The Davey Dialogues - An Exploration of the Scientific Foundations of Human Culture. John C. Madden
and published several tracts in defence of the Irish wing of the Church (which was Calvinist). As a result, the King viewed him with disaffection. Today, his best-known work, published late in life, is Annales Veteris et Novi Testamenti (Annals of the Old and New Testament). In this work, he sets out a time scale for biblical events, starting with the creation of Earth in 4004 BC (October 23 at high noon to be precise). Stephen Jay Gould has written a rather nice article on Ussher that appears in his book, Eight Little Piggies: Reflections in Natural History.[20] In it he scolds a number of writers of geology textbooks who pillory Ussher for being so narrow-minded as to use the bible (though it turns out he also relied on other historical sources) to come up with such a ridiculously low number for the age of the universe.
Gould points out that Ussher was actually a rather broad-minded man who used any sources available to him to help in his task. Gould claims that Ussher’s estimate was simply considered to be the best of many competing estimates of the age of the universe in his day (and long after), primarily because he was prepared to examine all available sources. To be sure he made use of the copious data in the Old Testament about who begat whom and how old they were when the birth occurred, but this data still left some significant gaps. To close in on some of these gaps, Ussher referred to the works of secular historians, took account of the historical possibility that Christ was actually born in 4 BC (that is, before the death of Herod), and accounted for changes resulting from the adoption of the Gregorian calendar. Gould has written that Ussher’s figure for the age of Earth was actually a good deal higher than almost all other contemporary estimates, but this contention is open to serious doubt.
In As You Like It, Shakespeare has Rosalind observe to Orlando that “[t]he poor world is almost 6000 years old”. It is thought that the play was first performed in about 1600. Shakespeare died in 1616. Ussher was only nineteen in 1600 and didn’t die until 1656. His estimate of the age of Earth was completed in 1654. It is just possible that Shakespeare learned of Ussher’s estimate for the age of Earth some time after his play’s first performance, and added the line in for a contemporary audience for whom Ussher’s estimate was new, though as yet unpublished, news, but it seems a little unlikely. The facts as told in Wikipedia under the heading “Young Earth Creationism” strongly suggest that there were many estimates for a young Earth made between 1000 and 1700 AD. About fifty different estimates are listed in the article. These, in the main, were in the range 6000–3000 BC. Isaac Newton and Martin Luther, for example, weighed in with estimates of 4000 BC and 3961 BC respectively. Recall that Ussher was a senior prelate in the Church at the time that that wonderful literary masterpiece, the King James translation of the Bible, was being produced. It is hardly surprising that Ussher’s estimate was the one used by the translators. Nor is it surprising that he should, as a result, be the target of opprobrium from a variety of scientists now in possession of much more accurate information about the age of the Earth. Shakespeare’s reference to the planet’s age doubtless came from one or more of the many similar estimates current at the time.
It is important to remember that in Ussher’s lifetime, only about five hundred years ago, many tools now available for dating artifacts and events were unknown. In my generation, many people still either ignore or outright disbelieve the scientific evidence relating to the age of the universe and of Earth. The dissonance between the book of Genesis and what scientists have learned about our genesis is explained by most clerics by asserting that Genesis was always intended as a poem or fable of creation and was never meant to be taken literally. This assertion is a harmless example of historic revisionism, but it is certainly true that these days, most religious people have found a way to believe both the scientific discoveries and the religious texts, even when the two are incompatible. Those who have refused to do so have found themselves faced with some serious contradictions to resolve.
One of the falsehoods I was taught at school was that the oceans were getting gradually more and more saline, as Earth’s rivers continuously carried small concentrations of salt to the sea. We were told that the salt gradually increased in concentration in the ocean, while the water that carried the salt from the land was recycled by a process of evaporation, formation into clouds and then precipitation back onto land as rainfall. It was not until quite late in life that I learned that this interpretation of events is wrong. Our oceans are not getting saltier. As it happens, again according to a perceptive and interesting chapter in Eight Little Piggies, this particular misunderstanding has been around for quite a few centuries. A distinguished British scientist, Edmund Halley (he after whom Halley’s comet is named), tried to use this assumption as a way of estimating the age of Earth. Halley was born in the same year that Ussher died (1656) and is remembered principally for his contributions to astronomy and for his work on magnetic variation. He was Savilian Professor of Geometry at Oxford University, Astronomer Royal, and a distinguished member of the Royal Society.
Halley lamented the fact that measurements of the saltiness of the sea had not been made by the ancient Greeks and Romans so that he could compare the salinity he measured with that of ancient times, and thus derive a number for the rate at which oceanic salinity was increasing. Then, assuming that the rate of salinity increase was constant, and that the ocean started out as fresh water somewhere near the birth of Earth (both assumptions open to dispute), he reasoned that it should be possible to calculate the age of the oceans, and by extension, the approximate age of Earth. Lacking the all-important early measurements, he never made that estimate himself. However, in the late nineteenth century, Irish geologist John Joly did make an estimate using Halley’s method and came up with 100 million years as the age of the oceans, and thus, he assumed, of Earth – still a long way from current estimates of about 4.5 billion years, but also over ten thousand times closer than James Ussher’s attempt.
For reasons that are only fairly well understood, despite significant variations of salinity in the world’s oceans, overall, the salinity of the oceans appears to have reached a stable state. While salt is continually carried to the oceans by rivers, it is also constantly being used up by various life forms and, it is now believed, at least partially stripped from the ocean water inside hot vents. These vents are located on the ocean floor where tectonic plates are drifting slowly apart, permitting ocean water to penetrate deep into the hot ocean floor before being expelled – usually sulphur rich but relatively salt-free – back into the ocean. It has been estimated that all the water in our oceans is flushed through these hot vents on average once every 10 million years.[21]
Gould draws the following insightful lesson from this classic case of drawing incorrect conclusions as a result of faulty assumptions:
The best signs of history are objects so complex and so bound in webs of unpredictable contingency that no state, once lost, can ever arise again in precisely the same way. Life, through evolution, possesses this unrepeatable complexity more decisively than any other phenomenon on our planet. Scientists did not develop a geological time scale – the measuring rod of history – until they realized that fossils provided such a sequence of uniquely non-repeating events.[22]
While there are aspects of Gould’s statement that I don’t quite agree with (which I will discuss later), I was struck by the beauty of the insight. Most of the physical processes we observe have long ago reached some kind of natural equilibrium and so cannot be useful to demark time. The Halley ocean salinity test provides a nice example of this. However, life forms keep changing in unpredictable ways, and the odds of them reverting to a previous form are negligible. As a result, we can confidently associate an era with the existence of particular life forms, preserved as fossils. Perhaps there will be a time when human fossils will be useful to date soil strata from our era, in which case we had better not all opt to be cremated!
Gould’s observation about the use of fossils to date the age of rocks refers to research pioneered by British canal builder William Smith in the early 1800s. Smith discovered that many of the layers of rock that he had to dig through to build canals contained fossils and that the fossils tended to be different in each layer. As he toured about England and Wales, digging more and more canals, he found that he could correlate the layers he encountered at different sites by the similarity of their fossil content. In short, he could determine a relative time at which a rock stratum was laid down by the type of fossilized animals it contained, and could thus correlate the relative ages of the various strata he encountered throughout