tag: biology
11 proofs
Critical periods of heightened cortical plasticity close permanently after early development, rendering the adult brain largely incapable of experience-dependent reorganization comparable to juvenile levels.
Sources: Pizzorusso et al. 2002, Science 298:1248-1251, Hensch & Bilimoria 2012, Cerebrum, Gervain et al. 2013, Frontiers in Systems Neuroscience +3 more
Adult neurogenesis occurs in the human neocortex.
Sources: Bhardwaj et al. 2006 — Neocortical neurogenesis in humans is restricted to development. Proc Natl Acad Sci USA 103(33):12564-12568 (PubMed abstract), Spalding et al. 2013 — Dynamics of hippocampal neurogenesis in adult humans. Cell 153(6):1219-1227 (PMC full text)
Bulls charge because they are enraged by the color red.
Sources: Jacobs et al. 1998, Visual Neuroscience (PubMed), West Texas A&M University — Science Questions with Surprising Answers, ScienceABC — Do Bulls Really Hate the Color Red?
Hair and fingernails continue to grow for days after a person dies.
Sources: BMJ Medical Myths (Vreeman & Carroll, 2007) via PMC/NCBI, University of Arkansas for Medical Sciences (UAMS Health), FactMyth.com
Higher atmospheric CO2 is beneficial "plant food" with no net negative effects.
Sources: NASA Goddard Space Flight Center, NASA Earth Observatory: Global Warming, NOAA Ocean Service — Ocean Acidification +2 more
Microplastics ingestion from food, water, and air is currently causing major declines in human fertility and hormone disruption.
Sources: Amobonye et al. (2023) 'Microplastics: A Real Global Threat for Environment and Food Safety' — PMC9920460, Bures et al. (2025) 'Micro- and Nanoplastics as Disruptors of the Endocrine System' — PMC12249724, Conley et al. (2024) 'Microplastics exposure: implications for human fertility, pregnancy and child health' — PMC10794604 (Frontiers Endocrinology) +1 more
Over 80% of the brain's neurons are located in the cerebellum.
Sources: Herculano-Houzel S (2009) The human brain in numbers: a linearly scaled-up primate brain. Front Hum Neurosci 3:31. PMC2776484, von Bartheld CS, Bahney J, Herculano-Houzel S (2016) The search for true numbers of neurons and glial cells in the human brain. J Comp Neurol 524(18):3865-3895. PMC5063692, Herculano-Houzel S, Catania K, Manger PR, Kaas JH (2010) Coordinated scaling of cortical and cerebellar numbers of neurons. Front Neuroanat 4:12
The adult human brain has approximately 86 billion neurons and an average of 7,000 synapses per neuron, resulting in a total synaptic count exceeding 6 × 10^14.
Sources: Frontiers in Human Neuroscience, Herculano-Houzel 2009 (PubMed Central), UCLA Brain Research Institute, Brain Facts, BioNumbers BNID 112055, Harvard Medical School (citing Drachman 2005, Neurology)
The average person swallows eight spiders per year while sleeping.
Sources: Scientific American, Burke Museum — Arachnology & Entomology, Encyclopaedia Britannica +1 more
The human brain accounts for 2% of body weight but uses 20% of the body's oxygen at rest.
Sources: Raichle & Gusnard 2002 'Appraising the brain's energy budget' PNAS (via PMC), Basic Neurochemistry (NCBI Bookshelf): Regulation of Cerebral Metabolic Rate
The human brain does not generate new neurons in adulthood.
Sources: Moreno-Jiménez et al. 2019, Nature Medicine (PubMed abstract), Kempermann et al. 2018, Cell Stem Cell (PMC), Llorens-Martín et al. 2021, Journal of Neuroscience (PMC)