The layers of spherical rocks had lots of small gaps in them. The whole lot was trapped under a layer of silt and clay. The air pockets were what caused the floor to resonate, producing a drum-like sound. Those of you who have read or seen Dune may be reminded of the “drum sand” that attracts sandworms.
Lane’s interpretation is that people danced on the special floor to create sounds similar to thunder, or perhaps earthquakes. The dance floor is one of the vanishingly few examples where we can recreate something of the music of past cultures.
