The woman who dates Hobbits and giant apes

At the bottom of a pit dug three metres into a cave floor, Kira Westaway sat on a box, methodically pushing hollow tubes into the surrounding dirt and pulling them out.

It was July, 2003. The cave, named Liang Bua, was nestled in dense tropical jungles on Flores, an island at the eastern end of the Indonesian archipelago. Less than a year earlier, Westaway was a scuba instructor in Thailand with a successful business. Now she was a PhD student, spending her time scooping subterranean sediment samples. She planned to take the morsels of earth back to Australia to find out how old they were – and, by extension, the age of any artefacts found in the layers.

What she couldn’t plan for was what would be discovered the next day. A tiny skeleton belonging to a new hominin species – Homo floresiensis – would be unearthed just 20 centimetres underneath the very spot she was sitting. 

When revealed to the world, the “Hobbit” – as it was dubbed – would upturn our knowledge of human evolution and migration and be mired in years of controversy.

Science magazine would proclaim the bundle of bones the second-most important find of 2004 (after the discovery of water on Mars).

But that was to come. In the cool calm of Liang Bua, the student continued collecting her sediments, blissfully unaware of the wild ride that lay ahead.

Having spent most of her life in Asia and Australia, Westaway is now based at Macquarie University in Sydney, but a lingering accent betrays her birth country: England. As an undergraduate she was fascinated by the natural geography of Earth, thanks to a passionate teacher. She embarked on a science degree at the University of Liverpool, and a third-year subject in quaternary science got her well and truly hooked.

The Quaternary era – the past 2.6 million years – is marked by cycles of vast ice sheets and glaciation moving as far as 40 degrees latitude from the poles (covering Tasmania in the south, and New York in the north). “I really got into that,” she says. “Working on glaciers in Norway in crampons, doing that hard, crazy stuff – it was awesome.”

She followed her first degree with a masters in quaternary science at Royal Holloway, part of the University of London. It was there that she discovered luminescence dating.

This measures the amount of light that shines from minerals such as quartz and feldspar when they’re heated or illuminated. The brightness of the emitted light determines when the sample was last heated or exposed to sunlight.

Consider a grain of quartz on the ground. Over time, electrons energised by the decay of cosmic uranium, potassium and thorium isotopes become lodged in the quartz crystal lattice. When the grain is exposed to sunlight, that energy vibrates the lattice, releasing the electrons in a burst of light and “resetting” the clock to zero.

But if the quartz is washed into a cave by a stream, or blown in by wind and buried, it continues to accumulate electrons without being “reset”. The longer the grain is buried, the more electrons it collects and the brighter it glows when it is dug up by archaeologists and exposed to light again in a laboratory.

This is the underlying principle of optically stimulated luminescence dating. Thermally stimulated luminescence dating is similar, but measures the last time the sample was heated to around 400 to 500 °C.

Luminescence dating is often used in concert with radioisotope dating, which relies on comparing the ratio of isotopes in a sample to nut out how old it is. Carbon dating, for instance, measures the amount of carbon-14 in a sample, which decays by half every 5,730 years. After around 50,000 years, there’s very little carbon-14 left to detect.

Say you find a stone tool in an archaeological dig, Westaway says. Without knowing how old it is, you can’t say much about it. But using luminescence dating, you could find out when it and its surrounding sediment was buried. “Suddenly you put an age to the stone tool and it could be the oldest stone tool on the continent, or the first evidence that humans were making tools.

“Dating just puts that context, that meaning, on it. It really is a huge game-changer.”

After her masters degree, a dream PhD project popped up: based in London and assigning dates to sites in the Himalayas. But she didn’t get it. She was so put out, she says, she almost left the research realm for good. “But then I thought: If I drop out, is academia going to suffer? Probably not. But will I suffer? Yes! It’s my dream.”

So she did the research equivalent of cold-calling, sending her CV out to labs around the world. It worked. Shenghua Li from the University of Hong Kong offered her a scholarship to do a masters in optical dating of quartz, where she’d also analyse and date ancient sand dunes in Southern China.

It sounded perfect, yet Westaway didn’t know what to do. Her father had died the year before and she didn’t want to leave her mother. But when she asked her mum for advice, “she selflessly said, ‘do it’. So I left at 21 and I literally haven’t lived in England again since”.

So began the Asia adventures. After finishing her second masters – and being in her mid-20s – Westaway took a break. She travelled and became a scuba instructor, taking divers exploring reefs and wrecks.

Still, the idea of a research career remained squirrelled away in her mind. She was running a scuba diving shop in Thailand when she “had this thought that I wanted to do my PhD before I was 30”, she says. “So I did the ‘CV around the world’ thing again, because it worked so well the first time.”

This time, Robert “Bert” Roberts at the University of Wollongong answered the call. His project was digging up the floor of a cave in Indonesia. He needed someone with luminescence dating experience – and she’d be perfect for it.

Westaway had never been to Wollongong so Roberts urged her to have a look at the university website. It described a campus nestled by Mt Keira – not an exact match to “Kira” but “it was the weirdest thing and I knew I had to do it”. She gave up the dive shop and moved to Australia.

A few months later, Westaway, Roberts and their Indonesian and Australian colleagues were traipsing through the Indonesian jungle on the trail of Dutch missionary Theodor Verhoeven. Verhoeven taught at a seminary on Flores in the 1950s and 1960s, but he was also an accomplished amateur archaeologist. During his assignment, he uncovered modern human graves, stone tools and ancient animal fossils in numerous caves on the island.

When Verhoeven left to return to Europe, archaeologist Raden Soejono continued excavating the sites. He found more fossils and tools, but could only dig to around three metres before the walls of the pits became unstable and prone to caving in.

Roberts and his archaeologist colleague Mike Morwood wanted to dig as far as possible – down to the very bedrock itself – but realised they would have to learn the right techniques to keep the sites safe. So they completed a grave-digging course in Sydney, learning how to shore the sides of the pits with wood.

They took that technique to Indonesia, taught it to the local archaeological team leading the excavation and bingo! They could safely dig further than before. The deeper they dug, the further they peeled back the layers of human history.

Caves are natural shelters and can be used by generations of humans and other hominins who lived, cooked and died there. Dust and dirt covered scraps of cooked bone or discarded tools – if they weren’t buried on purpose – and locked them away under layers of compacted earth. There they could remain, safe from disturbance – until the archaeologists came along.

Westaway’s task was to assign dates to the layers of sediment laid down in the cave over the millennia and give context to any objects they found.

She arrived in March 2003. It was her first dig. While she’d been in caves before, she wasn’t prepared for Liang Bua, which means ‘cool cave’. “You just get this unbelievable awe when you walk in,” she says. “It could be dripping wet and hot outside, and you walk into this cave and it’s really cool and calm and has this lovely feeling about it.”

The cave is a natural hall, with a tall ceiling and flat floor. Most recently, Dutch missionaries used it as a school. One of Westaway’s colleagues on the dig, Indonesian archaeologist Rohkas Awe Due, even had lessons there as a kid. “And no wonder,” Westaway adds. “It’s such a nice place to hang out.”

But in Liang Bua in 2003 the archaeologists wanted to find evidence of Homo sapiens’ migration to Australia from Asia. In July, Westaway took her final samples, jumped on a plane back to Australia and walked into Roberts’ office the next day. She greeted him with: “Hey! I’m back!” Roberts replied: “Oh my god! They’ve found a skeleton.”

Between her flying out of Flores and arriving in Wollongong, the Indonesian researchers had dug two metres further, finding evidence of fire, remains of a now-extinct elephant-like creature called a Stegodon – and the skeleton of a small hominin.

None of the Western researchers were there at the time – just the Indonesian crew. “I’m glad it was them that found it and not us,” Westaway says. “It was their discovery.”

The skeleton was unveiled in Nature in October 2004: an almost complete skull along with leg, pelvis, hand and foot bones. The creature was probably female, around 30 years old when she died. While she stood just a metre tall, her feet were large for her body size – thus, H. floresiensis’ nickname “Hobbit”, after JRR Tolkien’s short-statured, big-footed heroes of The Lord of the Rings.

Westaway’s sediment analysis pegged the Hobbit’s life at 38,000 to 18,000 years ago – overlapping with H. sapiens, who arrived in Indonesia about 45,000 years ago, according to the evidence at that time.

And then descended the media attention. The specimen’s story was covered by Time, Der Spiegel, the BBC and National Geographic. But so too came the doubters. Rather than a new species, some claimed, the Hobbit was nothing more than a diseased modern human – perhaps suffering microcephaly, which could explain her grapefruit-sized head. Others thought she might be a dwarf.

An identical jawbone uncovered in further Liang Bua excavations in 2004 – and reported in Nature the following year – threw cold water on these theories. The original Hobbit and the second mandible’s owner lived 3,000 years apart. The odds of them both suffering the same head-shrinking disorder were incredibly small.

Re-excavating the cave in the years following also changed the timeline. Peculiar erosion patterns, not noticed in the initial excavations, meant the one sediment layer could be tens of thousands of years older than the layer directly above it.

During her first visit to Liang Bua – just before the Hobbit was unearthed – Westaway had inadvertently collected 50,000- and 18,000-year-old sediment layers in her tubes. When she mixed the samples and dated them, she ended up with an average age: around 36,000 years.

But the Hobbit lay in the older bank of sediment. It turns out the little hominin lived between 100,000 and 60,000 years ago – a revelation reported in Nature in 2016. Whether H. floresiensis as a species overlapped with modern humans is still open for debate.

Post-hobbit, Westaway didn’t rest on her laurels – far from it. Her work took her farther afield in southeast Asia and Australia again – not diving this time, but piecing together the climate at the time of the Hobbit and its ancestors.

In Punung in East Java, the woodland environment suddenly turned warm and tropical – illustrated by Stegodon, which preferred a more open habitat, being replaced by rainforest-dwelling orangutans and sun-bears in the fossil record. When that climatic shift occurred had only been roughly estimated – until Westaway and Morwood arrived on the scene.

Morwood spotted a flowstone – a flat, layered rock built up by millennia of mineral-rich water flowing over it, leaving minuscule deposits. “They’re awesome to date,” Westaway says. “They give you a minimum age for the sediment they cap. Without flowstones, I wouldn’t get half the evidence I get today.”Dating flowstones from the area along with breccia – jagged fragments of rock and fossils cemented together – she and her colleagues (many of whom were on the original Hobbit dig) concluded the climate turned tropical between 118,000 and 128,000 years ago.

So what does this mean for hominins at the time? Java is famously the site of the first Homo erectus fossils, discovered in 1891 by Dutch palaeoanthropologist Eugene Dubois. But Dubois also found teeth, attributed to H. sapiens, in breccia from a Sumatran cave called Lida Ajer.

Westaway and her colleagues rediscovered the cave, confirmed that the teeth were indeed modern human and dated the evidence. This research, published in Nature in August 2017, suggests that H. sapiens made it all the way to Asia by 73,000 to 63,000 years ago – some 20,000 years earlier than previously thought.

In 2013, as the history of the Hobbit and its ancestors was being brought to life, Morwood passed away, a year after being diagnosed with cancer. His death hit Westaway hard.

They had first met at a hotel in Ruteng, a town 10 km south of Liang Bua, the day before she set foot on the site. She was “young, fit, enthusiastic, feisty and inappropriately dressed in hip-hugging jeans, bare midriff and skimpy top”, Morwood wrote in his 2007 book, A New Human: The Startling Discovery and Strange Story of the ‘Hobbits’ of Flores, Indonesia. Being a traditional Catholic area, workers at Liang Bua put down their tools and stared.

Morwood couldn’t have the excavation disrupted whenever Westaway was on site – besides, those clothes were an occupational health and safety nightmare – so had a quiet word to her. The next day, she showed up to work in long baggy trousers and long-sleeved shirt. “Things quickly settled down and she proved a very competent and hard-working researcher,” Morwood’s book records.

He quickly became her mentor, but the teaching ran both ways. Westaway didn’t spend all her time in the cave; she spent a considerable amount of it out and about, exploring the surrounding landscape. This, Morwood thought, was a waste of time – to him, the important stuff was in the cave – until Westaway explained that figuring out when and how Liang Bua formed gave the archaeologists a maximum date of occupation and that all-important context for the evidence.

Even in his final days, Morwood had myriad projects and papers on the go. More than four years after his death, his name still appears in journals. He is included in the list of authors on Westaway’s August Nature paper. “I’m not just being respectful of his memory,” she says. “He was an integral part of the research.”

When we spoke (in July, 2017), Westaway had just returned from a trip to China. She had been invited to work on Gigantopithecus blacki – an extinct giant ape that, from just a few teeth and a couple of mandibles, palaeontologists think stood three metres tall and weighed half a tonne. “I often say I’ve moved from the smallest human on the planet to the largest ape,” she laughs. “If you mention to a palaeontologist that you work on ‘Giganto’, they all love it,” she adds. “It’s such a mystery.”

The mystery? Giganto died out 300,000 years ago, a time when many other apes (including humans) were flourishing. Westaway wants to find out why it disappeared when it did.

Meanwhile, she runs the luminescence laboratory and teaches at Macquarie, a post she’s held since 2008. “If you do luminescence, people will always want you to do research with them,” she says. “I get invitations to work with archaeologists, palaeontologist, biologists, geologists. Anyone who works with sediment needs to know the age of things. It just opens up all these opportunities.”

While Westaway has dipped in and out of academia – years of diving in Thailand, for instance – she has no regrets. “People think it was a U-turn but it actually fits in really well with what I’m doing now because all my work is in Asia,” she says. Her advice to younger researchers is it’s important to remember that career progression is rarely a set of simple steps: “You have to be aware that you’ll go on weird tangents. Things aren’t going to go to plan, but you’ll get to where you want to go eventually, even if it takes 20 years.”