Tag Archives: Mediterranean

The bottomlands

There’s a book from back in 1954, now out of print, called Engineer’s Dreams by Willy Ley (who was most notable as a spaceflight advocate). The book lays out various grandiose engineering projects that people have proposed over the years. Some of these dreams have actually been realized: after centuries of people talking about it, there is now a tunnel under the English Channel.

Others … well …

One project the book discusses is damming the Congo River, creating a huge lake in the Congo basin, then sending the water north to create another huge lake in Chad. (There’s a small lake there now, almost dried out, which was a lot bigger 10,000 years ago when Africa was wetter.) From Lake Chad, the water would be sent further north to create a great river – a second Nile — running through Libya into the Mediterranean. All that fresh water is just running uselessly into the Atlantic now. Why not send it someplace where it’s needed?

Another engineer’s dream is to refurbish the Mediterranean Sea by building a dam across the Strait of Gibraltar. This actually isn’t an impossible project. The strait is less than nine miles across at its narrowest, and about 3000 feet deep at its deepest. A dam across the strait would have some dramatic consequences. The Mediterranean loses more water from evaporation than it gains from the rivers running into it. The difference is made up by a flow of water from the Atlantic. Cut this off, and the sea will start shrinking. You could let the Mediterranean drop 330 feet before stabilizing it, run a huge hydroelectric plant at Gibraltar, and open up a whole lot of prime Mediterranean real estate.

Sadly, whenever people have dreamed great dreams, there have always been small-minded carpers and critics to raise objections. Okay, so maybe the mayors of every port on the Mediterranean would complain about their cities becoming landlocked. And maybe massively lowering the sea level in an earthquake-prone region would lead to a certain amount of tectonic readjustment before things settled down.

So probably the Gibraltar dam will never be built (although Spain and Morocco are considering a tunnel). But we’ve seen already that Mother Nature sometimes plays rough with her children, and it turns out (although Ley couldn’t have known this back in the 50s) that damming the Mediterranean has already been done. The story begins back in the Mesozoic (late March), when the Tethys Sea ran between the northern continent of Laurasia and the southern continent of Gondwanaland. The sea was still around 50 million years ago (April 11) when whales were learning to swim. But it has been gradually disappearing over time. When India crashed into Asia and raised the Himalayas, the eastern part of the sea closed off. And as Africa-Arabia moved north toward Eurasia, a whole chain of mountains was raised up, running from the Caucasus to the Balkans to the Alps. The Tethys Sea was scrunched between these: what’s left of it forms the Caspian, Black, and Mediterranean seas.

Starting about 6 million years ago, the story takes a really dramatic turn. The continents were in roughly there present positions, but the northern movement of the African tectonic plate, plus a decline in sea levels due to growing ice caps, shut off the Strait of Gibraltar, sporadically at first. With water from the Atlantic cut off, the Mediterranean began drying out. By 5.6 million years ago, it had dried out almost completely – the Messinian Salinity Crisis. (The Messinian Age is the last part of the Miocene Period). There were just some hyper-saline lakes, similar to the Great Salt Lake in Utah or the Dead Sea in the Near East, at the bottom of an immense desert more than a mile below today’s sea level. The Nile and the Rhone cut deep channels, far below their current levels, to reach these lakes. This lasted until 5.3 million years ago, when the strait reopened and a dramatic flood from the Atlantic restored the Mediterranean.

All this was happening just around that time that hominins were committing to bipedalism. Did the cataclysmic events in the Mediterranean basin have some influence on hominin evolution in Africa? At this point we can’t say.

Harry Turtledove, prolific writer of alternative history, has a novella, Down in the Bottomlands, set on an alternative Earth in which the Mediterranean closed off, dried out, and never reflooded. In the novella, terrorists are plotting to use a nuclear weapon to reopen the Mediterranean desert to the Atlantic – sort of Engineer’s Dreams in reverse.

Bring out your dead


Something major happened to Earth’s atmosphere in 535. We have reports from around the world of the sun being darkened or blotted out for more than a year, and evidence from tree rings and ice cores of an extreme cold spell. The culprit might have been dust thrown into the atmosphere by volcano or a comet. This on its own must have been bad news for the world’s population. But even more consequential was what happened starting seven years later. In 542, bubonic plague made an appearance in the Egyptian port of Pelusium, and rapidly spread around the Mediterranean, eventually reaching much of western Europe and Persia. (China seems to have gotten off more lightly.) It’s possible the epidemic had its origin among rodents in the east African Great Lakes region: disturbances to these populations after 535 may have contributed to the spread of plague, either up the Nile valley, or to trading towns on the Indian Ocean. Recent genetic evidence has confirmed that plague bacteria from this period are almost identical to those from the later, better known Black Death in the late Middle Ages. The plague struck repeatedly around west Eurasia for the next 200 years, before disappearing. The death toll must have been many tens of millions.

Major movements of peoples followed the plague in the sixth and seventh centuries. The Byzantine reconquest of most of the western Roman Empire, under Justinian, came undone as a new wave of Germanic barbarians, the Lombards, occupied Italy. The Anglo-Saxons expanded from the east of England to occupy most of present-day England. Slavs moved south to occupy most of the Balkans. And, most consequentially, Arabs under the banner of Islam occupied most of the Middle East and North Africa.

The selfish meme


In the first decades after the crucifixion of Jesus, the number of those who worshiped him as a resurrected savior was at most a few thousand, and probably many fewer. In 313, when Constantine issued the Edict of Milan mandating tolerance for Christianity, Christians numbered many millions. Thus, in two and a half centuries, Christian numbers had doubled at least ten times. On average, someone who lived to the age of seventy-five during this period could expect to live through an eight-fold increase in the numbers of Christians between her birth and her death.

Christianity began in confusion, controversy and schism and so it continued. A dominant orthodox church, with a recognizable ecclesiastical structure, emerged only very gradually and represented a process of natural selection — a spiritual survival of the fittest … The Darwinian image is appropriate: the central and eastern Mediterranean in the first and second centuries AD swarmed with an infinite multitude of religious ideas, struggling to propagate themselves. Every religious movement was unstable and fissiparous; and these cults were not only splitting up and multiplying but reassembling in new forms.

Paul Johnson A History of Christianity

If we’re going to apply Darwinian analogies to culture, we might want to distinguish between the selection of memes within people’s heads, and between them (intra- and inter-cephalic selection, if you will). Inside people’s heads, different ideas survive or fail depending on the benefits and costs they produce for their carriers, how well they fit with other ideas, and so on. Outside people’s heads, some ideas may spread because people work extra hard to propagate them. Christianity spread as rapidly as it did partly because it radically exalted the Spirit over the Flesh. As Clement (a relative moderate among early Christians) wrote “Our ideal is not to experience desire at all.” A consequence is that the new religion effectively sterilized a fraction of its hosts, who gave up on the normal business of marrying and raising children, and turned into cultural super-propagators.

Two ways of life were given by the Lord to his church. The one is above nature, and beyond common human living; it admits not marriage, childbearing, property nor the possession of wealth. . . . Like some celestial beings, these gaze down upon human life, performing the duty of a priesthood to Almighty God for the whole race. . . . And the more humble, more human way prompts men to join in pure nuptials, and to produce children, to undertake government, to give orders to soldiers fighting for right; it allows them to have minds for farming, for trade, and for the other more secular interests as well as for religion.

Eusebius, quoted in Peter Brown The Body and Society: Men, Women and Sexual Renunciation in Early Christianity

Women were another important vector for the spread of Christianity. Both pagans and Christians agreed they were over-represented among converts. Celsus, a pagan critic of Christianity, took a dim view of this, sounding like a modern critic of advertising for children: “Christians must admit that they can only persuade people destitute of sense, position, or intelligence, only slaves, women, and children, to accept their faith.” Tatian, a Christian apologist, was cheerier: “They say of us, that we gabble nonsense among females, half grown people, girls, and old women. Not so. Our maidens philosophize, and at their distaffs speak of things divine.”

Of course some of the same observations (e.g. regarding the overcoming of desire and religious celibacy) could be made about the spread of Buddhism during the same period, suggesting that there are general principles at work in the spread of religions, as in the spread of microorganisms.

For a sophisticated scholarly treatment along these lines of the interaction of selfish genes and selfish memes check out Mixed Messages: Cultural and Genetic Inheritance in the Constitution of Human Societies, by cultural anthropologist Robert Paul.

Plagues and peoples


Every day on Logarithmic History we cover an interval 5.46% shorter than the preceding day. From covering the first 754 million years after the Big Bang on January 1, we’re down to just under one century worth of history today.

And it’s a bad century for both Rome and China. Rome goes through an economic crisis, with a huge currency devaluation. Political life goes to hell too. From 235-284 there are 20 Emperors; 18 of them die violently. The Roman Empire experiences multiple, destructive invasions by barbarians. It recovers toward the end of the century, but in a heavily militarized and authoritarian form. And in China the Han dynasty disappears entirely after 220, to be replaced by three kingdoms of barbarian origin.

This coincidence of catastrophes may be more than just bad luck. Put it this way: If we look at the Big Picture, going way back on our calendar, and turning for a moment from human history to the evolution of life, we can summarize biological evolution since the Cambrian as:

but …

  • Now and then, a physical catastrophe punctuates the history of life, causing mass extinctions, from which living things slowly recover.

Returning to human history, we can summarize social evolution since the adoption of agriculture as:

  • A process of escalation, in which conflicts between rival groups (kin groups, empires, and – we will see – major religions) are drivers of increasing social complexity …


  • Now and then, a biological catastrophe – in the form of an epidemic of some new disease – punctuates human history, causing major population losses, and often political and social collapse as well (i.e. the “germs” in Guns, Germs and Steel).

One such catastrophe contributed to the collapse of New World societies in the face of Old World diseases after 1492. But the Old World too must have had its own earlier catastrophes as the great killer diseases – the diseases of civilization that need a minimum population to keep going – established themselves.

Epidemic disease may have made a major contribution to the fall of Rome and of Han China. Rome suffered two massive epidemics, one from 165-180, another from 251-266. It’s plausible (and someday geneticsts will tell us whether it’s true or not) that these epidemics represent the arrival of smallpox and measles in the West. And we’ll run into bubonic plague in a few days time (October 13). There may be a similar story to tell about China, also stricken by epidemics at this time. The opening of the Silk Road and of trade across the Indian Ocean allowed precious goods and new ideas to travel between civilizations. It also opened the way for lethal microorganisms. (In addition to “Guns, Germs and Steel,” a classic book here is William McNeill’s Plagues and Peoples.)

Enjoy it while it lasts

118-221 CE

If a man were called to fix the period in the history of the world, during which the condition of the human race was most happy and prosperous, he would, without hesitation, name that which elapsed from the death of Domitian [96 CE] to the accession of Commodus [180 CE]. The vast extent of the Roman empire was governed by absolute power, under the guidance of virtue and wisdom. The armies were restrained by the firm but gentle hand of four successive emperors, whose characters and authority commanded involuntary respect.

Edward Gibbon, The Decline and Fall of the Roman Empire, Chapter 3

Gibbon doesn’t include China in this assessment of the state of the world, but for that country too, under the Eastern Han dynasty, there was a period of stability and prosperity, lasting from the death of the usurper Wang Mang in 24 CE to the outbreak of the Yellow Turban peasant uprising in 184 CE. During this time, the Roman and Han empires so completely dominated their respective portions of Eurasia that they enjoyed relative peace. Toward the end of the second century CE, both empires had populations around 50-60 million; world population was perhaps 190 million. In the succeeding centuries both empires would experience major population declines and political collapse. As a result, the world’s total population may have declined as well.

(After this I’ll give dates as numbers without the “CE”.)

The historical Jesus

8 – 117 CE

The historical Jesus will be to our time a stranger and an enigma. The study of the Life of Jesus has had a curious history. It set out in quest of the historical Jesus, believing that when it had found Him it could bring him straight into our time as a Teacher and Savior. It loosed the bands by which He had been riveted for centuries to the stony rocks of ecclesiastical doctrine, and rejoiced to see life and movement coming into the figure once more, and the historical Jesus advancing, as it seemed to meet it. But He does not stay: He passes by our time and returns to His own … by the same historical inevitability by which the liberated pendulum returns to its original position. (Albert Schweitzer, The Quest of the Historical Jesus)

Taking stories of the past seriously is not the same as taking them literally, as we’ve already seen in the cases of Crater Lake and the Exodus. By the time Albert Schweitzer wrote the words above, scholars of the New Testament, working for more than a century, especially in Germany, had pieced together an account of Jesus and his message very much at variance with millennia-old Christian doctrine. It’s a testament to Schweitzer’s intellectual integrity that he – a believing Christian – followed the evidence where it took him. His general conclusions (although not all the details) are now very much the scholarly mainstream. Bart Ehrman summarizes in Jesus: Apocalyptic Prophet of the New Millennium:

Jesus is best understood as a first-century Jewish apocalypticist. This is a shorthand way of saying that Jesus fully expected that the history of the world as we know it (well, as he knew it) was going to come to a screeching halt, that God was soon going to intervene in the affairs of this world, overthrow the forces of evil in a cosmic act of judgment, destroy huge masses of humanity, and abolish existing human political and religious institutions. All this would be a prelude to the arrival of a new order on earth, the Kingdom of God. Moreover, Jesus expected that this cataclysmic end of history would come in his own generation, at least during the lifetime of his disciples. It’s pretty shocking stuff, really. And the evidence that Jesus believed and taught it is fairly impressive.

The study of the past – by biologists, geologists, physicists, and philologists – had a disturbing effect on the intellectual equilibrium of a Christian society. No doubt it will go on disturbing us, Christian or not.

Mirror empires

After centuries of division into warring states, China was united in 221 BCE, under the short-lived Qin and then the long-lived Han dynasties. Just a few years later, in 209 BCE, the nomads of the steppe north of China were united under the Xiongnu confederation.

China, like Rome, provides an instance of empire formation along a metaethnic frontier between civilized and barbarian peoples. But it also differs from the Roman case. The Roman frontier kept pushing into barbarian territory for many centuries. The descendants of Asterix and Obelisk would eventually forget their identity as Gauls, and become Romans.


But in the Far East, the steppe north of China would not support agriculture, and the people who lived there would continue their nomad way of life and retain a separate ethnic identity. For centuries after 221 BCE, China held off the barbarians by a combination of military measures (notably of course the Great Wall) and bribery (poorly disguised as “gifts” from Emperor to subject). The Xiongnu held together as a centralized state because their ruler managed the flow of trade and tribute from China. In effect, Qin/Han and Xiongnu were “mirror empires,” facing off across the line between Sown and Steppe.