Historical Chronicles

The ancient DNA evidence has transformed our understanding of the demographic history of Britain in ways that are still being processed and debated.

The famous Cheddar Man — whose genome was analyzed in 2018 and whose features were reconstructed from his skull — dates to around 7,000 BCE and shows the ancestral type of the people who were in Britain before the farming revolution.

He had dark skin, blue or green eyes, and dark or brown hair.

He was not replaced by the incoming Neolithic farmers entirely. The Mesolithic Britons contributed their genes to the mixed population that emerged from the Neolithic transition — meaning some portion of the indigenous Mesolithic British DNA persisted into the people who built Stonehenge and Avebury.

By the Iron Age, the population of Britain was a complex genetic mixture of multiple waves of migration and local development. Identifying any of them as simply "Celtic" or simply "indigenous" in the genetic sense is impossible.

The culture of Iron Age Britain was Celtic in its language and many of its art forms. But the people who carried that culture were genetically diverse — and the cultural heritage they expressed was layered with contributions from multiple periods and multiple populations going back to the very first inhabitants of the island after the last ice age.

LiDAR technology — Light Detection and Ranging — uses laser pulses fired from aircraft to create extraordinarily detailed three-dimensional maps of the ground surface, penetrating tree cover and other vegetation to reveal features invisible to conventional aerial photography.

Since its application to British landscape archaeology in the early years of the 21st century, LiDAR has transformed our knowledge of the prehistoric landscape.

A LiDAR survey of the area around Stonehenge published in 2014 revealed over 60 previously unknown monuments in the vicinity of the site — including a massive timber structure that may have served as a stadium or viewing platform for ritual events at the monument.

The Durrington Walls complex — the large Neolithic settlement and henge monument about 3 kilometers from Stonehenge — was revealed to be considerably more extensive and complex than previously understood. The settlement associated with it is now believed to have been the largest settlement in Neolithic Britain, potentially housing thousands of people during the construction seasons of the Great Monument.

The landscape of Stonehenge, as revealed by LiDAR surveys in the past decade, is incomparably richer than even 20 years ago.

We are not at the end of this story. Features that were unknown, invisible at ground level, and undetectable from conventional aircraft have emerged in their hundreds.

The work of understanding what was in Britain before the Romans has barely begun.

New Grange in Ireland is part of the same Atlantic megalithic tradition as Stonehenge — and it illustrates the developmental trajectory of astronomical architecture beautifully.

Built around 3,200 BCE on a ridge above the River Boyne in County Meath, it consists of a large circular mound covering a passage of 19 meters leading to a cruciform chamber, all constructed from large stone slabs.

The corbelled roof of the inner chamber — in which large flat stones are laid in successive courses that project progressively inward until they meet at the top — has remained waterproof for 5,000 years without any mortar or jointing material.

And at the winter solstice, the light of the rising sun enters New Grange through a specially constructed roof box above the entrance and travels along the 19-meter passage to illuminate the floor of the inner chamber for about 17 minutes.

This light box is not a coincidence. It is a precisely engineered feature designed to capture the light of the rising sun on the exact days of the winter solstice.

To build it, the builders had to know in advance where the rising sun would appear on the horizon at the solstice, at the exact latitude of the monument, and at the exact height of the roof box above the floor of the passage.

They had to know this before the roof was in place — because there was no way to adjust it afterward.

The finishing of the sarsen stones at Stonehenge is itself an extraordinary technical achievement.

The surfaces of the upright stones were dressed smooth — using hammerstones to pound away the rough natural surface of the sandstone over large areas of the stone face. The lintels were shaped with deliberate curves on their outer face to match the curvature of the circle they formed. So that the outer face of the completed circle was a perfect arc rather than a series of flat-faced segments.

This is precision work at monumental scale. Requiring the kind of geometric understanding that allows a craftsman to calculate how much material to remove from each part of a lintel face to produce a specific curve — when the lintel will be in position 20 meters above the ground.

And the mortise and tenon joints that locked the lintels to the uprights — the tongue and groove joints that locked adjacent lintels to each other — required the matching of carved features across massive stone surfaces with tolerances that, given the weight of the stones involved, had no margin for error.

The same joinery technique used by carpenters.

Applied to 25-ton blocks of sandstone.

Who taught these people how to do this?

The answer the evidence supports is that they taught themselves — over a thousand years of working with large stones, developing a tradition of precision stonework that produced Stonehenge as its culmination.

The isotope analysis of human remains from the area around Stonehenge during the main construction period tells a remarkable story.

Individuals buried in the vicinity of Stonehenge show a wide geographic spread of origins — their teeth reflecting the geology of regions across Britain rather than the local chalk of Wiltshire.

People came from Wales. From the north of England. From Scotland. From Cornwall and the southwest.

This is not an accidental gathering. This is a pilgrimage — a deliberately organized mobilization of people from across the island around a project of such cultural and religious significance that it overrode local and regional differences in identity.

The analysis of animal bones from the contemporary settlement at Durrington Walls adds another layer. The cattle being consumed were killed in mid-winter — and isotope analysis of those bones shows they had been grazed in different parts of Britain and brought specifically to Durrington Walls for slaughter and consumption.

Animals transported from across Britain to feed the workforce.

People traveling from across Britain to do the building.

This is the infrastructure of a sophisticated state-level political organization — the capacity to command resources and coordinate labor across a wide geographic area.

All of this in 2,500 BCE. All of this for a monument on the Wiltshire chalk.

Lake Agassiz was one of the largest freshwater lakes in Earth's history.

At its maximum extent, it covered an area larger than modern Ontario — in fact, larger than all the modern Great Lakes combined. It was held behind the retreating Laurentide ice sheet, a glacial lake dammed by ice rather than bedrock.

When the dam failed — and the timing of its catastrophic drainage is one of the most studied questions in Quaternary geology — the volume of fresh water released into the North Atlantic was enormous.

The drainage event is documented in the geological record. The outflow channels are preserved. The sediment signatures are visible in ocean cores. The event happened.

Whether it happened at the right time and with sufficient magnitude to trigger the Younger Dryas remains a matter of ongoing research. Some dating reconstructions place the drainage slightly before the Younger Dryas onset. Others find the timing ambiguous.

The meltwater disruption hypothesis is the strongest conventional explanation for the Younger Dryas.

It accounts for the cooling. It does not fully account for the synchronous disruptions across three isolated ice systems that appear in the geological record simultaneously with the cooling onset.

That gap is where the impact hypothesis finds its opening.

The conventional explanation for the Younger Dryas begins with the thermohaline circulation.

This is Earth's ocean conveyor belt — the system of currents that moves warm tropical water northward toward the poles, where it cools, becomes denser and saltier, sinks to the deep ocean, and returns southward as cold deep currents. The system drives much of the climate regulation that makes Northern Europe and northeastern North America habitable.

Its most vulnerable point is the North Atlantic, where the warm surface water sinks.

Fresh water is less dense than salt water. If a massive pulse of fresh water enters the North Atlantic at the sinking zone, it can prevent the warm water from sinking, slowing or stopping the circulation.

The conventional explanation for the Younger Dryas: as the ice age was ending and the great ice sheets of North America were retreating, they created enormous glacial lakes. One of those lakes — Lake Agassiz, which held more water than all modern Great Lakes combined — catastrophically drained into the North Atlantic. The freshwater pulse disrupted the thermohaline circulation. The circulation shutdown caused the abrupt cooling.

This explanation is well-supported by evidence.

The question is whether it accounts for the full scale and synchronicity of what the geological record shows.

The single most difficult element of the Younger Dryas impact debate for the critics is the synchronicity.

Individual markers in the black mat — the platinum, the nano-diamonds, the magnetic microspherules — each have potential alternative explanations when considered in isolation.

The synchronicity argument is different.

It asks: what process deposited all of these markers simultaneously at sites across four continents, in the same thin stratigraphic layer, at the same radiocarbon date?

Volcanism can account for platinum. But volcanism does not produce nano-diamonds.

Impact can account for nano-diamonds. But a single impact should produce a crater, and none has been found.

Widespread fire can account for carbon enrichment. But fire does not explain the magnetic microspherules.

The critics have alternative explanations for each individual marker. The challenge is providing an alternative explanation for all of them appearing together, simultaneously, globally.

The 2023 comprehensive review that was skeptical of the hypothesis described the cumulative evidence as self-contradictory — but did not provide a unified alternative account.

That gap — between the critique of individual markers and the unified explanation of the synchronicity — is where the hypothesis continues to find its foothold.

The temporal relationship between the Younger Dryas and Göbekli Tepe is one of the more interesting features of this entire conversation.

The Younger Dryas ended approximately 11,700 years ago. Göbekli Tepe's earliest excavated structures date to approximately 11,600 years ago, give or take the uncertainties of radiocarbon dating at that range.

The site sits in the immediate aftermath of the cold period.

Whatever the people who built Göbekli Tepe experienced during the Younger Dryas — whatever 1,200 years of cold and disrupted ecosystems meant for populations in southeastern Anatolia — they emerged from it and almost immediately began the construction of something that took generations to complete.

The standard model sees this as evidence that human organizational complexity emerged in the post-Younger Dryas warm period as improving conditions allowed population growth and social complexity to develop.

The alternative position notes the proximity differently: what if the organizational complexity Göbekli Tepe demonstrates was not emerging, but surviving? What if the people who built it were carrying something through the cold rather than developing it after?

Both interpretations fit the site's timeline.

Neither has yet been definitively established.

The site itself does not tell us which is true. It tells us only that the builders were there, and that they built, and that they buried what they built.

The critics of the lost civilization hypothesis are correct about one thing: the surveys of the submerged shelves have not returned civilization-scale finds.

What those surveys have found is consistent with what the standard model predicts — the scattered traces of hunter-gatherers, not the infrastructure of urban civilization.

This is a real data point. It is not nothing.

But the context matters.

The 27 million square kilometers of submerged land from the ice age period is enormous. The surveys conducted to date have covered a fraction of that area. Side-scan sonar covers the seabed in swaths measured in kilometers. The total coverage of the relevant shelves represents a small percentage of the available territory.

The searches have been concentrated in areas of research interest that were determined before the lost civilization hypothesis became a prominent consideration. They have not been systematic surveys specifically designed to look for the evidence in question.

This does not mean the evidence is there. The negative results of the existing surveys are real.

But it means the argument that absence of evidence from these surveys constitutes evidence of absence is premature.

The search that could settle this question has not yet been conducted.