Common Origins - Marmoset and Human Brain Development

Common marmoset, Callithrix jacchus

Peterwchen, CC BY-SA 4.0,
via Wikimedia Commons

As in humans, infants of common marmosets interact with several caregivers from birth and are thus exposed to intensive social interaction.

Image: Judith Burkart/UZH

Brain Development Marmosets | | UZH

Creationists like to pretend there is nothing in common between humans and the rest of the animal kingdom because humans were magically created as the special creation of a god who made all the 'lower' animals for our use, then gave us dominion over everything. This makes creationists feel really important.

The truth however is that we have very much in common with other animals and particularly with the species to which we are most closely relates and with whom we share the most recent common ancestor as we and they evolved and diversified over the same period of time to arrive at our present state.

This is reflected in the nested hierarchies into which the different branches of the evolutionary tree can be arranged in, anatomy, physiology and DNA and in the way our bodies develop through embryology and continued into childhood.


And yet creationists insist we are not only a different species, but a different 'kind' of animal, even a different category of life altogether, even though none of the difference they insist apply to different taxons as evidence of evolution apply to humans in respect of the other great apes.

The common marmoset, Callithrix jacchus, and their evolutionary relationship to humans. The common marmoset (Callithrix jacchus) is a small primate species native to the forests and scrublands of northeastern Brazil. Known for its expressive face, tufted ears, and squirrel-sized body, it’s a popular species for scientific research, primarily because it shares some interesting genetic and behavioural traits with humans. Here’s an overview of its characteristics, behaviour, and evolutionary relationship with humans.

Physical Characteristics

• Size: Common marmosets are small, weighing only about 300-400 grams, with a body length of 7-10 inches (18-25 cm) and a long, bushy tail.
• Appearance: They have a distinctive look with white ear tufts, a small face, and wide eyes. Their fur is mostly brownish-grey with a mix of white and black, allowing them to blend into their arboreal habitat.
• Hands and Feet: Like other New World monkeys, they have claws on most fingers (rather than flat nails like humans), which helps them cling to trees.

Habitat and Diet

• Environment: Marmosets thrive in forests, especially in areas with dense foliage where they can find food and avoid predators. They’re highly adaptable and can be found in both natural and urbanized settings in Brazil.
• Diet: They’re omnivores, feeding on tree sap, insects, fruits, and small animals. They use their specialized incisor teeth to gouge tree bark and access sap, which is a key component of their diet.

Social Structure and Behaviour

• Social Groups: Marmosets live in family groups typically led by a dominant pair. Groups consist of 5-15 individuals, often including multiple generations, with cooperative care of young by both parents and other group members.
• Communication: Marmosets are highly social and communicate through vocalizations, scents, and body language. They produce different calls depending on the context, and some sounds are ultrasonic, beyond human hearing range.
• Reproduction: These primates have a unique reproductive system, where dominant females can suppress the reproduction of other females in the group. They often give birth to twins, and group members assist in raising the young, a rare behaviour in mammals that echoes human familial cooperation.

Relationship to Humans

Marmosets belong to the infraorder Simiiformes, which includes all monkeys and apes, meaning they’re more distantly related to humans than other primates like chimpanzees and gorillas, who are part of the hominoid lineage. However, they still share significant genetic similarities with humans—about 92% of their DNA. They’re one of the smallest primates often studied for insights into human aging, neurological diseases, and genetics because of several interesting parallels:

• Brain and Behaviour: While their brains are much smaller than humans', they share many structural and functional aspects, including similar regions that govern emotions, memory, and sensory processing.
• Lifespan and Aging: Marmosets age quickly for a primate, with a lifespan of around 12-16 years. They exhibit aging patterns similar to humans, including changes in the immune system, body mass, and cognitive abilities, which is valuable in studying aging processes.
• Social and Parenting Behaviours: Cooperative parenting and close social bonds within groups mirror certain aspects of human social structures.

Conservation Status

The common marmoset is currently listed as "Least Concern" by the IUCN, though habitat loss and pet trade are concerns. They adapt well to different environments, which has helped their survival, but their populations are still vulnerable to ecological changes.

In summary, while common marmosets diverged from humans over 40 million years ago, their unique traits and social behaviours make them a valuable species for understanding certain aspects of human biology and psychology, providing insight into genetic, neurological, and social characteristics that bridge the gap between humans and other primates.

Now, as though to drive another nail into the coffin of that primitive superstition, scientists have just shown how the brains of humans and the common marmoset monkey follow parallel development, demonstrating their common origins.

Common marmosets and humans have similar prolonged periods of childhood where child care is shared amongst several adults, so the children experience intense socialisation as they develop juts as human children do, and because their brains are fundamentally the same as human brains, the same areas develop in the same way and at the same stage in their development:

Similarities in Brain Development Between Marmosets and Humans

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In common marmosets, the brain regions that process social interactions develop very slowly, extending until early adulthood, like in humans. During this time, all group members are involved in raising the infants, which contributes to the species’ strong socio-cognitive skills.

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The development of primate brains is shaped by various inputs. However, these inputs differ between independent breeders, such as great apes, and cooperative breeders, such as the common marmoset (Callithrix jacchus) and humans. In these species, group members other than the parents contribute substantially to raising the infants from birth onwards.

A group of international researchers led by Paola Cerrito from the University of Zurich’s Department of Evolutionary Anthropology studied how such social interactions map onto brain development in common marmosets. The study provides new insights into the relationship between the timing of brain development and the socio-cognitive skills of marmosets, in particular their prosocial and cooperative behaviours.

Prolonged learning from social interactions

The research team analysed brain development using magnetic resonance data and showed that in marmosets, the brain regions involved in the processing of social interactions exhibit protracted development – in a similar way to humans. These brain regions only reach maturity in early adulthood, allowing the animals to learn from social interactions for longer.

Like humans, immature marmosets are surrounded and cared for by multiple caregivers from birth and are therefore exposed to intense social interaction. Feeding is also a cooperative business: the immature animals are fed by group members and as they get older they have to beg for food because their mothers are already busy with the next offspring. According to the study, the need to elicit care from several group members significantly shapes brain development and contributes to the sophisticated socio-cognitive motivation (and observed skills) of these primates.

A model for human evolution

Given their similarities with humans, marmosets are an important model for studying the evolution of social cognition.

Our findings underscore the importance of social experiences to the formation of neural and cognitive networks, not only in primates, but also in humans. This insight could have an impact on various fields, ranging from evolutionary biology to neuroscience and psychology.

Paola Cerrito, first author
Department of Evolutionary Anthropology
University of Zurich, Zürich, Switzerland.

The early-life social inputs that characterize infants’ life in cooperatively breeding species may be a driving force in the development of humans marked social motivation.

Publication:

Paola Cerrito, Eduardo Gascon, Angela C. Roberts, Stephen J. Sawiak, Judith M. Burkart.
Neurodevelopmental timing and socio-cognitive development in a prosocial cooperatively breeding primate (Callithrix jacchus). Science Advances, 30 October 2024. DOI: 10.1126/sciadv.ado3486

Abstract
Primate brain development is shaped by inputs received during critical periods. These inputs differ between independent and cooperative breeders: In cooperative breeders, infants interact with multiple caregivers. We study how the neurodevelopmental timing of the cooperatively breeding common marmoset maps onto behavioral milestones. To obtain structure-function co-constructions, we combine behavioral, neuroimaging (anatomical and functional), and neural tracing experiments. We find that brain areas critically involved in observing conspecifics interacting (i) develop in clusters, (ii) have prolonged developmental trajectories, (iii) differentiate during the period of negotiations between immatures and multiple caregivers, and (iv) do not share stronger connectivity than with other regions. Overall, developmental timing of social brain areas correlates with social and behavioral milestones in marmosets and, as in humans, extends into adulthood. This rich social input is likely critical for the emergence of their strong socio-cognitive skills. Because humans are cooperative breeders too, these findings have strong implications for the evolution of human social cognition.

INTRODUCTION
Strong social cognition and prosociality are, from a very young age, hallmarks of the human mind compared to the closest living relatives, the nonhuman great apes (1). Because of our peculiar life history, characterized by early weaning and extensive allomaternal care starting from very early in infancy, human development is embedded in a world filled with other individuals, including parents, siblings, and other family members. Thus, this is the context in which human toddlers’ strong social cognition and prosociality develops (2). It is this same period that is also the most important for the formation of the neural bases of higher-order social, emotional, and communicative functions (3). Not unexpectedly then, several independent lines of evidence, spanning neuroscience, pediatrics, primatology, and psychiatry, point to the fundamental role that the relative timing of brain development and social interactions have for the acquisition of social cognition and prosocial behaviors (4).

During ontogeny, total brain volume increases until reaching its adult levels. This volumetric increase is the product of gray matter (GM) volume (GMV) increase until a peak value is reached in childhood, after which it decreases concurrently with synaptic pruning and white matter volumetric increase (5). In addition, the ontogenetic trajectories of cerebral GM are heterochronous, such that both maximum GMV and GM reduction rate vary across brain regions. The importance of the temporal patterns of brain development in shaping the adult phenotype becomes apparent, for example, in the case of autism spectrum disorder (ASD). Deviations from the normal range of developmental timing of the cortex can profoundly affect socio-cognitive skills and are one of the main factors linked to the occurrence of ASD (3). Specifically, several studies have found that early brain overgrowth during the first years of life strongly correlates with ASD [e.g. (6)] and a meta-analysis of all published magnetic resonance imaging (MRI) data by 2005 revealed that the period of greatest brain enlargement in autism is during early childhood (7), with about a 10% volume increase compared to controls during the first year of life. Hence, individuals affected by ASD present an accelerated early-life brain growth and achieve a final brain volume that is not different from that of controls, but they achieve it earlier than controls. Recent works with human brain organoids has confirmed the accelerated maturation of the cortex in the ASD phenotype, especially interneurons (8, 9). Consequently, given this accelerated early-life brain development, fewer social inputs are available during the period when the GMV reduces to adult size and differentiates via experience-dependent pruning. Accelerated development of functional connectivity between certain brain areas [e.g., amygdala–prefrontal cortex (PFC)] can also be a consequence of early-life stress, which, in turn, can cause adverse physiological conditions such as increased anxiety and cortisol levels (10). Unfortunately, so far, nothing is known regarding the impact of changes in brain developmental timing within nonhuman species. That is, we do not know if, within a given nonhuman species, alterations in ontogenetic trajectories of the brain have an impact on the adult behavioral phenotype. However, comparative studies across species with different ontogenetic trajectories and social behaviors can help us shed light on the relationship between the two.

The importance of social inputs occurring during prolonged brain maturation and slow developmental pace has also been highlighted in the context of human evolutionary studies. The remarkable brain growth and development occurring postnatally in humans arguably allows the brain to be influenced by the social environment outside of the uterus to a greater extent than that seen in other great apes (11), who are not cooperative breeders (12). Hawkes and Finlay (13) show that, in addition to weaning our infants earlier than expected (based on allometric scaling with other life-history variables), human neonates have an especially delayed neural development, which is likely correlated with the energetic trade-offs stemming from the large size and high caloric demand of our brain (14). In addition, we observe that, in humans, compared to other great apes, myelination is much prolonged and continues well into adulthood (15).

Common marmosets (Callithrix jacchus) are cooperatively breeding platyrrhine monkeys. Like humans, but unlike other great apes (12), they rely on extensive allomaternal care and share many life-history traits (e.g., short interbirth intervals and a hiatus between menarche and first reproduction) with humans (16). They also show remarkable prosociality (4, 15) [much more than great apes (16)] and strong socio-cognitive abilities, which have been argued to correlate with cooperative breeding (17–20). However, the neurobiological features underlying the socio-cognitive abilities promoting the prosocial behavior are poorly understood. Moreover, experimental research has shown that, in common marmosets (hereafter marmosets), there is a critical period for the development of social behaviors (21), although the relationship between developmental timing of the brain and these early-life social interactions is poorly understood.

Given these similarities with humans, marmosets are becoming an ever-more important model in neuroscience (22–25) and particularly in research investigating the neurobiological and neurodevelopmental bases of social cognition. As in humans, immature marmosets are surrounded and cared for by multiple caregivers from the first day on. The entire family is typically present during birth, and oxytocin levels increase not only in mothers but also in all group members (26). Group members contribute appreciably to carrying the infants and, once infants start eating solid food, frequently share food with them. After a peak provisioning period, adults are increasingly less willing to share food with them (27–29). During this period, intense and noisy negotiations over food are frequent, with immatures babbling and begging and adults eventually giving in—or not. Intriguingly, when doing so, immatures appear to take into account how willing individual adults are to share and will insist in more and longer attempts with adults who are generally less likely to refuse them. Soon after, immatures have to compete for attention and food not only with their twin sibling but also with the next offspring that are born far before they themselves are independent because, like in humans, marmosets are weaned early and mothers have their next offspring soon after (30). By now, the immatures still have not reached puberty; this only happens shortly before yet another set of younger siblings is born. Typically, with these new arrivals, the immatures start to act as helpers themselves and thus face the developmental task of switching from being a recipient of help to becoming a provider of help and prosocial acts (31). This is thus the developmental context in which marmosets’ socio-cognitive skills develop.

The goal of this study is to map these behavioral milestones specific to a cooperatively breeding primate to its region-specific brain development to better understand the social interactions in which infants engage during the differentiation period of brain regions selectively implicated in processing social stimuli. Our working hypothesis is that, like in humans, social interactions with several caregivers during this critical period profoundly contribute to the co-construction of the marmoset brain, the maturation of socially related associative areas, and therefore the emergence of prosocial behaviors. For that purpose, we sought to determine if there is a relationship between the temporal profile of the developing marmoset brain and the early-life social interactions that may help explain their sophisticated socio-cognitive skills at adulthood.

To compare the timing of brain development to that of these behavioral milestones and developmental tasks of attaining nutritional independence, we focused on brain regions that, in adult marmosets, are selectively activated by the observation of social interactions between conspecifics but not by multiple but independently behaving marmosets, as identified by Cléry et al. (32). We tested if these brain regions share similar developmental trajectories based on the developmental patterns of regional GMV. To potentially reveal a coordinated ontogenetic profile underlying the “tuning” of the social brain in marmosets, we then compared these neurodevelopmental patterns to longitudinal data of infant negotiations with caregivers in relation to food (as measured by the frequency of food begging). Last, because it is known that brain regions whose activations correlate with performance on a given task strengthen and get fine-tuned with age (33, 34), we assessed if there is stronger connectedness between areas that develop according to similar developmental trajectories and share similar response to social interaction stimuli.

We thus combined several types of previously published data from marmosets to provide a unified picture of structural brain development alongside the development of social interactions between infants and multiple caregivers necessary to ensure survival (infant provisioning). These included structural MRI (sMRI) data of GM of 53 cortical areas and 16 subcortical nuclei acquired from a developmental cohort (aged 13 to 104 weeks) of 41 male and female marmosets (35), functional MRI (fMRI) data mapping the brain areas activated by the observation of social interactions in marmosets (32), food sharing interactions in five family groups of marmosets including a total of 26 adults and 14 immatures [from 1 to 60 weeks of age (27)], and cellular-resolution data of corticocortical connectivity in marmosets obtained via 143 retrograde tracer injections in 52 young adult marmosets of both sexes (36).

Overall, we make the following predictions:

1. P1: Cortical regions that show significantly stronger activation during the observation of social interactions (32) share similar structural neurodevelopmental profiles, which are distinct from those regions showing significantly stronger activation during the observation of nonsocial activities.
2. P2: That those same brain regions showing a significantly stronger activation during the observation of social interactions exhibit a protracted development, reaching their adult volume later than the other regions.
3. P3: The developmental trajectory of infant negotiations with caregivers in relation to food (as measured by the frequency of food begging) is more similar to that of brain regions responding more strongly to the observation of social interactions than to the other regions.
4. P4: Functional connectivity is stronger between regions with similar developmental timing and response strength to the observation of either social or nonsocial behaviors and weaker between regions with different developmental timing and response strength.

If the brains of humans an marmosets are fundamentally similar and develop the same way, perhaps a creationist could explain in what way, apart from their tail and their claws in place of human flat finger nails, marmosets are a different 'kind' to humans, and then explain why the same reasoning doesn't place the great apes in the same 'kind' as humans.

Creationism Refuted - How We Inherrited Part Of Our Anti-Viral Immune Response From A Microbial Ancestor

Credit: Pedro Leão.

A comparison of immune proteins called viperins from Asgard archaea (left) and from a group of more complex life that includes humans, called eukaryotes (right). The three-dimensional shapes (a.k.a. structures) are strikingly similar, suggesting they also function similarly.

Credit: Pedro Leão.

Next Time You Beat a Virus, Thank Your Microbial Ancestors | College of Natural Sciences

Multicellular organisms are collections of specialised eukaryote cells, which are themselves collections of prokaryote cells that have been around for several billion years before getting together to form more complex cells.

And those prokaryote cells - bacteria and archaea - had had to cope with viruses which arose as soon as there were replicating assemblages of DNA for them to parasitize and co-opt the replication mechanism to make more copies of themselves.

The result was one of the first evolutionary arms races as the prokaryotes evolved ways to prevent themselves being parasitised and viruses evolved ways to overcome the microbes defences.

And, or course, the later eukaryote, complex cells that were to form the multicellular organisms inherited these antiviral defences and carried on the arms race with viruses, so it makes sense to find some of the remnants of these microbial defences, probably modified, inside our own cells, and forming a first line of defences.

This is a simple prediction of the Theory of Evolution and the resulting descent with modification from a common ancestor from billions of years ago.

What information do you have on the anti-viral proteins, Asgard Viperin and Eukaryote Viperin? Asgard Viperin and Eukaryote Viperin are both antiviral proteins that play crucial roles in the innate immune response, particularly in targeting and neutralizing viral infections. They belong to a broader family of proteins called Viperin (virus inhibitory protein, endoplasmic reticulum-associated, interferon-inducible). Viperin is a well-known antiviral protein that is highly conserved across various species, including archaea, bacteria, and eukaryotes. Here's a breakdown of what is known about Asgard Viperin and Eukaryote Viperin:

1. Asgard Viperin
   • Origin: Asgard Viperin is derived from the Asgard archaea, a group of microorganisms that are thought to be closely related to the last common ancestor of archaea and eukaryotes. These archaea were discovered in deep-sea hydrothermal vent environments and are considered important in studying the evolution of complex life forms.
   • Function: Asgard Viperin has been identified as an antiviral protein that provides insights into the ancient mechanisms of immune defense. Its function is similar to that of Viperin in eukaryotes, where it inhibits viral replication by targeting viral components or the cellular machinery viruses depend on for replication.
   • Structure and Mechanism: Like other Viperins, Asgard Viperin is likely to have a radical SAM (S-adenosylmethionine) domain, which is critical for its antiviral activity. This domain allows the protein to produce a reactive radical species, which can interfere with viral processes, such as the synthesis of nucleotides that viruses require for replication.
   • Evolutionary Significance: The discovery of Asgard Viperin highlights the ancient origins of antiviral defense mechanisms. It suggests that the strategies used by modern eukaryotic cells to combat viruses may have deep evolutionary roots.
2. Eukaryote Viperin
   • Origin: Eukaryote Viperin is found in eukaryotic organisms, including humans. It is one of the interferon-stimulated genes (ISGs) that are upregulated in response to viral infection. This protein is highly conserved across various species, from simple eukaryotes like algae to complex organisms like mammals.
   • Function: In eukaryotes, Viperin is a key player in the innate immune response. It exerts its antiviral effects through multiple mechanisms, depending on the type of virus. For example:
     • Inhibition of Viral Replication: Viperin can interfere with the replication of viruses by altering lipid metabolism or disrupting the assembly of viral particles.
     • Interaction with Cellular Machinery: It can inhibit viral RNA polymerase, thereby preventing the replication of RNA viruses.
     • Modulation of Immune Response: Viperin can enhance the production of other antiviral molecules and modulate the signaling pathways involved in the immune response.
   • Mechanism of Action: The radical SAM domain is crucial for the antiviral activity of Viperin in eukaryotes. This domain facilitates the formation of a radical species that can interfere with the function of viral proteins or the host cell machinery that viruses exploit.
   • Clinical Relevance: Understanding the role of Viperin in the immune response has significant implications for developing antiviral therapies. Since Viperin is involved in the response to a wide range of viruses, enhancing its activity could be a potential strategy for treating viral infections.

Comparative Insights

• The study of Asgard and Eukaryote Viperin provides valuable insights into the evolution of antiviral defense mechanisms. The presence of similar antiviral proteins in both archaea and eukaryotes suggests that these defense strategies are ancient and have been conserved throughout evolution.
• While both Asgard and Eukaryote Viperin share functional similarities, their specific roles and mechanisms may differ due to the differences in their cellular environments and the types of viruses they encounter.

Research Significance

• The discovery and study of Asgard Viperin contribute to our understanding of the origin of eukaryotic cells and their immune systems. It also opens up new avenues for research into the evolution of antiviral defenses and the development of new antiviral strategies based on ancient mechanisms.

Understanding these proteins, particularly in the context of their evolutionary history and their function in modern organisms, is crucial for advancing our knowledge of immune responses and the development of antiviral therapies.

And this is precisely what researchers in the College of Natural Science at The University of Texas at Austin have found. They have shown that the proteins Asgard Viperin from the Asgard archaea and the Eukaryote viperin, possessed by eukaryotes including humans are structurally (and functionally) very similar.

Next Time You Beat a Virus, Thank Your Microbial Ancestors

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Two of our key defenses against viruses have persisted for billions of years, arising before complex life.

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When you get infected with a virus, some of the first weapons your body deploys to fight it were passed down to us from our microbial ancestors billions of years ago. According to new research from The University of Texas at Austin, two key elements of our innate immune system came from a group of microbes called Asgard archaea.

Specifically, viperins and argonautes, two proteins that are known to play important roles in the immune systems of all complex life — from insects to plants to humans — came from the Asgard archaea. Versions of these defense proteins are also present in bacteria, but the versions in complex life forms are most closely related to those in Asgard archaea, according to the new scientific study published in the journal Nature Communications.

This research bolsters the idea that all complex life, called eukaryotes, arose from a symbiotic relationship between bacteria and Asgard archaea.

It adds more support to the fact that the Asgards are our microbial ancestors. It says that not only did eukaryotes get all these rich structural proteins that we’ve seen before in Asgards, now it’s saying that even some of the defense systems in eukaryotes came from Asgards.

Associate Professor Brett J. Baker, senior author
Associate professor of integrative biology and marine science
Department of Integrative Biology
University of Texas at Austin, Austin, TX, USA.

The researchers identified for the first time a large arsenal of defense systems in archaea that were previously known only in bacteria.

When viperins detect foreign DNA, which might indicate a dangerous virus, they edit the DNA so that the cell can no longer make copies of the DNA, which stops the virus from spreading. When argonautes detect foreign DNA, they chop it up, also halting the virus. Additionally, in more complex organisms, argonautes can block the virus from making proteins in a process called RNA silencing.

Viral infections are one of the evolutionary pressures that we have had since life began, and it is critical to always have some sort of defense. When bacteria and archaea discovered tools that worked, they were passed down and are still part of our first line of defense.

Assistant Professor Pedro Leão, lead author
Department of Microbiology - RIBES
Radboud University, Nijmegen, The Netherlands.

The researchers compared proteins involved in immunity across the tree of life and found many closely related ones. Then they used an AI tool called ColabFold to predict whether ones that had similar amino acid sequences also had similar three-dimensional shapes (aka structures). (It’s the shape of a protein that determines how it functions.) This showed that variations of the viperin protein probably maintained the same structure and function across the tree of life. They then created a kind of family tree, or phylogeny, of these sister amino acid sequences and structures that showed evolutionary relationships.

A family tree of immune proteins called viperins from different organisms. Versions of viperin found in complex life forms, called eukaryotes (green), fit within the group of viperins from Asgard archaea (purple).

Credit: University of Texas at Austin.

Finally, the researchers took viperins from Asgard archaea genomes, cloned them into bacteria (so the bacteria would express the proteins), challenged the bacteria with viruses, and showed that Asgard viperins do in fact provide some protection to the modified bacteria. They survived better than bacteria without the immune proteins.

This research highlights the integral role cellular defenses must have played from the beginning of both prokaryotic and eukaryotic life. It also inspires questions about how our modern understanding of eukaryotic immunity can benefit from unraveling some of its most ancient origins.

Emily Aguilar-Pine, co-author Department of Integrative Biology
University of Texas at Austin, Austin, TX, USA.

It’s undeniable at this point that Asgard archaea contributed a lot to the complexity that we see in eukaryotes today, so why wouldn’t they also be involved in the origin of the immune system? We have strong evidence now that this is true.

Assistant Professor Pedro Leão

Other authors, all from UT, are Mary Little, Kathryn Appler, Daphne Sahaya, Kathryn Currie, Ilya Finkelstein and Valerie De Anda.

This work was supported by the Simons and Moore foundations (via the Moore-Simons Project on the Origin of the Eukaryotic Cell) and The Welch Foundation.

Abstract
Dozens of new antiviral systems have been recently characterized in bacteria. Some of these systems are present in eukaryotes and appear to have originated in prokaryotes, but little is known about these defense mechanisms in archaea. Here, we explore the diversity and distribution of defense systems in archaea and identify 2610 complete systems in Asgardarchaeota, a group of archaea related to eukaryotes. The Asgard defense systems comprise 89 unique systems, including argonaute, NLR, Mokosh, viperin, Lassamu, and CBASS. Asgard viperin and argonaute proteins have structural homology to eukaryotic proteins, and phylogenetic analyses suggest that eukaryotic viperin proteins were derived from Asgard viperins. We show that Asgard viperins display anti-phage activity when heterologously expressed in bacteria. Eukaryotic and bacterial argonaute proteins appear to have originated in Asgardarchaeota, and Asgard argonaute proteins have argonaute-PIWI domains, key components of eukaryotic RNA interference systems. Our results support that Asgardarchaeota played important roles in the origin of antiviral defense systems in eukaryotes.

Introduction
Organisms across the tree of life contain complex defense systems (DS) to battle viral infections^1,2,3. Over the past decade, dozens of new DS have been identified and characterized in bacteria, sparking a debate about a potential link between these systems and the origins of innate immune mechanisms in eukaryotes. More recently, protein components of bacterial NLR (Nucleotide-binding domain leucine-rich repeat), CBASS (Cyclic oligonucleotide-based antiphage signaling system), viperins (virus-inhibitory protein, endoplasmic reticulum-associated, interferon (IFN)-inducible), argonautes, and other DS have been shown to exhibit homology with proteins involved in the eukaryotic immune system⁴. Most of the research on prokaryotic defense systems has focused on bacteria, with archaea representing <3% of the genomes in these studies^5,6,7. Thus, very little is known about the diversity or evolution of these systems in archaea.

Recently, diverse novel genomes have been obtained belonging to the archaea most closely related to eukaryotes, commonly referred to as “Asgard” archaea, the phylum Asgardarchaeota⁸. In addition to being sister lineages to eukaryotes, these archaea also contain an array of genes that are hallmarks of complex cellular life involved in signal processing, transcription, and translocations, among other processes⁹. The Asgard archaea are descendants of the ancestral host that gave rise to eukaryotic life. One newly described order, the Hodarchaeales (within the Heimdallarchaeia class), shared a common ancestor with eukaryotes⁸. Here, we characterize defense systems in archaea and show that Asgard archaea have a broad array of these DS. We also show that Asgards contributed to the origins of innate immune mechanisms in eukaryotes.

Fig. 2: Evolutionary history and anti-phage activity of Asgard viperins.

A Phylogenetic analysis of viperins. Viperins phylogeny revealed ancestral links of eVip (eukaryotic viperin) with asVip (asgard viperin) (nodes marked in red), particularly those within the Heimdallarchaeia class (including Kariarchaeaceae (2), Heimdallarchaeaceae (3) and Hodarchaeales (5)). The size of the dots on the nodes is proportional to bootstrap values ranging between 60 and 100. B Structure-based homology of viperins. Consistent with the sequence homology-based phylogenetic tree, the eVip structure appears to have been inherited from asVip (red node). The darker green color represents reference sequences predicted experimentally. The size of the dots at the center of the nodes is proportional to bootstrap values ranging between 50 and 100. C Superposition of an eVip structure, predicted by X-ray diffraction (green), and the structural models of an asVip, archaeal viperin (arVip), and bacterial viperin (from left to right). The yellow color in the models emphasizes the high conservation of the viperin catalytic site across the tree of life. The information regarding bacteria, archaea, asgard archaea and eukaryotes in panels (A–C) are represented by the pink, blue, purple and green color respectively. D Anti-T7 phage activity of asVip in E. coli. Nine asVip (asVip 26,11,20,25,16,12,17,23,8) exhibited anti-viral activity as indicated by the p-values (*p < 0.05; **p < 0.01). E Anti-T7 phage activity of asVip after codon optimization for their expression in E. coli. One asVip from a Hodarchaeales organism provided protection against viral infection (asVip 19). The center line of each box plot denotes the median; the box contains the 25^th to 75^th percentiles. Black whiskers mark the 5th and 95^th percentiles. pVip34 is a prokaryotic viperin selected as a positive control from Bernheim et al.¹³. Each experimental condition includes, on average, 53 plaques pooled from three biological replicates. A two-tailed t-test was used to calculate statistical significance in figures (E, D).

Fig. 3: Evolutionary history of Asgard argonaute proteins.

A Phylogeny of long type argonaute proteins from archaea, bacteria, and eukaryotes with cyclases as outgroup (grey). B Structure-based homology of argonautes. C Structural alignment of asAgo5 and 4OLA (eAgo) MID and PIWI domains (left), and the graphic model of the corresponding alignments (right). Salmon regions on the alignment highlight strong conservation (low RMDS values). Red amino acids in the structural alignment, and their respective models represent the 4OLA conserved functional residues in MID and PIWI. The information regarding bacteria, archaea, asgard archaea and eukaryotes are represented by the pink, blue, purple and green color respectively. The size of the dots on the nodes is proportional to bootstrap values ranging between 70 and 100.

Leão, P., Little, M.E., Appler, K.E. et al.
Asgard archaea defense systems and their roles in the origin of eukaryotic immunity.
Nat Commun 15, 6386 (2024). https://doi.org/10.1038/s41467-024-50195-2

Copyright: © 2024 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

A highly-conserved antiviral protein across all eukaryote cells speaks loudly of common ancestry. The fact that a very similar protein is found in an "Asgard" archaea is strongly supportive of the theory that the fist eukaryote cells were alliances of bacteria and archaea and that the "Asgard" archaea contributed antiviral protection on this early eukaryote, showing common ancestry extending back beyond the first eukaryotes.

Of course, the less intelligent creationists will now be chanting 'Common Ancestry', but the more intelligent cultists would realise that that would mean the first eukaryote cells arose after Adam and Eve, because these antiviral proteins wouldn't have been needed until after 'Sin' had allowed viruses to 'devolve' by 'genetic entropy' (© Michael J. Behe), unless they don't understand how having an arms race with oneself is not the sign of an intelligent designer.

Creationism in Crisis - Common Origins of Horns, Antlers and Ossicone In Hooved Mammals

Genetics show the common origins of horned, hooved mammals

A diverse array of mammal headgear is on display in the Museum’s Richard Gilder Center for Science, Education, and Innovation as part of the Louis V. Gerstner, Jr. Collections Core.

Alvaro Keding/ ©AMNH

Diverse Mammal Headgear Evolved from Common Ancestor | AMNH

Although the horns of cattle, gazelles and goats look very different to the antlers of deer and the ossicones on the head of a giraffe, and indeed, they are constructed differently, the cells they develop from in the embryo are the cells of the 'neural crest' that also develop into the face rather than the rest of the cranium. That and the fact that the underlying genetic control of their growth is sufficiently similar, provides compelling evidence that they share a common origin from which they, and the orders of which they are typical, have diverged.

This is the conclusion of two researchers at the American Museum of Natural History and Baruch College and the CUNY Graduate Center, who have just published their findings, open access in the journal, Communications Biology. It is also explained in an American Museum of Natural History press release:

Common Ancestry - How Young Chimps Learn To Use Tools - Just Like Human Children

Chimpanzee Zinda fishing for termites in Gombe National Park

Photo: Nick Riley

Wild western chimpanzee using a stick tool to extract high-nutrient food.

Credit: Liran Samuni, Taï Chimpanzee Project (CC BY 4.0)

Protracted development of stick tool use skills extends into adulthood in wild western chimpanzees | PLOS Biology

Chimpanzees are famous for making and using tools, especially sticks, for obtaining nutritional foods like grubs and termites, but using them takes time, just like a human child needs to develop motor skills to use tools such as pens and pencils with sufficient dexterity.

How they do so, and the stages they go through, was described recently in an open access paper in PLOS Biology by a team of animal behaviourists from l'Institut des Sciences Cognitives Marc Jeannerod (The Marc Jeannerod Institute of Cognitive Sciences), Lyon, France; the Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany, and the German Primate Center, Göttingen, Germany, who analyzed film of wild chimpanzees making and using stick tools in the Taï National Park, Côte d’Ivoire.

They concluded that, like human children, acquiring motor skills is not just a matter of practice, important though that it, but also depends on a protracted childhood during which they observe and copy adults with the necessary skills. In other words, young chimpanzees learn skill from their parents and elders, like a human apprentice.

The team's work was explained in information made available ahead of publication by PLOS, and published in SciTechDaily.com:

Evolution News - An Atlas Of The Human Ovary Shows Common Ancestry of Mammals

Ovarian follicle

Human ovarian follicle

First atlas of the human ovary with cell-level resolution is a step toward artificial ovary | University of Michigan News

This piece of research caught my eye, not so much because it refutes creationism with its daft notion of the special creation of humans as separate from all the other animals but because it's reminiscent of the research I used to be involved with in my first profession - a research technician in Oxford University's Department of Human Anatomy.

The research our small group was doing involved the hormonal control of reproduction in guinea pigs, which involved preparing light microscope slides of sections of guinea pig ovaries, and later on, transmission electron micrographs of ovarian tissues.

Like humans, guinea pigs have oestrus cycles where they periodically shed eggs from their ovaries regardless of whether they have mated or not. This is unlike some other mammals which ovulate soon after mating, stimulated to do so by the act of mating. Unlike human females, guinea pigs are only receptive for two or three days before and just after they ovulate. Outside that receptive period, they have a closure membrane that makes penetration impossible.

Creationism in Crisis - How Early Modern Humans Survived a Massive Super-Volcano Which Spurred Their Migration Out Of Africa

Northern Africa.
Inset: Part of South West Ethiopia around Shinfa-Meta 1 site

Excavations at a Middle Stone Age archaeological site, Shinfa-Metema 1, in the lowlands of northwest Ethiopia, revealed a population of humans at 74,000 years ago that survived the eruption of the Toba super-volcano.

Photo courtesy https://topographic-map.com, Open Database License (ODbL) v1.0

Toba super-eruption unveils new insights into early human migration | ASU News

This, the fourth in a clutch of very recent papers that casually and unintentionally refute creationism simply by revealing the facts that run counter to the claims of creationists. It concerns the effects of a devastating volcanic eruption of Mount Toba in Indonesia 64 thousand years before creationists think there was life on Earth, or even an Earth to have life on it.

They believe this because a bunch of Middle Eastern pastoralists made up a tale to fill the gaps in their knowledge and understanding and describe a magic man in the sky creating a small flat planet with a dome over it, just a few thousand years earlier.

The facts are those revealed by a research team which included Curtis Marean, Christopher Campisano and Jayde Hirniak from Arizona State University who have shown that not only did African populations of humans survived the effects of this volcano, the most devastating in human history, but that its effects may have facilitated human dispersal out of Africa into Eurasia. They have presented their evidence in the form of a paper in Nature and explained the research in a University of Arizona news release:

Creationism in Crisis - How Hair Evolved From A Keratin Gene In A Frog-Human Common Ancestor

Western clawed toad, Xenopus tropicalis

Genetic basis for the evolution of hair discovered in the clawed frog

Western Clawed Frog, Xenopus tropicalis
Carries the precursor gene for mammalian hair.

"When sorrows come, they come not single spies but in battalions" - Claudius in Hamlet.

That was never more true of creationism than it is today with the publication of not just the usual casual refutation of creationism we've come to expect most days, but of four disparate papers each of which casually and unintentionally refutes creationism to anyone who understands biology and is familiar with the basic dogmas of the creation cult, simply by revealing real-world facts.

The papers range from this one, which shows how mammalian hair has its genetic origins in a common human-amphibian ancestor, through how a female butterfly evolved Batesian mimicry, through the discovery of a giant Amazonian dolphin from 16 million years before creationists think Earth existed, to how early modern humans survived a super-volcano eruption in South-West Ethiopia a mere 64,000 years before 'Creation Week'.

With so many papers I'll do my best to cover all of them in the next few days, so keep checking back!

Firstly, the evolutionary origin of mammalian hair.

The gene for this originated in a common ancestor of humans (and the other mammals) and a modern clawed frog. The gene controls the growth of keratin, of which the claws of a clawed frog are composed, as is mammalian hair. The evidence for this common origin was found by researchers from the Medical University of Vienna, Austria, led by led by Leopold Eckhart. The team have published their findings open access in Nature Communications and described their work in a Medical University of Vienna new release:

Creationism in Crisis - Evolution By Loss Of Complexity - How A Mutation Cost Our Ancestors Their Tails

A mutation cost our simian ancestors their tails

Photo: Getty / Steve Adams

Change in Genetic Code May Explain How Human Ancestors Lost Tails | NYU Langone News

In that distant, pre-'Creation Week' history of Life On Earth, 25 million years before creationists think Earth was created out of nothing, and all living things on it were magicked into existence without ancestors, a 'jumping gene' inserted a short length of DNA termed AluY, into the gene which controls tail length in monkeys, and the resulting tailless monkeys went on to diversify into the apes - gibbons, siamangs, orangutans, gorillas, chimpanzees, bonobos, and the hominins which were to evolve into the Australopithecines and the Homo genus, including Homo sapiens, all of which still possess that short insertion in the TBXT gene, which otherwise is identical to one of the gene which grow the tail of the simians.

As an example of design, it is one of the least intelligent, since, instead of removing all the genes required to grow a tail, the 'designer' simply broke an essential gene and left all the others to do nothing apart from having to be replicated in every cell in every ape that ever lived, as an example of the massive waste and unnecessary complexity that characterises an evolved process and gives the lie to any notion of any intelligence being involved.

By inserting the AluY snippet into a mouse BBXT gene the researchers found a variety of tail effects, including mice born without tails. They also showed that there was a small increase in the incidence on neural tube defects (spina bifida) in mice.

Quite why tailless would have been selected for during the evolution of these ancestors of the modern apes is a matter for speculation; maybe a tail was becoming an encumbrance for a brachiating mode of locomotion as opposed to running along the top of branches and jumping from branch to branch, which the smaller monkeys used, where a tail was an important balance organ. For a heavier ape hanging beneath the branches by its arms, there would have been less need for a balance organ and a tail would have been liable to damage and infection.

How this was discovered by a team led by researchers at New York University Grossman School of Medicine, is the subject of an open access paper in Nature and a NYU Langone Health news release:

Creationism in Crisis - How An Ancient Retrovirus Evolved To Create The Vertebrate Brain

A myelinating oligodendrocyte (green)

Credit: Peggy Assinck,
ALTOS Labs-Cambridge Institute Of Science

Ancient retroviruses played a key role in the evolution of vertebrate brains | ScienceDaily

Schematic diagram of a neuron show the myelin sheath as the electrical insulator of the axon.

Wikimedia Commons (CC BY-SA 3.0)

Extinct Late Devonian placoderm Bothriolepis canadensis. Myelin first appeared in these primitive early fish

Credit: Nobumichi Tamura / Stocktrek Images / Getty.

Creationists generally hate endogenous retrovirus (ERV's) because:

1. They are one of the strongest pieces of evidence of common descent appearing in the same locations in the genome of all organisms in a clade, forming nested hierarchies exactly as the Theory of Evolution predicts. The probability of the same viral DNA appearing in the same locus in all species in a clade by chance is, of course, so small it can be dismissed as an explanation.
2. They form a large part of the 'junk' DNA carried by all organisms, which, although a small proportion of it is transcribed into RNA, the RNA doesn't get translated into proteins and most of it doesn't serve any purpose. Some, but by no means all of it may have some regulatory functions.
3. Occasionally, an ancient ERV may have become exapted for some useful purpose unrelated to the original virus, so showing how new genetic information can enter a genome, flatly contradicting creationist's claims that no new information can arise within a genome because the second law of thermodynamics [sic] and Shannon Information Theory somehow forbids it.
4. An ERV serving a useful purpose also contradicts creationist claims that, while their favourite creator god is responsible for all the good stuff, another creator, called 'Sin', is responsible for the harmful stuff like parasites and viruses. Yet in those exapted ERVs we have viruses providing something that is beneficial and therefore, according to creationist dogma, must have been provided by their god!
5. Lastly, the examples of where ancient ERVs have mutated and provided some additional ability or function, such as enabling the formation of the myeline sheath in vertebrates, can't be regarded as detrimental mutations, yet creationist dogma, courtesy of the hapless Micheal J. Behe, is that all mutations are 'devolutionary'[sic].

Creationism in Crisis - How Mammalian Brains All Work The Same Way - Just Like They Evolved From A Common Ancestor

MIT neuroscientists have found that the six anatomical layers of the mammalian brain cortex show distinct patterns of electrical activity which are consistent throughout the entire cortex and across several animal species, including humans.

Credit: Image: Jose-Luis Olivares, MIT; iStock

Andrea Danti/Shutterstock.com

Study reveals a universal pattern of brain wave frequencies | MIT News | Massachusetts Institute of Technology.

It's a central dogma of creationism that humans are a special form of life created distinct from all other animals. This is one of the appeals of creationism to those who have such a high opinion of themselves that they like to believe they were created by and have a special relationship with the creator of the entire Universe, which it created specifically with them in mind.

However, when we look for evidence of this biological difference, we find instead evidence that we have the same biology as all other mammals and have much more in common than the relatively small differences that, like all other species, place us in a separate taxon. The similarities for a nested hierarchy which shows how closely (or distantly) related we are to the other mammals, particularly, in descending order, the other African great apes, the other anthropoid apes, the old-world monkeys and the other primates.

But creationists particularly like to point to our greater intelligence and aesthetic appreciation of art and music, and our ability to communicate. However, they too can be shown to be fat from unique to humans, who differ in those respects only by degree. Having special abilities with an organ of our body no more makes us a special creation than an elephant's special abilities with its trunk makes elephants a special creation, or a dolphin's special abilities with sonar makes dolphins a special creation.

Now, a team of neuroscientists from Massachusetts Institute of Technology (MIT), Cambridge, MA, USA and Vanderbilt University, Nashville, TN, USA have shown that there are six distinct layers of the mammalian brain cortex and that each of these is associated with the same distinctive pattern of electrical activity. Their results were the subject of an open access paper in Nature Neuroscience a few days ago.

Creationism In Crisis - How We Have Evolved To Understand What Other Primates Are Saying

Can we decode the language of our primate cousins? - Medias - UNIGE

The UNIGE team wanted to find out whether the frontal and orbitofrontal regions of our brain activate in the same way when faced with human and simian vocalisations.

© Leonardo Ceravolo

One of the things that creationist frauds hate is the evidence of common descent in the form of redundant structures that now serve little or no function, but which were present in an ancient ancestor. Their problem with them is that they are evidence of common ancestry and make no sense as the work of an intelligent designer. What rational designer includes details and complications that have no function?

For example, humans and many herbivores such as rhinoceroses still have the enzymes for digesting the chitin exoskeleton of insects and other arthropods, even though they never eat them. However, the ancestral stem mammal was an insectivore, but there has been no selection pressure to remove the mechanism for digesting them as the herbivores evolved, so this retention is like a fossil, showing evidence of common ancestry.

Another example is the tendency for the hairs on our neck (and back, arms and shoulders if we have any hair there) to stand up when we are startled as an automatic part of the fight or flight response and a remnant of when making yourself look bigger was a benefit to a hairy ape suddenly surprised by a potential predator.

Now scientists at the University of Geneva, Switzerland, have discovered another largely redundant ability that only makes sense as something retained from an ancient primate ancestor which is present in modern primates where it still has a useful function, and in humans where its function is redundant for all practical purposes; humans subconsciously recognise the vocalisations of other primates.

This is just another in the list of redundant structures that are evidence of evolution and common ancestry:

Creationism in Crisis - Human And Chimpanzee Language Developments Have A Common Origin

[left caption]

[Right caption/credit]

Young chimps develop language in the same way that human babies do.

New study reveals similarities between chimpanzee and human language development | University of Portsmouth

The traditional creationist argument for the daft notion that humans were specially created without ancestors and are thus a different sort of creation to the other animals, is normally to point at unique characteristics of humans, oblivious of the fact that, by definition, any species will have unique characteristics that define it as a distinct species.

One of these supposedly unique abilities is the ability to communicate with complex languages. This again ignores the fact that orcas or killer whales form social groupings with unique cultures and vocalizations with which they communicate with members of their own pod.

Now research by scientists from the University of Portsmouth in England, the University of Neuchâtel in Switzerland, and Université Clermont Auvergne in France have shown that there are clear similarities between the development of language in humans and the development of vocal communication in chimpanzees, strongly pointing to its origin in a common ancestor.

Creationism in Crisis - How Human Shoulders and Elbows Show Our Common Ancestry With Chimpanzees

Apes and early humans evolved more flexible arms than monkeys, such as the mangabeys shown here, to safely get out of trees.

Photo by Luke Fannin

Our Shoulders and Elbows Began as Brakes for Climbing Apes | Dartmouth

Every week is a bad week for creationists but this one is shaping up to be especially bad, with a clutch of peer reviewed papers which either show creationist is a counter-factual superstition, or that any putative designer can only be regarded as a malevolent entity, forever plotting new ways to make its creation suffer with more effective parasite.

The first of these is a paper by Dartmouth researchers, published in The Royal Society Open Science, which shows that the human shoulder and elbow joints probably evolved in an arboreal ape ancestor on the evidence that chimpanzees have the same adaptations.

The adaptations evolved to act as brakes as the apes lowered themselves from trees, reducing their chance of falling or injuring these joints because of their relatively large bodies.

The research, and its significance for understanding human evolution, is explained in a Dartmouth news release:

Creationism in Crisis - Evolution by Loss of Genetic Information, or What Made us Human

Creationism in Crisis

Evolution by Loss of Genetic Information, or What Made us Human

Illustration by Michael S. Helfenbein

‘Deletions’ from the human genome may be what made us human | YaleNews

A trio of papers out recently should make creationists feel even more despondent, if only they could find the courage to read them, and if they could understand their contents. I'll write about them over the next couple of days, time willing.

The first, published yesterday in Science, concerns a new study led by researchers at Yale and the Broad Institute of MIT and Harvard, which has shown that, in addition to gaining some new genes that allowed us to speak, for example, what also differentiates us from chimpanzees is about 10,000 lost pieces of DNA, some as small as a few base pairs.

This of course, flies in the face of creationist dogma which says loss of genetic information is always deleterious and so can't contribute to evolution. It's something that creationist guru Michael J. Behe ludicrously calls 'devolution', which is a nonsense term, since there is no mechanism by which deleterious mutations can accumulate in the species gene pool, unless, rarely, they are closely linked to a strongly beneficial mutation.

But then Behe is writing primarily for a readership that doesn't understand what evolution is or the processes that cause it and who have no intention of ever finding out. Instead, they tell themselves that 'evolutionists' believe a mutation can turn a one species into another as a single event. As we've come to expect, creationist dogma is counter-factual because it's based on deliberate misinformation.

These are the same people who have boon fooled into believing that mainstream biologists are turning against the Theory of Evolution and turning to their childish superstition with its magic and an unevidenced supernatural magician. Another creationists delusion refuted by this research paper.

That this is not a case of chimpanzees gaining something that their common ancestor with humans did not have is evidenced by the fact that the genetic information chimpanzees still have is also in the genome of many other mammals. The probability of multiple species all gaining the same small fragments of DNA are incalculably small.

So, what benefits did these deletions convey? That they did so is concluded from the fact that they are present in all humans so must have given a common ancestor and advantage early in. As the Yale News article by Bill Hathaway explains:

Creationism in Crisis - Modern Humans Are Not The First To Appreciate Art

How we discovered that Neanderthals could make art

Reconstruction of a Neanderthal woman

Morten Jacobsen (CC BY 2.5)

Creationist superstition says that human beings were made somehow differently to all the other animals, although they can never say how, exactly. Some believe only humans have an unproven and undefined magic entity living inside their body, called a 'soul', but other animals don't have this magic ingredient; others argue that animals also have this magic ingredient. They disagree endlessly on this point simply because they have no facts by which to determine the truth. If the 'soul' was detectable, the issue could be resolved easily and quickly. As it is, all they have is dogma.

But whatever their view of who has a magic soul and who doesn't, high on their list of abilities that humans have that other animals allegedly don't have will be aesthetic appreciation of art, music, love, etc. Some attribute this to the magic soul thing, others are happy to regard it as part of some unique aspect of human psychology, neuro-physiology, and/or genetics, so, of course, any evidence that another species has aesthetic appreciation is a major embarrassment for them.

However, with regard to artistic appreciation, there is now strong evidence that our cousin species, Neanderthals, could make artistic or symbolic designs, so, since we are related through a common ancestor - probably Homo heidelbergensis or Homo erectus, if indeed they were different species, it is highly likely that at least the potential for making symbolic drawings was present in that ancestor.

How do we know Neanderthals could make art?

In this article reprinted from The Conversation under a Creative Commons license, Dr Chris Standish, Postdoctoral Fellow of Archaeology, and Professor Alistair Pike, Professor of Archaeological Sciences, both of Southampton University, Hampshire, UK, present the evidence.

The article is reformatted for stylistic consistence. The original can be read here:

How we discovered that Neanderthals could make art

Neanderthal art.

Credit: P. Saura

Chris Standish, University of Southampton and Alistair Pike, University of Southampton

What makes us human? A lot of people would argue it is the ability of our species to engage in complex behaviour such as using language, creating art and being moral. But when and how did we first become “human” in this sense? While skeletal remains can reveal when our ancestors first became “anatomically modern”, it is much harder for scientists to decipher when the human lineage became “behaviourally modern”.

One of the key traits of behavioural modernity is the capacity to use, interpret and respond to symbols. We know that Homo sapiens have been doing this for at least 80,000 years. But its predecessor in parts of Eurasia, the Neanderthal, a human ancestor that became extinct around 40,000 years ago, has traditionally been regarded as uncultured and behaviourally inferior. Now our new study, published in Science, has challenged this view by showing that Neanderthals were able to create cave art.

The earliest examples of symbolic behaviour in African Homo sapiens populations include the use of mineral pigments and shell beads – presumably for body adornment and expressions of identity.

However, evidence for such behaviour by other human species is far more contentious. There are some tantalising clues that Neanderthals in Europe also used body ornamentation around 40,000 to 45,000 years ago. But scientists have so far argued that this must have been inspired by the modern humans who had just arrived there – we know that humans and Neanderthals interacted and even interbred.

Wall in Maltravieso Cave showing three hand stencils (centre right, centre top and top left).

Credit: H. Collado

Cave art is seen as a more sophisticated example of symbolic behaviour than body ornamentation, and has traditionally been thought of as a defining characteristic of Homo sapiens. In fact, most researchers believe that the cave art found in Europe and dating back over 40,000 years must have been painted by modern humans, even though Neanderthals were around at this time.

Dating cave art

Unfortunately, we have a poor understanding of the origins of cave art, primarily due to difficulties in accurately dating it. Archaeologists typically rely on radiocarbon dating when trying to date events from our past, but this requires the sample to contain organic material.

Calcium carbonate crust overlying pigment in La Pasiega.

Credit: J. Zilhão

Cave art, however, is often produced from mineral-based pigments which contain no organics, meaning radiocarbon dating isn’t possible. Even when when it is – such as when a charcoal-based pigment has been used – it suffers from issues of contamination which can lead to inaccurate dates. It is also a destructive technique, as the sample of pigment has to be taken from the art itself.

Uranium-thorium dating of carbonate minerals is often a better option. This well-established geochronological technique measures the natural decay of trace amounts of uranium to date the mineralisation of recent geological formations such as stalagmites and stalactites – collectively known as “speleothems”. Tiny speleothem formations are often found on top of cave paintings, making it possible to use this technique to constrain the age of cave art without impacting on the art itself.

A new era

We used uranium-thorium dating to investigate cave art from three previously discovered sites in Spain. In La Pasiega, northern Spain, we showed that a red linear motif is older than 64,800 years. In Ardales, southern Spain, various red painted stalagmite formations date to different episodes of painting, including one between 45,300 and 48,700 years ago, and another before 65,500 years ago. In Maltravieso in western central Spain, we showed a red hand stencil is older than 66,700 years.

Ladder shape in red painted in the La Pasiega cave.

Credit: C.D Standish, A.W.G. Pike and D.L. Hoffmann

These results demonstrate that cave art was being created in all three sites at least 20,000 years prior to the arrival of Homo sapiens in western Europe. They show for the first time that Neanderthals did produce cave art, and that is was not a one off event. It was created in caves across the full breadth of Spain, and at Ardales it occurred at multiple times over at least an 18,000-year period. Excitingly, the types of paintings produced (red lines, dots and hand stencils) are also found in caves elsewhere in Europe so it would not be surprising if some of these were made by Neanderthals, too.

Drawing of the ladder symbol painted on the walls.

Credit: Breuil et al. (1913)

We don’t know the exact meaning of the paintings, such as the ladder shape, but we do know they must have been important to Neanderthals. Some of them were painted in pitch black areas deep in the caves – requiring the preparation of a light source as well as the pigment. The locations appear deliberately selected, the ceilings of low overhangs or impressive stalagmite formations. These must have been meaningful symbols in meaningful places.

Our results are tremendously significant, both for our understanding of Neanderthals and for the emergence of behavioural complexity in the human lineage. Neanderthals undoubtedly had the capacity for symbolic behaviour, much like contemporaneous modern human populations residing in Africa.

To understand how behavioural modernity arose, we now need to shift our focus back to periods when Homo sapiens and Neanderthals interacted and to the period of their last common ancestor. The most likely candidate for this ancestor is Homo heidelbergensis, which lived over half a million years ago.

It is perhaps also now time that we move beyond a focus on what makes Homo sapiens and Neanderthals different. Modern humans may have “replaced” Neanderthals, but it is becoming increasingly clear that Neanderthals had similar cognitive and behavioural abilities – they were, in fact, equally “human”.
Chris Standish, Postdoctoral Fellow of Archaeology, University of Southampton and Alistair Pike, Professor of Archaeological Sciences, University of Southampton

Published by The Conversation.
Open access. (CC BY 4.0)