CHANGE between generations

Key ideas in support of




Panta rhei kai ouden menei

“everything flows, nothing stands still”





FITNESS: Genes are the genetic material passed between generations to direct relatives (children get 50% of your genes)  but also passed by assisting the reproduction of more-or-less close relatives (nephews & nieces, for example each get 25% of your genes).  The former is Direct fitness and represents the number of offspring an individual is responsible for, but the latter is  indirect fitness and represents the offspring begotten by the genetic relatives of the individual. Many more of an individual’s genetic contribution to future generations may be indirect than direct.  All decendents bear some proportion of the original individual’s genes.  Inclusive fitness is the term that represents direct+indirect fitness.  The numbers of offspring were the currency of early genetic research but is now more aware of successful offspring.  

Natural selection favours genes that increase the reproductive success of their carriers, but it is not necessary that all individuals that share a given genotype have higher reproductive success. It suffices that carriers of the genotype reproduce more successfully on the average than those possessing alternative genotypes. A parent shares half of its genes with each progeny, so a gene that promotes parental altruism is favoured by natural selection if the behaviour’s cost to the parent is less than half of its average benefits to the progeny. Such a gene will be more likely to increase in frequency through the generations than an alternative gene that does not promote altruistic behaviour. Parental care is, therefore, a form of altruism readily explained by kin selection. (In other words, the parent spends energy caring for the progeny because it increases the reproductive success of the parent’s genes.) (Brittanica discussion of Kin Selection)

  • in A&O, art is often best treated as a form of COMMUNICATION, and we invest onsiderable effort in trying to understand the DEEP ETHOLOGY of its EXPRESSION (by an artist) and its RECEPTION (by the artist’s audience).  STATE of the artist’s MIND (as well as that of the audience) is of great interest.  This resonates with the expression of THEORY of MIND (thinking about what others are thinking). 
  • INFERENCE about the evolution of cognitive competencies.  The workings and state-of-mind of an organism may be inferred by artifacts of their behavior (including artifacts of your own behavior at your most creative or inspired).  We could interview you, but personal testamony is very susceptable to misrepresentation, no matter how authentic the witness seeks to be.  (The power of FILLING-IN to tell the best possible story)
  1. EVOLUTION (like DEVELOPMENT) is about change
  2. TRAITS – can be a PROCESS or a PRODUCT (“artifact”)
    1. Hierarchy
    2. Genes and memes
    3. Diversity and genetic polymorphism
    1. Converging or Alternative mechanisms
    2. On the Origin of Cooperation
  6. BRICOLAGE  (facis de necessitate virtute”)
    1. From Animal Signals to Art 
  10. WORDS and BIAS


in A&O we position our inquiry by treating the CREATION of art, its EXPRESSION (sometimes termed “realization”), and its RECEPTION by a viewer, as TRAITS with causes and consequences subject to change in evolutionary and developmental time.


Any organism that exists today is the descendent of an unbroken line of descent from the earliest organisms.  All the struggles and trials, pleasures and pains of ancestors of every living organism are summarized in each of them.

“Each of us is all the sums he has not counted: subtract us into nakedness and night again, and you shall see begin in Crete 4,000 years ago, a love that ended yesterday in Texas . . . each moment is the fruit of forty thousand years. the minute winning days, like flies, buzz home to death, and every moment is a window on all time” (Thomas Wolfe, Look Homeward, Angel 1929)  [3]





key observations and their inferences

  • Overproduction [individuals tend to produce as many offspring as possible]
  • Stability [population size seems to remain stable from generation to generation in stable environments]
  • Limited resources [there is not enough for everyone]
  • COMPETITION: Struggle for existence inferred
  • Variability [offspring manifest varying traits]
  • Heritability [traits are to some extent inherited]
  • DIFFERENTIAL SURVIVAL (=Natural selection) inferred [some traits allow their bearers to produce more offspring than other individuals = be more fit]
  • EVOLUTION: Over many generations, differential survival leads to changes in the frequencies of genes and thus the traits they influence.





ADAPTATION. The processes by which organisms or groups of organisms maintain homeostasis in and among themselves in the face of both short-term environmental fluctuations and long-term changes in the composition and structure of their environments.”  (Rappaport, 1971).


SEXUAL SELECTION.  “Sexual selection is a “special case” of natural selection. Sexual selection acts on an organism’s ability to obtain (often by any means necessary!) or successfully copulate with a mate” (Evolution 101, Berkeley)


SELECTION PRESSURE can be exerted by any elements of the developmental environment with which an organism must cope to fully express its latent potential in a way that enhances FITNESS. It can affect the organism at any stage in development.


FITNESS.  The extent to which an individual contributes to subsequent generations is is manifested through its phenotype—the corporeal, manifest expression of gene activity.  It is profoundly affected by the environment at all stages of development—that is, “the fitness of a given phenotype can also be different in different selective environments.”     (Wikipedia on Fitness). 





  1. EVOLUTION (like DEVELOPMENT) is about change, but the key questions framed deal with change across generations, not within a single individual. Causes and consequences of behavior are sought from clues provided by ancestors and contemporary species that are thought to resemble an ancestor in some interesting way.  A pervasive trope in evolutionary thought is the manner in which we cope with other organisms—and even other living elements within ourselves—and how those strategies become fixed in the genome.    


The methods of evolution work to inform us about

  1. how a trait has come to have its present form (compare languages from many contemporary cultures) and
  2. how traits can provide clues about the ancestral conditions that shaped it (paleolithic art). 


  1. TRAITS: are described/defined attributes of the organism at any level of organization from the subcellular to the social.  They can be corporeal (cells, organisms) or ephemeral (actions, behavioral patterns). 
    1. The hierarchical organization of traits is cause for much misunderstanding or intellectual mischief.  Traits are determined by the activation (or quiescence) of specific genes, often in combination.  The complexity becomes astonishing in itself due to the polygenic nature of the trait: they are typically determined by the converging actions of multiple genes. The genes themselves are typically pleiotropic: they influence multiple traits, often cascading through the levels of organization. 


  1. GENES and MEMES.  Traits are determined by the environment in which they are formed: the availability of resources: raw chemical materials and the energy to forge them into a distinctive trait begins with the architectural/architectonic actions of genes.




SPANDRELS and BRICOLAGE— TRAITS are resources that often have collateral effects, one of which can be utilized for adaptive functions other than the function for which the trait was originally selected.  It resembles multitasking, but there may be no coordination involved–it is making the best of available resources 

  1. COMPETITION and COOPERATION. “Evolution is based on a fierce competition between individuals and should therefore reward only selfish behavior. Every gene, every cell, and every organism should be designed to promote its own evolutionary success at the expense of its competitors. Yet we observe cooperation on many levels of biological organization. Genes cooperate in genomes. Chromosomes cooperate in eukaryotic cells. Cells cooperate in multicellular organisms. There are many examples of cooperation among animals. Humans are the champions of cooperation: From hunter-gatherer societies to nation-states, cooperation is the decisive organizing principle of human society. No other life form on Earth is engaged in the same complex games of cooperation and defection. The question of how natural selection can lead to cooperative behavior has fascinated evolutionary biologists for several decades.


3a. Converging or Alternative mechanisms

From “Five Rules for the Evolution of Cooperation” (Martin A. Nowak 2006):

Here Nowak discussed five possible mechanisms for the evolution of cooperation:

  • kin selection (relinquish personal fitness for others with whom you share more-or-less genes)
  • direct reciprocity (exchange of favors with another individual, probably frequently encountered)
  • indirect reciprocity (offering favors with expectation of reciprocity as a cultural norm; enhances reputation)
  • network reciprocity (a group of cooperators can out-compete non-cooperators)
  • group selection. (competition is between groups more than between individuals)


“Social Selection?” According to sexual selection principles, males and females compete to maximize their fitness, and a key way to do this is by minimizing their investment in specific offspring: it is often manifest as “who does the most parenting.”   Joan Roughgarden believes (“The Genial Gene: Deconstructing Darwinian Selfishness” 2009) “sexual selection: should be renamed “social selection” to emphasize the extent to which parents cooperate rather than compete.  For example, in sexual selection, the first direct parental investment in offspring is the relative amount of tissue/nutrients contributed.  Females provide a huge egg, but males “cheat” & provide little more than genes in the head of a sperm. But Roughgarden can show mathematically that this is the best way to meet conflicting needs. (book review of “The Genial Gene”)       


























































COMPETITION and COOPERATION.   “In a field defined by the cruel logic of natural selection, group selection appears to be the rare hint of virtue. The one biological force pushing back against the obvious advantages of greed and deceit.   ‘I see human nature as hung in the balance between these two extremes,’ Wilson says.  ‘If our behavior was driven entirely by group selection, then we’d be robotic cooperators, like ants.  But, if individual-level selection was the only thing that mattered, then we’d be entirely selfish.  What makes us human is that our history has been shaped by both forces.   We’re stuck in between.’”  (E.O. Wilson quoted by Jonah Lehrer in The New Yorker “Kin and Kind” Mar 5, 2012 pp. 36-42  q on p 42.)




















































































What constitutes “cooperation” is a matter of common usage — arguably, most complex organisms are amalgams of ancestors (and/or parts of their genomes) … including cellular endosymbionts such as “mitochondria.”    coping with competition or cooperation (link needs repair)




A cooperator is someone who pays a cost, c, for another individual to receive a benefit, b. A defector has no cost and does not deal out benefits. Cost and benefit are measured in terms of fitness. Reproduction can be genetic or cultural. In any mixed population, defectors have a higher average fitness than cooperators. Therefore, selection acts to increase the relative abundance of defectors. After some time, cooperators vanish from the population. Remarkably, however, a population of only cooperators has the highest average fitness, whereas a population of only defectors has the lowest. Thus, natural selection constantly reduces the average fitness of the population. Fisher’s fundamental theorem, which states that average fitness increases under constant selection, does not apply here because selection is frequency-dependent: The fitness of individuals depends on the frequency (= relative abundance) of cooperators in the population. We see that natural selection in well-mixed populations needs help for establishing cooperation.” 



Competition—cruel, bloody competition—was part of the cultural background for thinking about evolution since a compelling line in Tennyson’s “In Memorium” became part of everyone’s thinking:  “Nature red in tooth and claw.”  The ideas and imagery are charasimatic, compelling, activating cognitive pathways that have priority because of their association with danger.  


Inferences about competition have biased thinking in evolutionary theory for two hundred years. Karl Marx admired Darwin and his ideas and may have seen the implicit cooperation more clearly.  At extremes (like those of determinism), competition and cooperation have implications for human political ideology.





Adaptation is . . .   “The processes by which organisms or groups of organisms maintain homeostasis in and among themselves in the face of both short-term environmental fluctuations and long-term changes in the composition and structure of their environments.”  (Rappaport, 1971)   (homeostasis refers to stability of (mostly) internal processes that are essential for life; they are maintained by a dynamic balance of the multiple interacting systems that operate in an organism.) (see A&O Glossary)


The ESSENCE of “EVOLUTION” then, is that biologically relevant information is transmitted from one generation to the next.





The current understanding of fitness is dispositional . That is to say, fitness is a disposition of a trait to reproduce better than competitors. It is not deterministic. If two twins are identical genetically, and therefore are equally fit, there is no guarantee that they will both survive to have equal numbers of offspring. Fitness is a statistical property. What ‘owns’ the fitness isn’t the organism, but the genes. They will tend to be more often transmitted so far as what they deliver is better ‘engineered’ to the needs of the organisms in the environment in which they live. And you can determine that, within limits, by ‘reverse engineering’ the traits to see how they work [Dennett 1995: chapter 8].”

Moreover, fitness exists over and above the properties of the individual organisms themselves. There are three debated ways to construe this. Fitness can be a relation of genes to other genes. Fitness can be a supervenient property – that is, it can be a property of very different physical structures (of ants, aardvarks and artichokes) [Sober 1984]. Or fitness can be seen as an emergent property, a property of systems of a certain complexity and dynamics [Depew and Weber 1995]. Whether fitness is a genetic, organismic or system property is a hot topic in modern philosophy of biology. I think the system interpretation is the way to approach it [Weber and Depew 1996, Depew and Weber 1995].  (Rappaport, 1971)  

(homeostasis refers to stability of (mostly) internal processes that are essential for life; they are maintained by a dynamic balance of the multiple interacting systems that operate in an organism.) (see A&O Glossary)



  1. THE PROBLEM OF ALTRUISM (see A&O Glossary)

why should an individual relinquish resources (including time and energy) that might contribute to its fitness?   why should it endanger meeting its own needs or promotion of its own offspring?

go to  ALTRUISM (link needs repair)


  1. RITUALIZATION (see A&O Glossary) is the aggregate of processes that lead to a behavioral pattern becoming for precise and efficient over time: most dramatically manifest in communicative patterns (The Peacock’s Tail; the Lizard’s Dewlap)



  1. WORDS represent thoughts and states of mind.  WORDS, like all incoming (afferent) information, passes though filters that have been acquired from an organism’s congenital make-up (our neurosensory competence is limited to specific wave lengths of light or patches and amplitudes of sound) and acquired abilities (the environment (not least cultural) enables or diminishes or sensitivity).  Meanings are tweaked and adjusted according to experience (and thus expectations) or even blocked if they are perceived as so remote from experience that they might just be errors to be neglected. 

WORDS and bias

ARE WORDS MEMES?  Do ideas derive their present form because of the linguistic environment in which we attempt to represent them.      (and see “Words are Fossil Poetry”)

Parameters of perception, cognition, expression.  In pursuit of causes and consequences of art, we continue a concern for congenital versus acquired traits.   The pervasive, effects of bias—dispositions for particular parameters of perception, cognition   

It is remarkably difficult to tease apart congenital traits from cultural—those attributable to development in a specific human-constructed/anthropogenic environment.  But clues that contribute to a coherent narrative are commonly extracted from comparisons of a familiar culture with others that have been developing independently for a significant amount of time—at least long enough so that languages are no longer mutually understandable.   Words represent ideas and therefore indicate ways of thinking, patterns of thought that may be represented with more or less precision and accuracy in one culture than in another.   (look in on A&O—COMMUNICATIONS: Linguistic relativity)

In this we should also include ART, as styles and tropes are expressed –in this we may be able also to discern relative inborn versus acquired manners of expression:  For example, phosphenes are images that are internally generated in the nervous system before cultural influences can alter them.  We would expect humans that express themselves visually—artists, perhaps—to represent these images in very similar ways.    



Even more compelling is comparing ancient, even prehistoric cultures to our own, in search of how these people may have thought, looking for the “ancestral condition”—earliest representations of forms of thought important in our contemporary experience. Hints about the evolution of cognitive competencies. What traits are highly conserved (relatively immune from change) or labile (easily changed)—changeability itself is an attribute of traits that can have a genetic background, presumably based on selection pressures of ancestral environments (such as the ENVIRONMENT of EVOLUTIONARY ADAPTEDNESS ( EEA[4]) which might have been very changeable itself (temperate climates) or very stable (near the poles of the earth or the equator or the deep ocean)

  1. What can paleolithic art tell us about the minds of ancestors? 
    1. Read Lascaux’s Picassos by Katy Waldman (SLATE, OCT. 18 2012 9:09 AM)
    2. Since archaeologists can’t administer psychological tests to early humans, they have to examine artifacts left behind. When new technologies or ways of living appear in the archaeological record, anthropologists try to determine what sort of novel thinking was required to fashion a spear, say, or mix paint or collect shellfish. The past decade has been particularly fruitful for finding such evidence. And archaeologists are now piecing together the patterns of behavior recorded in the archaeological record of the past 200,000 years to reconstruct the trajectory of how and when humans started to think and act like modern people. By Erin Wayman in Smithsomian Magazine, June 25, 2012[5]

For example, “A shell etched by Homo erectus is by far the oldest engraving ever found, challenging what we know about the origin of art and complex human thought,” displacing Homo sapiens as “the first species to produce abstract, non-functional designs” (Brahic 2014)[6]   

  1. COMPARATIVE ART:  expressions of non-human organisms.
    1. Architecture
    2. Dance
    3. Expressive art of chimpanzees and elephants …






[1] Character displacement is the phenomenon where differences among similar species whose distributions overlap geographically are accentuated in regions where the species co-occur, but are minimized or lost where the species’ distributions do not overlap.  Character displacement – Wikipedia 

[2]  Behavior patterns are often pleiotropic in that they can serve multiple functions.  An action or behavior pattern in an animal that meets a biological need but also is a signal of fitness in sexual selection;  often they can be “emancipated” from their original adaptive function but be retained and possibly emphasized for its role in display or other social interaction.  The intensity of selection can lead stereotyped expression and cn become independent of any direct physiological significance.

[3].  “In June 1926, Wolfe once again sailed for Europe and began writing notes and phrases for the novel about his life that became Look Homeward, Angel. For the next two years he divided his time between Europe and New York working feverously to complete his massive manuscript he initially called O Lost. Completing the novel in Spring 1928, the manuscript began making the rounds of publishers while Wolfe continued his travels in Europe. // In the fall of 1928, while in Vienna, Wolfe received a letter from Maxwell E. Perkins, the legendary editor at Charles Scribner==s Sons, asking him to meet with him in New York to discuss O Lost. //  Wolfe returned to New York and on January 9, 1919, the manuscript was formally accepted for publication by Scribner’s. That spring Wolfe gave the novel a more evocative title—Look Homeward, AngelCC(the manuscript had been trimmed down by Wolfe and Perkins to a more commercially viable length of 240,000 words). // Look Homeward, Angel was published on October 18, 1929 and created an uproar in Asheville. The novel was condemned from street corner to pulpit and banned from the public library. There are more than 200 characters in the novel, all easily identifiable citizens of Asheville. Wolfe received death threats, and it was not until 1937 that he felt safe to return to his hometown. // Look Homeward, Angel proved both a critical and commercial success, and Maxwell Perkins was eager for Wolfe to produce a new novel as soon as possible.”  (From htp:// (December 6, 2003)

[4] EEA:  The unique aggregation of selection pressures that are acting on any trait is constantly changing. It is unlikely that any biotic environment in which an adaptation emerged is still intact — the adaptive peak Optimum utility of a trait) is always receding: That is, no contemporary trait can be completely adaptive (in Reeve and Sherman’s (1993) sense) because they were selected for in an environment that no longer exists.  This is sometimes called the “environment of evolutionary adaptedness” (EEA). Often applied to the environment in which a particular species evolved, but perhaps more usefully applied to a particular trait. [more] (link needs repair)

[5] “In the 1970s, the consensus was [that] Modern cognition evolved in Europe 40,000 years ago. That’s when cave art, jewelry and sculpted figurines all seemed to appear for the first time. The art was a sign that humans could use symbols to represent their world and themselves, archaeologists reasoned, and therefore probably had language, too. Neanderthals living nearby didn’t appear to make art, and thus symbolic thinking and language formed the dividing line between the two species’ mental abilities. (Today, archaeologists debate whether, and to what degree, Neanderthals were symbolic beings.)

One problem with this analysis was that the earliest fossils of modern humans came from Africa and dated to as many as 200,000 years ago—roughly 150,000 years before people were depicting bison and horses on cave walls in Spain. Richard Klein, a paleoanthropologist at Stanford University, suggested that a genetic mutation occurred 40,000 years ago and caused an abrupt revolution in the way people thought and behaved. [recalls “The Breakdown of Consciousness and the Origin of the Bicameral Mind”]

… artifacts recovered over the past decade in South Africa— such as pigments made from red ochre, perforated shell beads and ostrich shells engraved with geometric designs—have pushed back the origins of symbolic thinking to more than 70,000 years ago, and in some cases, to as early as 164,000 years ago. Now many anthropologists agree that modern cognition was probably in place when Homo sapiens emerged.

Marean thinks symbolic thinking was a crucial change in the evolution of the human mind. But symbolic thinking may not account for all of the changes in the human mind, says Thomas Wynn, an archaeologist at the University of Colorado. Wynn and his colleague, University of Colorado psychologist Frederick Coolidge, suggest that advanced “working memory” was the final critical step toward modern cognition.

Working memory allows the brain to retrieve, process and hold in mind several chunks of information all at one time to complete a task. A particularly sophisticated kind of working memory “involves the ability to hold something in attention while you’re being distracted,” Wynn says. In some ways, it’s kind of like multitasking. And it’s needed in problem solving, strategizing, innovating and planning.

… there are artifacts that do seem to relate to advanced working memory. Making tools composed of separate pieces, like a hafted spear or a bow and arrow, are examples that date to more than 70,000 years ago. But the most convincing example may be animal traps, Wynn says. At South Africa’s Sibudu cave, Lyn Wadley, an archaeologist at the University of the Witwatersrand, has found clues that humans were hunting large numbers of small, and sometimes dangerous, forest animals, including bush pigs and diminutive antelopes called blue duikers. The only plausible way to capture such critters was with snares and traps.

The appearance of a slow and steady buildup may just be a consequence of the quirks of preservation. Organic materials like wood often decompose without a trace, so some signs of behavior may be too ephemeral to find. It’s also hard to spot new behaviors until they become widely adopted, so archaeologists are unlikely to ever locate the earliest instances of novel ways of living.

Some see a slow progression in the accumulation of knowledge, while others see modern behavior evolving in fits and starts. Archaeologist Franceso d’Errico of the University of Bordeaux in France suggests certain advances show up early in the archaeological record only to disappear for tens of thousands of years before these behaviors—for whatever reason—get permanently incorporated into the human repertoire about 40,000 years ago.  “It’s probably due to climatic changes, environmental variability and population size,” d’Errico says.

He notes that several tool technologies and aspects of symbolic expression, such as pigments and engraved artifacts, seem to disappear after 70,000 years ago. The timing coincides with a global cold spell that made Africa drier. Populations probably dwindled and fragmented in response to the climate change. Innovations might have been lost in a prehistoric version of the Dark Ages. And various groups probably reacted in different ways depending on cultural variation, d’Errico says.  “Some cultures for example are more open to innovation.”

Erin Wayman writes’s Homind Hunting blog.  Photo Gallery   Related Content

[6] By Catherine Brahic New Scientist    3 December 2014    Shell ‘art’ made 300,000 years before humans evolved

A shell etched by Homo erectus is by far the oldest engraving ever found, challenging what we know about the origin of art and complex human thought

THE artist – if she or he can be called that – was right-handed and used a shark’s tooth. They had a remarkably steady hand and a strong arm. Half a million years ago, on the banks of a calm river in central Java, they scored a deep zigzag into a clam shell.

“Half a million years ago, on the banks of a calm river, someone scored a deep zigzag into a clam shell”

We will never know what was going on inside its maker’s head, but the tidy, purposeful line (pictured above right) has opened a new window into the origins of our modern creative mind.

It was found etched into the shell of a fossilised freshwater clam, and is around half a million years old – making the line by far the oldest engraving ever found. The date also means it was made two to three hundred thousand years before our own species evolved, by a more ancient hominin, Homo erectus.

“It is a fascinating discovery,” says Colin Renfrew, an archaeologist at the University of Cambridge. “The earliest abstract decoration in the world is really big news.”

The shell was dug up in Trinil, Indonesia, in the 1890s by Dutch geologist Eugene Dubois, and was one of many fossil finds in the area, including bones of Homo erectus and several animals.

The shell collection sat in a museum in Leiden, the Netherlands, for over a century. Seven years ago, PhD student Stephen Munro, now at the Australian National University in Canberra, was in the country for a few days and stayed with archaeologist Josephine Joordens of the University of Leiden. She was re-exploring the Dubois collection at the time, and as Munro was also studying ancient molluscs, Joordens encouraged him to take a look. Pressed for time, he photographed each one before heading back to Australia.

“A week later I received an email,” Joordens recalls. “He wrote that there was something strange on one of the shells and did I know what it was?”

Ever since then, Joordens and her team have been meticulously documenting all the Dubois clams. Sediment inside them and tiny grains pulled from cracks were dated, to reveal that they had been buried between 430,000 and 540,000 years ago (Nature, DOI: 10.1038/nature13962).

One turned out to be a tool, its sharpened edge probably used for scraping. Many were pierced where the clam’s muscle attaches to the shell. When the team made similar holes in live clams, the damage to the muscle forced them open.

“It must have been a fairly quiet riverine environment with lots of shells,” says Joordens. “Probably hominins living in the area exploited it.” She says the entire site was buried suddenly, possibly the result of a volcanic eruption or a flash flood.

Meanwhile, Francesco d’Errico, a palaeoanthropologist at the University of Bordeaux in France, known for his work on early hominin engravings, tried to replicate the etch, down to its microstructure. He tested three pointed tools: a flint, a shark’s tooth and a steel scalpel. The shark’s tooth – many of which were also found at the Java site – offered the closest match.

The experiments showed that the line is too deep and straight to have been made by an idle hand. Fresh Pseudodon clam shells have a dark brown coat, so the etch would have made a striking white line. All this suggests that it was made deliberately, and yet, unlike tools, the mark has no obvious function. It may have been a decoration, or a practice run for a decoration on another object.

That’s important because Homo sapiens was thought to be the first species to produce abstract, non-functional designs. No other animal, not even a chimpanzee, has ever been known to make non-functional markings.

“It’s very carefully done,” says Andrew Whiten, a psychologist and primatologist at the University of St Andrews in the UK. “There is a wonderfully straight section and the [etch] turns in one continuous line. That’s not just intentional but careful in what strikes as a very modern way. Apes aren’t doing that. It would be staggering if they did.”

So did the etching have some kind of meaning for its maker? And what can it tell us about the origins of complex human thought and artistic expression?

“We cannot look into the mind of the person who made it,” says Joordens. But we can speculate. One thing the marks suggest is that half a million years ago, these distant ancestors already had some sense of aesthetics.

“So far,” says Renfrew, “we haven’t had much indication that H. erectus was doing much other than making beautiful tools and hand axes.” Some see a sense of aesthetics in the tools – perhaps even making their owners more attractive to potential mates. But that is controversial and, besides, tools are undeniably useful.

Still, d’Errico suggests the lines might have been a sort of signature, indicating ownership. That would mean they had a function of sorts, but takes nothing away from their abstract nature.

“Whether the zigzag pattern had a specific meaning or was merely a sort of doodle seems irrelevant,” says David Edelman, a neuroscientist who was most recently at Bennington College in Vermont. What is significant is that the shape is not immediately linked to anything concrete or to survival.

“Regardless of intent, the very process of rendering a geometric form would seem to indicate the workings of a mind no longer tethered solely to the here and now, but capable of a uniquely abstract form of conscious ‘wandering’,” Edelman says.

The etch also suggests H. erectus was integrating different domains of knowledge – thought to be a key stage in the evolution of our creative minds. “Our results indicate that these shells were seen at the same time as a source of food, a raw material to make tools, and a canvas on which to produce engravings,” says d’Errico.

With only a few lines on a single shell, it is impossible to say how unusual the Trinil aesthete was at the time. It’s possible – likely, according to some – that many more etchings were made on materials that did not survive or remain to be found. Or the zigzag could have been the work of a rare early creative mind.

Either way, the Trinil shell offers a compelling insight. Bones tell us about how our ancestors looked and moved. They say very little about thoughts. So in the end, perhaps the most striking aspect is the etching’s familiarity. “In a way,” says Joordens, “it is emotionally touching, seeing something so old that looks like something you could have made yourself.”

This article appeared in print under the headline “Etched in time”  More on these topics: books and art   human evolution