RESEARCH BASE
Search 3,721 documents across 34 fields — every claim tier-rated by evidence
3,633 are the core, quality-scored corpus (34 lettered sections — see How We Work); the remaining 88 are cross-corpus synthesis documents (68 InterDocs, 12 Connections, 8 Theories) also indexed here.
1,723 results for "System 2" — page 21 of 87
ZD_4_10 — Complexity Theory in Biology — Kauffman, Wolfram, Edge of Chaos
The application of complexity theory to biology — the study of how complex, adaptive, self-organizing structures and behaviors emerge in living systems from the interactions of simpler components — has been one of the mo
ZD_4_04 — Mathematical Modeling and Simulation
Mathematical modeling — the art and science of translating real-world phenomena into mathematical language — is how scientists bridge theory and observation. A mathematical model is a simplified mathematical representati
L_1_01 — Ancient DNA & Population Genetics
Modern paleogenomics has shown that human evolution was shaped by interbreeding, population structure, and repeated demographic turnover rather than a simple single-line progression. Ancient DNA revealed previously unkno
L_1_05 — Human Skin Color — Evolution, Latitude, and Cultural Significance
Human skin color is one of the most visible and most misunderstood traits in our species. The variation is primarily a product of natural selection balancing two competing needs: protection of folate (vitamin B9) from UV
L_1_13 — Homo Naledi: Underground Burial and Primitive Morphology
Homo naledi is one of the most unexpected and controversial hominin discoveries of the 21st century. Announced in 2015 by Lee Berger (University of the Witwatersrand) and an international team, the species was recovered
L_4_05 — Paleogenomics Methods and Ancient DNA
Paleogenomics — the study of ancient genomes — has transformed archaeology, anthropology, and evolutionary biology over the past two decades, recognized by the 2022 Nobel Prize in Physiology or Medicine awarded to Svante
L_4_01 — Ancient DNA from Sediment — Environmental DNA Revolution
Environmental DNA (eDNA) recovery from sediments has revolutionized our ability to detect the presence of organisms — including ancient humans — without requiring the discovery of any bones, teeth, or artifacts. The land
L_4_09 — Selective Sweeps and Positive Selection in Humans
A selective sweep occurs when a beneficial allele rises rapidly in frequency under positive natural selection, carrying nearby linked variants along with it (genetic hitchhiking) and reducing genetic variation across the
L_4_10 — Sex Chromosome Evolution
Sex chromosomes — the genetic elements that determine biological sex in many organisms — represent one of the most remarkable stories in genome evolution. In mammals, the XX/XY system prevails: females have two X chromos
L_4_08 — Genetic Genealogy and Forensic Genomics
Genetic genealogy — the use of DNA testing for genealogical purposes — has undergone an explosive expansion since the early 2000s, driven by direct-to-consumer (DTC) genetic testing companies (23andMe, AncestryDNA, MyHer
L_3_16 — Genomic Imprinting & Evolutionary Conflict
Genomic imprinting — the epigenetic phenomenon in which a subset of genes (~100–200 in mammals) are expressed from only one parental allele, with the other allele silenced by DNA methylation and histone modification esta
L_3_06 — Genetics of Intelligence and Cognition
The genetics of intelligence — one of the most studied yet contentious areas in behavioral genetics — has established that cognitive ability, as measured by standardized tests, has a substantial heritable component (~50–
L_3_11 — Genetics of Taste and Dietary Adaptation
Taste perception — the ability to detect sweet, salty, sour, bitter, and umami (savory) stimuli — is mediated by genetically encoded receptor proteins whose variation across individuals and populations reflects evolution
L_3_08 — Genetics of Skin, Hair, and Eye Color
Human pigmentation — skin, hair, and eye color — is one of the best-understood complex traits in human genetics, with a relatively modest number of genes explaining a large proportion of variation compared to most polyge
L_5_10 — Neandertal Introgression: Which Genes and Why They Persisted
When modern humans (Homo sapiens) migrated out of Africa ~60,000-70,000 years ago and encountered Neanderthals (Homo neanderthalensis) in western Asia and Europe, the two species interbred — and the genetic legacy of tha
L_5_15 — Genetic Genealogy: DNA Ancestry Testing and Population History
Genetic genealogy — the use of DNA testing to determine relationships and ancestry — has revolutionized both personal genealogy and population genetics since the early 2000s. Three types of DNA analysis provide different
L_5_03 — Pharmacogenomics and Ancestral Medicine
Pharmacogenomics — the study of how genetic variation influences individual responses to drugs — bridges genetics, pharmacology, and clinical medicine. Humans carry extensive polymorphism in genes encoding drug-metaboliz
L_5_06 — Genetic Adaptation to Disease: Malaria, Plague, TB
Infectious disease has been the most powerful selective force on the human genome throughout history. Pathogens — particularly malaria, plague, tuberculosis, smallpox, and cholera — have killed more humans than all other
L_5_13 — The Microbiome-Brain Axis: Gut Bacteria, Mood & Consciousness
The microbiome-gut-brain axis — bidirectional communication between the trillions of gut microorganisms and the central nervous system — has emerged as one of the most significant frontiers in neuroscience and consciousn
Y_4_08 — Sleep Science — REM, NREM, and the Ancient Understanding of Sleep
Sleep science has undergone a revolution in the 21st century, fundamentally altering our understanding of why humans sleep. The landmark 2012 discovery of the glymphatic system by Maiken Nedergaard revealed that the brai
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