Marcus Alexander, PhD, MD
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Hospital Resident
Biography
Marcus Alexander is a physician-scientist working as a Resident Physician in the Department of Radiology and Biomedical Imaging at Yale School of Medicine. His research is focused on systems neuroscience of social cognition, including questions in neurobiology of social connections. His work has combined computational methods, behavioral experiments, molecular biology and field interventions. Previous research has included single-cell genomics of brain tumors, microbiome metagenomics, and field interventions in Honduras, India, and China.
Last Updated on July 06, 2026.
Departments & Organizations
Education & Training
- Pre-residency Clinical Fellow
- University of Miami Miller School of Medicine (2025)
- MD
- Frank H. Netter School of Medicine at Quinnipiac University
- Visiting Investigator
- Memorial Sloan-Kettering Cancer Center
- Research Fellow
- National Institutes of Health
- Postdoctoral Research
- Stanford University
- Howard Hughes Medical Institutes MD Research Fellow
- Stanford University
- PhD
- Harvard University
- MPhil
- University of Oxford
- BA
- Yale University
Research
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Overview
Biology of Social Interactions
Behavioral Experiments and Social AI
To find out more, please visit: My personal homepage, and the lab website of the Human Nature Lab.
Medical Research Interests
Community Networks; Gastrointestinal Microbiome; Genomics; Metagenomics; Social Behavior
Public Health Interests
Health Policy; Genetics, Genomics, Epigenetics; Global Health
ORCID
0000-0001-8627-7534- View Lab Website
Human Nature Lab
Research at a Glance
Yale Co-Authors
Frequent collaborators of Marcus Alexander's published research.
Publications Timeline
A big-picture view of Marcus Alexander's research output by year.
Research Interests
Research topics Marcus Alexander is interested in exploring.
Laura Forastiere, PhD
Nicholas Christakis, MD, MPH, PhD
Declan Barry, PhD
Lauretta Grau, PhD
Lynn Madden, PhD, MPA
Patrick G. O'Connor, MD, MPH, MACP
27Publications
678Citations
Social Behavior
Publications
Featured Publications
Mass gatherings for political expression had no discernible association with the local course of the COVID-19 pandemic in the USA in 2020 and 2021
Feltham E, Forastiere L, Alexander M, Christakis N. Mass gatherings for political expression had no discernible association with the local course of the COVID-19 pandemic in the USA in 2020 and 2021. Nature Human Behaviour 2023, 7: 1708-1728. PMID: 37524931, DOI: 10.1038/s41562-023-01654-1.Peer-Reviewed Original ResearchCitationsAltmetricAlgorithms for seeding social networks can enhance the adoption of a public health intervention in urban India
Alexander M, Forastiere L, Gupta S, Christakis NA. Algorithms for seeding social networks can enhance the adoption of a public health intervention in urban India. Proceedings Of The National Academy Of Sciences Of The United States Of America 2022, 119: e2120742119. PMID: 35862454, PMCID: PMC9335263, DOI: 10.1073/pnas.2120742119.Peer-Reviewed Original ResearchCitationsAltmetricMindfulness Meditation Activates Altruism
Iwamoto SK, Alexander M, Torres M, Irwin MR, Christakis NA, Nishi A. Mindfulness Meditation Activates Altruism. Scientific Reports 2020, 10: 6511. PMID: 32300129, PMCID: PMC7162971, DOI: 10.1038/s41598-020-62652-1.Peer-Reviewed Original ResearchCitationsAltmetricMeSH Keywords and ConceptsAssortative mating at loci under recent natural selection in humans
Nishi A, Alexander M, Fowler JH, Christakis NA. Assortative mating at loci under recent natural selection in humans. Biosystems 2019, 187: 104040. PMID: 31585150, PMCID: PMC7471337, DOI: 10.1016/j.biosystems.2019.104040.Peer-Reviewed Original ResearchCitationsAltmetricMeSH Keywords and ConceptsConceptsAssortative matingSingle nucleotide polymorphismsGenetic assortative matingStrong recent positive selectionGroups of SNPsRecent natural selectionRecent positive selectionPopulation stratificationDisassortative matingEvolutionary trajectoriesNatural selectionEntire genomePositive selectionDiscernible lociSpecific lociCryptic relatednessGenetic correlationsMatingLociGenomeAllele frequenciesHuman couplesHumansMatesSpeciesContext Modularity of Human Altruism
Alexander M, Christia F. Context Modularity of Human Altruism. Science 2011, 334: 1392-1394. PMID: 22158815, DOI: 10.1126/science.1202599.Peer-Reviewed Original ResearchCitationsAltmetric
2025
Demographic and social determinants of the interval from symptom onset to diagnosis of pediatric brain tumors: a study of the Connecticut Tumor Registry.
Lambert W, Alexander M, Ayers J, Anuar A, Swett K, Gonsalves L, Cantor E, Martin J, Bookland M, Hersh D. Demographic and social determinants of the interval from symptom onset to diagnosis of pediatric brain tumors: a study of the Connecticut Tumor Registry. Journal Of Neurosurgery Pediatrics 2025, 35: 612-620. PMID: 40153845, DOI: 10.3171/2024.12.peds24394.Peer-Reviewed Original ResearchThis study investigates factors affecting diagnostic delays in pediatric brain tumors, showing that age, tumor biology, and some symptoms significantly impact the time to diagnosis, with implications for earlier treatment and care equity.Activating antiviral immune responses potentiates immune checkpoint inhibition in glioblastoma models
Seetharam D, Chandar J, Ramsoomair C, Desgraves J, Medina A, Hudson A, Amidei A, Castro J, Govindarajan V, Wang S, Zhang Y, Sonabend A, Valdez M, Maric D, Govindarajan V, Rivas S, Lu V, Tiwari R, Sharifi N, Thomas E, Alexander M, DeMarino C, Johnson K, De La Fuente M, Nasany R, Noviello T, Ivan M, Komotar R, Iavarone A, Nath A, Heiss J, Ceccarelli M, Chiappinelli K, Figueroa M, Bayik D, Shah A. Activating antiviral immune responses potentiates immune checkpoint inhibition in glioblastoma models. Journal Of Clinical Investigation 2025, 135: e183745. PMID: 40091830, PMCID: PMC11910234, DOI: 10.1172/jci183745.Peer-Reviewed Original ResearchCitationsAltmetricMeSH Keywords and ConceptsConceptsImmune checkpoint inhibitionCheckpoint inhibitionViral mimicryRecurrent GBMCell infiltrationResponse to ICIGlioblastoma modelPoor immune cell infiltrationResponse to checkpoint inhibitionImmune responseTumors to immunotherapyAntitumor immune responseResponse to immunotherapyMurine orthotopic modelImmune checkpoint expressionCD8 cell infiltrationImmune cell infiltrationAntiviral immune responseInnate antiviral immune responsePD-L1Checkpoint expressionRecurrent glioblastomaEndogenous retroelementsPotential immunotherapyOrthotopic model
2024
Gut microbiome strain-sharing within isolated village social networks
Beghini F, Pullman J, Alexander M, Shridhar S, Prinster D, Singh A, Matute Juárez R, Airoldi E, Brito I, Christakis N. Gut microbiome strain-sharing within isolated village social networks. Nature 2024, 637: 167-175. PMID: 39567691, PMCID: PMC11666459, DOI: 10.1038/s41586-024-08222-1.Peer-Reviewed Original ResearchCitationsAltmetricConceptsVillage social networksClusters of speciesMicrobiome sequencing dataGut microbiome compositionStrain-level dataMicrobiome biologySequence dataSpecies-levelSocial networksMicrobial sharingPhenotypic impactMicrobiome compositionMicrobiomeSocial network mapsCo-villagersSocial nicheExtended social environmentPeripheral peopleGutSocial connectionsSocial environmentFace-to-face social networksClusters of peopleRelationship typesVillageRates and predictors of loss to follow-up for sporadic vestibular schwannomas undergoing imaging surveillance.
Morshed R, Bauman M, Alexander M, Alegre M, Peris Celda M, Van Gompel J, Neff B, Carlson M, Driscoll C, Link M. Rates and predictors of loss to follow-up for sporadic vestibular schwannomas undergoing imaging surveillance. Journal Of Neurosurgery 2024, 142: 788-796. PMID: 39423436, DOI: 10.3171/2024.6.jns232904.Peer-Reviewed Original ResearchCitationsAltmetricMeSH Keywords and ConceptsConceptsWait-and-scan managementWait-and-scanImaging follow-upImaging surveillanceSporadic VSFollow-upVestibular schwannomaTumor sizeFactors associated with lossPatient adherence to follow-upQuality of life advantagesMedian tumor diameterMRI follow-upSingle-center studySporadic vestibular schwannomaAdherence to follow-upMultivariate logistic regressionLogistic regression analysisUpfront treatmentAssociated with lossTumor diameterPredictors of lossSurveillance recommendationsClinical evaluationTreating institutionEnvironmental, socioeconomic, and health factors associated with gut microbiome species and strains in isolated Honduras villages
Shridhar S, Beghini F, Alexander M, Singh A, Juárez R, Brito I, Christakis N. Environmental, socioeconomic, and health factors associated with gut microbiome species and strains in isolated Honduras villages. Cell Reports 2024, 43: 114442. PMID: 38968070, PMCID: PMC11290354, DOI: 10.1016/j.celrep.2024.114442.Peer-Reviewed Original ResearchCitationsAltmetricConceptsGut microbiomeGut microbiome speciesSpecies-level profilingSequenced microbiomesMetagenomic dataMicrobiome speciesHost phenotypeBacterial speciesHuman phenotypesMesoamerican highlandsSeveral speciesGutSpeciesMicrobiomePhenotypeAssociated with body mass indexCommunity-based cohortBody mass indexConsistent with previous findingsSocioeconomic factorsIsolated villagesHousehold wealthMass indexHostStrain
Academic Achievements & Community Involvement
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Activities
activity Microbiome and Social Networks
09/01/2019 - PresentResearchDetailsCopan Ruinas, Copán Department, Hondurasactivity Pay-it-Forward Intervention to Increase STD Testing Among MSM
05/01/2017 - 08/01/2019ResearchDetailsGuangzhou, Guangdong Province, China; Beijing, Chinaactivity Network-targeting Randomized Controlled Trial to Accelerate Adoption of Iron-fortified Salt for Prevention of Anemia
11/01/2018 - PresentResearchDetailsMumbai, MH, Indiaactivity Network-targeting Randomized Controlled Trial to Accelerate Adoption of Maternal and Child Health Education in Honduras
04/01/2016 - PresentResearchDetailsCopan Ruinas, Copán Department, HondurasCollaborators- Christakis, Nicholas
- Forastiere, Laura
- Keegan, Thomas
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- Map of social network targets in a randomized controlled trial on adoption of new health-related behaviors in Mumbai, India.
- Mapping in-person social networks in Honduran village communities reveals patterns of disease contagion, allowing for the study of how the microbiome affects community health.
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