Chapter 28

DNA Backpacking - East Africa to East Bristol

A word of warning before you decide whether to embark on this chapter.

A couple of friends who have proof-read it didn't particularly enjoy it or see the relevance, finding it either a bit boring, contrived and/or out of place.

It is supposed to illustrate the unlikely and fortutious journey my genes, over unimaginable centuries, have taken from their early appearance in Africa to their current residence in Downend.  It's a story that fascinates me but maybe I've missed a trick in trying to explain why, or then again perhaps it's just a topic that doesn't appeal to everyone.

200,000 years, 20,000 miles and virtually all on foot - one heck of a backpacking trip!

Wherever you go on the planet you’ll find people.  We’re a species with near-global distribution and although people can look quite different and speak different languages we can nevertheless easily recognise each other as distant cousins.

But where did our species first appear and how did we end up being everywhere?  We now know we’re a species of African ape that has, quite fortunately, evolved in ways that enabled our ancestors to survive, thrive and expand across the whole world.  In contrast to other species we have discovered ways to fabricate tools, to create shelters and fire, to make clothes and other ingenious inventions.  Combined with an ability to plan and communicate, we have reached and survived in places that would seem quite alien to an African ape, sometimes crossing rivers and oceans in the process.  And along the way have developed societies that have risen and fallen, and created stories, art, beliefs and symbols that can be passed on from generation to generation.

Sometimes I stop to wonder how I ended up here in Bristol.  What travels have my ancestors, all half-a-million of them, been on?  How have they made it all that way from the valleys of East Africa?  What did they see and experience in the course of all these ancient wanderings?

Paleontologists (study of extinct species) use fossil records to group modern walking apes (Homo) into various species.  Typically with academics there is some debate but the main consensus allows for four main family trees one of which, Homo sapiens, is ours and the only survivor.  We were not the only travellers: each of the four species made it out of Africa.  Homo erectus reached China about a million years ago whilst Homo heidelbergensis evolved as another lineage about 800,000 years ago with fossils having been found in both Africa and Europe.  From this branch it is thought sprang Homo neanderthals around 600,000 years ago and later ourselves Homo sapiens at around 200,000 years back.

Until recently fossiled bones and tools have provided the only basis for these theories.  Now the amazing ability to trace lineage through our genes makes it possible to look back across the millennia, tracking population movements and their ebbs and flows, interactions, extinctions and expansions.

Now……

In every one of the millions of cells in my body, sitting in the mitochondria, the sub-cell capsule package that generates the body’s energy, is the DNA that has been passed down my maternal line.  Similarly in the nucleus of each cell is the Y-chromosome DNA which unlocks the paternal secrets - but this source leaves a more complicated trail so it’s easiest to look back along my mother’s ancestry.

So my DNA has a story to tell and luckily there’s some functionality in the Time Machine that can discover it.

First let’s spin the Time Zone Dial as far to the left as it can go.  The ‘Dawn of Time’ setting can transport us back three million years to when the first specimens of a new ape, capable of standing and walking on two legs, appeared on our planet.  We’re right back to the base of the family tree called Hominin and at this distance it’s just not possible to track my DNA: the lineage and mutations are just too fragmented.

But we can gaze out on an African landscape and wonder at the strange little group of chimpanzees nervously gathered by the edge of the scrub.  Chattering amongst themselves they gathered berries from nearby shrubs, alert to danger from a whole host of nasty predators.  Just over a metre tall, without fur, fangs, or claws they would seem to have been easy prey but luckily they possessed different attributes.  They stood, they walked, they could run and, just possibly, they possessed a rudimentary ability to communicate.  Over the next million years they somehow survived, despite little sign of expansion or innovation.  The fossil record is sparse and entirely African.

And then about two million years ago the tree forked.  A tiny few of the random genetic mutations that occur every generation would prove favourable to the ape’s environment and be reinforced.   A new lineage slowly evolved.

Observing from the Time Machine, now set to one million years in the past, it’s clear that the chimp-derivatives have already left behind some of their simian characteristics in the African forests.  Now we can recognise a human-like gait and body proportions with a flat face, prominent nose, and sparse body hair coverage.  Taller, averaging 1.5m, heavier at 55kg and with a larger head (and brain) our little group has clearly found methods to adapt to the world around them.  And something else has happened.  They’ve spread across large areas of Europe and Asia, from Iberia to Java and along the way developed some sea-faring ability, a talent for making rudimentary stone tools and the capability to use fire.  Key to their survival has been a varied diet that has been boosted further with the discovery of new methods of hunting.  What has triggered this step-change, those first strides along the ancestral road that allowed an embryonic awareness, imagination and ingenuity?

The opening scene in ‘2001 - A Space Odyssey’ speculates that the original spark for awareness occurred when a tribe of ape-men encountered a black monolith left by ancient alien visitors, launching Mankind on the journey that has led, with increasing speed, to the Moon and beyond.

More likely perhaps is that another random combination of electricity, chemicals and molecules occurred in the brain, possibly similar to what happened in the original primordial soup recipe that fostered the first cellular life on the planet.  This time the reactions and impulses between the cells enabled a ‘consciousness’ that could be retained and developed between the growing neural pathways.  Evolution did the rest, deciding in its own usual non-negotiable way that such a development was advantageous to the species.  Another limb grew from the Homo erectus tree limb.  Around 700,000 years ago the fossil records reveal that a new species had evolved.  Homo Heidelbergensis became the next stage in our evolution, spreading alongside existing species throughout Africa and Europe before eventually becoming extinct around 300,000 years in the past. But it is from this limb that two strong branches grew.

One branch became our older archaic cousins, the Neanderthals who first appeared around 600,000 years ago and were the main hominid found in Europe for the almost the next half-million years.

The second branch is more exciting - finally, after two million years of desperately slow evolutionary time travel, we’ve reached a crucial point.  I can now set the ‘Extract DNA memory’ button and follow my maternal line backwards in time so that it’s possible to tap into my own latent memory banks, tucked away in the deepest corners of every cell.

We’re going right back to the point, 200,000 years in the past when a new shoot springs from the tree - it’s been named Homo sapiens.

African Eve - 190,000 years ago - Omo River - Ethiopia

The hunt would take all day.  It had been several weeks since our last success and the regular diet of fruit and berries was becoming monotonous.  The prospect of an energy-laden feast of cooked meat added excitement to the tribe as the leader assigned roles.  Being a runner and my task was simple.  Once the target antelope had been identified I and a few others had the challenge of chasing it down to the point where it was too exhausted to go further.  Job done we would wait for the strong fighting team to catch us up.  Armed with their sharpened stone and wooden weapons they would despatch the unfortunate beast and butcher it for easier transport back to our camp.

I have evolved for endurance running. 

Just look at my feet.  The big toe that other primates use for grasping has aligned with my other toes to provide a stable platform.  I have arches, many small bones held in place by tendons and ligaments that act like springs each time my foot hits the ground, stretching and then giving energy back as my foot lifts off.  Then add my Achilles tendon, another massive spring around the heel, (currently in October 2022 giving me problems) and the long levers of our legs and associated muscles.  Combine these with strong back muscles to stop me pitching forward when running and big gluteus maximus bottom muscles to swing the legs from the hip joint.  They’re hardly used when I walk but come into their own when I run.

Ever wondered why the soles of our feet are so ticklish?  Numerous nerve endings provide signals continuously about the terrain over which I’m moving, allowing the feet, legs and posture to instantly adapt and optimise the motion.  Walk barefoot on grass, sand or stones and you’ll be bombarded with information.

Note on ‘barefoot running’ - there’s a growing school of thought that we’ve been conned by the massive advertising and promotions by footwear companies such as Nike and Adidas into wanting increasingly elaborate cushioned trainers to run faster and protect our joints from the pounding they get from running on the pavements and trails.  The alternate view claims we’ve already got great running footwear at the end of our legs and so just need to toughen up our soles again.  There are plenty of examples from Africa to Mexico of people who can run across all sorts of landscapes either barefoot or with just the absolute minimum protection against sharp stones or thorns.

The running fraternity are just beginning to take note and minimalist ‘barefoot' shoes are now appearing in the shops.  A bit like going back to running in your plimmos at junior school - these Vibobarefoots have dropped the cushioning from 12mm to 3mm.  Shame they haven’t done the same with the price!

It’s not just the legs and feet.  My heart and lungs are designed to carry me at a steady pace for long periods and with little body hair or fur I can keep cool during extended exercise.

The antelope was edgy, its fast-twitch muscles could accelerate instantly and it took off as soon as the herd sensed our presence.  For five minutes it sprinted into the distance before it had to stop to recover.  Twenty minutes later, jogging, we’d caught it up and off it raced again and the pattern would repeat.  Its recovery periods became longer whilst we just ticked along, jogging across the huge plain, which one day would be known as the Great Rift Valley.  Eventually, after two or three hours, the beast was exhausted, all energy lost it could run no further whilst we were still more than capable of jogging further.  We easily tracked it down, encircled it and waited for the others to join us to finish it off.

I’d burnt about 1000 calories - the 500kg antelope would easily provide over a million calories, feeding and energising all our tribe of a hundred or so people for several weeks.  So definitely worth the effort and, before someone invented bows and arrows, it was our only way of hunting large beasts.  By the afternoon we’d returned successfully to the rest of the tribe, established by a bend in the slowly meandering river.

Around the campfire in the evening we watched the storyteller act out the favourite legends and tales of the tribe, his grunts, squeals and clicks combining with expressions, gestures and actions to entrance most of his audience.  The night was clear and the numerous bright lights rolled slowly overhead in the blackness, almost all following the same path every night, unchanging.  I’d seen the stories before and my curious mind wandered again in different directions.  ‘We’d come close to the steep hills at the edge of the valley - what was beyond?  And the river - where did it disappear to?'

The old woman noticed my faraway look - she was ancient and reputed to be the respected great-grandmother to almost all of us in the tribe.  Her knowing smile seemed to encourage an exploratory idea that was taking shape in my mind.  Maybe

one day I would go and take a look.

Note - In human genetics, the Mitochondrial Eve (also called African Eve) is the matrilineal most recent common ancestor of all living humans.  In other words, she is defined as the most recent woman from whom all living humans descend in an unbroken line purely through their mothers and through the mothers of those mothers, back until all lines converge on one woman. The conclusion appears to be that all current human mitochondrial DNA originated from a single population from Africa, at the time dated to between 140,000 and 200,000 years ago.

One common misconception surrounding Mitochondrial Eve is that since all women alive today descended in a direct unbroken female line from her, she must have been the only woman alive at the time. However, some DNA studies indicate that the size of the ancient human population never dropped below tens of thousands.  Other women living during Eve's time may have descendants alive today but not in a direct female line.

An inescapable fact: despite what politics, religion and other social beliefs or prejudices might purport is that the actual biological evidence takes all of our ethnic diversity right back to a few dark-skinned early human hunter-gatherers, managing to live quite successfully in the Great Rift Valley.

Out of Africa   90,000 years ago   Bab-al-Mandab  

Every day I walked along the beach and around the cliffs, seeking anything edible that had washed in with the tide, hoping something substantial would turn up.  Scouring rock pools for shellfish could help but it wouldn’t fill empty stomachs.  Some of the tribe would sit for hours on the rocks, or out in our rudimentary boats, trying to catch fish with makeshift traps but this sort of fishing wasn’t for me.

I was a swimmer.

My choice was to hunt with a sharp stick, diving below the surface when the sea was calm, stalking and trying to stab any fat fish I was lucky enough to encounter. We needed everything our beach-combing and fishing could find.  The land was dry, there was little food to be found from the sparse vegetation and it seemed worse each season.  The old people claimed our ancestors lived in a land where regular rain turned the land green and bountiful but, to the younger members of tribe, this was a fanciful dream.

Some days I’d sit and stare out across the sea: on a clear day it was possible to glimpse what looked like distant red cliffs on the horizon.  Was this where the birds flew to?  Was there another land there where life might be easier?  Some days I’d abandon the daydreaming and spear-fishing.  When the waves appeared, elegant lines on the sea rising to rolling peaks before breaking in a rush to the beach I’d join the other youngsters and swim out into the sea, enjoying the thrill of hurtling to the shore engulfed by the surf.  Occasionally we’d find a flat piece of driftwood and lay down on it carving patterns on the wave as we were swept in to the beach.  One of the others even managed to stand up for a few moments!

An idea evolved.  Maybe we should cross the sea - it looked possible?  A few boats lashed together could take several families.  Paddle during the day in the direction that the golden and silver discs appeared and, if still going at night, just keep those tiny bright shining lights, that millennia later would be known as Sirius, Vega and Aldebaran, above your right shoulder.

Note - There is evidence of people living on the East African coast by 125,000 years ago with shells, hearths and stone tools found at sites in Eritrea.  But around 90,000 years ago the Earth was plunged into a freezing, dry glacial period. Sea levels plummeted as water was absorbed by the great northern ice sheets and the land from the Horn of Africa northwards becoming increasingly arid.  During this period the strait of water at Bab-al-Manbab separating Africa from Arabia was only 11km wide.

Whilst there are no traces yet found for early human boats it seems reasonable to assume that humans living by the sea would have had the ingenuity to invent them.  Small watercraft would have enabled them to cross river mouths and better exploit coastal resources.  If they could see Arabia across the water and if their families were struggling to survive on the African coast, such a voyage might seem a sensible option.

The genetic-trace points to two routes out of Africa. The southern migration as described above and a more northerly exodus by land across the Sinai desert both sometimes flowing back and forth as climatic conditions impacted on the region.  By 75,000 years ago the fossil, tool and genetic records indicate that Homo sapiens had already spread along the coastline from Arabia to India.

Toba Indonesia - 75,000 years ago

The eastern sky exploded.  An enormous bright white flash that hurt the eyes and only slowly subsided to a red glow across the whole horizon.  None of the old ones had seen anything like it before and a nervous apprehension settled on the tribe.

And then, not even half a day later, the air was filled with a tremendous rumbling thunder, the trees swayed and buckled.  Hiding in the caves we thought the world was ending.  All through the night the thunder roared and the wind howled and it was daybreak before the noise was replaced by an eerie silence.  We emerged to a new land where the sun had disappeared behind a blanket of cloud, where it rained constantly for weeks, a dirty foul rain that couldn’t be drunk. When the rain finally stopped everything had become coated in layers of clogging dust.  And it was quickly becoming colder.  The elders performed rituals to bring back the sun but with no success.  The plants were dying, the trees were dying, the big beasts were dying and we were suddenly in danger of following them into oblivion.

Note - The Toba super-volcano eruption occurred at the present location of Lake Toba in Indonesia, about 75,000 years ago.

The erupted mass was at the very least 12 times greater than that of the largest volcanic eruption in recent history, the 1815 eruption of Mount Tambora in Indonesia, which caused the 1816 ’year without a summer’ in the northern hemisphere. Toba's erupted mass deposited an ash layer of about 15 cm thick over the whole of South Asia.  A blanket of volcanic ash was also deposited over the Indian Ocean, Arabian Sea and the South China Sea.  Such a super-volcanic eruption on this scale must have led to very extensive injection of ash and noxious gases into the atmosphere, with worldwide effects on weather and climate.  This volcanic winter resulted in a drop of the global mean surface temperature by 3–5 °C.  Evidence from Greenland ice cores indicates an abrupt climate change heralding a 1,000-year period of markedly low temperatures. 

There is substantial fossil evidence to confirm that numerous species became extinct.

Our choice was simple.  Stay and die of starvation or leave and hope for the best.  The old ones advocated staying and appealing to the gods for things to improve. I found myself leading the remainder who joined me following the river towards the coast, 20 days’ walk away.  Maybe things wouldn’t be so bad there.  It was the wrong direction.  Barely half-way on our trek south we met other small groups straggling towards us.  Their stories of huge waves destroying everything for a day’s walk inland from the coast were difficult to believe.  The forest had been flattened and the land covered by water; barely anything had survived.

We turned north, tracing the river slowly upstream, passing numerous tribes that had perished or given up.  We rapidly adapted to survive. Changing our diet to live off what was available, like the small animals that seemed to be less affected, or the hardier fruits and berries.  Developing new hunting methods to capture the animals living below ground or that flew in the air.  Making warmer clothing, hardier shelters and better tools.   Working together, sharing skills, finding new ways to communicate.

Many, many days later the river led us to the foothills of a towering mountain range.  Another choice.  Follow the deep valley that plunged north into the hills or skirt eastwards taking a less challenging route.  Both options relied on nothing more than hope that things would be better around the next bend or over that distant hill.  We opted for the hills and mountains, eventually crossing into the plains beyond through a gap that would one day be known as the ‘Khyber Pass.’  My uncle and aunt and their families turned east following the river later to be called ‘Indus’ as it eventually weaved a way through the seemingly impregnable mountain range.  ( In 1943, 70,000 years in the future my grandfather would find himself defending the same Khyber Pass from potential hostile invaders.)

Note - The Toba eruption has been linked to a genetic bottle-neck in human evolution which may have resulted from a severe reduction in the size of the total human population due to the effects of the eruption on the global climate.  According to the genetics, around this time human populations sharply decreased to around only 20,000. It is supported by some genetic evidence suggesting that today's humans are descended from a very small population of between 1,000 and 10,000 breeding pairs that existed at this time.

The theory suggests that the eruption resulted in a global ecological disaster, including destruction of vegetation and fauna along with severe drought in the tropical rainforest belt and in monsoonal regions.  This volcanic winter could have largely destroyed the food sources of humans and caused a severe reduction in population sizes.  However ancient stone tools in India were found above and below a thick layer of ash from the Toba eruption and were very similar across these layers, suggesting that the dust clouds from the eruption did not totally wipe out this local population. The evidence from pollen analysis has suggested prolonged deforestation in South Asia, implying that the Toba eruption may have forced humans to adopt new adaptive strategies to survive and to migrate in small bands north-west into central Asia and the middle-east or eastwards on a path that would eventually lead them back to a recovering south-east Asia, Indonesia and beyond.

Footprints - Mungo Lake, Willandra NSW Australia 30,000 yrs ago

The stories told of the Dreamtime - the days when the Ancestors first arrived in the Land.  Travelling on the back of the giant turtle they crossed the sea from the distant islands beyond the horizon.  The Land was green to the north, in the direction of the sun and red in the opposite direction where a few brighter stars, standing out from the multitude, formed a cross high in the night sky.  The animals were strange, including some enormous beasts that then lived in the land of forests, rivers, bush and desert.  The Ancestors spread outwards, eventually after many years finding a harmony with the landscape, the flora and the fauna.

My tribe settled by the lakes that were fed by the glaciers and rivers flowing from the high hills to the east.  They lived off the land, hunter-gatherers who gave birth to their own culture, one that spawned their distinctive paintings, jewellery and folklore.  Sometimes their tribe fought other rival groups, sometimes they joined together for celebrations.

A distant cousin wandered across the landscape - for nearly half the year he had been on a spiritual walkabout, following the song-lines that linked rocky outcrops to water-holes to caves to creeks to hills to trees.  Returning from his travels it started to rain heavily as he neared the camp, turning the dry clay surface into a clingy morass causing him to leave a trail of muddy footprints across the plain. The downpour quickly passed, to be replaced by a strong breeze that dried the mud and blew a layer of fine sand across his path, covering his tracks.

Thirty thousand years later a Visitor Centre sits near where the fossilised footprints were discovered along with shells, bones, tools and ornaments excavated from the ancient encampment that nestled alongside the long dried-up lake.

Note - When the last Ice Age ended, the rivers dried up and what became known as the Willandra Lakes, turned into dusty flat basins.

The genetic evidence suggests that around 50,000 years ago the original colonists started to arrive in dribs and drabs as they followed the land bridges and made the short sea-crossings along the chain of islands leading from south-east Asia.  Landing on the great coastal plain of northern Australia they would have encountered tropical forests that slowly blended southwards into arid bush.  The animals would have been distinctly unfamiliar: strange-looking marsupials which had evolved along their own routes in that isolated continent.  Some were truly monstrous including a huge emu-like bird a three-metre tall giant kangaroo and an enormous carnivorous lizard.  These giant megafauna all become extinct around 40,000 years ago and their demise seemed to coincide neatly with the arrival of humans.

Chauvet Cave Art Gallery - Ardeche Valley - France 25,000 yrs ago

For years the tribe had been fleeing.  Not in a panic-laden rush to escape, as though being chased by rivals or a wild animal, but in an almost constant drift that saw us moving on, year after year, heading westwards away from the invincible enemy.  We’d been forced to leave our homes in the foothills of the mountains as the temperatures plummeted, the land froze and most of the animals left.  We tried to resist, adapting our weapons and clothes, moving deeper into the caves for shelter and hunting the few hardy beasts that remained.   But the battle was finally lost when the enemy finally emerged from the mountains and scraped and rumbled its way down the valleys, onwards to the edge of the plain.  Nothing survived the forces of the Ice Empire; even the great forests were engulfed as the glaciers advanced leaving everything in their wake buried deep in a frozen tomb.

The journey across the plain had been perilous.  Other tribes had fought to protect their settlements and hunting grounds.  The winters were harsh and food was scarce.  Dangerous animals took some of us: we were particularly fearful of the big sabre-toothed cat and the bears that lurked in the forests.  We crossed a mighty turquoise river; frozen in the winter it flowed south towards the weakened sun during the summer.

Eventually we found a valley amongst the hills that rose from the tundra of the plain.  Sparse woods covered the lower slopes, home to the wolves and ibex, and there were caves scattered amongst the cliffs of the escarpments where cave-lions or bears lurked.  On the plateau above the valley the grasslands teemed with game; roaming woolly rhinoceroses, deer, bison and the occasional herd of mammoths.  Could this valley could be the end of our travels?  Cautiously we explored the cave systems, driving out the bears and leopards and moving our families in, thankful for the protection they offered.  The only other inhabitants in the area were a small tribe of the strange, sturdy humans who lived higher up the valley.  Their tools and weapons weren’t as good as ours and despite being hardy and brave hunters they didn’t seem particularly interested in trading or working together.  From the very top of the cliffs I had an uninterrupted view to the east where on a crisp, clear day I could see, still glistening on the horizon, the shimmering white light that confirmed that ice still ruled in our old homeland.

During the long winter nights staying deep in the caves, around the glowing fires, we told stories and created images on the cave walls using ochre and other pigments.  My niece was a talented painter and her scenes of animals came alive in the flickering light.  I had no such skill and my only contribution was the occasional handprint.

Note - The last Ice Age spanned the period 25,000 to 11,000 years ago covering the high Alps in an ice sheet and driving glaciers down the valleys.  Much of Europe was steppe-tundra and the human inhabitants lived in caves hunting the herds of animals that roamed the region.  Adapting to the harsh conditions it seems that around this period the Homo sapien branch of the human family-tree became superior and the fossil and archaeological records of the Neanderthals finally disappeared after 600,000 years of survival across Europe and Asia.  They’d been getting along just fine all this time - so did we kill them off, or did we just out-compete them with better tools, hunting methods and social networks?  Or could remnants of the Neanderthal population still be around, assimilated into the expanding modern human population as it flowed westwards across Europe?  Certainly, genetically, parts of the Neanderthals DNA live on.  Up to 4% of the genome of modern day humans can be traced to Neanderthal ancestry implying that there was some limited interaction between the two species.

The Chauvet-Pont-d'Arc Cave in the Ardèche department of south-eastern France contains some of the best-preserved figurative cave paintings in the world as well as other evidence of Upper Paleolithic life.  The River Ardeche which flows through the gorge is popular and demanding trip for kayaks and canoes. (See Holiday Chapter)

Solstice - Bristol - Britain 4,500 years ago

We have been called the Beaker People and had crossed the narrow sea only a few generations earlier, claiming the valleys and lowlands and establishing our small distinctive settlements across most of the island.  The previous dark-skinned inhabitants had slunk off to their caves or slowly adopted our more sophisticated ways and merged into our communities.  We built huts, we grew crops, we smelted bronze tools, we made bronze weapons for hunting, we kept dogs and horses and we still continued to gather fruits and berries.

Now….

Follow the great estuary upstream until the point it starts to narrow and a river flows in from the south.  Join one of the trading ships arriving from the lands to the south bringing copper ore, the latest jewellery and the distinctive shaped pottery that our culture is named after and sail up the river with the tide, south-eastwards through a deep wooded gorge with steep cliffs.  Where the land levels off into a wider basin leave the boat and walk upstream along the banks of a smaller river flowing in from the north-east.  Within a couple of hours of easy strolling upstream lies our small village.

Several months ago the whole village had walked back down to the main river to witness a magnificent sight.  Large, low boats were being rowed slowly upstream, each one bearing a huge stone slab that amazingly had been shipped from the far mountains of the land across the great estuary.  Destined to form part of the giant stone circle on the Great Plain just a two-day walk away it seemed impossible to imagine how 80 of these bluestones could be transported all that way by boat and then dragged across the land to the sacred site. 

Note - next time you’re walking by the Avon just imagine the scene - a Neolithic flotilla of boats making their way upstream 4,500 years ago.  Just one of several theories

Now, as the days had become increasingly shorter, we’d made the journey to The Plain ourselves.  Camped just a short distance away, the massive henge seemed awesome.  Every village had sent men to help drag and lever the stones into place and they had achieved what seemed impossible.  Later as the winter solstice sun set, perfectly framed between the two uprights of the tallest standing stones as it sank lower, casting some final dim light onto the altar stone, we joined the hundreds of others in giving thanks for the closing year.  Later we celebrated mid-winter night, singing and dancing around the blazing campfires as Sirius, Vega and Aldebaran dominated the starry sky.  The following dawn we gathered at the Stones again to witness the rise of the solstice sun in the south-east heralding the start of another year.

Note - The presence of modern humans in Britain has only been continuous since about 12,000 years ago at the end of the last ice-age.

These modern humans were highly adaptable hunter-gatherers. Their ability to innovate was different from all preceding species. They lived in larger groups, had wider social networks and moved over larger distances.  This extended interaction led to the sharing of stories and information, including the spread of new ideas and knowledge.  Axes, bows and knives replaced the stone tools.

Cheddar Man whose remains were found in 1903 in Gough’s Cave, Cheddar Gorge was a Mesolithic hunter-gatherer with dark skin.  He lived around 10,000 years ago and has the genetic markers of skin pigmentation usually associated with sub-Saharan Africa.  This discovery is consistent with a number of other Mesolithic human remains discovered throughout Europe.  Until recently it was always assumed that humans quickly adapted to have paler skin after entering Europe about 45,000 years ago as pale skin is better at absorbing UV light and helps humans avoid vitamin D deficiency in climates with less sunlight.  Increasingly however the evidence suggests that the arrival of white-skinned humans in Britain is a recent development and occurred only over the last 5,000 years.

From 4,500 years ago Britain saw significant population change as a group of people living in Central Europe whose ancestors had previously migrated from the Eurasian Steppe migrated west and finally arrived in Britain.  The DNA data suggests that over a span of only several hundred years the migrations of people from continental Europe led to an almost complete replacement of Britain's earlier Neolithic inhabitants.  DNA also shows that these Beaker folk, named after their distinctive pottery, would have had generally different pigmentation that of the population they replaced.  In comparison, the Beaker tribes brought genes with a reduction in skin and eye pigmentation, leading to lighter skin, blue eyes and blonde hair becoming more common in the population.

The period from 5000 to 2500 years ago was the heyday of henge building.  Across the whole of Britain there are many examples of Neolithic and Mesolithic stone circles, standing stones and burial mounds. The prime example is of course, Stonehenge and speculation continues about its primary purpose - observatory, temple, meeting place?  Its layout certainly suggests some form of celestial importance.

The sarsen stones, erected at the centre of the site in about 2500 BC, were carefully aligned to line up with the movements of the sun.  If you were to stand in the middle of the stone circle on mid-summer’s day, the sun rises just to the left of the Heel Stone, an outlying stone to the north-east of the monument.  On mid-winter’s day, turning 180° to face towards the south-west, the sun would originally have set between the two uprights of the tallest trilithon at the head of the sarsen horseshoe.  It would have dropped down into the Altar Stone, a sandstone block which was placed across the solstice axis.

Amber Alert  -   The last two thousand years

Suddenly there’s a warning light flashing on the Time Machine’s control panel.  The ‘Time Zone’ dial is right over to the setting for the last two thousand years but the ‘DNA Extract’ sensor has detected a problem.  It seems to have identified a number of rogue genes that could be a threat to the well-being and potential future of the homo sapien family tree. 

The ‘xenophobic’ and ‘misogyny’ genes appear to have be growing in their influence on human behaviour and when combined with the ‘power and greed’ gene the result can prove disastrous.  The evidence of a problem for our species can be seen from the historical records. 

Just take on its own the xenophobic gene, which appears to have a particularly strong influence on the minds of fair-skinned populations, and has resulted in, at best, severe prejudices and at its worst, mass persecutions.  Until comparatively recently, around 30,000 years ago, we were all dark-skinned and the lighter skin-pigment genes only started to develop as the modern humans reached Central Europe and needed less protection from ultra-violet radiation.  It seems to be an evolutionary flaw to allow such a small genetic difference, when compared to the huge overall genome, to have such an impact on the behaviour of some of the species. 

And it becomes worse when combined with the power/greed gene.  There’s an unpleasant aspect of human interactions that in some societies allows the strong to exploit the weak or to grab all the resources in order to obtain more power and wealth.  It would have been wonderful to imagine the scenes spawned by voyages of discovery during the last few centuries when long lost family members finally met up again after 50,000 years or more of separation.  Everyone would have tales to tell of incredible journeys and amazing survival experiences, art and culture to share and different skills and knowledge to pass on.  What a great family reunion it should have been although some fair-skinned members of the family may have been shocked to meet their rather darker skinned forefathers!

Sadly the white-skinned folk of Europe, with their rapidly improving technologies, had no time or respect for their distant cousins who had also managed by themselves to reach distant lands half-a-world away.  They didn’t care that these people had often found ways to live in a broad, harmonious balance with the land they inhabited and animals they shared it with.  The only rejoicing for the discovery of their relatives was for the opportunity to exploit, destroy and commit genocide.  For the indigenous people of Australia, North and South America, Africa and elsewhere the story was the same.  The white people from Europe conquered by virtue of weapons, numbers and disease and proceeded to treat the land, fauna and flora as their own personal treasure chest.

After 200,000 years of a fantastic journey my DNA, handed down and moulded over 8000 generations, has an amber light flashing.  Evolution and society need to find the way to eliminate or mitigate the self-destructive effect of these unpleasant, tiny errors in the genetic code and discover the key that will allow the human family tree to grow stronger and healthier into the future.

And so - suddenly I’m here.  Physically I’ve travelled little, growing up in Nottingham and settling near Bristol.  My genes and DNA can tell a different story.  Just take a couple of small examples from amongst all the other millions of latent skills, memories and characteristics that my mother passed on to me from her mother and her mother(s) before that, randomly mixed every generation with my forefathers.  My running and swimming genes, honed somewhere on an African plain or by a mighty river or sea, were just waiting patiently to be activated eons later.

I wonder what else all those mothers and fathers have handed down to me over the countless generations that I might never unlock.

Thanks to Alice Roberts and her book Ancestors for background and a few sentences.

Image removed: Lucy (Homo Australopithecus) 3 million years ago -  Awash Valley Ethiopia

Image removed :   2001 A Space Odyssey monolith ( SketchForum/Kubrick/MGM), Footprints Mungo National Park  Java Man (Homo erectus) 2million to 150,000 years ago in both Africa and Eurasia

Image removed:    Toba Eruption (YouTube), Cave art, Beaker people and pottery National History Museum  Bronze-age-craft    

Nine Maidens, Boskednan, Cornwall - Ekaterina Sheath