The tech helping debunk long-held archaeological beliefs

In recent years, airborne laser scanning technology lidar, which can penetrate thick foliage and vegetation, has led to the dramatic discovery of a vast, 2,000-year-old Mayan settlement hidden beneath a Central American rainforest, as well as medieval cities beneath Cambodian jungles, for example.

After more than three decades of application, ancient DNA has helped rewrite human history and unlocked secrets of the evolution of language, migration, and even the origins of the Black Death.

Rather than physically dismantling mummified remains, Egyptologists use close X-ray scanning to digitally unwrap artefacts, leaving them intact. Techniques such as mass spectrometry and X-ray fluorescence allow them to look at the composition without disturbing ancient objects. And to identify mysterious bones from digital evidence, investigators have printed 3D replicas from digital scans – and succeeded in identifying mummified crocodiles from ancient Egypt among other animals.

Archaeologists can use field data to recreate immersive 3D virtual replicas of ancient worlds and Stone Age cave dwellings to learn more.

Science – alongside academic sleuthing – also allows for more granular dating. Since its discovery in the 1940s, carbon dating remains the most common method and is ideal for studying the last 50,000 to 60,000 years of history. Uranium-thorium dating – which measures different rates of radioactive decay – goes back further and has revealed the oldest known rock on Earth – a 4.4-billion-year-old crystal. Another technique – luminescence – reveals when an object was last exposed to heat or sunlight and uncovers changes to landscapes over hundreds of thousands of years.

Science and archaeology today are firmly entwined, says Dr Nathaniel Erb-Satullo, lecturer in archaeological science at Cranfield University's Forensic Institute. "Studying ancient technology using modern analytical science techniques allows us to tell the stories where we might not have written records of invention or innovation," he says. "It allows us to poke holes in Eurocentric notions about what kinds of people and societies have the capacity to innovate."

Scientific techniques have upended previous ideas of the past. Here we look at just a handful.

What killed Ötzi the Iceman?

To a storm of international interest back in 1991, hikers discovered Ötzi 'the Iceman'– fossilised Neolithic remains, some 5,300 years old, frozen in an Alpine glacier. Since then, the Tyrolean mummy has become a sensation – in demand by tourists and scientists alike. A vast range of techniques have helped unlock the secrets of these mummified remains and of life at that time, that just a few decades ago would have been impossible. But research seems to raise as many questions as it has answered – including what killed him.

A decade ago, analysis of ancient proteins in two tiny samples of brain tissue revealed some 500 different proteins – ten of these linked to blood and coagulation – indicating that blood clots formed in his brain before he died. CT scans confirm a head injury. But an arrow wound in his left shoulder suggests he most likely bled to death.

Science has left few stones unturned, from his clothes and weapons to his intestines, hair and fingernails.

Multispectral techniques revealed 61 tattoos on his body, possibly medicinal; DNA analysis revealed the origin of the animal fur and skins of his clothing. Chemical inspection shows, surprisingly, the copper in his axe originated miles away in southern Tuscany.

After scientists were able to map his genome, they discovered from blood donors' DNA that Ötzi had 19 male descendants or relatives living in Tyrol. Protein analysis revealed that Ötzi died after eating alpine ibex and red deer, rather than a solely vegetarian diet as once believed. Analysis of moss in his intestines by Scottish scientists reveals it originated from the bottom of a south Tyrol valley, suggesting he may have travelled up a gorge to end up where he was found 3,200m above sea level.

A most recent study by researchers casts doubts on where exactly he died, suggesting that he had previously melted out of ice rather than lying frozen in situ over millennia and been transported down the mountain by natural events.

The secret jaw of birds

Secrets of a toothed bird which were locked away in a lump of rock for 67 million years have finally been revealed after Cambridge University scientists used CT scanning to examine a fossil found in a Belgian quarry in the 1990s.

First examined 20 years ago, the rock around the fossil was never removed, but technology has now allowed a closer look.

And the results overturn a long-held belief about the evolution of modern birds. Close scans revealed what was thought to be a shoulder bone was instead a crucial part of the bird's palate. And this shows that the bird, one of the world's last toothed specimens from the age of the dinosaurs, had a modern hinged jaw – a mobile beak – far earlier than was previously known to exist.

Since 1867, birds have been put into two categories – those with an ancient, fused jaw (similar to humans, who only move the lower jaw independently) as seen in ostriches, and those with a modern jaw – a flexible, hinged joint – previously believed to be a modern evolution and now found in 99 per cent of birds. This suggests the origin of this mobile jaw predates rather than postdates the evolution of 'ancient' jaws – that ostriches and emus may have evolved 'backwards' to a more primitive condition, for reasons scientists have yet to understand.

"This fossil helps us understand the evolutionary origins of the incredible living biodiversity of birds today," says palaeontologist Dr Daniel Field. "This overturns more than 150 years of ornithological dogma."

The earliest map of the stars?

Multispectral imaging of Christian texts from an Egyptian monastery has revealed hidden histories and possibly the earliest ever attempt to record the stars. Notations believed to be the lost work of an ancient Greek astronomer in the 2nd century BCE were spotted by an academic poring over hidden text.

Interest in the documents grew in 2012 when a student, visiting the UK, spotted a Greek passage by an astronomer on the Aramaic manuscripts transcribed in the 10th or 11th century. US scientists began imaging the manuscripts and analysis revealed that, beneath the existing writing, older notations had been scraped and rubbed out so a scribe could reuse the parchment – common practice at that time.

By taking visible images of the parchment in blue, green and red, and combining these with an infrared image and X-ray imaging, scientists used computing power to unveil hidden markings. This technique has already revealed hidden text on Dead Sea Scrolls. Imaging of the Egyptian manuscripts revealed several pages relating to astronomy which radiocarbon dating suggests were from the 5th and 6th centuries.

But when a UK biblical scholar looked more closely at the images during lockdown, he was excited to discover what he believed to be even earlier notations – accurate star coordinates of the Corona Borealis, which astronomical charts show were probably observed around 129 BCE. Historians believe these were noted by Hipparchus, often thought to be the greatest astronomer of Ancient Greece and the first astronomer to note the location of stars using two separate coordinates. This is tantalising evidence of Hipparchus's long lost star catalogue, which scholars of the ancient world have known about for hundreds of years, and which predates the 2nd century CE star catalogue of astronomer Ptolemy.

Mysteries of the Iron Age

For decades, archaeologists puzzled over an iron dagger found more than a century ago in the tomb of Egyptian King Tutankhamun. The boy king's rule (1361-1352 BCE) corresponds to the late Bronze Age – a time when iron objects were rare and direct evidence of iron smelting is absent.

Only in 2016, chemical analysis confirmed that the dagger, with high levels of nickel, originated from an iron meteorite – viewed by ancient Egyptians as a gift from the gods.

Primary schools today teach a neat sequential version of early history – Stone Age to Bronze Age to Iron Age, says Dr Erb-Satullo. "But in some parts of the world, that sequence breaks down – it's far from universal. In Sub Saharan Africa, iron precedes bronze (a copper-tin alloy) for instance." It's more interesting, he says, to ask why people organised themselves differently and how they adapted to new technologies. "What was going on in the wider society at that time?"

Using chemical and mineralogical research and geospatial analysis, Dr Erb-Satullo has overturned assumptions that Georgia had the earliest example of a major iron-smelting industry and that these were in fact copper-smelting sites. "Why do we care about accurately reconstructing early iron innovation? The industrial production of iron is of fundamental importance to our modern society. Understanding how it emerged is crucial to understanding where we are today," he says. Surprisingly, the strength and hardness we value in iron today was probably not the initial spur for innovation – it was first used in jewellery and ceremonial items.

Camels of Ancient Arabia

When archaeologists discovered some giant stone sculptures of camels in northern Saudi Arabia, they estimated them to be around 2,000 years old based on stylistically similar works found in the ancient Jordanian city of Petra. But a research team went on to analyse these cliff carvings and concluded the initial estimate was out by thousands of years and these camels might be up to 8,000 years old. Other scholars suspected they might belong to the Neolithic era but lacked the evidence or any organic matter to inspect.

Using a variety of measurement tools, the team set about inspecting the weather-worn reliefs. Optically stimulated luminescence dating measures energy emitted after an object has been exposed to daylight – this allowed researchers to track erosion back in time to when the camels were pristine – with the help of many detailed photographs. This intricate inspection led researchers to spot seven further animal reliefs that had faded so severely they were no longer visible to the human eye. Researchers used a further technique, X-ray fluorescence spectrometry, to analyse the elemental composition of materials and test for manganese. Animal bones found nearby underwent mineral testing – the harsh desert had destroyed any collagen – and the team were able to confirm that these huge camels were between 7,000 and 8,000 years old – older than Stonehenge or the Pyramids of Giza. This makes them the oldest large-scale animal reliefs in the world.

Ancient cave drawings - but are they art?

A small group of researchers used a relatively low-tech approach to decoding mysterious series of dots and symbols found beside some 600 Ice Age cave paintings across Europe which have long puzzled experts. An amateur archaeologist pored over archives of these drawings of reindeer, fish, types of cattle and bison, made some 20,000 years ago, to search for common patterns and found evidence of early timekeeping. He collaborated with UK academics to decipher the enigmatic abstract markings as the earliest known form of a lunar calendar. Marks beside an animal seem to coincide with months of breeding and giving birth – as referenced with their modern-day descendants – which may have been useful to the Ice Age people who hunted for meat. This makes these the earliest record-keeping systems discovered by 10,000 years.

Early cave art has long been studied as the work of modern humans and has been notoriously difficult to date. Scientists have now confirmed a contentious claim that Neanderthals painted in caves tens of thousands of years earlier. These extinct cousins have long been considered relatively unsophisticated and lacking the cognitive ability for symbolic expression. In 2018, a study attributed red ochre 'paint' on stalagmites in a southern Spanish cave to the extinct hominids after dating revealed it was at least 65,500 years old. Modern humans settled in Europe 45,000 years ago. However, some scientists contended these markings may have natural causes.

Now new analysis through electron microscopy, X-ray diffraction, and chemical examination reveals that pigments came from outside the cave and their composition and location show they had been made by splattering and blowing, with some markings made nearly 20,000 years apart. Scientists say these dates indicate that Neanderthals did paint the stalagmites, though their meaning is unknown. Experts liken the discovery to a 'smoking gun' and say Neanderthals may have behaved more like modern humans than previously thought.