Editing Laughter (section)

== Nature ==
[[File:Human–canine friendship - smiling girl hugging her dog at golden hour in Laos.jpg|thumb|150 px|right|A young girl from [[Laos]] laughing while hugging her [[dog]]]]
Laughter might be thought of as an audible expression or appearance of excitement, an inward feeling of joy and happiness. It may ensue from [[joke]]s, [[tickling]], and other stimuli completely unrelated to psychological state, such as [[nitrous oxide]]. One group of researchers speculated that noises from infants as early as 16 days old may be vocal laughing sounds or laughter.<ref>{{cite journal | url=http://www.pri.kyoto-u.ac.jp/ai/papers/ref3/kawakami2006.pdf | doi=10.1016/j.earlhumdev.2005.07.011 | pmid=16185829 | volume=82 | issue=1 | title=Origins of smile and laughter: A preliminary study | journal=[[Early Human Development]] | pages=61–66 | url-status=dead | archive-url=https://web.archive.org/web/20110928222941/http://www.pri.kyoto-u.ac.jp/ai/papers/ref3/kawakami2006.pdf | archive-date=2011-09-28 | year=2006 | last1=Kawakami | first1=Kiyobumi | last2=Takai-Kawakami | first2=Kiyoko | last3=Tomonaga | first3=Masaki | last4=Suzuki | first4=Juri | last5=Kusaka | first5=Tomiyo | last6=Okai | first6=Takashi }}</ref> However, the weight of the evidence supports the appearance of such sounds at 15 weeks to four months of age.

[[Laughter research]]er {{Interlanguage link multi|Robert Provine|es}} said: "Laughter is a mechanism everyone has; laughter is part of universal human vocabulary. There are thousands of languages, hundreds of thousands of dialects, but everyone speaks laughter in pretty much the same way." Babies have the ability to laugh before they ever speak. Children who are born blind and deaf still retain the ability to laugh.<ref>{{cite journal | last1 = Gervais | first1 = Matthew | last2 = Sloan Wilson | first2 = David | year = 2005 | title = The Evolution and Functions of Laughter and Humor: A Synthetic Approach | journal = [[Quarterly Review of Biology]] | volume = 80 | issue = 4| pages = 395–430 | doi=10.1086/498281| pmid = 16519138 | s2cid = 22275729 }}</ref>

Provine argues that "Laughter is primitive, an unconscious vocalization." Provine argues that it probably is genetic. In a study of the "Giggle Twins", two happy [[twin]]s who were separated at birth and only reunited 43 years later, Provine reports that "until they met each other, neither of these exceptionally happy ladies had known anyone who laughed as much as they did." They reported this even though they had been brought together by their adoptive parents, who they indicated were "undemonstrative and dour". He indicates that the twins "inherited some aspects of their laugh sound and pattern, readiness to laugh, and maybe even taste in humor".<ref>{{cite web |url=http://men.webmd.com/features/why-do-we-laugh |title=WebMD 2002 |publisher=Men.webmd.com |access-date=2011-12-26 |archive-date=2011-12-22 |archive-url=https://web.archive.org/web/20111222093933/http://men.webmd.com/features/why-do-we-laugh |url-status=dead }}</ref>

Scientists have noted the similarity in forms of laughter induced by tickling among various [[primate]]s, which suggests that laughter derives from a common origin among primate species.<ref>[http://news.bbc.co.uk/2/hi/science/nature/8083230.stm "Tickled apes yield laughter clue"], News.BBC.co.uk, June 4, 2009.</ref><ref>{{cite journal | doi = 10.1016/j.cub.2009.05.028 | pmid=19500987 | volume=19 | issue=13 | title=Reconstructing the Evolution of Laughter in Great Apes and Humans | journal=[[Current Biology]] | pages=1106–1111| year=2009 | last1=Davila Ross | first1=Marina | last2=j Owren | first2=Michael | last3=Zimmermann | first3=Elke | s2cid=17892549 | doi-access=free | bibcode=2009CBio...19.1106D }}</ref>

The [[spotted hyena]], another species of animal, was also known as the laughing hyena because of the way it sounds when it communicates.

A very rare neurological condition has been observed whereby the sufferer is unable to laugh out loud, a condition known as [[aphonogelia]].<ref>{{cite journal|doi=10.1001/archneurpsyc.1931.02230010169012 |date=1930-07-16 |journal=[[Archives of Neurology and Psychiatry]] |volume=25 |issue=1 |pages=157 |first=Max |last=Levin|title=Inability to Laugh Audibly: Aphonogelia }}</ref>