Field: Technology
A Neanderthal Genetic Legacy Continues to Sculpt Modern Human Physiques
Published | Technical Staff
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Despite their disappearance over 40,000 years ago, the legacy of Neanderthals endures not merely in ancient relics, but within the genomes—and phenotypes—of millions of living humans. In a groundbreaking study published in *Current Biology*, an international team led by Dr. Philipp Kanis at the Max Planck Institute for Evolutionary Anthropology has elucidated how a single archaic allele in the growth hormone receptor gene (GHR) continues to modulate human musculoskeletal traits today.
Neanderthals, *Homo neanderthalensis*, emerged between 300,000 and 400,000 years ago, radiating throughout western Eurasia and evolving a suite of skeletal adaptations: pronounced supraorbital ridges, a distinct occipital bun, a capacious, barrel-shaped thorax, and robust musculature. These anatomical specializations generated a recognizable composite portrait, fueling early hypotheses of an evolutionary divergence from *Homo sapiens*. Sequencing of Neanderthal genomes later confirmed an extended period of reproductive isolation extending over nearly half a million years. However, as modern humans surged out of Africa, interbreeding episodically blurred the boundaries, introducing approximately 2% Neanderthal ancestry into the genomes of present-day non-African populations.
To parse the genetic basis for Neanderthals’ robust build, Kanis and colleagues interrogated ancient and modern whole-genome datasets, focusing on the GHR gene. GHR encodes the cellular receptor for growth hormone (GH), a principal effector in the somatotropic axis regulating postnatal growth, muscle deposition, and skeletal development. Comparative sequence analysis of high-coverage Neanderthal genomes revealed a distinctive GHR allotype characterized by two derived, non-African amino acid substitutions. The functional consequences of these residues were interrogated in vitro by engineering human cell lines to express either the Neanderthal or modern human variant of GHR. Upon exposure to physiological concentrations of GH, the ‘Neanderthalized’ cells exhibited a significantly augmented proliferation rate and potentiated downstream signaling (notably, via the JAK2/STAT5 pathway), as measured by phospho-STAT5 abundance and cell cycle progression indices.
Population genetic analyses, leveraging over one million genotypes and biomedical records from global biobanks, confirmed that this Neanderthal GHR allele persists in contemporary humans, particularly at frequencies approaching 20% in South and East Asian populations, and is nearly absent in sub-Saharan Africa—mirroring known patterns of Neanderthal admixture. Phenotypic association analyses demonstrated that adult carriers of the archaic allele are on average both taller and heavier than non-carriers; crucially, body composition studies attributed this additional mass predominantly to increased lean muscle rather than adiposity. Furthermore, detailed craniofacial morphometric measurements revealed that carriers display subtle, Neanderthal-consistent traits: shorter mandibular rami, a higher incidence of dental overbite, and abbreviated tooth roots (taurodontism). These craniofacial distinctions, notably, become manifest only after puberty, congruent with the developmental timeline of GH surges.
The convergence of divergent lines of evidence—cellular functional assays and large-scale human cohort analyses—underscores the powerful and persistent influence of archaic introgression on the biological architecture of modern *Homo sapiens*. As Dr. Kanis remarked, the mutual corroboration between molecular and population data forms a rarely paralleled demonstration of evolutionary genetics in human biology. Co-author Dr. Hugo Zeberg is careful to note, however, that while the Neanderthal GHR variant exerts measurable effects, it represents only one node within a polygenic network shaping stature, muscle mass, and craniofacial growth. “It cannot explain the Neanderthal body type on its own, and it certainly does not determine a person’s overall appearance,” Zeberg observes.
The findings illuminate the molecular stratigraphy of our evolutionary past—demonstrating how a single Neanderthal-derived genetic element continues to sculpt the living body. In an era of genomic medicine, such discoveries both nuance our understanding of human diversity and highlight the deep-time connectivity of our species’ biological inheritance.
Neanderthals, *Homo neanderthalensis*, emerged between 300,000 and 400,000 years ago, radiating throughout western Eurasia and evolving a suite of skeletal adaptations: pronounced supraorbital ridges, a distinct occipital bun, a capacious, barrel-shaped thorax, and robust musculature. These anatomical specializations generated a recognizable composite portrait, fueling early hypotheses of an evolutionary divergence from *Homo sapiens*. Sequencing of Neanderthal genomes later confirmed an extended period of reproductive isolation extending over nearly half a million years. However, as modern humans surged out of Africa, interbreeding episodically blurred the boundaries, introducing approximately 2% Neanderthal ancestry into the genomes of present-day non-African populations.
To parse the genetic basis for Neanderthals’ robust build, Kanis and colleagues interrogated ancient and modern whole-genome datasets, focusing on the GHR gene. GHR encodes the cellular receptor for growth hormone (GH), a principal effector in the somatotropic axis regulating postnatal growth, muscle deposition, and skeletal development. Comparative sequence analysis of high-coverage Neanderthal genomes revealed a distinctive GHR allotype characterized by two derived, non-African amino acid substitutions. The functional consequences of these residues were interrogated in vitro by engineering human cell lines to express either the Neanderthal or modern human variant of GHR. Upon exposure to physiological concentrations of GH, the ‘Neanderthalized’ cells exhibited a significantly augmented proliferation rate and potentiated downstream signaling (notably, via the JAK2/STAT5 pathway), as measured by phospho-STAT5 abundance and cell cycle progression indices.
Population genetic analyses, leveraging over one million genotypes and biomedical records from global biobanks, confirmed that this Neanderthal GHR allele persists in contemporary humans, particularly at frequencies approaching 20% in South and East Asian populations, and is nearly absent in sub-Saharan Africa—mirroring known patterns of Neanderthal admixture. Phenotypic association analyses demonstrated that adult carriers of the archaic allele are on average both taller and heavier than non-carriers; crucially, body composition studies attributed this additional mass predominantly to increased lean muscle rather than adiposity. Furthermore, detailed craniofacial morphometric measurements revealed that carriers display subtle, Neanderthal-consistent traits: shorter mandibular rami, a higher incidence of dental overbite, and abbreviated tooth roots (taurodontism). These craniofacial distinctions, notably, become manifest only after puberty, congruent with the developmental timeline of GH surges.
The convergence of divergent lines of evidence—cellular functional assays and large-scale human cohort analyses—underscores the powerful and persistent influence of archaic introgression on the biological architecture of modern *Homo sapiens*. As Dr. Kanis remarked, the mutual corroboration between molecular and population data forms a rarely paralleled demonstration of evolutionary genetics in human biology. Co-author Dr. Hugo Zeberg is careful to note, however, that while the Neanderthal GHR variant exerts measurable effects, it represents only one node within a polygenic network shaping stature, muscle mass, and craniofacial growth. “It cannot explain the Neanderthal body type on its own, and it certainly does not determine a person’s overall appearance,” Zeberg observes.
The findings illuminate the molecular stratigraphy of our evolutionary past—demonstrating how a single Neanderthal-derived genetic element continues to sculpt the living body. In an era of genomic medicine, such discoveries both nuance our understanding of human diversity and highlight the deep-time connectivity of our species’ biological inheritance.