Archaeology Excavation

Nestled high in West Himalaya, India’s Valley of Flowers National Park is renowned for its meadows of endemic alpine flowers and outstanding natural beauty. This richly diverse area is also home to rare and endangered animals, including the Asiatic black bear, snow leopard, brown bear and blue sheep. The gentle landscape of the Valley of Flowers National Park complements the rugged mountain wilderness of Nanda Devi National Park. Together they encompass a unique transition zone between the mountain ranges of the Zanskar and Great Himalaya, praised by mountaineers and botanists for over a century and in Hindu mythology for much longer.

The Greenish Warbler, long considered an idealized example of a single species that diverged into two as it expanded its range, has a much more checkered family history than biologists previously realized.

Ring species are a continuous loop of related populations, each adapted to its local environment, with two terminal populations in the loop meeting but now unable to mate. But an in-depth genomic analysis published today in Nature by University of British Columbia researchers reveals that the Greenish Warbler's genetic migration through central Asia involved periods of geographic separation and hybridization.

"We've shown that the evolution of ring species is much more complex than the smooth and continuous divergence envisioned by the classic model," says UBC zoologist Miguel Alcaide, the paper's lead author.
"If you view the ring of Greenish Warbler subspecies as a river, over the years the flow of populations has experienced periods of isolation--as if forming ponds during a draught--which accelerated genetic differences. This would have been interspersed with periods of flooding, or rapid exchange between populations. Interbreeding after range expansion has been, however, much more restricted among neighboring populations exhibiting substantial differences in morphology and behavior."

Originally expanding out of southern Asia, subspecies of greenish warbler have diverged around the expanse of the Tibetan plateau over thousands of years, with two distantly related populations meeting again in the north, in central Siberia. Since early observations in the 1930s, biologists have thought the terminal sub-species incapable of mating. The new analysis shows that small regions of the western Siberian genome can be found in some of the eastern Siberian birds, indicating some successful hybridization between those forms.
"Given the new genomic evidence for historical breaks in gene flow, it's remarkable that traits such as plumage and song show such gradual change around the ring," says UBC researcher Darren Irwin, senior author on the paper and an expert who has studied greenish warblers since the 1990s. "And despite the small amount of hybridization between the most distantly related forms in central Siberia, they remain highly distinct in songs, plumage and genomic patterns."


"Overall, despite the complex patterns of gene flow, the Greenish Warbler still has the central characteristics of a ring species: two mostly distinct populations connected by a chain of populations in which traits and genes change progressively from one species to the other," says Irwin.

By evaluating the bacteria and fungi found in fossilized feces, microbiologists are providing evidence to help support archeologists’ hypotheses regarding cultures living in the Caribbean over 1,500 years ago. They report their findings today at the annual meeting of the American Society for Microbiology.

“Although fossilized feces (coprolites) have frequently been studied, they had never been used as tools to determine ethnicity and distinguish between two extinct cultures. By examining the DNA preserved in coprolites from two ancient indigenous cultures, our group was able to determine the bacterial and fungal populations present in each culture as well as their possible diets,” says Jessica Rivera-Perez of the University of Puerto Rico, Rio Piedras, who presented the study.

Various indigenous cultures inhabited the Greater Antilles thousands of years ago. The Dominican Republic and Puerto Rico have thousands of pre-Columbian indigenous settlements belonging to extinct cultures that migrated to the Caribbean at some point in history.

Archaeological excavations in Vieques, Puerto Rico unearthed hand-made tools and crafts as well as fossilized feces dating from 200 to 400 A.D. The presence of two distinct styles of craftsmanship, as well as other clues obtained from the dig sites, suggested these artifacts belonged to two distinct cultures.

“One culture excelled in the art of pottery; in fact, their signature use of red and white paint helped identify them as descendants from the Saladoids, originating in Saladero, Venezuela. In contrast, the second culture had exquisite art for crafting semiprecious stones into ornaments, some of which represented the Andean condor. This helped archaeologists identify the Bolivian Andes as possible origins of this Huecoid culture,” says Rivera-Perez.

To help confirm these archeological hypotheses, Rivera-Perez and her colleagues examined the DNA preserved in coprolites from both Saladoid and Huecoid settlements and compared the bacterial and fungal populations found in each. Major differences were detected between the fecal communities of these cultures, providing additional support that they may have had different origins. Additionally, they found fungal and corn DNA in the Huecoid coprolite that suggests the consumption of an Andean fermented corn beverage, further confirming the theory that the Huecoids originated in the Bolivian Andes.

“The study of the paleomicrobiome of coprolites supports the hypothesis of multiple ancestries and can provide important evidence regarding migration by ancestral cultures and populations of the Caribbean,” says Rivera-Perez.

Header Image : Example of a coprolite: Lloyds Bank coprolite : fossilised human faeces dug up from York, England by archaeologists.

Between 850,000 and 950,000 years ago a small party set out across the upper reaches of an estuary. The group was made up of at least five individuals, including adults and children, while the tidal mudflats they were navigating lay at the mouth of what is now the Thames. Flowing almost 100 miles north of its current course, the river debouched into the North Sea through modern Norfolk.

There is nothing to suggest that the group’s journey was in any way extraordinary. Its members ambled slowly in a southerly direction, following the course of the river and frequently making detours towards its channel. These people did not return the way they came, but they left a jumbled mass of footprints in their wake.

Those fragile impressions in the soft esturine clay proved remarkably durable. At high tide they were submerged and swiftly filled with the sediments that would preserve them for almost a million years. By the time the footprints reappeared, in May 2013, they were the earliest traces of a human journey in Britain.

Stepping-off point
The waters that exposed the ancient footprints at Happisburgh are no longer laying down sediments. Instead,
that stretch of Norfolk coastline is retreating at an alarming pace. As we saw in Current Archaeology 288, the same waves collapsing cliff faces and demolishing houses are exposing the remains of long-extinct animals – and the earliest traces of human activity ever discovered in Britain. It was this archaeological silver-lining that brought Dr Martin Bates of the University of Wales Trinity Saint David (Lampeter) to Happisburgh last year.

‘I was doing geophysical survey with my brother Richard, to try and map the course of the ancient estuary channels under the modern cliffs,’ Martin explains. ‘As part of that work we lay out 400m of cable and put 80 electrodes into the ground. Our computer spends about an hour taking a series of measurements, and during that time we’ve got nothing to do. So we went and had a look at the deposits on the beach. And there in front of us was this strangely patterned surface.’

The footprints were exposed a short distance to the south of a site the team call Happisburgh 3. Eighty flint tools discovered there are believed to date back between 850,000 – 950,000 years, making them the earliest relics of human activity in Britain. If the footprints belonged to the same period, they would be one of the earliest sets in the world. Only the 3.5m-year-old footprints made by a human ancestor at Laetoli in Tanzania and the 1.5m-year-old examples from Ileret and Koobi Fora in Kenya are more ancient.

Previously the oldest human footprints in Europe were from Roccamonfina in Italy, which date back 350,000 years. So how could the team date the Happisburgh footprints?

‘It is really down to the sediments in which the footprints were made,’ explains Dr Nick Ashton, Co-Director of the Happisburgh Project and British Museum Curator. ‘Elsewhere along the coast, old estuary silts at a similar depth are associated with a range of animal and plant remains. Among them is a very early form of mammoth, for example, which we know became extinct about 800,000 years ago.’

‘The sediments themselves also provide a clue. At the moment, compasses point north, but in the past there have been periods when the Earth’s magnetic field reversed and a compass would have pointed south. Because these sediments were laid down very slowly, the iron minerals within them orientated themselves on the magnetic pole at the time. By measuring that, we can say they formed during a period of reversal. Putting all of this together narrows down the date to between 850,000 and 950,000 years ago.’

‘It was pretty lucky we had as long as we did,’ says Martin. ‘The sand on that beach is very abrasive, and the footprints were simply scoured away over a number of tidal cycles. I don’t know how long they’d been exposed when I saw them, but we are probably looking at a window of about a month in which they could be spotted and recorded before they were lost forever. There were about two weeks between the time when I said “This is what I think they are” and their destruction.’

‘The trail was about 3m wide and 10m long,’ Nick remembers. ‘Its recording took place over several days and used a technique called multiple image photogrammetry, undertaken by Sarah Duffy from York University. This takes a series of images from different angles and uses software to stitch them together into a 3D model. Using colouring to show different depths within the prints we could begin to see the various parts of the feet. In one we could even make out four of the five toes.’

Mud larking
Once the footprints had been recorded, they were studied by Dr Isabelle De Groote at Liverpool John
Moores University. ‘These are clearly human footprints,’ she observes. ‘In the best-preserved prints you can see the heel, the arch of the foot and then the ball of the foot and the toes. Humans are the only ones who leave footprints like these. Other primates have a divergent big toe – that is, one coming out at the side. And humans do a very distinctive heel strike when they walk, rolling off onto the ball of the foot.

‘Both small prints and large prints were present. What I was able to do was measure the length and the width of the footprint in order to estimate how many individuals were there. Over the whole surface there were a huge number of hollows, and I ended up identifying a total of 49 that were clearly footprints. They were made by at least five different people, and there were at least two or three children in the group, the smallest of which can be estimated to have been about 3ft tall.

‘The largest prints, of which there are three, come from a single individual with the equivalent of a modern UK size 8 foot and a height of about 5ft 8in. We believe that this is likely to be a male. A slightly smaller individual could be an adult female, or perhaps a young adult male. There’s no reason why we should not think of them as a family, but because we’re only seeing the prints of a few individuals we cannot be certain whether it was a single family unit or a larger group.’

Nothing beats the excitement of hands-on archaeology, and with the new digging season almost upon us, there is no time to lose.

This is a chance to get practical experience, either before heading off to university, or putting into practice what has been studied in theory. But for most, this is simply a glorious way to pass the time.

Our guide covers the full gamut of locations, periods, and types: from fieldwalking to recording and cataloguing, from early Neolithic to Medieval and later – there is something for everyone. Some jobs require stamina, but many do not. Young or old, fit or not, time rich or time poor, all you need is enthusiasm and a desire to get involved.

Use the options below to sort the digs by area, by cost, or by time period – whatever your budget or area of interest, there will be something to suit you. If you don’t have much time to spare try the ‘Dig for a Day’ list, or ‘All Inclusive’ if you want food and accommodation within the cost. There is also an Advice and Useful Info page that will help you know what to expect, along with advice from both diggers and supervisors, as well as a handy checklist so nothing gets forgotten!

So, if you are passionate about Prehistory, interested in the Iron Age, ruminating about Romans, or looking for a new angle on the Saxons, get out into the fresh air and discover…who knows what?

In your complete guide to archaeological excavations around the country, there is no excuse not to join in: look through our list of digs, find one that suits you – then enjoy getting dirty digging up the past!