The research team employed isotopic analyses of fossilized hominin teeth, focusing specifically on carbon and oxygen isotope signatures embedded in the dental enamel. These chemical remnants provide a direct window into the diets of our ancient ancestors. By tracing isotopic ratios characteristic of graminoids—a group encompassing grasses and sedges—the scientists could pinpoint when early humans began incorporating these plants into their diets. Surprisingly, these chemical markers indicate a pronounced behavioral shift toward graminoid consumption several hundred thousand years before the morphological adaptations in teeth emerged, challenging the long-held assumption that physical traits and behaviors evolve concurrently.

This temporal lag between behavior and morphology exemplifies what evolutionary biologists term “behavioral drive.” Behavior often acts as a leading force in evolutionary trajectories, enabling organisms to exploit new ecological niches and resources prior to the full suite of anatomical specializations necessary for such exploitation. In the context of early hominins, this means that despite possessing teeth that were not yet ideal for processing gritty, fibrous plant tissues, they nonetheless intensified their consumption of graminoids, relying on cultural and technological innovations such as rudimentary tools and fire to aid in food acquisition and preparation.

Detailed analyses of molar morphology reveal that while hominin teeth generally diminished in overall size—shrinking by roughly five percent every 1,000 years—their molars simultaneously grew longer. This elongation is interpreted as an adaptive modification facilitating more efficient breakdown of tough vegetative fibers. However, this dental evolution significantly lagged behind the initial dietary transition toward grass consumption, with substantial changes in tooth shape and size only materializing approximately two million years ago. Species such as Homo habilis and Homo ergaster exemplify this dental shift, their evolved molars better suited for chewing and processing cooked plant materials.

Isotope data also pinpoint a dramatic dietary pivot around 2.3 million years ago involving Homo rudolfensis. During this period, carbon and oxygen isotope ratios in their teeth shifted sharply, indicative of reduced direct grass consumption and increased intake of oxygen-deprived water sources. This unique signature aligns closely with the exploitation of underground plant storage organs like tubers, bulbs, and corms, which contain starch-rich carbohydrates encased within oxygen-limited tissues. The consistent availability and high nutritional value of such underground resources likely played a critical role in supporting the growing energetic demands of larger brains and bodies in these hominins.

The team’s findings suggest that early humans’ dietary flexibility was not just a passive response to environmental change, but an active driver of evolutionary processes. The strategic reliance on underground plant organs provided a dependable carbohydrate reservoir that required less physical risk than hunting and offered abundant calories year-round. Access to these subterranean resources, facilitated by manual digging tools, allowed hominins to thrive in open grassland ecosystems where fruits and insects were less plentiful or seasonal.

Perhaps most compellingly, this research argues that early human innovation and cultural adaptation spontaneously prompted major evolutionary shifts in physiology. The precedence of behavior over morphology challenges the traditional anthropological narrative which posits that bodily adaptations are prerequisites for novel behaviors. Instead, hominins’ early embrace of tough, grassy plants and underground starches motivated the gradual dental transformations that eventually optimized their diets, highlighting the co-evolution of culture and biology.

The implications of this study extend beyond understanding prehistoric diets; they inform the fundamental question of what set early humans apart from other primates. While many primates adapted to specific dietary niches with corresponding anatomical specializations, hominins demonstrated unmatched behavioral plasticity by exploiting grass-based food sources ahead of physical device. This flexibility likely conferred significant survival advantages, enabling them to colonize diverse habitats and develop complex social systems.

Moreover, this evolutionary narrative resonates with the centrality of grasses in modern human civilizations. Contemporary global economies heavily depend on a handful of grass species—such as rice, wheat, corn, and barley—that constitute primary calorie sources. The ancestral behavior of embracing graminoids as a staple food thus represents a foundational step in the trajectory leading to agriculture and civilization itself. Recognizing this deep history reinforces the notion that human success derives not only from biological innovation but also from strategic behavioral choices.

Lead author Luke Fannin encapsulates this perspective: early hominins’ willingness to integrate suboptimal foods into their diet, despite morphological inadequacies, reveals a core human trait—adaptive behavioral flexibility. This flexibility, rather than morphologically deterministic traits alone, illuminated a pathway for evolutionary success. As anthropologists revisit long-standing assumptions about the synchrony of morphological and behavioral evolution, these findings herald a paradigm shift in interpreting the hominin fossil record.

Senior author Nathaniel Dominy emphasizes the power of isotope analysis as a revolutionary tool in paleoanthropology. Since behavior rarely fossilizes, reliance on physical traits alone has obscured the timing and nature of ancient behavioral innovations. Chemical signatures preserved in teeth emerge as irrefutable evidence for dietary shifts, underscoring the critical role of new methodologies in elucidating human evolutionary history.

Collectively, the evidence from this study reframes behavioral change as a potent evolutionary force capable of driving morphological adaptations. By embracing behavior as both a survival strategy and an evolutionary catalyst, we gain a richer understanding of how our ancestors navigated and transformed their environments. This nuanced view illuminates the dynamic feedbacks between culture, biology, and environment that shaped the human lineage.

In conclusion, the revelation that behavior led morphological evolution in early hominins underscores a unique hallmark of our species’ emergence. The early adoption of graminoid consumption millions of years ago, preceding dental evolution by hundreds of thousands of years, not only exemplifies the principle of behavioral drive but also marks a pivotal juncture in the evolution of human diets. It is a testament to the ingenuity and adaptability that have propelled our species from the African savannas to global dominance.

Subject of Research: People

Article Title: Behavior drives morphological change during human evolution

News Publication Date: 31-Jul-2025

Web References: https://doi.org/10.1126/science.ado2359

Image Credits: L to R: Public domain; Don Hitchcock; Fernando Losada Rodríguez (rotated)

Keywords: Early humans, Human evolution, Hominins, Social sciences, Anthropology, Anthropogenesis, Human adaptation, Applied anthropology, Homo sapiens, Physical anthropology, Research methods, Adaptive evolution, Evolution, Isotopes

The cemetery at Tiszafüred-Majoroshalom uniquely spans two significant cultural epochs: the Middle Bronze Age Füzesabony culture and the Late Bronze Age Tumulus culture. This continuity offers a rare opportunity to examine lifestyles before and after a watershed moment in Central European history. The multidisciplinary approach entailed detailed isotopic assays on human remains, particularly focusing on nitrogen, carbon, and strontium isotope ratios, complemented by archaeobotanical scrutiny of dental calculus microremains, allowing for unprecedented insights into ancient diets and mobility patterns.

Nitrogen stable isotope analysis revealed marked societal disparities in diet within the Middle Bronze Age community. Access to animal protein was highly stratified, suggesting a complex social fabric where dietary privileges were unequally distributed. However, as the region transitioned into the Late Bronze Age, these differences diminished significantly. The diet homogenized and faced a reduction in overall nutritional richness, challenging earlier conceptions that Late Bronze Age populations, particularly those affiliated with the Tumulus culture, maintained robust pastoralist economies dependent on animal husbandry.

Carbon isotopic data provided compelling evidence for the introduction of broomcorn millet into the region’s subsistence economy at the dawn of the Late Bronze Age. This crop, known for its fast growth cycle and high caloric yield, emerged as a strategic resource. This finding represents the earliest direct evidence of millet consumption in European contexts, underscoring broad-scale agricultural transformations impacting food security and social organization during the period.

Strontium isotope studies brought to light distinct changes in mobility patterns between the Middle and Late Bronze Age populations. Whereas the Middle Bronze Age community included numerous individuals of non-local origin, likely from proximate regions such as the Upper Tisza basin and Northern Carpathians, the Late Bronze Age inhabitants showed a reduction in immigrant presence. Moreover, newcomers in this later period appeared to originate from geographically more distant areas, including Transdanubia and the Southern Carpathians, heralding shifts in migration routes and possibly the sociopolitical landscape of the Great Hungarian Plain.

Radiocarbon dating anchored these changes firmly to around 1500 BCE, coinciding with the rise of the Tumulus culture across Central Europe. The influx of new communities from western regions during this time supports archaeological hypotheses of widespread cultural diffusion and population movements that shaped the Bronze Age’s complex demographic tapestry.

Significantly, archaeological evidence indicates a profound transformation in settlement patterns contemporaneous with these biological shifts. Large, long-inhabited tell-settlements characteristic of the Middle Bronze Age were abandoned, replaced by less centralized, dispersed habitation networks. This settlement reorganization likely contributed to—and reflected—a loosening of social hierarchies, a theory consistent with isotopic data showing diminishing dietary stratification and reduced animal protein consumption at the societal level.

Microremain analysis from dental calculus provided a nuanced picture of dietary change. The marked decline in animal protein intake among Late Bronze Age individuals contradicts the enduring assumption that Tumulus culture populations primarily practiced pastoralism. Instead, the data suggest a more diversified subsistence base, with greater reliance on plant-based resources, especially millet, reshaping entrenched narratives of Bronze Age economies and social structures.

The integrative methodology employed by Hajdu, Cavazzuti, and colleagues encapsulates a transformative approach to bioarchaeological research. By combining isotopic geochemistry, archaeobotany, and traditional archaeological context, the study transcends disciplinary boundaries, allowing for a holistic reconstruction of ancient lifeways. This multifaceted perspective is critical in deciphering the complex processes underlying cultural and demographic transitions in prehistoric Europe.

Published in the prestigious journal Scientific Reports, the findings illuminate how shifts in mobility patterns, dietary practices, and social organization during the Late Bronze Age were synchronized with significant cultural and ecological changes. The dissolution of hierarchical social stratification, evidenced by dietary uniformity, and the movement toward more flexible settlement models signal broader adaptive responses within prehistoric societies to internal and external pressures.

Moreover, these results provide a compelling framework for reevaluating the origins and characteristics of the Tumulus culture, one of Central Europe’s defining Bronze Age phenomena. Contrary to long-held assumptions positioning it as dominantly pastoral, the new data highlight a complex society negotiating identity, economy, and social organization through multifarious strategies.

This research not only pushes back the earliest confirmed introduction of millet in Europe but also offers a detailed narrative connecting agricultural innovation with societal adaptation and migration dynamics. Such integrative bioarchaeological investigations serve as essential touchstones for understanding prehistoric human resilience and cultural evolution amid environmental and social transformations.

In sum, the Tiszafüred-Majoroshalom cemetery project epitomizes the power of advanced scientific techniques applied in tandem with archaeological intelligence to unravel the intricacies of human pasts. By revealing how people navigated profound challenges around 1500 BCE—reshaping diets, migration flows, and social networks—this study provides critical insights relevant to broader discourses on prehistoric Europe’s cultural and biological landscapes.

Subject of Research: Bioarchaeological investigation of the Bronze Age cemetery at Tiszafüred-Majoroshalom, focusing on mobility, diet, and social organization around 1500 BCE.

Article Title: Isotope and archaeobotanical analysis reveal radical changes in mobility, diet and inequalities around 1500 BCE at the core of Europe

News Publication Date: 20-May-2025

Web References:

• https://www.nature.com/articles/s41598-025-01113-z
• http://dx.doi.org/10.1038/s41598-025-01113-z

References:

• Kovács, T. (1995). Auf Mitteleuropa weisende Beziehungen einiger Waffenfunde aus dem östlichen Karpatenbecken. In B. Hänsel (Ed.), Handel, Tausch und Verkehr im bronze- und früheisenzeitlichen Südosteuropa. Prähistorische Archäologie in Südosteuropa 11. Südosteuropa-Gesellschaft, München-Berlin, pp. 173–185.
• Dani J., Horváth A., Gémes A., Fülöp K., Szeniczey T., Tarbay JG., et al. (2025). New radiocarbon dates from the Bronze Age Tiszafüred-Majoroshalom site (Eastern Hungary). Radiocarbon, 67(2), 428–440. DOI: 10.1017/RDC.2024.123

Image Credits: Kovács 1995, Abb. 1/A, 2-3 and Dani János et al. 2025

Keywords: Anthropology, Anthropogenesis, Homo sapiens, Economics, Paleoanthropology, Human diversity, Genetic paleoanthropology, Human remains