Snake detection theory: Difference between revisions

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{{short description|Evolutionary hypothesistheory regarding primate vision}}

[[File:Vipera_aspis_aspis.jpg|thumb|alt=Vipera Aspis.| Vipera Aspis. According to the Snake Detection Hypothesis, venomous, and life-threatening snakes, including [[asp viper]]s, were crucial for the evolution of primates' visual systems.]]

The '''snake detection theory''' (sometimes more correctly referred to as SDT)'''snake detection hypothesis'''),<ref>{{cite journal|last1=Isbell|first1=Lynne A.|authorlink=Lynne Isbell|title=Snakes as agents of evolutionary change in primate brains|journal=Journal of Human Evolution|date=1 July 2006|volume=51|issue=1|pages=1–35|doi=10.1016/j.jhevol.2005.12.012|pmid=16545427|bibcode=2006JHumE..51....1I |citeseerx=10.1.1.458.2574}}</ref><ref>{{cite book|last1=Isbell|first1=Lynne A.|title=The Fruit, the Tree, and the Serpent|date=2009|url=https://books.google.com/books?id=yKzIuw4YBCoC&pg=PR7&dqq=The+Fruit,%2C+the+Tree,%2C+and+the+Serpent+isbell#v=onepage&qpg=The%20Fruit%2C%20the%20Tree%2C%20and%20the%20Serpent%20isbell&f=falsePR7|publisher=Harvard University Press|language=en|isbn=9780674033016}}</ref><ref name=":0">{{Cite web |last1=Allman Updyke |first1=Erin |last2=Welsh |first2=Erin |name-list-style=and |year=2022 |orig-date=31/05/2022 |title=Episode 97 Snake Venoms: Collateral Damage |url=https://thispodcastwillkillyou.com/2022/05/31/episode-97-snake-venoms-collateral-damage/ |website=This Podcast Will Kill You |publisher=Exactly Right Network}}</ref> also sometimes called the '''snake detection hypothesis''', suggests that [[snakes]] have contributed to the evolution of [[primates]]' visual systemsystems in primates.

According to the hypothesistheory, predatory pressure on early primate populations from snakes has selected individuals who arewere betterbest able to

recognize them, improving their survival chances and therefore transferring such skill to their offspring. From this point of view, snakes were responsible for the modification and expansion of primate visual systems which made [[visual perception|vision]] the most developed sensory interface with the external environment for modern primates.

In her book ''The Fruit, the Tree, and the Serpent'' (2009),<ref>{{cite book|last1=Isbell|first1=Lynne A.|title=The Fruit, the Tree, and the Serpent|date=2009|url=https://books.google.com/books?id=yKzIuw4YBCoC&pg=PR7&dqq=The+Fruit,%2C+the+Tree,%2C+and+the+Serpent+isbell#v=onepage&qpg=The%20Fruit%2C%20the%20Tree%2C%20and%20the%20Serpent%20isbell&f=falsePR7|publisher=Harvard University Press|language=en|isbn=9780674033016}}</ref> [[anthropologist]] [[Lynne Isbell]] writes that snakes evolved to be difficult to detect and mortally dangerous. Surviving the peril of snakes for millions of years required selective pressure favoring primates' specialized visual systems. Compared to that of other mammals, the [[Pulvinar nuclei|pulvinar]] region of the brain &ndash; which helps to visually detect relevant objects &ndash; is disproportionately large and effective in the brains of primates (including [[human]]s).

The concept of snakes being a special threat to humans has been confirmed by population-based studies. [[Ophidiophobia]] (phobia of snakes) is one of the most common and intense phobias among the general population. Furthermore, a study reported that around 50% of the people experience dreams about snakes.<ref>{{cite journal|last1=Sagan|first1=Carl|title=Dragons of Eden: Speculations on the Evolution of Human Intelligence|date=26 September 2012|url=https://books.google.com/?id=BQxZsou&pg=PA249&dq=the+dragons+of+eden#v=onepage&q=the%20dragons%20of%20eden&f=false|publisher=Random House Publishing Group|language=en}}</ref>

== Empirical studies ==

Many empirical studies have found evidence for the theory.

Many empirical studies have found evidence for the hypothesis. Primates, including humans, are able to quickly detect snakes.<ref>{{cite journal|last1=Ohman|first1=A.|last2=Flykt|first2=A.|last3=Esteves|first3=F.|title=Emotion drives attention: detecting the snake in the grass|journal=Journal of Experimental Psychology. General|date=2001|volume=130|issue=3|pages=466–478|pmid=11561921|issn=0096-3445|doi=10.1037/0096-3445.130.3.466|citeseerx=10.1.1.640.3659}}</ref><ref>{{cite journal|last1=Shibasaki|first1=Masahiro|last2=Kawai|first2=Nobuyuki|title=Rapid detection of snakes by Japanese monkeys (Macaca fuscata): an evolutionarily predisposed visual system|journal=Journal of Comparative Psychology|date=2009|volume=123|issue=2|pages=131–135|doi=10.1037/a0015095|pmid=19450020|issn=0735-7036}}</ref>

SomePrimates, studies have found thatincluding humans, can quickly detect snake images before subjective visual perceptionsnakes.<ref>{{cite journal|last1=Ohman|first1=A.|last2=SoaresFlykt|first2=JA. J|last3=Esteves|first3=F.|title=OnEmotion the automatic nature of phobicdrives fearattention: conditioneddetecting electrodermalthe responsessnake toin maskedthe fear-relevant stimuligrass|journal=Journal of AbnormalExperimental Psychology. General|date=19932001|volume=102130|issue=13|pages=121–132466–478|pmid=843668811561921|issn=00210096-843X3445|doi=10.1037/00210096-843X3445.102130.3.466|citeseerx=10.1.1211.640.3659}}</ref> However, the pre-conscious detection of snake stimuli is still under debate by the scientific community.<ref>{{cite journal|last1=GrassiniShibasaki|first1=SimoneMasahiro|last2=HolmKawai|first2=Suvi K.|last3=Railo|first3=Henry|last4=Koivisto|first4=MikaNobuyuki|title=WhoRapid is afraiddetection of thesnakes invisibleby snake?Japanese Subjectivemonkeys visual(Macaca awarenessfuscata): modulates posterior brain activity foran evolutionarily threateningpredisposed stimulivisual system|journal=BiologicalJournal of Comparative Psychology|date=1 December 20162009|volume=121123|issue=Part A2|pages=53–61131–135|doi=10.10161037/j.biopsycho.2016.10.007a0015095|pmid=2776037119450020|issn=0735-7036}}</ref>

SnakesSome imagesstudies werehave provedfound tothat behumans detectedcan moredetect rapidlysnake comparedimages tobefore othersubjective fear-relevantvisual stimuli:perception.<ref>{{cite empiricaljournal|last1=Ohman|first1=A.|last2=Soares|first2=J. evidencesJ.|title=On havethe shownautomatic thatnature snakesof arephobic morefear: rapidlyconditioned detectedelectrodermal comparedresponses to [[spiders]]masked fear-relevant accordingstimuli|journal=Journal toof theAbnormal snakePsychology|date=1993|volume=102|issue=1|pages=121–132|pmid=8436688|issn=0021-843X|doi=10.1037/0021-843X.102.1.121}}</ref> detectionHowever, hypothesisthe pre-conscious becausedetection theof [[arachnid]]ssnake were,stimuli historically,is astill lessunder relevantdebate threatby tothe scientific primatescommunity.<ref>{{cite journal|last1=ÖhmanGrassini|first1=ArneSimone|last2=SoaresHolm|first2=SandraSuvi CK.|last3=JuthRailo|first3=PernillaHenry|last4=LindströmKoivisto|first4=Björn|last5=Esteves|first5=FranciscoMika|title=EvolutionaryWho derivedis modulationsafraid of attentionthe toinvisible twosnake? commonSubjective fearvisual stimuli:awareness Serpentsmodulates andposterior hostilebrain humansactivity for evolutionarily threatening stimuli|journal=Journal of CognitiveBiological Psychology|date=1 FebruaryDecember 20122016|volume=24121|issue=1Part A|pages=17–3253–61|doi=10.10801016/20445911j.2011biopsycho.6296032016.10.007|issnpmid=2044-591127760371|s2cid=9516831}}</ref>

Regardless, in experiments, images of snakes have been detected more rapidly than other fear-relevant stimuli: empirical studies have shown that snakes are more rapidly detected than [[spiders]].

Snake stimuli are particularly distracting during perceptual tasks, suggesting that the brain preferentially processes snake stimuli, even when attentional processes are demanded by other targets.<ref>{{cite journal|last1=Soares|first1=Sandra C.|title=The lurking snake in the grass: interference of snake stimuli in visually taxing conditions|journal=Evolutionary Psychology|date=15 April 2012|volume=10|issue=2|pages=187–197|pmid=22947633|issn=1474-7049}}</ref>

SnakeAccording enhancedto the snake detection wastheory, foundthis alsois inbecause youngthe [[arachnid]]s were, historically, a less relevant threat to childrenprimates.<ref>{{cite journal|last1=LoBueÖhman|first1=VanessaArne|last2=DeLoacheSoares|first2=JudySandra SC.|last3=Juth|first3=Pernilla|last4=Lindström|first4=Björn|last5=Esteves|first5=Francisco|title=DetectingEvolutionary thederived Snakemodulations inof the Grass: Attentionattention to Fear-Relevanttwo Stimulicommon byfear stimuli: AdultsSerpents and Younghostile Childrenhumans|journal=PsychologicalJournal Scienceof Cognitive Psychology|date=1 MarchFebruary 20082012|volume=1924|issue=31|pages=284–28917–32|doi=10.11111080/j20445911.1467-92802011.2008.02081.x|pmid=18315802629603|languages2cid=en146142767|issn=09562044-79765911}}</ref>

Snake stimuli are particularly distracting during perceptual tasks, suggesting that the brain preferentially processes snake stimuli, even when attentional processes are demanded by other targets.<ref>{{cite journal|last1=Soares|first1=Sandra C.|title=The lurking snake in the grass: interference of snake stimuli in visually taxing conditions|journal=Evolutionary Psychology|date=15 April 2012|volume=10|issue=2|pages=187–197|doi=10.1177/147470491201000202|pmid=22947633|s2cid=34814663|issn=1474-7049|doi-access=free|hdl=10316/102719|hdl-access=free|pmc=10481044}}</ref>

Enhanced snake detection has also been found in young children.<ref>{{cite journal|last1=LoBue|first1=Vanessa|last2=DeLoache|first2=Judy S.|title=Detecting the Snake in the Grass: Attention to Fear-Relevant Stimuli by Adults and Young Children|journal=Psychological Science|date=1 March 2008|volume=19|issue=3|pages=284–289|doi=10.1111/j.1467-9280.2008.02081.x|pmid=18315802|s2cid=12776572|language=en|issn=0956-7976}}</ref>

Brain imaging investigations have found further evidence for the theory. Support for the idea of a high visual sensitivity to snakes has been proven in primate neural activity in response to snake threats.<ref>{{cite journal|last1=Van Le|first1=Quan|last2=Isbell|first2=Lynne A.|last3=Matsumoto|first3=Jumpei|last4=Nguyen|first4=Minh|last5=Hori|first5=Etsuro|last6=Maior|first6=Rafael S.|last7=Tomaz|first7=Carlos|last8=Tran|first8=Anh Hai|last9=Ono|first9=Taketoshi|last10=Nishijo|first10=Hisao|title=Pulvinar neurons reveal neurobiological evidence of past selection for rapid detection of snakes|journal=Proceedings of the National Academy of Sciences of the United States of America|date=19 November 2013|volume=110|issue=47|pages=19000–19005|doi=10.1073/pnas.1312648110|pmid=24167268|issn=1091-6490|pmc=3839741|bibcode=2013PNAS..11019000V|doi-access=free}}</ref> Non-invasive electroencephalogram ([[EEG]]) studies have found an enhanced visual brain activity in response to images of snakes in humans.<ref>{{cite journal|last1=Van Strien|first1=J. W.|last2=Eijlers|first2=R.|last3=Franken|first3=I. H. A.|last4=Huijding|first4=J.|title=Snake pictures draw more early attention than spider pictures in non-phobic women: evidence from event-related brain potentials|journal=Biological Psychology|date=2014|volume=96|pages=150–157|doi=10.1016/j.biopsycho.2013.12.014|pmid=24374241|issn=1873-6246|url=http://repub.eur.nl/pub/51065|hdl=1765/51065|s2cid=16106346|hdl-access=free}}</ref><ref>{{cite journal|last1=Van Strien|first1=Jan W.|last2=Franken|first2=Ingmar H. A.|last3=Huijding|first3=Jorg|title=Testing the snake-detection hypothesis: larger early posterior negativity in humans to pictures of snakes than to pictures of other reptiles, spiders and slugs|journal=Frontiers in Human Neuroscience|date=2014|volume=8|pages=691|doi=10.3389/fnhum.2014.00691|pmid=25237303|pmc=4154444|issn=1662-5161|doi-access=free}}</ref><ref>{{cite journal|last1=Van Strien|first1=Jan W.|last2=Christiaans|first2=Gerwin|last3=Franken|first3=Ingmar H. A.|last4=Huijding|first4=Jorg|title=Curvilinear shapes and the snake detection hypothesis: An ERP study|journal=Psychophysiology|date=2016|volume=53|issue=2|pages=252–257|doi=10.1111/psyp.12564|pmid=26481589|hdl=1874/322508 |issn=1540-5958|hdl-access=free}}</ref><ref>{{cite journal|last1=He|first1=Hongshen|last2=Kubo|first2=Kenta|last3=Kawai|first3=Nobuyuki|title=Spiders do not evoke greater early posterior negativity in the event-related potential as snakes|journal=NeuroReport|date=10 September 2014|volume=25|issue=13|pages=1049–1053|doi=10.1097/WNR.0000000000000227|pmid=25026534|s2cid=27839800|issn=1473-558X}}</ref><ref>{{cite journal|last1=Grassini|first1=Simone|last2=Holm|first2=Suvi K.|last3=Railo|first3=Henry|last4=Koivisto|first4=Mika|title=Who is afraid of the invisible snake? Subjective visual awareness modulates posterior brain activity for evolutionarily threatening stimuli|journal=Biological Psychology|date=2016|volume=121|issue=Pt A|pages=53–61|doi=10.1016/j.biopsycho.2016.10.007|pmid=27760371|s2cid=9516831|issn=1873-6246}}</ref>

== References ==

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{{reflist}}

[[Category:Evolution of primates]]

[[Category:Snakes]]