Deep-time and contingency

As a palynologist (a palaeontologist specialising in fossil spores, pollen and plankton), I’ve always been interested in the succession of events in geological history. Many of the most dramatic events, extinctions, migrations, occurred before the start of the Quaternary, around 2.5 million years ago and so would be described as ‘deep-time’. But the way that I have thought about geological history and deep-time as a ‘one way single track street’ has changed a little recently, after reading a new book published by the philosopher William MacAskill. The book is called What We Owe the Future. I’m now fascinated by the possibility of different tracks in geological history resulting from different outcomes at points of contingency (‘what if’ moments). This is a slightly different topic to what I usually write in my role as DDE Director of Europe, Middle East and Africa, but perhaps something that deep-time specialists might consider in the future as we move to more and more sophisticated models and simulations. DDE, through the DDE platform, is developing models like this that track the events of Earth history. Perhaps models in the future could even track the alternative futures of Earth history. If that confuses you, read on.

What We Owe the Future

What We Owe the Future by William MacAskill, published in 2022, is a book about moral choices for the future. It puts forward the case for something called ?‘longtermism’, which is the idea that we should think more about the distant future and the wellbeing of future human beings, intelligent life and civilisation. William MacAskill is a philosopher and philanthropist at the University of Oxford. He thinks that we are at a crucial point in history - with our science and technology - in being able to help improve the ?well-being of people who aren’t born yet. MacAskill talks a lot about contingency and chance (‘what if?’ moments) – in other words tracing the possibilities of different decision points or turning points in human history. He describes how crucial certain turning points have been in human progress, for example the abolition of slavery. He examines the element of contingency in some of these turning points (considering ‘what if this had happened, and not that’). In the main bulk of the book, he shows how our present knowledge of history, science and technology should put us in a great position to influence the Earth for good into the distant future through good decision making. It’s very inspiring.

Turning points in early human history

As a palaeontologist, I’m interested in some of the ‘what if?’ moments in early human history, for example, the migration of Homo sapiens out of Africa. MacAskill’s book also shows some interest in this. It is surprising how contingent the evolution of Homo sapiens has been and how different things could have been with only small alterations of geography or climate. Homo, as a genus, began in the Pleistocene ice-age. Africa remained warm during ?the Pleistocene and ‘incubated’?species of Homo that spread out of Africa looking for land or following the savanna climate as it grew and shrank across the Sahara and Middle East. The most contingent part of this concerned the precise route out of Africa. Migration was not impossible across the Strait of Gibraltar (too deep to walk across and too far to swim), so Homo drifted in waves across the land corridor of the Isthmus of Suez, which was land all the way through the Pleistocene. But if the Pleistocene seas had flooded the isthmus, what would Homo sapiens look like now?

Another highly contingent event was the creation of the Isthmus of Panama about 3 million years ago. This separated the Atlantic and Pacific oceans and started off the Gulf Stream, influencing Northern Hemisphere climate ever since, and allowing terrestrial species to migrate between the Americas. It may also have made Africa colder, windier, and drier, perhaps prompting the evolution of Australopithecus, the earliest of our ancestors . How would modern humans look if this thin neck of land had never formed?

Deep-time turning points

There are obviously thousands of other highly contingent turning points in deep time. Some are unknowable because we don’t have the data to identify them – the detailed configurations of palaeoclimate and palaeogeography for example.?The alternative futures of those turning points are also difficult to know; but where it might be possible, plotting alternative futures might be interesting and enlightening?- a bit like the way that alternative statistical simulations can be run for modern climate forecasts. An example of an event that interests me as a researcher is the Palaeocene-Eocene Thermal Maximum, well known for being one of the fastest and most extreme climate events in the Phanerozoic. Oxygen isotopes through the PETM indicate that sea surface temperatures rose by between 5 and 8°C, suggesting that the Earth’s oceans reached their warmest for 65 million years during this short time period. Palaeontologists and stratigraphers have studied many areas during the PETM, and one of those areas is the present day North Sea. Its geographical setting during the PETM was such that it was a sensitive recorder of changes in northwest Europe at the time, partly because it was much more enclosed than it is now, with a land bridge for at least part of the period between northern France and southern England. With a slightly higher sea level that allowed exchange of marine waters through what is now the English channel, how might the local effects of the PETM have been different, for example salinity, nutrient availability and coastal hydrology (Fig. 1)? The succession of North Sea vegetation belts during the PETM have been well established (e.g. Kender et al. 2012) but how might they have been different with a more open North Sea? This ‘alternative future’ would be useful to understand now as northwest Europe faces rapid warming and ecological change at similar rates to those of the PETM, and the present North Sea is open across the English Channel.

Fig. 1. Geochemical, micropaleontologic, and sedimentologic data for North Sea core 22/10a-4 (see Kender et al. 2012). How might salinity etc. have been different with a less enclosed North Sea??

A challenge

I know these ways of thinking ?are perhaps foreign to deep-time stratigraphers and palaeontologists but they may be useful in?the future. I lay down a challenge to my DDE colleagues, and to stratigraphers and palaeontologists everywhere!

References

Kender, S, Stephenson, M H, Riding J B, Leng, M J, Knox, R W O’B., Vane, C H, Peck, V L, Kendrick, C P, Ellis, M A, and Jamieson, R. 2012. Marine and terrestrial environmental changes in NW Europe preceding carbon release at the Paleocene–Eocene transition.?Earth and Planetary Science Letters, 353-354, 108-120.

MacAskill?W. (2022). What We Owe the Future, Oneworld Publications. 352 pp., ISBN:?9780861542505?