Dear Researcher Community,
My name is Brian Starr, and I am a breeder of Rattus rattus with a keen interest in the historical and genetic aspects of the species.
I’m writing to share a hypothesis I’ve developed about the MC1R mutation in Rattus rattus, which causes the black coat color, and its potential role in making black rats more effective plague vectors during the Black Death (1346–1353) and later pandemics. In short, the mutation upregulates cAMP signaling, which could have moderately reduced inflammation during Yersinia pestis infections (e.g., 2–3-fold increase in anti-inflammatory IL-10 and 30–50% reduction in TNF-α, based on studies like Catania et al., 2004 (https://pubmed.ncbi.nlm.nih.gov/15001661/), potentially extending survival by 1–2 days. This might have allowed black rats to sustain flea-mediated transmission longer, while the plague contributed to increased prevalence of the MC1R mutation in European populations of Rattus rattus through selective pressure favoring these mutants.
To my knowledge, Europe is the only region where the majority of Rattus rattus have the mutation and although it may be due to improved camouflage in European households, it is possible that infectious disease may have also been a factor, and historical records and or zooarchaeology may shed some light on this.
I’ve posted a detailed article on this in my r/rattusrattus subreddit (https://www.reddit.com/r/rattusrattus/comments/1m5w3wk/how_the_plague_shaped_black_rats_and_black_rats/), including how archaeology (e.g., ancient DNA sequencing of rat remains) could test correlations between MC1R prevalence and plague dates (e.g., 1346, 1361, 1665). It’s grounded in studies like Kambe et al. 2011 (https://pubmed.ncbi.nlm.nih.gov/21800996/) on MC1R in Rattus rattus and Yu et al. 2022 (https://pubmed.ncbi.nlm.nih.gov/35504912/) on rat dispersal in Europe.
I’m curious if anyone in the research community is pursuing this or knows of other researchers who might be interested in pursuing this—perhaps geneticists, zooarchaeologists, or plague ecologists? I’ve identified some potential collaborators, but I’d love any recommendations.
As a breeder, I could contribute non-invasive insights from my population, such as behavioral observations or samples for genetic sequencing (no plague experiments, of course). I’d be happy to connect with interested parties or share more details.
Thank you for your time, and I look forward to any thoughts or suggestions from this community.
Best regards,
Brian Starr