← back to the slideshow

Sources.

Every study, article and photo used in bpls. Where sources disagree, the slide says so. Nothing here is medical advice.

Studies and references

  1. Thorndike (1920). A constant error in psychological ratings. Journal of Applied Psychology.
  2. Dion, Berscheid & Walster (1972). What is beautiful is good. Journal of Personality and Social Psychology.
  3. Langlois et al. (2000). Maxims or myths of beauty? A meta-analytic and theoretical review. Psychological Bulletin.
  4. Willis & Todorov (2006). First impressions: making up your mind after a 100-ms exposure to a face. Psychological Science.
  5. OkCupid (2009). “Your Looks and Your Inbox.” OkTrends blog. Not peer-reviewed.
  6. Feingold (1988). Matching for attractiveness in romantic partners and same-sex friends. Psychological Bulletin.
  7. Esteve et al. (2016). The end of hypergamy: global trends and implications. Population and Development Review.
  8. Kniffin & Wilson (2004). The effect of nonphysical traits on the perception of physical attractiveness. Evolution and Human Behavior.
  9. Young, Hellawell & Hay (1987). Configurational information in face perception. Perception.
  10. Langlois & Roggman (1990). Attractive faces are only average. Psychological Science.
  11. Farkas et al. (1985). Vertical and horizontal proportions of the face in young adult North American Caucasians. Plastic and Reconstructive Surgery.
  12. Scott et al. (2014). Human preferences for sexually dimorphic faces may be evolutionarily novel. PNAS.
  13. Mills et al. (1986). Comparing 2.5%, 5%, and 10% benzoyl peroxide on inflammatory acne vulgaris. International Journal of Dermatology.
  14. Smith et al. (2007). A low-glycemic-load diet improves symptoms in acne vulgaris patients. American Journal of Clinical Nutrition.
  15. Paruthi et al. (2016). Recommended amount of sleep for pediatric populations (AASM consensus). Journal of Clinical Sleep Medicine.
  16. Axelsson et al. (2010). Beauty sleep: perceived health and attractiveness of sleep deprived people. BMJ.
  17. Stricker, Faigenbaum & McCambridge (2020). Resistance training for children and adolescents. Pediatrics (AAP clinical report).
  18. AAP Committee on Nutrition (2011). Sports drinks and energy drinks for children and adolescents: are they appropriate? Pediatrics.
  19. American Academy of Pediatrics. Backpack safety guidance (10–20% of body weight). HealthyChildren.org.
  20. Vos et al. (2017). Added sugars and cardiovascular disease risk in children (AHA scientific statement). Circulation.
  21. USDA MyPlate and Harvard T.H. Chan School of Public Health, Healthy Eating Plate.
  22. Carskadon (2011). Sleep in adolescents: the perfect storm. Pediatric Clinics of North America.
  23. Twin studies on the heritability of adult height (estimates vary by population).
  24. Ward et al. (2018). Nasal distortion in short-distance photographs: the selfie effect. JAMA Facial Plastic Surgery.
  25. Mita, Dermer & Knight (1977). Reversed facial images and the mere-exposure hypothesis. Journal of Personality and Social Psychology.
  26. Huang et al. (2017). It doesn’t hurt to ask: question-asking increases liking. Journal of Personality and Social Psychology.
  27. Singh et al. (2023). Blue-light filtering spectacles (Cochrane systematic review). Cochrane Database of Systematic Reviews.
  28. American Cancer Society. Antiperspirants and breast cancer risk.
  29. 988 Suicide & Crisis Lifeline (US): call or text 988.
  30. Slater et al. (1998), Infant Behavior and Development
  31. Langlois et al. (1987), Developmental Psychology.
  32. Ramsey et al. (2004), Developmental Science
  33. Langlois, Ritter, Casey & Sawin (1995), Developmental Psychology
  34. Badr & Abdallah (2001), Infant Behavior and Development
  35. Dion & Berscheid (1974), Sociometry
  36. Dion (1972), Journal of Personality and Social Psychology
  37. Clifford & Walster (1973), Sociology of Education.
  38. Ritts, Patterson & Tubbs (1992), Review of Educational Research
  39. French, Robins, Homer & Tapsell (2009), Labour Economics
  40. Landy & Sigall (1974), Journal of Personality and Social Psychology
  41. Talamas, Mavor & Perrett (2016), PLOS ONE
  42. Hamermesh & Parker (2005), Economics of Education Review
  43. Benson, Karabenick & Lerner (1976), Journal of Experimental Social Psychology
  44. Langlois et al. (2000), Psychological Bulletin
  45. Wilson & Eckel (2006), Political Research Quarterly
  46. López Bóo, Rossi & Urzúa (2013), Economics Letters
  47. Hosoda, Stone-Romero & Coats (2003), Personnel Psychology
  48. Mobius & Rosenblat (2006), American Economic Review
  49. Hamermesh & Biddle (1994), “Beauty and the Labor Market,” American Economic Review.
  50. Scholz & Sicinski (2015), Review of Economics and Statistics
  51. Judge & Cable (2004), Journal of Applied Psychology. Figures in 2002 dollars.
  52. Rule & Ambady (2008), Psychological Science
  53. Mueller & Mazur (1996), Social Forces
  54. Berggren, Jordahl & Poutvaara (2010), Journal of Public Economics
  55. Todorov et al. (2005), “Inferences of competence from faces predict election outcomes,” Science.
  56. Zebrowitz & Montepare (2008), Social and Personality Psychology Compass
  57. Mazzella & Feingold (1994), Journal of Applied Social Psychology
  58. Sigall & Ostrove (1975), Journal of Personality and Social Psychology
  59. Stewart (1980), Journal of Applied Social Psychology. An observational study of actual court cases.
  60. Zebrowitz & McDonald (1991), Law and Human Behavior
  61. Mocan & Tekin (2010), Review of Economics and Statistics
  62. Walster, Aronson, Abrahams & Rottman (1966), Journal of Personality and Social Psychology
  63. Luo & Zhang (2009), Journal of Personality
  64. Eastwick & Finkel (2008), Journal of Personality and Social Psychology
  65. Kurzban & Weeden (2005), Evolution and Human Behavior
  66. Hitsch, Hortaçsu & Ariely (2010), American Economic Review (decile figures from their 2005 working paper)
  67. Rudder (2009), OkTrends (official OkCupid blog)
  68. Lee, Loewenstein, Ariely, Hong & Young (2008), Psychological Science
  69. Feingold (1990), Journal of Personality and Social Psychology
  70. Rhodes (2006), Annual Review of Psychology
  71. Oosterhof & Todorov (2008), PNAS; Todorov, Olivola, Dotsch & Mende-Siedlecki (2015), Annual Review of Psychology
  72. Olivola & Todorov (2010), Journal of Experimental Social Psychology
  73. Carré & McCormick (2008), Proceedings of the Royal Society B. Follow-up: Deaner et al. (2012), Journal of Research in Personality.
  74. Langlois & Roggman (1990): blends of 16 or 32 faces were rated more attractive than almost all the faces used to make them.
  75. Ambady & Rosenthal (1993), Journal of Personality and Social Psychology.

How the history was sourced

Each history slide rests on the outlet and date shown here, or on the outlet named in its text.

  1. ADL, 6 Nov 2019
  2. Pelzer et al., 2021
  3. Vice, 20 Jun 2018
  4. Fortune, 9 Nov 2017
  5. Wikipedia, accessed 2 Nov 2026
  6. American Association of Orthodontists, 23 Jan 2024
  7. Business Insider, 8 Nov 2023; CBS Baltimore, 6 Nov 2023
  8. Sociology of Health & Illness, 2025
  9. CBS News, 26 Oct 2026

Photo credits

All photos are from Wikimedia Commons (or images it hosts under CC0) and are used under their own licences. They were resized and cropped.

  1. A female model with dark hair pulled back, photographed straight on in a close portrait at Paris Fashion Week. Myles Kalus Anak Jihem, CC BY-SA 4.0, via Wikimedia Commons (cropped) source
  2. A female model with short swept-back dark hair and hoop earrings, photographed straight on at Milan Fashion Week. Myles Kalus Anak Jihem, CC BY-SA 4.0, via Wikimedia Commons (cropped) source
  3. A female model with natural short curly hair and drop earrings, photographed straight on backstage at Paris Fashion Week. Myles Kalus Anak Jihem, CC BY-SA 4.0, via Wikimedia Commons (cropped) source
  4. A female model with long straight dark hair parted to the side, photographed straight on at Paris Fashion Week. Myles Kalus Anak Jihem, CC BY-SA 4.0, via Wikimedia Commons (cropped) source
  5. A female model with dark hair slicked back and light eyes, shown in three-quarter view at the Cannes Film Festival. Martin Kraft, CC BY-SA 4.0, via Wikimedia Commons (cropped) source
  6. A male model with dark swept-back hair, blue eyes and a short beard, wearing a cream overcoat over a striped shirt and brown tie, photographed at a fashion event. Walterlan Papetti, CC BY-SA 4.0, via Wikimedia Commons (cropped) source
  7. A male model with short dark swept-up hair and strong eyebrows, wearing a burgundy velvet jacket and black bow tie, photographed on a red carpet. Pedro J Pacheco, CC BY-SA 4.0, via Wikimedia Commons (cropped) source
  8. A young male model with swept-back light brown hair and light stubble, wearing a black tuxedo with a bow tie, photographed at a red carpet event. Lionel Villanueva, CC BY-SA 4.0, via Wikimedia Commons (cropped) source
  9. A male model with tousled dark hair and light stubble, wearing a black tuxedo jacket and bow tie, photographed at an awards event. Pedro J Pacheco, CC BY-SA 4.0, via Wikimedia Commons (cropped) source
  10. A male model with curly dark hair and light stubble smiles softly at the camera outdoors, wearing a grey t-shirt with a thin gold chain. Gabriella Sinisi, CC BY-SA 3.0, via Wikimedia Commons (cropped) source
  11. A tall wooden ladder rising into a clear blue sky. Mykl Roventine, CC BY 2.0, via Wikimedia Commons source
  12. A dark house at night with its windows lit, standing under tall pine trees against a deep blue sky. Henry Söderlund, CC BY 2.0, via Wikimedia Commons source
  13. An empty bridge road at night, lined with streetlights glowing in thick fog. Pierre Selim Huard, CC BY 3.0, via Wikimedia Commons source
  14. Black round-framed glasses folded on an open notebook, with loose printed pages blurred behind. Shixart1985, CC BY 2.0, via Wikimedia Commons source
  15. A hiker with walking poles, seen from behind, climbing a sunny dirt path under a bright blue sky. Timothy A. Gonsalves, CC BY-SA 4.0, via Wikimedia Commons source
  16. A yellowed fabric tailor's measuring tape coiled on a pale surface. Restemarkt, CC BY-SA 4.0, via Wikimedia Commons source
  17. A pair of badly worn-out grey canvas sneakers seen from below, with torn fabric and dirty, split soles. Wolfmann, CC BY 4.0, via Wikimedia Commons source
  18. Four pairs of fine stainless steel tweezers laid out on a white background. Nadina Wiórkiewicz (Nadine90), CC BY-SA 3.0, via Wikimedia Commons source
  19. A chrome safety razor and a shaving brush resting on a polished metal stand against a white background. Evan-Amos, public domain, via Wikimedia Commons source
  20. Rubber-coated weight plates on a gym dumbbell rack, in a dim gym with machines blurred behind. Shixart1985, CC BY 2.0, via Wikimedia Commons source
  21. A plate of two fried eggs with salad and cheese, next to a glass of orange juice and a bread roll. HaJunkiyada, CC BY-SA 4.0, via Wikimedia Commons source
  22. Vintage hand-operated hair clippers lying open on green felt. Andy Mabbett, CC BY-SA 4.0, via Wikimedia Commons source
  23. Macro photo of a single dark hair with its tip split into several frayed strands. RealGatba, CC0 1.0, via Wikimedia Commons source
  24. A plain white dinner plate seen from above with baked fish, roast potatoes, carrots and broccoli on a dark table. HaJunkiyada, CC BY-SA 4.0, via Wikimedia Commons source
  25. A plain plate of roasted chicken, rice and peas with carrots on a dark table. HaJunkiyada, CC BY-SA 4.0, via Wikimedia Commons source
  26. A single tea bag with a blank green tag on a white background. Jan Mesaros (Pixabay), CC0 1.0, via Wikimedia Commons source
  27. A patterned armchair in a calm sunlit room with warm yellow walls and a wooden floor. Shixart1985, CC BY 2.0, via Wikimedia Commons source
  28. A quiet country road stretching toward a large sun rising through orange morning mist. Susanne Nilsson, CC BY-SA 2.0, via Wikimedia Commons source
  29. A hand pulling the bead chain of a window blind, with soft daylight glowing through the fabric. Shixart1985, CC BY 2.0, via Wikimedia Commons source
  30. A vintage rangefinder camera resting on a wooden table printed with an old map, with a blurred book and cup behind. Shixart1985, CC BY 2.0, via Wikimedia Commons source
  31. A man seen from behind standing upright against a plain light backdrop, shoulders level and arms relaxed at his sides. Biswarup Ganguly, CC BY 3.0, via Wikimedia Commons source
  32. A plaster cast of upper and lower teeth held in a black metal dental articulator on a dentist's chair. Lee Haywood, CC BY-SA 2.0, via Wikimedia Commons source
  33. A chrome twin-bell alarm clock on a wooden shelf beside a window. Santeri Viinamäki, CC BY-SA 4.0, via Wikimedia Commons source
  34. An unmade bed from above, with rumpled sheets, crumpled pillows and a pushed-aside duvet. maxronnersjo, CC BY-SA 3.0, via Wikimedia Commons source
  35. A grey sports t-shirt laid flat on a wooden floor with damp sweat patches under the arms and along the hem. Hannah Clover, CC BY-SA 4.0, via Wikimedia Commons source
  36. A small square glass bottle of blue-green cologne with a black cap, standing on a pale wooden surface. Santeri Viinamäki, CC BY-SA 4.0, via Wikimedia Commons source
  37. A yellow toothbrush with a swirl of red, white and blue toothpaste on its bristles, on a white surface. Steve Buissinne (cropped), CC0 1.0, via Wikimedia Commons source
  38. Four dental handpieces hanging from the instrument holder of a dentist's treatment unit. Jamain, CC BY-SA 3.0, via Wikimedia Commons source
  39. Four people seen from behind sitting side by side on a low stone wall, looking out at the sea. Shixart1985, CC BY 2.0, via Wikimedia Commons source
  40. Hands preparing coffee beside two small cups on a copper tray on a wooden kitchen table. Shixart1985, CC BY 2.0, via Wikimedia Commons source
  41. Close-up of a round metal microphone grille against a black background. Olivier, CC BY 3.0, via Wikimedia Commons source

Software: reveal.js (MIT), GSAP (free standard licence). Fonts: League Gothic, Oswald, Source Sans Pro, Merriweather (OFL); Roboto Mono, Special Elite (Apache 2.0). By Yerc.