An unusually long and complex research paper has caught the attention of the scientific community, sparking questions about the ideal length of a paper. The study, by computational biologist Manolis Kellis and his colleagues, was published in Nature1 in July. Spanning 35 pages, it contains more than 20,000 words, and has 16 figures — or 61, if those in the Supplementary information are included. It describes changes in the genes, cellular pathways and cell types of people with Alzheimer’s disease across six regions of the brain, and provides a detailed atlas of gene expression.
When Kellis, who runs a computational-biology laboratory at the Massachusetts Institute of Technology (MIT) in Cambridge, shared the paper on X (formerly Twitter), the size of it seemed to divide his peers. Some were complimentary: “It must have taken a lot of effort and resources to get this done, so all in all, it is a great paper,” one response read. Others were concerned about its usefulness. “How can anyone read this article, let alone review and critique the work?” asked another user.
An analysis of paper characteristics across scientific fields2, published in 2023, suggests that this study is an outlier in the medical and health sciences, where papers typically hover around ten pages in length. However, it is not so unusual when compared with papers in subject areas such as mathematics, law or the humanities — all of which often exceed 20 pages.
Kellis’s work raises the question of how accessible research papers should be, and how readers in and beyond academia are expected to consume them. For example, is it better to publish large data sets alongside long and dense papers, to keep the information contained in one place? Or should researchers home in on specific topics and publish their results across several papers?
Alireza Haghighi, a geneticist at Harvard Medical School in Boston, Massachusetts, says that there is value in the former approach, particularly at a time when data sets are becoming increasingly large. “Although focus has traditionally been important in publications, we must acknowledge the complexity of new methods and the huge volumes of data generated today,” says Haghighi. “Not all papers can or should be understood in one hour.”
Does size matter?
Papers that provide broad, detailed overviews and extensive data sets — sometimes called ‘atlases’, in the omics fields of genomics, transcriptomics and proteomics — allow researchers to see the big picture, says Haghighi. They enable readers to “identify connections across different areas, and generate new hypotheses”, he explains, and adds that he sees them as drivers of innovation that can guide large-scale, integrative research initiatives better than a more focused paper might.
Responding to the discussion on X, Kellis said he understands that some people will be overwhelmed by his lab’s paper. He likened the work to “a good book with many chapters and many pages”, and said that “each paragraph, parenthesis, panel, supplementary figure, can hide potential hints and secrets that the authors themselves may have missed”. Kellis also suggested that for those who were overwhelmed by the results, tools such as the ChatGPT Consensus app, which is regarded as an academic search engine, could be useful for summarizing some of the paper’s findings.
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Li-Huei Tsai, a neuroscientist at MIT and a corresponding author on the paper, told Nature Index that she is proud of the work, which has “produced important insights into genomic underpinnings of Alzheimer’s vulnerability and resilience”. Kellis did not respond to Nature Index’s request for comment.
Researchers who spoke to Nature Index flagged a number of issues with big, data-dense articles. Luke Dabin, an epigeneticist at the Indiana University School of Medicine in Indianapolis, is a “huge fan” of big data sets and atlas papers, because they have the potential to be a hotbed for generating hypotheses and can inform the design of future experiments. But Dabin says that such papers can sometimes be difficult to interpret — even by scientists working in the same field — and can have quality-control issues. “The Kellis paper has 475 figure panels and is difficult for me to digest, let alone someone with no training or experience in single-cell omics,” Dabin says. Haghighi agrees that accuracy can become a problem in large papers. “We should appreciate that atlas maps are more prone to inaccuracies due to their scope and complexity,” he says.
Such papers can also be resource-heavy for journal editors to publish. It took almost two years for Kellis’s paper to progress from acceptance to publication, although it might not have been under review the entire time. A spokesperson for Nature noted that “the length of the review process for papers submitted to Nature varies considerably from manuscript to manuscript”, and said that its primary focus is “to ensure that a rigorous peer-review process takes place”. (Nature Index’s news and supplement content is editorially independent of its publisher, Springer Nature.)
On X, Kellis noted that “it was a Herculean task by the reviewers and editors, as it was of course for the authors, to go through every figure, every panel, and every result” as part of the publishing process.
A case for brevity?
Some researchers argue that there is simply not enough time to read such long and dense papers. “The readership on most academic papers is low anyway, so writing a long paper is just inviting it not to be read even more,” says Daniel Price, an astrophysicist at Monash University in Melbourne, Australia, and former editor-in-chief of the journal Publications of the Astronomical Society of Australia, which publishes research on data-heavy topics such as modelling and computational astronomy.
Price says it’s unlikely that anyone has ever read the entirety of one of his monster astrophysics papers3, which clocks in at 82 pages and has 57 figures. “It’s definitely too long,” he says of the paper, admitting that it could easily have been 60 pages instead. The problem with going long, he adds, is that it’s “undisciplined” and compromises the ability to self-edit.
Haghighi says some improvements could be made to long, data-heavy papers. He suggests that publishers standardize the way such papers are formatted and published by introducing new editorial guidelines and implementing “a dynamic, continuous review process” that allows authors to update their work regularly over time, after publication. “I appreciate that this might not be easy,” says Haghighi, but “it would make the review process more effective and consistent and make it easier for the scientific community”.
Formatting guidelines at most major journals tend to favour shorter articles with fewer figures. Nature, for instance, suggests the typical length of biological, clinical and social sciences papers should not normally exceed 8 pages, or 4,300 words, and 5–6 figures. That said, it does not enforce specific limits, and instead leaves this up to the editor’s discretion.
In astrophysics, a field that is characterized by vast data sets that are often analysed by large, international teams, there are some examples of how a research finding can be broken down into more digestible parts. For instance, after the first image of a black hole was captured by the Event Horizon Telescope — a global network of radio telescopes run by a group of more than 300 scientists — the team published 6 papers in a special edition of The Astrophysical Journal Letters. Each paper presented an aspect of the research, looking at methodology, specific features of the black hole and the image itself.
Price thinks paper series such as this are “definitely a better idea” than one long paper, and adds that there is a lot to be said for concise papers. He points to a 2016 paper published by the LIGO Scientific Collaboration4 — a conglomerate of more than 100 institutions collaborating in the search for gravitational waves — after its seminal detection of gravitational waves using instruments in Washington and Louisiana. “It’s eight pages [ten, including references] and it revolutionized astrophysics,” he says.
