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image Due to a surprising conversation on twitter, I will be making a detour into the realms of the pre-historic ( I promise no dinosaurs) and the origins of mankind.

Or maybe the origins of simple evolution…

A comment on twitter can lead to a 1,000 words quite literally. Want to know more? Come on lets take a walk through time.

The Discovery of Pre-History

It is quite simply the story of mankind. Five million years ago there were no humans on earth, nor among the existing apes and monkeys could we recognise in appearance or behaviour a recognisable humankind. Today we see humankind in all its diversity.

Literacy  has only been available for two centuries in some parts of the world. The earliest written records go back no further than 3,500 years and despite what religion would have us believe, we did not begin 6,000 years ago, our roots go back much further  than man made religions.

Archaeology gives us our answers, it is the study of the human past, on the basis of  material remains, it allows us to approach human existance over the expanse of time, And what an adventure that is!

THE IDEA OF PREHISTORY

Two centuries ago pre history did not exist, not only that but the very notion of pre-history had not been formulated. There was absolutely no idea that the human past evolved  through tens of thousands of years of development and change. Many scholars followed the argument of the 17th Century cleric Archbishop Ussher, who calculated that the earth was created in 4004 BCE. This was an extra ordinary claim based on his calculations via the bible, some people you may notice still adhere to this nonsense. Of course,  if the world could be dated to 4004 BCE via religious texts why would anyone begin to have a notion of ‘pre-history’?

Most human cultures were founded on and incorporated a view of the world involving a system of basic beliefs, related to the prevailing religious tenets. They had no idea of deep time beyond their creation myths.. The very idea of ‘pre-history’ could not develop until it realised religious texts were not the only source of information about the past.

Early excavations made in ancient cities and burial sites were to illustrate what was already known from texts. It can be argued, the birth of archaeology owed much to the passions of the great collectors, princes and cardinals of the Renaissance who enjoyed the romance of Greek and Roman statuary. Noblemen embarked on the ‘grand tour’ and came back with ancient artefacts, still adorning the great houses all over Europe. The practice of digging therefore was to satisfy the appetites of early collectors rather than the thirst for ancient knowledge.

The discovery in the 18th century of the cities of Pompeii and Herculaneum, led to more energetic and systematic excavations. Within half a century it would be claimed as a scientific discipline. Two important steps triggered the intellectual advances through which the very concept of ‘pre-history’ became possible.

GEOLOGY

image The first advancement was geology, scholars like Georges Cuvier in France and William Smith in England, had recognised that the record of the rocks and successive strata and accompanying fossils, must imply there was not a ‘Great Flood’ but a more complex narrative.

For the first time we could apply pre-history to humans through material remains found in the rocks. Today most of us are familiar with the ‘flint tools’ now associated with ‘the stone age’. To us it is obvious they were made by man, however, one of the great zoologists of the Renaissance Olisses Aldrovandi, described the stone tools as being :-

“due to an admixture of a certain exhalation  of thunder and  lightening  with metallic matter, chiefly in dark clouds, which is coagulated by the circumfused moisture and conglutinated into a mass and subsequently indurated by heat, like a brick”

A description that border on the nonsensical. The above shows clearly that what is obvious to us was not so obvious four centuries ago.

John Frere in 1797, wrote to the Secretary of the Society of Antiquities in London, submitting some flint implements found at Hoxne near Diss in Suffolk. They were found 12 feet below the surface. Frere wrote:-

“They are, I think evidently weapons of war, fabricated and used by people who had not the use of metals.  The situation in which these weapons were found may tempt us to refer them to a very remote period indeed, even beyond that of our present world.”

We are  on the brink of a new paradigm, Frere is implying that the existing view of things, based on the Book of Genesis may not be sufficient. It follows then that the human past must extend over many thousands of years.

The consequences of accepting the ‘flint tools’ were humanly produced and produced at the same time as the extinct animals in the same find, implies the vast antiquity of humankind. Today we speak in millions not thousands of years for our earliest ancestors.

The discipline of pre-history now became possible.

THE REVELATION OF 1859

In 1859, the distinguished geologist Joseph Prestwich and the archaeologist John Evans read a paper to the Royal Society entitled ‘The Antiquity of Man’.

That same year Charles Darwin published ‘On the Origin of Species by Means of Natural Selection’ and a whole new vista opened up forever. Darwin’s suggestion of a biological mechanism of universal application, namely natural selection of living forms by the survival of the fittest, allowed it’s  application to the human species also. This was a challenge Darwin met in 1871 with the ‘Descent of Man’.

It invited anthropologists and archaeologists to document the paths and processes by which our own species Homo Sapiens emerged.

HUMAN ORIGINS IN TIME DEPTH

imageThe first home of palaeolithic archaeology was France, in the  gravel beds of the river Somme. It was possible to reconstruct a succession of phases based on the lithic industries. It was during the course of these excavations that the foundation of palaeolithic archaeology was first laid down and some of the research techniques developed that remain standard today.

In 1860 in a cave at the site of Aurignac, 18 human skeletons were found. In a rock shelter in Les Eyzies, deliberate  buriels  were unearthed. These were the fossilised remains of ‘Cro-Magnon man’ now recognised as belonging to our own species. In a cave in the Valley of Neander in Germany more fossilised human remains were found. they are no recognised as belonging to a different species, Neanderthals.

Pre-history took on new meaning with the discovery of these two species as they lived in Europe during the same period. There now began a study of human evolution that continues to capture the imagination. The focus soon expanded beyond France and Germany.

Earlier Hominid remains were discovered in Java. Homo Erectus is considered to be  1.5 million years old, but as Charles Darwin had predicted the earliest finds would come from Africa. In 1925 Raymond Dart discovered a fossil skull ‘Austropithecus africanus’ a much earlier ancestor for Homo Erectus. Louis and mary Leakey found a rich series of fossils in Tanzania.

The fossil record was becoming rich enough to allow the outline of a ‘family tree’ of descent for our species from the much earlier apes of the Tertiary period, the geological era preceeding, Quaternary and the Pleistocene. In the space of a few decades what had seemed to some of Darwin’s contemporaries wild and implausible was now backed up by substantial evidence! Pre-history in the making…

THE RADIOCARBON REVOLUTION

The second half of the 20th century saw major changes in the nature of pre-history. The development of radiometric dating methods including radiocarbon allowed a process independent of assumptions about cultural developments etc. It could be applied equally to non-literate societies.The beauty of his method was it could work without archeological assumptions about date or time.

image It was now possible to date fossils documenting the various stages of human evolution and their accompanying artefacts. Human evolution could now be addressed with a new rigour and set in a more coherent context.

In 1947 chemist Willard Libby established the principle of carbon dating, an achievement that won him the Nobel Prize in 1960.

The carbon in all plants is formed through photosynthesis of atmospheric carbon, which contains a small but constant proportion of radiocarbon, along with the much greater proportion of the stable isotope carbon-12. So does the carbon in the body of all animals, ultimately derived from plants in the normal working of the food chain. When a plant or animal dies, the radiocarbon present in its body in that small but fixed proportion is gradually but steadily depleted through radioactive decay. The process has a ‘half life’ of about 5,730 years, the time it takes for half of thread carbon to disappear. Libby realised by measuring the proportion of the carbon-14 remaining int the sample against the stable isotope carbon-12, he could determine the time elapsed from death.

The technical complexities do set a limit of precision of radio carbon determinations and  as we go back in time to the limits of the method, around 50,000 years the errors increase.

The half life of the relevant isotope, carbon-14 is such that after 50,000 years there is hardly any left. but there are other radio active isotopes that are called into play to measure ages further back. For example, we can use the isotope potassium-40, which has a half life of about 1.3 billion years. Its concentration in the rock and that of its decay product argon-40 can be calculated.

Radiometric dating has been the most important gift to archaeologists made by the natural sciences.

The opportunities offered by radio metric dating has transformed our understanding of human origins by setting the human fossil record upon a chronological basis. It is now widely agreed that somewhere between 8 and 6 million years ago we share a common ancestor with the other apes. The genus ‘Homo’ is first represented by ‘Homo Habilis’ some 2.5 million years ago.

ENTER DNA

The discovery by Francis Crick and Jim Watson in 1953 ( for which they received the Nobel Prize in 1962 ) of the double helix, at last offered a clear mechanism through which Darwin’s Theory of Evolution could finally be understood.

Mitochondrial DNA (mtDNA) is passed through the female line from mother to daughter. With the passage of thousands of years, different lineage develops, this offers the basis for a research techniques allowing DNA samples to be taken from living individuals all over the world, which can then be compared.

Archaeo genetic analysis is currently widespread in anthropology and archaeology. It has been used to study the origin of language and  language families by considering the genetic relationships of the speakers. It has been used on the madden of Neanderthal fossils to consider their relationship with our own species, and it has been used effectively to consider the date and routes of the human dispersal from Africa.

Geneticist Peter Forster put it clearly and coherently in 2004.

On the basis of mtDNA  we can assert all living humans are closely related and descended from ancestors living in Africa from around 200,000 years ago.

The remarkable feature of all this DNA work is based on modern samples taken from a living population, and that their analysis allows the reconstruction of pre history.

Our past is within us…!

***

RECOMMENDED FURTHER READING

A Hundred Years of Archaeology by G E Daniel.

The Idea of Pre-History by G Daniel.

Philosophical Transactions of The Royal Society of London by P Forster.

Archaic States by G M Feinman.

Man Made Himself by G Childs.

A History of Archaeological Thought by Bruce Trigger.

 

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