Neanderthal DNA in Indians: The 2025 Study That Changed Everything

For decades, the study of Neanderthal DNA focused almost exclusively on European populations. The assumption was simple: since Neanderthals lived primarily in Europe and western Asia, Europeans must carry the most interesting Neanderthal legacy. That assumption was shattered in 2025, when a landmark study published in Cell analyzed 2,762 Indian genomes and discovered something extraordinary. Indians collectively carry the most diverse archive of Neanderthal DNA of any modern population on Earth.

This finding did not just rewrite the textbooks on archaic human admixture. It placed India at the center of one of the most important questions in human evolution: how did our ancestors interact with Neanderthals, and what does that legacy mean for the health and biology of 1.4 billion people alive today?

The 2025 Cell Study: What Researchers Found

The study, led by researchers at the CSIR-Centre for Cellular and Molecular Biology (CCMB) in Hyderabad alongside international collaborators, was part of the broader IndiGenomes project. The team sequenced and analyzed whole genomes from 2,762 individuals representing over 275 distinct ethnolinguistic groups across India. This was, at the time, the largest and most diverse genomic survey of any single country.

The researchers used advanced computational methods to identify archaic DNA segments, comparing Indian genomes against high-coverage Neanderthal reference genomes from Vindija Cave (Croatia) and the Altai Mountains (Siberia), as well as the Denisovan genome from Denisova Cave. Their introgression-detection pipeline, building on methods like IBDmix and Sprime, allowed them to identify archaic segments even in populations with complex admixture histories.

The Numbers That Surprised Everyone

The headline numbers were striking enough. The average Indian genome contains approximately 1.43% Neanderthal DNA, which is slightly lower than the European average of 1.8-2.1% but significantly higher than what many researchers had previously assumed for South Asian populations. Additionally, Indians carry roughly 0.10% Denisovan DNA, a figure that places them between East Asians (who typically carry more Denisovan ancestry) and Europeans (who carry less).

But the truly revolutionary finding was not about averages. It was about diversity. When the researchers pooled all the unique Neanderthal DNA segments found across Indian populations, they discovered that these fragments, when assembled together, could cover approximately 50% of the Neanderthal genome. No other single-country dataset had come close to this figure. European datasets typically recover 20-30% of the Neanderthal genome from comparable sample sizes.

Population	Avg. Neanderthal %	Avg. Denisovan %	Neanderthal Genome Recovery
Indians (2,762 genomes)	1.43%	0.10%	~50%
Europeans (comparable datasets)	1.8-2.1%	0.02-0.04%	~20-30%
East Asians (comparable datasets)	1.9-2.3%	0.15-0.20%	~25-35%
Melanesians	1.9-2.2%	3.0-5.0%	N/A (small samples)

Why India Is a Neanderthal DNA Archive

The answer to why India preserves such extraordinary Neanderthal diversity lies in India's unique demographic history. Three factors conspire to make the subcontinent an unparalleled repository of archaic human DNA.

1. Endogamy: Thousands of Genetic Time Capsules

India's caste and tribal system created thousands of endogamous communities, many of which have maintained reproductive isolation for 1,500 to 3,000 years. Each of these communities represents, in genetic terms, a semi-independent drift experiment. When a Neanderthal DNA segment entered a community's gene pool, it could be preserved or lost independently of what happened in neighboring communities.

In Europe, by contrast, gene flow between populations was relatively frequent throughout the last 10,000 years. This meant that population-wide selection pressures acted more uniformly, purging certain Neanderthal variants from the European gene pool altogether. In India, a variant purged from one community might survive in another simply because the two groups did not exchange genes.

2. Multiple Waves of Admixture

Modern Indians descend from at least three major ancestral populations: the Ancestral South Indians (ASI), related to the Andamanese and distantly to Southeast Asian hunter-gatherers; the Ancestral North Indians (ANI), related to Central Asian and Iranian populations; and various East Asian-related groups, particularly in northeastern and eastern India. Each of these ancestral streams carried its own distinct package of Neanderthal DNA, acquired during different episodes of human-Neanderthal contact at different times and places.

The ANI component brought Neanderthal segments acquired during the expansion of modern humans through Central Asia and the Iranian plateau, approximately 50,000-45,000 years ago. The ASI lineage may carry traces of an even older, potentially separate interbreeding event, possibly occurring as modern humans first moved through the Arabian Peninsula and into South Asia. These distinct pulses of admixture mean that Indian genomes contain Neanderthal DNA from multiple source populations, dramatically increasing the total diversity of archaic segments.

3. Large Effective Population Size

Despite endogamy reducing gene flow between communities, India's overall population has been enormous for millennia. A large meta-population can collectively maintain more genetic diversity than a small one, even when subdivided. The sheer number of Indian communities, each preserving its own subset of Neanderthal variants, creates a situation where the collective archive is vast even though any single individual carries only about 1.43% Neanderthal DNA.

Health Implications: What Neanderthal DNA Does in Indian Bodies

Neanderthal DNA is not just an ancestral curiosity. These archaic segments contain functional genes that actively influence the biology and health of modern Indians. The 2025 study, along with earlier research, identified several key areas where Neanderthal variants have measurable health effects.

COVID-19 and Immune Response

One of the most widely reported Neanderthal-health connections involves a segment on chromosome 3 (specifically around the genes CCR9 and CXCR6) that was identified early in the pandemic as a major risk factor for severe COVID-19. This Neanderthal-derived haplotype increases the risk of hospitalization by approximately 60% for carriers.

The 2025 study found that this risk haplotype is carried by approximately 30% of South Asian populations, compared to around 16% of Europeans and virtually 0% of East Asians. This may have contributed to the severity of COVID-19 waves in India. However, the picture is nuanced: a separate Neanderthal-derived variant on chromosome 12, near the OAS gene cluster, confers protection against severe COVID-19, and this protective variant is also common in Indian populations at frequencies of 25-40%.

Immune System Genes: The TLR Connection

Beyond COVID-19, Neanderthal DNA has significantly shaped the Indian immune system through contributions to the Toll-like receptor (TLR) gene family. TLR1, TLR6, and TLR10, all of which play critical roles in pathogen recognition, carry Neanderthal-derived variants at high frequencies in Indian populations. These variants appear to enhance innate immune responses to bacterial infections, a clear advantage in the pathogen-rich tropical environment of South Asia.

The study estimated that Neanderthal variants in immune-related genes are under positive selection in Indian populations, meaning they have been actively favored by natural selection over tens of thousands of years. This is one of the clearest examples of beneficial Neanderthal inheritance in any human population.

Metabolism and the "Thrifty Gene" Hypothesis

Several Neanderthal-derived variants identified in the Indian dataset affect genes involved in lipid metabolism, insulin signaling, and adipose tissue distribution. Some researchers have speculated that these variants, originally adaptive in the cold, calorie-scarce environments where Neanderthals evolved, may contribute to the heightened susceptibility to type 2 diabetes and metabolic syndrome observed in South Asian populations.

Specifically, Neanderthal variants near the SLC16A11 gene and in the TCF7L2 regulatory region were found at elevated frequencies in several Indian populations. Both loci are well-established type 2 diabetes risk genes. While these variants likely provided metabolic advantages in prehistoric environments with seasonal food scarcity, they may now contribute to metabolic disease in the context of modern diets and sedentary lifestyles.

Skin, Hair, and Environmental Adaptation

The study also identified Neanderthal variants affecting keratin genes (involved in skin and hair structure), melanin-related genes (affecting skin pigmentation), and circadian rhythm genes. These variants show a latitude-dependent distribution within India, with some Neanderthal skin-related variants appearing at higher frequencies in northern populations and lower frequencies in southern populations. This pattern suggests that natural selection has fine-tuned Neanderthal contributions based on local environmental conditions across the subcontinent.

Neanderthal DNA Variation Across Indian Communities

One of the most fascinating aspects of the 2025 study was the documentation of how Neanderthal DNA varies across India's diverse population groups. The researchers found systematic patterns that reflect the deep population history of the subcontinent.

The ANI-ASI Gradient

Total Neanderthal DNA percentage correlates strongly with ANI (Ancestral North Indian) ancestry. Populations with higher ANI ancestry, such as Brahmins from northern states, Rajputs, and Khatris, tend to carry 1.6-1.9% Neanderthal DNA, approaching European levels. Populations with higher ASI ancestry, such as Paniya, Irula, and other tribal groups from South India, tend to carry 0.9-1.2% Neanderthal DNA.

This gradient makes sense given that ANI ancestry derives from populations that migrated through Central Asia, where contact with Neanderthal populations was more sustained. However, the ASI-related groups, despite carrying less total Neanderthal DNA, contribute many unique archaic segments not found in ANI-heavy populations. Some of these may derive from an early, independent interbreeding event between modern humans and Neanderthals in southern Asia.

Tribal Populations: Rare Archaic Segments

Tribal populations, particularly those in southern and central India, proved to be treasure troves of rare Neanderthal variants. The Irula of Tamil Nadu, the Paniya of Kerala, the Birhor of Jharkhand, and the Gond of central India all carried archaic DNA segments found in no other population group sampled worldwide. These unique segments likely reflect ancient gene flow events that have been preserved due to the long-term isolation of these communities.

Some tribal groups also showed elevated Denisovan ancestry compared to caste populations, with certain communities reaching 0.15-0.20% Denisovan DNA. This suggests that the ancestors of ASI populations may have had contact with Denisovan populations or Denisovan-admixed groups in Southeast or South Asia, a finding that adds to the growing evidence that Denisovan range extended much further south and west than the Siberian cave where they were first discovered.

Northeastern India: A Distinct Archaic Profile

Populations from northeastern India, including Naga, Mizo, and Khasi groups, showed a distinct archaic DNA profile that more closely resembles East Asian patterns. These groups tend to carry 1.5-1.8% Neanderthal DNA and 0.15-0.25% Denisovan DNA, with the Denisovan component being notably higher than in most other Indian populations. The Neanderthal segments in these groups overlap more with those found in Han Chinese and Japanese populations than with those found in western Indian groups, reflecting the East Asian ancestry of these communities.

What This Means for Your DNA Test

If you are Indian and have taken or are considering a DNA test, the findings from the 2025 study have important implications for how to interpret your archaic ancestry results.

Why Global Tests May Underestimate Indian Archaic Ancestry

Most commercial DNA tests, including 23andMe and AncestryDNA, calibrate their Neanderthal detection algorithms primarily against European reference populations. Because the Neanderthal segments common in Indians differ significantly from those common in Europeans, global tests may fail to detect some India-specific archaic segments. The 2025 study identified hundreds of Neanderthal DNA fragments that are unique to Indian populations and would not appear in European-calibrated reference panels.

This means that your "Neanderthal percentage" on a global test may be an underestimate. Helixline addresses this by using an Indian-specific reference panel and archaic DNA detection methods calibrated for South Asian populations, providing more accurate archaic ancestry estimates.

How Helixline Reports Neanderthal DNA

Helixline's Genome Ultimate test includes a comprehensive archaic ancestry module that reports your total Neanderthal and Denisovan DNA percentages, identifies the specific archaic segments you carry and which chromosomes they are located on, flags Neanderthal variants with known health or trait associations, compares your archaic ancestry to other Indian communities, and identifies rare or unique archaic segments that may reflect your specific community's heritage. This level of detail is possible because Helixline has built its archaic DNA reference panel using Indian genomic data, including data from the IndiGenomes project and other South Asian studies.

The Bigger Picture: India's Role in Human Evolution

The 2025 study's findings extend beyond personal ancestry. They have fundamentally altered our understanding of the human story. India was not a peripheral player in the drama of human-Neanderthal interaction. It was a central stage.

The subcontinent lies along the Southern Dispersal Route, the coastal path that some researchers believe was the primary corridor for modern human expansion out of Africa approximately 60,000-70,000 years ago. If early modern humans encountered Neanderthal populations in southern Asia, and the genetic evidence increasingly suggests they did, then India may have been the site of some of the earliest and most consequential interbreeding events between our species and our archaic cousins.

Furthermore, the discovery that India's endogamous structure has preserved Neanderthal DNA segments lost elsewhere means that India may hold the key to reconstructing the Neanderthal genome more completely than any other source. As sequencing technology becomes cheaper and more Indian genomes are analyzed, researchers may eventually be able to computationally reconstruct a near-complete Neanderthal genome using only the fragments preserved in living Indian populations, a feat that would have seemed impossible a decade ago.

Frequently Asked Questions

How much Neanderthal DNA do Indians have?

Indians carry an average of 1.43% Neanderthal DNA and approximately 0.10% Denisovan DNA. However, the key finding from the 2025 Cell study is that Indians possess the most diverse collection of Neanderthal DNA segments of any modern population studied. Different Indian communities carry different Neanderthal fragments, and collectively, the Indian population retains enough unique Neanderthal sequences to reconstruct approximately 50% of the Neanderthal genome. Individual percentages vary by community, ranging from roughly 0.9% in some tribal groups with high ASI ancestry to 1.9% in groups with high ANI ancestry.

Why do Indians have more diverse Neanderthal DNA than Europeans?

India's extreme genetic diversity, with thousands of endogamous communities that have remained relatively isolated for millennia, has preserved a wider variety of Neanderthal DNA segments. While Europeans underwent population bottlenecks and more extensive gene flow that eliminated many Neanderthal variants, India's large population size and endogamous structure maintained different Neanderthal fragments in different communities. Additionally, Indian populations descend from multiple ancestral groups (ANI, ASI, East Asian) that each carried distinct Neanderthal segments from different interbreeding events, further increasing the total diversity.

Does Neanderthal DNA affect health in Indians?

Yes, several Neanderthal DNA variants have documented health effects in Indian populations. These include variants affecting immune response, particularly the chromosome 3 risk haplotype associated with severe COVID-19, which is carried by approximately 30% of South Asians. Neanderthal variants also influence Toll-like receptor genes (TLR1, TLR6, TLR10) that shape innate immunity, lipid metabolism genes that may contribute to type 2 diabetes risk, and genes involved in skin pigmentation and keratin production. Some Neanderthal variants that were beneficial in ancient environments may now contribute to metabolic conditions prevalent in South Asian populations.

Do tribal populations in India have different Neanderthal DNA?

Yes, the 2025 study found significant variation in Neanderthal DNA across Indian populations. Tribal groups with higher Ancestral South Indian (ASI) ancestry tend to carry slightly less total Neanderthal DNA (0.9-1.2%) but may retain unique archaic segments not found in any other population worldwide. Groups with higher ANI ancestry generally carry more Neanderthal DNA (1.6-1.9%), closer to European averages. Certain isolated tribal populations, such as the Irula, Paniya, Birhor, and Gond, carry rare Neanderthal variants found nowhere else on Earth, making them invaluable for understanding archaic human biology.

Can Helixline test my Neanderthal DNA percentage?

Yes, Helixline's Genome Ultimate test includes a detailed archaic ancestry report showing your Neanderthal and Denisovan DNA percentages. The report identifies specific Neanderthal variants you carry and their known associations with traits and health conditions. Because Helixline uses an Indian-specific reference panel calibrated with data from projects like IndiGenomes, the archaic ancestry estimates are more accurate for South Asian individuals than those from global testing services that primarily use European-calibrated detection methods.

Conclusion

The 2025 Cell study fundamentally changed our understanding of Neanderthal DNA in modern humans. By revealing that India's genetically diverse populations collectively preserve the richest archive of Neanderthal DNA on Earth, the study placed the subcontinent at the center of archaic human research. For the 1.4 billion people living in India and the global Indian diaspora, this means that your DNA carries not just the story of your community and your family, but a chapter of the human story that was previously invisible.

Whether you carry 0.9% or 1.9% Neanderthal DNA, that archaic heritage has shaped your immune system, your metabolism, and your biology in ways that scientists are only beginning to understand. And thanks to India's unique population structure, the Neanderthal DNA in your genome may include variants found nowhere else in the living world.

Explore more about your ancient ancestry with our guides on ANI and ASI ancestry in India and understanding your Indian DNA results.