What Akbari’s Reply Gets Wrong About Science

Akbari’s response reveals a deeper confusion about citation, replication, and scientific credit

I have now received a direct reply from Ali Akbari explaining why my earlier papers were not cited. That reply closes off the most charitable interpretation. This is no longer something that can be waved away as oversight, a missed paper, or a crowded reference list. The omission is now being defended on principle. And the principle is wrong. Nature’s own editorial policy says that earlier intellectual contributions must be properly described and appropriately cited, and Nature’s reviewer guidance tells referees to flag cases where conclusions are not original and to suggest relevant references.

Akbari’s explanation is that my studies were not cited because, in his view, they lacked proper calibration, did not adequately deal with inflation or multiple testing, and therefore did not count as relevant prior evidence for directional selection. That argument conflates two different claims. It treats “I think this paper is wrong” as equivalent to “this paper is irrelevant.” A paper can be disputable and still be prior work. A paper can be flawed and still be the earlier attempt to answer the same question. In science, criticism is a reason to cite and distinguish. It is not a reason to pretend the earlier paper does not exist. Nature’s own rule is not “cite only papers you approve of.” It is to acknowledge earlier contributions accurately.

The overlap here is not loose. In March 2024, Emil Kirkegaard and I published Evolutionary Trends of Polygenic Scores in European Populations From the Paleolithic to Modern Times in Twin Research and Human Genetics. That paper reported positive temporal trends for educational attainment, IQ, and SES-related scores in ancient Europe, alongside declines over time in schizophrenia, depression- and neuroticism-related scores. Akbari et al.’s West Eurasia preprint appeared in September 2024, and the Nature version was published on 15 April 2026. Their paper reports decreases in schizophrenia risk and increases in measures related to cognitive performance across West Eurasia. The overlap doesn't require the papers to be identical. Same broad region, same time-series logic, same cluster of cognitive and psychiatric traits, same directional story. They also report effects of deep ancestry on polygenic scores that broadly line up with what I had already found, including, for example, higher educational-attainment polygenic scores in Early European Farmers.

The overlap goes well beyond a few matching results. In my 2017 paper and again in my 2024 paper, I explicitly tested the broader Holocene accelerated-evolution model with ancient DNA, focusing on whether recent directional selection had pushed cognition-related variants upward through time. Akbari et al. later addressed that same basic model in the same broad West Eurasian context, with many of the same phenotypes and the same directional logic. The statistical machinery differs, but the core question does not.

The East Eurasian side is even harder to dismiss. On 30 January 2025, I published Directional Selection and Evolution of Polygenic Traits in Eastern Eurasia: Insights from Ancient DNA. I said explicitly that the paper was meant to test whether the earlier West Eurasian pattern could be replicated in the East. The answer, in that paper, was yes: education- and intelligence-related scores rose through time, while anxiety- and depression-related scores moved in the opposite direction. Then, on 4 April 2026, Barton et al. posted their preprint on convergent natural selection at both ends of Eurasia, with Akbari as one of the authors. By then I had already published the West Eurasian pattern and its East Eurasian extension.

That is why this is not just a dispute about “models.” Science tracks findings as well as frameworks. If one paper reports a directional increase in cognition-related polygenic scores and a directional decline in psychiatric-risk related scores over ancient time series, and a later paper reports the same broad pattern with more data or a more elaborate pipeline, the later paper is not starting from zero. It is confirming, refining, narrowing, or disputing an earlier result. Methodological superiority can justify a critical citation. It does not justify silence. Nature’s own guidance to reviewers only makes sense on that assumption: if the conclusions are not original, relevant references should be supplied.

This line of work also did not begin in 2024. Back in 2017, Woodley, Younuskunju, Balan, and I published Holocene Selection for Variants Associated With General Cognitive Ability: Comparing Ancient and Modern Genomes in Twin Research and Human Genetics. That paper compared ancient and modern genomes in order to test a Holocene selection hypothesis for cognitive-associated variants. It was not the same design as the later time-series papers, but it was obviously part of the same broader program: using ancient DNA to ask whether cognition-related alleles changed over the holocene.

The timeline alone makes the oversight defense implausible. Akbari et al.’s Nature paper shows “received” on 14 September 2024, “accepted” on 4 March 2026, and “published” on 15 April 2026. So this was not a manuscript that flashed by in a week. It sat in peer review for roughly a year and a half. I had already contacted the authors long before publication. Even if one imagines an email being overlooked, the papers themselves were sitting in the literature while this manuscript was being reviewed, revised, and defended. Akbari’s reply makes clear what happened in the end: not ignorance, but refusal.

The public peer review file makes his position look weaker, not stronger. Reviewers raised serious concerns about the statistical machinery, confounding, inflation, significance thresholds, and whether the polygenic claims were genuine or artifacts. One reviewer wrote that there were “major concerns about the statistical machinery and interpretations.” Another objected to the authors’ claim that they were exploiting something “not utilized in previous scans,” saying “This is not the case.” Another wrote that the title “rather overpromises.” The paper was not waved through on the ground that its authors had finally reached a uniquely rigorous standard that rendered all previous work irrelevant. It went through exactly what papers are supposed to go through: criticism, revision, qualification, and rebuttal.

By Akbari’s logic, any later author could erase prior work simply by declaring it methodologically insufficient, without any external scrutiny. But science cannot function that way. If that principle were accepted, citation would become a private reward system controlled by whoever publishes later from the stronger institution, with the bigger dataset, in the more prestigious journal. Smaller researchers would be acknowledged only when elite groups decided they were respectable enough. That is not a standard of rigor. It is a standard of power.

There are older examples of this problem. Mendel’s work was rediscovered in 1900 by later researchers who had obtained similar results, but rediscovery did not erase Mendel’s priority. Wegener’s continental-drift hypothesis was attacked for decades, yet plate tectonics did not make Wegener vanish from the history of the idea. Avery, MacLeod, and McCarty identified DNA as the transforming principle in 1944, and later work strengthened that case, but it did not make their paper irrelevant. In each case, later confirmation or methodological improvement changed the standing of the claim. It did not cancel the earlier contribution.

I am not claiming that my papers are beyond criticism. Of course they are open to criticism. They can be challenged, reanalyzed, corrected, or superseded. That is normal. What is not normal is the idea that directly relevant prior studies cease to count because a later author dislikes their methods. If anything, disagreement makes citation more necessary. Readers should be able to see the sequence of claims, the overlap in findings, and the points of dispute for themselves. Otherwise replication gets laundered into novelty, and the literature starts telling a false story about where an idea began.

Akbari is not just saying that he thinks my methods were weak. He is saying that this judgment frees him from the obligation to cite prior work that addressed the same question and reported earlier, overlapping results. That is not a defense of scientific standards. It is a rejection of one of the basic ways science keeps its own record honest.

You cite the earlier paper. You say where you think it went wrong. You explain what your method does better. You let readers see the continuity and the disagreement in the open. You do not reproduce the same broad empirical pattern, on the same class of traits, in the same historical frame, and then behave as though the earlier literature never existed.

Because this is no longer a matter of oversight, I am submitting a formal complaint to Nature about the failure to acknowledge directly relevant prior work. My aim is not to relitigate every methodological disagreement in public, but to correct the scientific record. If later authors believe an earlier paper is flawed, they are free to say so. What they are not free to do is treat it as though it never existed.

References

Piffer, D., & Kirkegaard, E. O. W. (2024). Evolutionary trends of polygenic scores in European populations from the Paleolithic to modern times. Twin Research and Human Genetics, 27(1), 30-49. https://doi.org/10.1017/thg.2024.8

Piffer, D. (2025). Directional selection and evolution of polygenic traits in Eastern Eurasia: Insights from ancient DNA. Twin Research and Human Genetics, 28(1). https://doi.org/10.1017/thg.2024.49

Piffer, D., & Kirkegaard, E. O. W. (2024). Predictive accuracy of polygenic scores from European GWAS among Chinese provinces. Mankind Quarterly, 65(1), 58-71. https://doi.org/10.46469/mq.2024.65.1.6

Woodley, M. A., Younuskunju, S., Balan, B., & Piffer, D. (2017). Holocene selection for variants associated with general cognitive ability: Comparing ancient and modern genomes. Twin Research and Human Genetics, 20(4), 271-280. https://doi.org/10.1017/thg.2017.37

Akbari, A., Barton, A. R., Gazal, S., Li, Z., Mah, M., Meyer, M., Mallick, S., Pinhasi, R., Rohland, N., Price, A. L., & Reich, D. (2024, September 15). Pervasive findings of directional selection realize the promise of ancient DNA to elucidate human adaptation [Preprint]. bioRxiv. https://doi.org/10.1101/2024.09.14.613021

Akbari, A., Perry, A., Barton, A. R., et al. (2026). Ancient DNA reveals pervasive directional selection across West Eurasia. Nature. https://doi.org/10.1038/s41586-026-10358-1

Barton, A. R., Rohland, N., Mallick, S., Pinhasi, R., Akbari, A., & Reich, D. (2026, April 4). Convergent natural selection at both ends of Eurasia during parallel radical lifestyle shifts in the last ten millennia [Preprint]. bioRxiv. https://doi.org/10.64898/2026.04.03.716344