Tag: fossils

Are these fossils dead, yet?

Non-living fossils and dead metaphors

Keith S. Taber

Fossil pottery?
(Images by by Laurent Arroues {background}) and OpenClipart-Vectors from Pixabay)

I was intrigued by some dialogue that was part of one of (physicist) Jim Al-Khalili's interviews for the BBC's 'The Life Scientific' series, where Prof. Al-Khalili "talks to leading scientists about their work, finding out what inspires and motivates them and asking what their discoveries might do for mankind".

The Life Scientific – interviews with scientists about their lives and work

This week he was talking to Dr Judith Bunbury of St. Edmund's College and the Department of Earth Sciences at Cambridge ('Judith Bunbury on the shifting River Nile in the time of the Pharaohs'). It was a fascinating interview, and in particular discussed work showing how the Nile River has repeatedly changed its course over thousands of years. The Nile is considered the longest river in Africa (and possibly the world – the other contender being the Amazon).

Over time the river shifts is position as it unevenly lay down sediment and erodes the river banks – (Image by Makalu from Pixabay)

The exchange that especially piqued my interest followed an account of the diverse material recovered in studies that sample the sediments formed by the river. As sediments are laid down over time, a core (collected by an auger) can be understood to have formed on a time-line – with the oldest material at the bottom of the sample.

Within the sediment, researchers find fragments of animal bone, human teeth, pottery, mineral shards from the working of jewels…

"Are you sure the Nile flows this far?" Using an auger to collect a core (of ice in this case) (Image by David Mark from Pixabay)

Dr Bunbury was taking about how changing fashions allowed the pottery fragments to be useful in dating material – or as the episode webpage glossed this: "pottery fragments which can be reliably time-stamped to the fashion-conscious consumers in the reign of individual Pharaohs".

This is my transcription of the exchange:

[JAK]: …a bit like fossil hunting
[JB]: well, I mean, we're just treating pottery as a kind of fossil
a kind of fossil, yeah, > no, absolutely >
< and it is a fossil <
yes, well quite, I can see the similarities.

Prof. Jim Al-Khalili interviewing Dr Judith Bunbury

Now Prof. Jim has a very gentle, conversational, interview style, as befits a programme with extended interviews with scientists talking about their lives (unlike, say, a journalist faced with a politician where a more adversarial style might be needed), so this exchange probably comes as close to a disagreement or challenge as 'The Life Scientific' gets. Taking a slight liberty, I might represent this as:

  • Al-Khalili: your work is like fossil hunting, the pottery fragments are similar to fossils
  • Bunbury: no, they ARE fossils

So, here we have an ontological question: are the pottery fragments recovered in archaeological digs (actually) fossils or not?

Bunbury wants to class the finds as fossils.

Al-Khalili thinks that in this context 'a kind of fossil' and 'like fossil hunting' are similes ("I can see the similarities") – the finds are somewhat like fossils, but are not fossils per se.

Read about science similes

So, who is right?

Metaphorical fossils

The term fossil is commonly used in metaphorical ways. For example, for a person to be described as a fossil is to be characterised as a kind of anachronism that has not kept up with social changes.

The term also seems to have been adopted in some areas of science as a kind of adjective. One place it is used is in relation to evidence of dampened ocean turbulence,

"The term 'fossil turbulence' refers to remnants of turbulence in fluid which is no longer turbulent."

Gibson, 1980, p.221

If that seems like a contradiction, it is explained that

"Small scale fluctuations of temperature, salinity, and vorticity in the ocean occur in isolated patches apparently caused by bursts of active turbulence. After the turbulence has been dampened by stable stratification the fluctuations persist as fossil turbulence."

Gibson, 1980, p.221

So, 'fossil turbulence' is not actually turbulence, but more the afterglow of the turbulence: a bit like the aftermath of a lively party which leaves its traces: the the chaotic pattern of abandoned debris provides signs there has been a party although there is clearly no longer a party going on.

An analogy for 'fossil turbulence'

Another example from astronomy is fossil groups of galaxies, which are apparently "systems with a very luminous X-ray source …and a very optically dominant central galaxy" (Kanagusuku, Díaz-Giménez & Zandivarez, 2016). It seems,

"The true nature of fossil groups in the Universe still puzzles the astronomical community. These peculiar systems are one of the most intriguing places in the Universe where giant elliptical galaxies are hosted [sic]."

Kanagusuku, Díaz-Giménez & Zandivarez, 2016

('Hosted' here also seems metaphorical – who or what could be acting as a host to an elliptical galaxy?)

The term 'fossil group' was introduced for "for an apparently isolated elliptical galaxy surrounded by an X-ray halo, with an X-ray luminosity typical of a group of galaxies" (Zarattini, Biviano, Aguerri, Girardi & D'Onghia, 2012): so, something that looks like a single galaxy, but in other respsects resembles a whole group of galaxies?

Close examination might reveal other galaxies present, yet the 'fossil' group is "distinguished by a large gap between the brightest galaxy and the fainter members" (Dariush, Khosroshahi, Ponman, Pearce, Raychaudhury & Hartley, 2007). Of course, there is normally a 'large gap' between any two galaxies (space contains a lot of, well, space), but presumably this is another metaphor – there is a 'gap' between the magnitude of the luminosity of the brightest galaxy, and the magnitudes of the luminosities of the others.

Read about science metaphors

Dead metaphors

One way in which language changes over time is through the (metaphorical) death of metaphors. Terms that are initially introduced as metaphors sometimes get generally adopted and over time become accepted terminology.

Many words in current use today were originally coined in this way, and often people are quite unaware of their origins. References to the hands of a clock or watch will these days be taken as simply a technical term (or perhaps for those who only familiar with digital clocks, a complete mystery?) In time, this may happen to 'fossil turbulence' or 'fossil galaxy groups'.

What counts as a fossil?

But it seems reasonable to suggest that, currently at least, these are still metaphors, implying that in some sense the ocean fluctuations or the galactic groups are somewhat like fossils. But these are not actual fossils, just as tin-pot dictators are not actually fabricated from tin.

So, what are actual fossils. The 'classic' fossil takes the form of an ancient, often extinct, living organism, or a part thereof, but composed of rock which has over time replaced the original organic material. In this sense, Prof. Al-Khalili seems correct in suggesting bits of pottery are only akin to fossils, and not actually fossils. But is that how the experts use the term?

According to the British Geological Survey (BGS):

Fossils are the preserved remains of plants and animals whose bodies were buried in sediments, such as sand and mud, under ancient seas, lakes and rivers. Fossils also include any preserved trace of life that is typically more than 10 000 years old. 

https://www.bgs.ac.uk/discovering-geology/fossils-and-geological-time/fossils/ 1

Now, pottery is not the preserved remains of plants or animals or other living organisms, but the site goes on to explain,

Preserved evidence of the body parts of ancient animals, plants and other life forms are called 'body fossils'. 'Trace fossils' are the evidence left by organisms in sediment, such as footprints, burrows and plant roots.

https://www.bgs.ac.uk/discovering-geology/fossils-and-geological-time/fossils 1

So, footprints, burrows, [evidence of] plant roots 2…or shards of pottery…can be trace fossils? After all, unearthed pottery is indirect evidence of living human creatures having been present in the environment, and, as the BGS also points out "the word fossil is derived from the Latin fossilis meaning 'unearthed'."

However, if the term originally simply meant something unearthed, then although the bits of pot would count as fossils – based on that argument so would potatoes growing in farmers' fields. So, clearly the English word 'fossil' has a more specific meaning in common use than its Latin ancestor.

But going by the BGS definition, Dr Bunbury's unearthed samples of pottery are certainly evidence of organisms left in sediment, so might be considered fossils. These fossils are not the remains of dead organisms, but neither is 'fossil' here simply a metaphor (not even a dead metaphor).

Work cited:
  • Dariush, A, Khosroshahi, H. G., Ponman, T. J., Pearce, F., Raychaudhury, S. & Hartley, W. (2007), The mass assembly of fossil groups of galaxies in the Millennium simulation, Monthly Notices of the Royal Astronomical Society, Volume 382, Issue 1, 21 November 2007, Pages 433-442, https://doi.org/10.1111/j.1365-2966.2007.12385.x
  • Gibson, Carl H. (1980) Fossil Temperature, Salinity, and Vorticity Turbulence in the Ocean. In Jacques C.J. Nihoul (Ed.) Marine Turbulence, Elsevier, pp. 221-257.
  • Kanagusuku, María José, Díaz-Giménez, Eugenia & Zandivarez, Ariel (2016) Fossil groups in the Millennium simulation – From the brightest to the faintest galaxies during the past 8 Gyr, Astronomy & Astrophysics, 586 (2016) A40, https://doi.org/10.1051/0004-6361/201527269.
  • Romero, I. C., Nuñez Otaño, N. B., Gibson, M. E., Spears, T. M., Fairchild, C. J., Tarlton, L., . . . O'Keefe, J. M. K. (2021). First Record of Fungal Diversity in the Tropical and Warm-Temperate Middle Miocene Climate Optimum Forests of Eurasia [Original Research]. Frontiers in Forests and Global Change, 4. https://doi.org/10.3389/ffgc.2021.768405
  • Zarattini, S., Biviano, A., Aguerri, J. A. L., Girardi, M. & D'Onghia, E. (2012) Fossil group origins – XI. The dependence of galaxy orbits on the magnitude gap, Astronomy & Astrophysics, 655 (2021) A103, DOI: https://doi.org/10.1051/0004-6361/202038722.
Notes:

1 "Fossils are the preserved remains of plants and animals whose bodies …". But this suggests that fungi do not form fossils. The same site points out that "We tend to think of fungi, such as mushrooms and toadstools, as being plants — but they are not. They neither grow from embryos nor photosynthesise and are put in a separate kingdom" (https://www.bgs.ac.uk/discovering-geology/fossils-and-geological-time/plants-2/) – yet does not seem to mention any examples of fungi that have been fossilised (so the comment could be read to be meant to suggest that fossil fungi are found as well as fossil plants; but could equally well be read to mean that as fungi are not plants they do not fossilise).

The second quote here is more inclusive: "Preserved evidence of the body parts of ancient animals, plants and other life forms…" The site does also specify that "Remains can include microscopically small fossils, such as single-celled foraminifera…" (https://www.bgs.ac.uk/discovering-geology/fossils-and-geological-time/fossils/).

So, just to be clear, fossil fungi have been found.



Fungal spores found in Thailand – figure 3 from Romero et al, 2021. These fossils were recovered form lignite (a form of coal) deposited in the Miocene epoch.
Copyright © 2021 Romero, Nuñez Otaño, Gibson, Spears, Fairchild, Tarlton, Jones, Belkin, Warny, Pound and O'Keefe; distributed under the terms of the Creative Commons Attribution License (CC BY).

2 If the roots were themselves fossilised then these would surely be body fossils as roots are parts of plant. Presumably this is meant to refer to the channels in soil when the roots grow through the soil.


What Homo erectus did next

Can we be certain about something that happened half a million years ago?

Keith S. Taber

What was going on in Java when Homo erectus lived there? (Image by Kanenori from Pixabay )

About half a million years ago a hominid, of the Homo erectus species, living in Java took a shell and deliberately engraved a mark on it. Now, I was not there when this happened, so my testimony is second hand, but I can be confident about this as I was told by a scientist that she was sure that this definitely happened.

"…we knew for sure that it must have been made by Homo erectus"

But how can we be so sure about something alleged to have occurred so long ago?

"A long time ago [if not] in a galaxy far, far away…." the skull of a specimen of Homo erectus (Image by Mohamed Noor from Pixabay ) [Was this an inspiration for the Star Wars stormtrooper helmet?]

I doubt Fifi would be convinced.1 Fifi was a Y12 student (c.16 years old) interviewed as part of the LASAR project who had reservations about palaeontology as it did not provide certain scientific knowledge,

"I like fossils though, I think they're interesting but I don't think I'd really like [working as a palaeontologist]…I don't think you could ever really know unless you were there… There'll always be an element of uncertainty because no matter how much evidence you supply there will always be, like, doubt because of the fact that you were never there…there'll always be uncertainty."

Fifi quoted in Taber, Billingsley & Riga, 2020, p.57

Learners can have alternative conceptions of the nature of science, just as much as they often do for forces or chemical bonding or plant nutrition. They often think that scientific knowledge has been 'proved', and so is certain (e.g., Taber, Billingsley, Riga & Newdick, 2015). An area like palaeontology where direct observation is not possible may therefore seem to fall short of offering genuine scientific knowledge.

The uncertain nature of scientific knowledge

One key feature of the nature of science is that it seeks to produce general or theoretical knowledge of the natural world. That is, science is not just concerned with providing factual reports about specific events but with developing general accounts that can explain and apply to broad categories of objects and events. Such general and theoretical knowledge is clearly more useful than a catalogue of specific facts – which can never tell us about the next occasion or what might happen in hypothetical situations.

However, a cost of seeking such applicable and useful knowledge is that it can never be certain. It relies on our ways of classifying objects and events, the evidence we have collected so far, our ability to spot the most important patterns -and the deductions this might support. So, scientific knowledge is always provisional in the sense that it is open to revision in response to new data, or new ways of thinking about existing data as evidence.

Read about the nature of scientific knowledge

Certainty and science in the media

Yet often reports of science in the media give the impression that science has made absolute discoveries. Some years ago I wrote about the tendency in science documentaries for the narrative to be driven by links that claimed "...this could only mean…" when we know that in science the available data always underdetermines theory (Taber, 2007). Or, to put it another way, we could always think up other ways of explaining the data. Sometimes these alternatives might seem convoluted and unlikely, but if we can suggest a possible (even when unconvincing) alternative, then the available data can never "only mean" any one particular proposed interpretation.

Read about scientific certainty in the media

Fossils from Java

Prof. Joordens who reported on how a shell had been deliberately marked by a member of the Homo erectus species hundreds of thousands of years ago.

(taken from her website at https://www.naturalis.nl/en/science/researchers/jose-joordens )

The scientist concerned was J.C.A (José) Joordens who is Professor in Hominin Paleoecology and Evolution, at Maastricht University. Prof. Joordens holds the Naturalis Dubois Chair in Hominin Paleoecology and Evolution. The reference to Dubois relates to the naturist responsible for finding a so-called 'missing link' in the chain of descent to modern humans,

"One of the most exciting episodes of palaeoanthropology was the find of the first transitional form, the Pithecanthropus erectus, by the Dutchman Eugène Dubois in Java during 1891-1892. …Besides the human remains, Dubois made a large collection of vertebrate fossils, mostly of mammals, now united in the so-called Dubois Collection."

de Vos, 2004

The Java man species, Pithecanthropus erectus (an upright ape/mokey-man), was later renamed as Homo erectus, the upright man.

'In Our Time' episode on Homo erectus

On an edition of BBC Radio 4's 'In Our Time' taking 'Homo erectus' as its theme, Prof. Joordens explained how some fossil shells collected by Dubois as part of the context of the hominid fossils had remained in storage for over a century ("The shells had been, well, shelved…"!), before a graduate student set out to photograph them all for a thesis project. This led to the discovery that one of the shells appeared to have been engraved.

This could only mean one thing…

This is what Prof. Joordens told the host, Melvyn Bragg,

"One shell that had a very strange marking that we could not understand how it ended up there…

It was geometric, like a W, and this is of course something that animals don't produce. We had to conclude that it must have been made by Homo erectus. And it must have been a very deliberate marking because of, we did experimental research trying to replicate it, and then we actually found it was quite hard to do. Because, especially fresh shells, they have a kind of organic exterior, and it's hard to push some sharp objects through and make those lines, so that was when we knew for sure that it must have been made by Homo erectus."

Prof. José Joordens talking on 'In Our Time'

We may consider this claim to be composed of a number of components, such as:

  • There is a shell with some 'very strange' markings
  • The shell was collected in Java in the nineteenth century
  • The shell had the markings when first collected
  • The markings were not caused by some natural phenomenon
  • The markings were deliberate not accidental
  • The markings were made by a specimen of Homo erectus

A sceptic might ask such questions as

  • How can we be sure this shell was part of the original collection? Could it have been substituted by mistake or deliberately?
  • How do we know the marks were not made more recently? perhaps by someone in the field in Java, or during transit form Java to the Netherlands, or by someone inspecting the collection?
  • Given that even unusual markings will occur by chance occasionally, how can we be certain these markings were deliberate? Does the mark really look like a 'W 'or might that be an over-interpretation. 2

And so forth.

It is worth bearing in mind that no one noticed these markings in the field, or when the collection was taken back to the Netherlands – indeed Prof. Joordens noted she had carried the shell around in her backpack (could that have been with an open penknife?) unaware of the markings

Of course, Prof. Joordens may have convincing responses to many of these questions – but a popular radio show is not the place to detail all the argument and evidence. Indeed, I found a report in the top journal Nature ('Homo erectus at Trinil on Java used shells for tool production and engraving') by Prof. Joordens and her team 3, claiming,

"One of the Pseudodon shells, specimen DUB1006-fL, displays a geometric pattern of grooves on the central part of the left valve [*]. The pattern consists, from posterior to anterior, of a zigzag line with three sharp turns producing an 'M' shape, a set of more superficial parallel lines, and a zigzag with two turns producing a mirrored 'N' shape. Our study of the morphology of the zigzags, internal morphology of the grooves, and differential roughness of the surrounding shell area demonstrates that the grooves were deliberately engraved and pre-date shell burial and weathering"

Joordens et al, 2015, p.229

[* Photgraphs are included in the paper. Some can also be seen at https://www.smithsonianmag.com/science-nature/oldest-engraving-shell-tools-zigzags-art-java-indonesia-humans-180953522/ ]

It may seem most likely that the markings were made by a Homo erectus, as no other explanation so far considered fits all the data, but theory is always under-determined – one can never be certain another scenario might be found which also fits the known facts.

Strictly, Prof. Joordens' contradicts herself. She claims the marks are "something that animals don't produce" and then claims an animal is responsible. She presumably meant that no non-hominid animal makes such marks. Even if we accept that (and, as they say, absence of evidence is not evidence of absence 4), can we be absolutely certain some other hominid might not have been present in Java at the time, marking the odd shell? As the 'In Our Time' episode discussed, Homo erectus often co-existed with other hominids.

Probably not, but … can we confidently say absolutely, definitely, not?

As Fifi might say: "I don't think you could ever really know unless you were there".

My point is not that I think Prof. Joordens is wrong (she is an expert, so I think she is likely correct), but just that her group cannot be absolutely certain. When Prof. Joordens says she knows for sure I assume (because she is a scientist, and I am a scientist) that this means something like "based on all the evidence currently available, our best, and only convincing, interpretation is…" Unfortunately lay people often do not have the background to insert such provisos themselves, and so often hear such claims literally – science has proved its case, so we know for sure. Where listeners already think scientific knowledge is certain, this misconception gets reinforced.

Meanwhile, Prof. Joordens continues her study of hominids in Java in the Studying Homo erectus Lifestyle and Location project (yes, the acronym is SHeLL).

Work cited:
Notes

1 As is usual practice in such research, Fifi is an assumed name. Fifi gave permission for data she contributed to the research to be used in publications on the assumption it would be associated with a pseudonym. (See: 'Using pseudonyms in reporting research'.)

2 No one is suggesting that the hominid deliberately marked the shell with a letter of the Roman alphabet, just that s/he deliberately made a mark that represented a definite and deliberate pattern. Yet human beings tend to spot patterns in random data. Could it just be some marks that seem to fit into a single pattern?

3 Josephine C. A. Joordens, Francesco d'Errico, Frank P. Wesselingh, Stephen Munro, John de Vos, Jakob Wallinga, Christina Ankjærgaard, Tony Reimann, Jan R. Wijbrans, Klaudia F. Kuiper, Herman J. Mücher, Hélène Coqueugniot, Vincent Prié, Ineke Joosten, Bertil van Os, Anne S. Schulp, Michel Panuel, Victoria van der Haas, Wim Lustenhouwer, John J. G. Reijmer & Wil Roebroeks.

4 At one time there was no evidence of 'noble' gases reacting. At one time there was no evidence of ozone depletion. At one time there was no evidence of superconductivity. At one time there was no evidence that the blood circulates around the body. At one time there was no evidence of any other planet having moons. At one time there was no evidence of protons being composed of even more fundamental particles. At one time there was no evidence of black holes. At one time there was no evidence that smoking tobacco was harmful. At one time there was no evidence of … [fill in your choice scientific discovery!]