Rosa Rubicondior: Creationism Refuted - How Humans Acquired Their Pathogens From Their Animals

We’ve long suspected that the transition to farming and animal husbandry opened the door to a new era of disease – now DNA shows us that it happened at least 6,500 years ago,” says Professor Eske Willerslev, author of the new study.

Illustration: William Brøns Petersen

Large-scale DNA study maps 37,000 years of disease history – University of Copenhagen

Young Earth creationist mythology has it that sin, shortly after the magical creation of two adult humans, caused death and disease to enter the world. Until then, so we are expected to believe, there had been no disease and nothing ever died — not even, apparently, the plants Adam, Eve and the other animals ate.

Reality, of course, is materially different from the mythology produced by scientifically ignorant ancient pastoralists and later scribes who knew nothing of bacteria, viruses, parasites, epidemiology or evolution, and who interpreted misfortune in magical terms. Disease was not a supernatural punishment introduced at a single moment by a talking snake, a disobedient couple and an irritable god. It was, and remains, a biological process involving organisms evolving, spreading, adapting and, sometimes, crossing from one host species into another.

And the evidence now shows that at least 6,500 years ago, diseases were passing from animals into the humans who lived alongside them. The domestication of animals, the growth of settled farming communities and the rise of pastoralism brought humans, livestock, waste, parasites and pathogens into much closer proximity than before. This has long been thought to explain why humans suffer from so many infectious diseases. It is also a point Jared Diamond made in Guns, Germs and Steel: The Fate of Human Societies, where he argued that Eurasia’s abundance of domesticable animals, and Europeans’ long exposure to the diseases associated with them, helped Europeans to dominate other populations, often with their pathogens acting as an advance guard against peoples with no previous exposure or immunity.

That view of the zoonotic origin of many human diseases has now been strongly supported by the work of researchers led by Professor Eske Willerslev, of the University of Copenhagen and the University of Cambridge, in a study published open access in Nature in July 2025. The team analysed DNA from more than 1,300 prehistoric individuals, some up to 37,000 years old. Their bones and teeth provided an extraordinary archive of ancient microbial DNA, revealing traces of bacteria, viruses and parasites that infected humans across deep Eurasian history.

The results suggest that close cohabitation with domesticated animals, together with large-scale migrations of pastoralists from the Pontic Steppe, played a major role in the spread of zoonotic diseases. The researchers found that identifiable zoonotic pathogens first appear in their data from around 6,500 years ago, became more widespread after about 6,000 years ago, and peaked roughly 5,000 years ago — precisely the sort of pattern expected if lifestyle, animal husbandry, mobility and population contact were driving disease transmission.

This is especially awkward for creationists because the evidence does not point to a sudden, supernatural transformation of the world’s biology. It does not show disease appearing overnight as the result of a mythical “Fall”. Instead, it shows a long, historical and evolutionary process, unfolding through early Eurasian human history as changing human behaviour created new ecological opportunities for pathogens.

The transfer of pathogens from animals to humans — as is believed to have happened with SARS-CoV-2, which probably passed from bats to humans, possibly through an intermediate host — is a classic example of evolution in action. A mutation, recombination event or other genetic change can enable a pathogen to exploit a new host, where natural selection then favours variants that reproduce and transmit more successfully in that new environment.

The Nature paper is accompanied by a press release from the University of Copenhagen’s Globe Institute and a Nature Podcast.

Background^ A Brief Timeline of Animal Domestication. Animal domestication was not a single event, still less a sudden supernatural provision of ready-made animals for human use. It was a long, uneven evolutionary process in which humans and other animals increasingly shared the same environments. Some animals first approached human settlements as scavengers or pest controllers; others were hunted, managed, penned, bred and eventually reshaped by artificial selection.

At least 15,800 years ago

Animal: Dog
Likely Origin or Early Centre: Western Eurasia, with deeper origins still debated
Significance: The first known domestic animal. Dogs were associated with hunter-gatherers long before farming began.

c. 11,000–10,000 years ago

Animal: Goats and sheep
Likely Origin or Early Centre: Fertile Crescent, including Anatolia, the Levant and the Zagros region
Significance: Among the earliest herd animals, providing meat, milk, hides and later wool.

c. 10,500–9,000 years ago

Animal: Pigs
Likely Origin or Early Centre: Western Asia and China, probably with more than one domestication process
Significance: Closely associated with settled farming communities and food waste around human settlements.

c. 10,500–8,500 years ago

Animal: Cattle
Likely Origin or Early Centre: Near East and South Asia, from different aurochs populations
Significance: Initially valued for meat, later also for milk, traction, manure, hides and wealth.

c. 9,500 years ago onward

Animal: Cats
Likely Origin or Early Centre: Near East/North Africa, with the precise origin still debated
Significance: Probably began as commensals attracted to rodents around grain stores. Modern domestic cat history is now thought to be more complex, with major later dispersal from North Africa.

c. 7,000 years ago

Animal: Donkey
Likely Origin or Early Centre: Africa
Significance: One of the earliest transport animals, important for trade, mobility and early states in arid regions.

5,500–4,200 years ago

Animal: Horse
Likely Origin or Early Centre: Eurasian steppe
Significance: Early horse management may have begun earlier, but the lineage ancestral to most modern domestic horses spread rapidly about 4,200 years ago, transforming transport, warfare and long-distance migration.

c. 3,650–3,250 years ago

Animal: Chicken
Likely Origin or Early Centre: Mainland Southeast Asia
Significance: Probably emerged from relationships between people, rice farming and red junglefowl; later spread westward across Eurasia.

c. 5,000–3,000 years ago

Animal: Camels
Likely Origin or Early Centre: Central Asia and Arabia
Significance: Bactrian camels and dromedaries became crucial animals for transport, trade and survival in arid landscapes.

The overall pattern is clear: domestication was gradual, regional and ecological. It intensified after the development of farming, when humans began living in larger, more settled communities with stored food, waste, livestock and higher population densities. These conditions created ideal opportunities for parasites and pathogens to evolve, persist and, in many cases, cross from animals into humans.

So, far from supporting the creationist notion of a sudden fall from a disease-free world, the history of domestication shows exactly what evolutionary biology predicts: changing environments, close contact between species, artificial selection, natural selection and the repeated opening of new ecological niches for microbes and parasites.

The Nature paper is accompanied by a press release from the University of Copenhagen’s Globe Institute and a Nature Podcast.

Large-scale DNA study maps 37,000 years of disease history
A new study maps infectious diseases across millennia and offers new insight into how human-animal interactions permanently transformed our health landscape.

World’s oldest trace of the plague

In the study, the researchers found 214 pathogens. A remarkable finding is the world’s oldest genetic trace of the plague bacterium Yersinia pestis, identified in a 5,500-year-old sample. The plague is estimated to have killed between one-quarter and one-half of Europe’s population during the Middle Ages.

In addition, the researchers found traces of diseases like:

Leprosy (Mycobacterium leprae) – 1,400 years ago
Malaria (Plasmodium vivax) – 4,200 years ago
Hepatitis B virus – 9,800 years ago
Diphteria (Corynebacterium diphtheriae) – 11,100 years ago

A research team led by Eske Willerslev, professor at the University of Copenhagen and the University of Cambridge, has recovered ancient DNA from 214 known human pathogens in prehistoric humans from Eurasia.

The study shows, among other things, that the earliest known evidence of zoonotic diseases – illnesses transmitted from animals to humans, like COVID in recent times – dates back to around 6,500 years ago, with such diseases becoming more widespread approximately 5,000 years ago. It is the largest study to date on the history of infectious diseases and has just been published in the scientific journal Nature.

The researchers analyzed DNA from over 1,300 prehistoric individuals, some up to 37,000 years old. The ancient bones and teeth have provided a unique insight into the development of diseases caused by bacteria, viruses, and parasites.

The results suggest that humans’ close cohabitation with domesticated animals – and large-scale migrations of pastoralist from the Pontic Steppe – played a decisive role in the spread of these diseases.

We’ve long suspected that the transition to farming and animal husbandry opened the door to a new era of disease – now DNA shows us that it happened at least 6,500 years ago. These infections didn’t just cause illness – they may have contributed to population collapse, migration, and genetic adaptation.

Professor Eske Willerslev, co-corresponding author.
Centre for Ancient Environmental Genomics and The Lundbeck Foundation GeoGenetics Centre
Globe Institute
University of Copenhagen
Copenhagen, Denmark.

Could have implications for future vaccines

The findings could be significant for the development of vaccines and for understanding how diseases arise and mutate over time.

If we understand what happened in the past, it can help us prepare for the future, where many of the newly emerging infectious diseases are predicted to originate from animals.

Associate Professor Martin Sikora, first author.
Centre for Ancient Environmental Genomics and The Lundbeck Foundation GeoGenetics Centre
Globe Institute
University of Copenhagen
Copenhagen, Denmark.

Mutations that were successful in the past are likely to reappear. This knowledge is important for future vaccines, as it allows us to test whether current vaccines provide sufficient coverage or whether new ones need to be developed due to mutations.

Professor Eske Willerslev.

Publication:
Sikora, M., Canteri, E., Fernandez-Guerra, A. et al.
The spatiotemporal distribution of human pathogens in ancient Eurasia.
Nature 643, 1011–1019 (2025). https://doi.org/10.1038/s41586-025-09192-8

Abstract
Infectious diseases have had devastating effects on human populations throughout history, but important questions about their origins and past dynamics remain1. To create an archaeogenetic-based spatiotemporal map of human pathogens, we screened shotgun-sequencing data from 1,313 ancient humans covering 37,000 years of Eurasian history. We demonstrate the widespread presence of ancient bacterial, viral and parasite DNA, identifying 5,486 individual hits against 492 species from 136 genera. Among those hits, 3,384 involve known human pathogens2, many of which had not previously been identified in ancient human remains. Grouping the ancient microbial species according to their likely reservoir and type of transmission, we find that most groups are identified throughout the entire sampling period. Zoonotic pathogens are only detected from around 6,500 years ago, peaking roughly 5,000 years ago, coinciding with the widespread domestication of livestock3. Our findings provide direct evidence that this lifestyle change resulted in an increased infectious disease burden. They also indicate that the spread of these pathogens increased substantially during subsequent millennia, coinciding with the pastoralist migrations from the Eurasian Steppe4,5.

Sikora, M., Canteri, E., Fernandez-Guerra, A. et al.
The spatiotemporal distribution of human pathogens in ancient Eurasia.
Nature 643, 1011–1019 (2025). https://doi.org/10.1038/s41586-025-09192-8

Copyright: © 2025 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

Again, the facts turn out not to need mythology. The evidence does not show a world created perfect, then suddenly corrupted by sin; it shows populations of real humans, living real lives, changing their relationship with other animals, and thereby changing the ecological opportunities available to microbes and parasites.

As humans domesticated animals, settled in larger communities, stored food, accumulated waste and moved across Eurasia with their herds, they created new pathways for infection. Pathogens did what evolving organisms do: they exploited opportunities, crossed species barriers where they could, adapted to new hosts and spread where human behaviour gave them the means to do so. No magic, no curse and no offended deity is required.

For creationists, the problem is obvious. A gradual, traceable history of disease, written in ancient DNA, is the very opposite of their childish tale of a sudden biological catastrophe caused by two people eating forbidden fruit. It places disease firmly in the real world of ecology, evolution, migration and domestication, not in the imaginary world of talking snakes, magic trees and inherited guilt.

And that is why discoveries such as this matter. They do not merely add detail to the history of human disease; they show yet again that science can recover the real past from physical evidence, while creationism can only try to force that evidence into a story that was never based on it in the first place. As usual, when mythology and evidence are compared, mythology loses.

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