Head to https://linode.com/scishow to get a $100 60-day credit on a new Linode account. Linode offers simple, affordable, and accessible Linux cloud solutions and services. Some practices and skills known by early humans have been lost to time. Sometimes this is because of changing environments or economic conditions, or sometimes, it's because the technology was so deadly that only a few were allowed to know it. Find out more with Michael Aranda in a new episode of SciShow! SciShow is on TikTok! Check us out at https://www.tiktok.com/@scishow ----- Support SciShow by becoming a patron on Patreon: https://www.patreon.com/scishow ----- Huge thanks go to the following Patreon supporters for helping us keep SciShow free for everyone forever: Tomás Lagos González, Sam Lutfi. Bryan Cloer, Christoph Schwanke, Kevin Bealer, Jacob, Jason A Saslow, Nazara, Tom Mosner, Ash, Eric Jensen, Jeffrey Mckishen, Matt Curls, Alex Hackman, Christopher R Boucher, Piya Shedden, Jeremy Mysliwiec, charles george, Chris Peters, Adam Brainard, Dr. Melvin Sanicas, Harrison Mills, Silas Emrys, Alisa Sherbow ------ Looking for SciShow elsewhere on the internet? SciShow Tangents Podcast: https://scishow-tangents.simplecast.com/ Facebook: http://www.facebook.com/scishow Twitter: http://www.twitter.com/scishow Instagram: http://instagram.com/thescishow #SciShow ---------- Sources: https://www.britannica.com/technology/pozzolana https://www.uh.edu/engines/epi2810.htm https://unews.utah.edu/roman-concrete/ https://pubs.geoscienceworld.org/msa/ammin/article/102/7/1435/353606/Phillipsite-and-Al-tobermorite-mineral-cements https://www.smithsonianmag.com/history/the-secrets-of-ancient-romes-buildings-234992/ https://www.britannica.com/technology/concrete-building-material https://www.britannica.com/topic/Pantheon-building-Rome-Italy ​​https://www.bbc.com/future/article/20210316-the-legendary-fabric-that-no-one-knows-how-to-make https://uh.edu/engines/epi385.htm https://library.oapen.org/bitstream/handle/20.500.12657/31335/631166.pdf?sequence=1#page=167 https://www.britannica.com/technology/Greek-fire https://www.jstor.org/stable/3106585?origin=crossref https://www.washingtonexaminer.com/weekly-standard/the-fog-of-war https://www.thedrive.com/the-war-zone/32867/fogbank-is-mysterious-material-used-in-nukes-thats-so-secret-nobody-can-say-what-it-is https://www.ldeo.columbia.edu/edu/eesj/gradpubs/GeneralMags/patel_chinesepurple_Archeology.pdf https://brill.com/view/journals/east/17/1/article-p94_6.xml https://pubs.rsc.org/en/content/articlehtml/2007/cs/b606268g Images: https://bit.ly/3wRfnlx https://commons.wikimedia.org/wiki/File:Vitruvius_bust_at_Technical_University_of_Munich.jpeg https://commons.wikimedia.org/wiki/File:20_to_40mm_recycled_aggregates_(6069277558).jpg https://commons.wikimedia.org/wiki/File:Puzzolane_stones_from_Vesuvius_Italy.jpg https://commons.wikimedia.org/wiki/File:Pouzzolane.jpg https://bit.ly/3tUXC2E https://commons.wikimedia.org/wiki/File:AAC_13.jpg https://commons.wikimedia.org/wiki/File:Caesarea_Concrete_Bath.jpg https://commons.wikimedia.org/wiki/File:Muslin_transparency_2015_Kolkata.jpg https://commons.wikimedia.org/wiki/File:Woman%27s_muslin_dress_and_straw_bonnet_c._1830.jpg https://commons.wikimedia.org/wiki/File:Ancient_Muslin_Depiction.jpg https://commons.wikimedia.org/wiki/File:Renaldis_muslin_woman.jpg https://commons.wikimedia.org/wiki/File:Victoria_Memorial_Kolkata_-_Muslin.jpg https://commons.wikimedia.org/wiki/File:DhakaCity1861.png https://commons.wikimedia.org/wiki/File:Gossypium_arboreum2.jpg https://bit.ly/3IVa0nO https://commons.wikimedia.org/wiki/File:Muslin_men.jpg https://commons.wikimedia.org/wiki/File:Greekfire-madridskylitzes1.jpg https://commons.wikimedia.org/wiki/File:Hand-siphon_for_Greek_fire,_medieval_illumination_(detail).jpg https://commons.wikimedia.org/wiki/File:Arbalest_flamethrower_Greek_fire,_Byzantine_Empire_(reconstruction).jpg https://commons.wikimedia.org/wiki/File:Trident_warheads.jpg https://www.flickr.com/photos/kevinpoh/3548617540 https://www.flickr.com/photos/carolemage/12930137013 https://commons.wikimedia.org/wiki/File:Recreated_colored_terracotta_warriors.jpg https://commons.wikimedia.org/wiki/File:Eastern_Han_Luoyang_Mural_of_Liubo_players.jpg https://www.mdpi.com/2073-4352/9/5/273/htm https://commons.wikimedia.org/wiki/File:Tripod_cauldron,_earthenware_with_paint,_Western_Han_Dynasty.JPG https://commons.wikimedia.org/wiki/File:HKU_MAG_Fung_Ping_Shan_Museum_Han_Dynasty_Horse.JPG https://commons.wikimedia.org/wiki/File:Egyptian_blue_Altes_Museum.JPG https://commons.wikimedia.org/wiki/File:Western_Han_blue_glass_bowl.JPG https://commons.wikimedia.org/wiki/File:British_Museum_Chinese_jade_Han_dynasty_Frog_11022019_1615.jpg https://commons.wikimedia.org/wiki/File:Eastern_Han_Dynasty_tomb_fresco_of_chariots,_horses,_and_men,_Luoyang_2.jpg https://commons.wikimedia.org/wiki/File:British_Museum_Bi_Glass_disc_Eastern_Zhou_or_Han_dynasty_11022019_1639.jpg