Lineage Exchange Depth and Clarity

# The Recursive Mosaic of Humanity: How Lineage Exchanges Shaped Global Diversity

Kenneth Parrott

## Abstract

Human diversity is not the product of isolated origins, but of recursive exchanges among hominin lineages. Each major migration and reintegration created distinct mosaics of traits that remain visible in modern populations. This paper argues that the features observed across the globe today—craniofacial variation, skin tone, body proportions, and metabolic traits—are the living evidence of when and where recursive lineage exchanges occurred. By tracing these braids through Europe, South Asia, Oceania, and the Americas, we demonstrate that humanity is unified not by purity of ancestry, but by patterned recursion.

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## 1. Introduction

The first wave of research into archaic admixture demonstrated that modern humans carry Neanderthal and Denisovan DNA (Green et al., 2010; Reich et al., 2010). Later work has expanded this view to include “ghost” populations in Africa and mosaic hybridization across Asia (Durvasula & Sankararaman, 2020; Slon et al., 2018). Yet these findings are often treated as isolated admixture events.

This paper proposes a recursive model: lineage exchanges did not happen once but repeatedly, and their reintegration created distinctive regional mosaics. Modern human variation is therefore best understood not as racial division but as fractal echoes of these recursive braids.

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## 2. Europe: Neanderthal Recursions

- Early modern humans entered Europe ~45,000 years ago (Fu et al., 2014).

- They repeatedly encountered Neanderthals, leading to multiple introgression events.

- Neanderthal ancestry shaped traits related to immune function, keratin filaments, and fat metabolism (Dannemann & Kelso, 2017).

- The recursive blending explains European variation in robusticity, facial form, and adaptation to colder climates.

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## 3. South Asia: A Mixing Bowl

- South Asia absorbed flows from both west (Neanderthal-enriched) and east (Denisovan-enriched).

- Genetic studies confirm South Asians carry unique combinations of both archaic lineages (Narasimhan et al., 2019).

- This region exemplifies the recursive model: repeated inflows stacked to produce today’s high linguistic, genetic, and cultural diversity.

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## 4. Oceania: The Deepest Braid

- Populations of Melanesia and Aboriginal Australia carry the highest known levels of Denisovan ancestry (2–5%) alongside the global Neanderthal baseline (Reich et al., 2010; Huerta-Sánchez et al., 2014).

- Fossil evidence shows erectus persisted in Indonesia until ~100k years ago (Antón, 2003), raising the possibility of additional admixture layers.

- Oceanians therefore represent the richest recursion: *sapiens* + Neanderthal + Denisovan + possible erectus echoes + ghost signals.

- Their traits—robust craniofacial form, hair variation, altitude tolerance—reflect this compounded heritage.

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## 5. The Americas: New Recursions in a New World

- The Americas were settled ~15–20k years ago via Beringia (Goebel et al., 2008).

- Migrant groups already carried Neanderthal and Denisovan signatures.

- In the Americas, fresh adaptations arose:

- High-altitude survival in the Andes (Beall, 2014).

- Shovel-shaped incisors, a dental trait linked to Asian ancestry (Scott & Irish, 2017).

- These traits show that recursion did not stop at Eurasia—it continued as populations adapted to novel landscapes.

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## 6. The Recursive Mosaic Model

- Each region’s modern diversity is the product of multiple reintegrations, not a single admixture.

- Features today are **living fossils of ancient flows**:

- Europe = repeated Neanderthal recursions.

- South Asia = dual Neanderthal/Denisovan stacking.

- Oceania = deepest braid of all lineages.

- The Americas = final echo, with new adaptations layered onto old ancestries.

This model reframes diversity as recursion: the more times lineages crossed and reintegrated, the richer the mosaic.

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## 7. Conclusion

The recursive mosaic model explains why humanity is simultaneously one and many. We are one species, braided together by flows of genes, yet diverse because each region carries a different recursive history. Our features are not divisions but echoes of encounters.

To understand modern variation, we must look not for purity but for recursion—the patterned reintegration of lineages across time and space.

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## References

- Antón, S. C. (2003). Natural history of *Homo erectus*. *Yearbook of Physical Anthropology*, 46, 126–170.

- Beall, C. M. (2014). Adaptation to high altitude: Phenotypes and genotypes. *Annual Review of Anthropology*, 43, 251–272.

- Dannemann, M., & Kelso, J. (2017). The contribution of Neanderthals to phenotypic variation in modern humans. *American Journal of Human Genetics*, 101(4), 578–589.

- Durvasula, A., & Sankararaman, S. (2020). Recovering signals of ghost archaic introgression in African populations. *Science Advances*, 6(7), eaax5097.

- Fu, Q., et al. (2014). Genome sequence of a 45,000-year-old modern human from western Siberia. *Nature*, 514(7523), 445–449.

- Goebel, T., Waters, M. R., & O’Rourke, D. H. (2008). The late Pleistocene dispersal of modern humans in the Americas. *Science*, 319(5869), 1497–1502.

- Green, R. E., et al. (2010). A draft sequence of the Neanderthal genome. *Science*, 328(5979), 710–722.

- Huerta-Sánchez, E., et al. (2014). Altitude adaptation in Tibetans caused by introgression of Denisovan-like DNA. *Nature*, 512(7513), 194–197.

- Narasimhan, V. M., et al. (2019). The formation of human populations in South and Central Asia. *Science*, 365(6457), eaat7487.

- Reich, D., et al. (2010). Genetic history of an archaic hominin group from Denisova Cave. *Nature*, 468, 1053–1060.

- Scott, G. R., & Irish, J. D. (2017). *Human Tooth Crown and Root Morphology: The Arizona State University Dental Anthropology System*. Cambridge University Press.

- Slon, V., et al. (2018). The genome of the offspring of a Neanderthal mother and a Denisovan father. *Nature*, 561, 113–116.

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