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Alcohol discrimination and preferences in two species of
nectar-feeding primate
Samuel R. Gochman, Michael B. Brown and Nathaniel J. Dominy
Article citation details
R. Soc. open sci. 3: 160217.
http://dx.doi.org/10.1098/rsos.160217
Review timeline
Original submission:
Revised submission:
Final acceptance:
25 March 2016
9 June 2016
21 June 2016
Note: Reports are unedited and appear as
submitted by the referee. The review history
appears in chronological order.
Review History
RSOS-160217.R0 (Original submission)
Review form: Reviewer 1
Is the manuscript scientifically sound in its present form?
Yes
Are the interpretations and conclusions justified by the results?
Yes
Is the language acceptable?
Yes
Is it clear how to access all supporting data?
Yes/yes.
Do you have any ethical concerns with this paper?
No
Have you any concerns about statistical analyses in this paper?
Yes
© 2016 The Authors. Published by the Royal Society under the terms of the Creative Commons
Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use,
provided the original author and source are credited
Downloaded from http://rsos.royalsocietypublishing.org/ on June 16, 2017
2
Recommendation?
Major revision is needed (please make suggestions in comments)
Comments to the Author(s)
Title: best restricted to ...in two species of nectar feeding primate
p. 2, l. 6. The recent literature documents dietary ethanol ingestion at low concentrations, but not
necessarily as an "important source of calories"
p. 2, l. 8. The prior loris result is better presented in intro, not abstract.
p. 3, l. 8. As before on calories; earlier literature suggests a variety of roles, including but not
predominated by the caloric value of ethanol.
p. 3, l. 38-42. This alcoholic sap is anthropogenically manipulated and maintained, so is not a
natural system.
p. 4, l. 20. "likely a spurious mutation"; why? Isn't its consequences what's being evaluated here?
p. 4, l. 33. The sucrose content data vary dramatically from the "low sugar reward of 2.8%";
please clarify. Possibly effects of fermentation?
p. 5, l. 3. ...are unknown...
p. 5, l. 23. What is the captive diet? How can alcohol exposure (e.g., within ripe fruits) necessarily
be excluded?
p. 6, l. 5. 99.5% ethanol is not pure 100%; please recalculate the presented ethanol levels
accordingly. Also, if stock solutions of sucrose and ethanol were made at the indicated
concentrations, then how could the sucrose percentage remain constant (l. 13) if aqueous ethanol
is then added to it? More details on the methods are required here.
p. 7, l. 24. no differential consumption among solutions [not variables]
p. 7, l. 28. The a priori characterization of 1% ethanol as low seems inappropriate; why not
simply treat alcohol concentration as a continuous variable? For the slow loris, categorical
designation of 1% as low and 2% as high seems particularly arbitrary. Lumping 0% and 1% is
also problematical. I encourage the authors to rethink the statistical analysis; Figure 3 is key here
as this may be widely replicated as evidence of primate attraction to alcohol, but embeds the
aforementioned problems.
p. 7, lines 47-57. This paragraph belongs in the methods, not results.
p. 9, l. 24. This sentence is probably unncessary given restrictions detailed in the following
sentences.
p. 9, l. 34. "sample bias"; vague, better draw attention just to the need for more phylogenetic
sampling, both at molecular and behavioral levels.
p. 9, l. 41, and elsewhere. ADH4 is only one of many enzymes involved in ethanol metabolism,
so the absence of the A294V mutation may be irrelevant if there is compensation elsewhere in the
Downloaded from http://rsos.royalsocietypublishing.org/ on June 16, 2017
3
pathway. A few sentences about the various ADH's and ALDH's known to occur in primates
would be useful.
p. 9, l. 52. Not so much preservation as presence of the mutation that is evidence.
Figure 2c; there appears to be an insect in the photo; perhaps worth pointing out that
invertebrates may also be attracted to fermenting nectar!
Figure 3. for mass designation (in the upper right corner), better ethanol mass, or consumed mass
Review form: Reviewer 2 (Christina Campbell)
Is the manuscript scientifically sound in its present form?
Yes
Are the interpretations and conclusions justified by the results?
Yes
Is the language acceptable?
Yes
Is it clear how to access all supporting data?
Yes
Do you have any ethical concerns with this paper?
No
Have you any concerns about statistical analyses in this paper?
No
Recommendation?
Accept with minor revision (please list in comments)
Comments to the Author(s)
This is a well written paper on an ever increasingly important topic. I only have minor
comments.
1. In the second paragraph in the Background Section, I strongly suggest that you clearly define
Robert Dudley's "Drunken Monkey Hypothesis" - as this really was the first hypothesis to
generate research on this topic, and make it clear that his hypothesis is NOT about the animals
getting drunk, but chronically consuming and seeking out low levels of ethanol.
2. On the page 4, line 39 - this is the first time you mention the slow loris in the main text and so
you should include the scientific name here.
3. In the methods section - please discuss why the volumes of solutions are different for the two
species.
4. In a more general statement, I would like you to tone down the importance of the Milton
paper - it is the only real article that refutes this whole idea and it is seriously flawed for two
reasons - one it is based on a questionnaire and not actual data, and 2. the questionnaire only
asked people to talk about signs of obvious intoxication - which is NOT what most of us who
study this subject think is important. Indeed we all think the overt intoxication is a very rare
event and irrelevant to Dudley's hypothesis.
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4
Decision letter (RSOS-160217)
18-May-2016
Dear Mr Gochman,
The editors assigned to your paper ("Alcohol discrimination and preferences of nectar-feeding
primates") has now received comments from reviewers. We would like you to revise your paper
in accordance with the referee and Subject Editor suggestions which can be found below (not
including confidential reports to the Editor). Please note this decision does not guarantee
eventual acceptance.
Please submit a copy of your revised paper within three weeks (i.e. by the 10-Jun-2016). If we do
not hear from you within this time then it will be assumed that the paper has been withdrawn. In
exceptional circumstances, extensions may be possible if agreed with the Editorial Office in
advance.We do not allow multiple rounds of revision so we urge you to make every effort to
fully address all of the comments at this stage. If deemed necessary by the Editors, your
manuscript will be sent back to one or more of the original reviewers for assessment. If the
original reviewers are not available we may invite new reviewers.
To revise your manuscript, log into http://mc.manuscriptcentral.com/rsos and enter your
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It is a condition of publication that all supporting data are made available either as
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5
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All submissions, other than those with a single author, must include an Authors’ Contributions
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critically for important intellectual content; and 3) final approval of the version to be published.
All contributors who do not meet all of these criteria should be included in the
acknowledgements.
We suggest the following format:
AB carried out the molecular lab work, participated in data analysis, carried out sequence
alignments, participated in the design of the study and drafted the manuscript; CD carried out
the statistical analyses; EF collected field data; GH conceived of the study, designed the study,
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Please acknowledge anyone who contributed to the study but did not meet the authorship
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Once again, thank you for submitting your manuscript to Royal Society Open Science and I look
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Matthew Allinson,
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on behalf of Kevin Padian
Subject Editor, Royal Society Open Science
[email protected]
Downloaded from http://rsos.royalsocietypublishing.org/ on June 16, 2017
6
Comments to Author:
Reviewers' Comments to Author:
Reviewer: 1
Comments to the Author(s)
Title: best restricted to ...in two species of nectar feeding primate
p. 2, l. 6. The recent literature documents dietary ethanol ingestion at low concentrations, but not
necessarily as an "important source of calories"
p. 2, l. 8. The prior loris result is better presented in intro, not abstract.
p. 3, l. 8. As before on calories; earlier literature suggests a variety of roles, including but not
predominated by the caloric value of ethanol.
p. 3, l. 38-42. This alcoholic sap is anthropogenically manipulated and maintained, so is not a
natural system.
p. 4, l. 20. "likely a spurious mutation"; why? Isn't its consequences what's being evaluated here?
p. 4, l. 33. The sucrose content data vary dramatically from the "low sugar reward of 2.8%";
please clarify. Possibly effects of fermentation?
p. 5, l. 3. ...are unknown...
p. 5, l. 23. What is the captive diet? How can alcohol exposure (e.g., within ripe fruits) necessarily
be excluded?
p. 6, l. 5. 99.5% ethanol is not pure 100%; please recalculate the presented ethanol levels
accordingly. Also, if stock solutions of sucrose and ethanol were made at the indicated
concentrations, then how could the sucrose percentage remain constant (l. 13) if aqueous ethanol
is then added to it? More details on the methods are required here.
p. 7, l. 24. no differential consumption among solutions [not variables]
p. 7, l. 28. The a priori characterization of 1% ethanol as low seems inappropriate; why not
simply treat alcohol concentration as a continuous variable? For the slow loris, categorical
designation of 1% as low and 2% as high seems particularly arbitrary. Lumping 0% and 1% is
also problematical. I encourage the authors to rethink the statistical analysis; Figure 3 is key here
as this may be widely replicated as evidence of primate attraction to alcohol, but embeds the
aforementioned problems.
p. 7, lines 47-57. This paragraph belongs in the methods, not results.
p. 9, l. 24. This sentence is probably unncessary given restrictions detailed in the following
sentences.
p. 9, l. 34. "sample bias"; vague, better draw attention just to the need for more phylogenetic
sampling, both at molecular and behavioral levels.
p. 9, l. 41, and elsewhere. ADH4 is only one of many enzymes involved in ethanol metabolism,
so the absence of the A294V mutation may be irrelevant if there is compensation elsewhere in the
Downloaded from http://rsos.royalsocietypublishing.org/ on June 16, 2017
7
pathway. A few sentences about the various ADH's and ALDH's known to occur in primates
would be useful.
p. 9, l. 52. Not so much preservation as presence of the mutation that is evidence.
Figure 2c; there appears to be an insect in the photo; perhaps worth pointing out that
invertebrates may also be attracted to fermenting nectar!
Figure 3. for mass designation (in the upper right corner), better ethanol mass, or consumed mass
Reviewer: 2
Comments to the Author(s)
This is a well written paper on an ever increasingly important topic. I only have minor
comments.
1. In the second paragraph in the Background Section, I strongly suggest that you clearly define
Robert Dudley's "Drunken Monkey Hypothesis" - as this really was the first hypothesis to
generate research on this topic, and make it clear that his hypothesis is NOT about the animals
getting drunk, but chronically consuming and seeking out low levels of ethanol.
2. On the page 4, line 39 - this is the first time you mention the slow loris in the main text and so
you should include the scientific name here.
3. In the methods section - please discuss why the volumes of solutions are different for the two
species.
4. In a more general statement, I would like you to tone down the importance of the Milton
paper - it is the only real article that refutes this whole idea and it is seriously flawed for two
reasons - one it is based on a questionnaire and not actual data, and 2. the questionnaire only
asked people to talk about signs of obvious intoxication - which is NOT what most of us who
study this subject think is important. Indeed we all think the overt intoxication is a very rare
event and irrelevant to Dudley's hypothesis.
Author's Response to Decision Letter for (RSOS-160217)
See Appendix A.
RSOS-160217.R1 (Revision)
Review form: Reviewer 1
Is the manuscript scientifically sound in its present form?
Yes
Are the interpretations and conclusions justified by the results?
Yes
Is the language acceptable?
Yes
Is it clear how to access all supporting data?
Yes
Do you have any ethical concerns with this paper?
No
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8
Have you any concerns about statistical analyses in this paper?
No
Recommendation?
Accept as is
Comments to the Author(s)
My prior concerns have been adequately addressed in revision.
Decision letter (RSOS-160217.R1)
21-Jun-2016
Dear Mr Gochman,
I am pleased to inform you that your manuscript entitled "Alcohol discrimination and
preferences in two species of nectar-feeding primate" is now accepted for publication in Royal
Society Open Science.
You can expect to receive a proof of your article within approximately 10 working days. Please
contact the production office ([email protected]) to let us know if you are
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As the issue version of your paper will be the only version to be published I would advise you to
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On behalf of the Editors of Royal Society Open Science, we look forward to your continued
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Best wishes,
Andrew Dunn
Royal Society Open Science
http://rsos.royalsocietypublishing.org/
Reviewer(s)' Comments to Author:
Reviewer: 1
Comments to the Author(s)
My prior concerns have been adequately addressed in revision.
Appendix A
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Dartmouth College
Department of Anthropology
•
HANOVER
6047 Silsby Hall
SAMUEL R. GOCHMAN
•
•
NEW HAMPSHIRE
(603) 646-1849
•
•
03755-3547
FAX: (603) 646-1140
email: [email protected]
09June2016
KevinPadian
SubjectEditor,RoyalSocietyOpenScience
DepartmentofIntegrativeBiology
UniversityofCalifornia,Berkeley
3060ValleyLifeSciencesBuilding
Berkeley,CA94720-3140
Re:RoyalSocietyOpenSciencemanuscriptno.RSOS-160217
DearProfessorPadian:
Wearegratefulfortheopportunitytoreviseandresubmitmanuscriptno.RSOS-160217,titled
"Alcoholdiscriminationandpreferencesintwospeciesofnectar-feedingprimate"bySamuelR.
Gochmanetal.WeappreciateandagreewiththeconstructivecommentsofReviewers1and2
andwehaverevisedourmanuscriptaccordingly.Inaddition,weaffirmcompliancewithall
requiredend-sections,includingdataaccessioninDryad.Ourresponsetoeachreviewer
commentisenumeratedanddetailedbelow:
Reviewer1
1. Comment:Title:bestrestrictedto...intwospeciesofnectarfeedingprimate
Ourresponse:weagreewiththissuggestionandwehavechangedtitleto“Alcohol
discriminationandpreferencesintwospeciesofnectar-feedingprimates”
2. Comment:p.2,l.6.Therecentliteraturedocumentsdietaryethanolingestionatlow
concentrations,butnotnecessarilyasan"importantsourceofcalories"
Ourresponse:weagreewiththissuggestionandwehavemodifiedthetexttoread“a
supplementalsourceofcalories”
3. Comment:p.2,l.8.Thepriorlorisresultisbetterpresentedinintro,notabstract.
Ourresponse:Reviewer1makesacompellingsuggestion,andwearegenerallyinfavor
ofremovingeffusivesentences,buttodeletethisparticularsentencewoulddisguisesome
oftheunderlyingmotivationforthestudybyCarriganetal.andthepresentexperiment,
whichentailsaslowloris(asoutlinedintheintroduction).So,wewouldrespectfully
requestpreservationofthissentenceintheabstract.
4. Comment:p.3,l.8.Asbeforeoncalories;earlierliteraturesuggestsavarietyofroles,
includingbutnotpredominatedbythecaloricvalueofethanol.
Ourresponse:Weagreethatourearlierwordingplacedundueemphasisonthecalorie
contentofalcohol,andwehaveadjustedthesentencetoread:“Mountingevidence
Downloaded from http://rsos.royalsocietypublishing.org/ on June 16, 2017
suggeststhatdietaryethanol,oralcohol,isaprevalentcomponentinthenaturaldietsof
nonhumanprimates.”
5.Comment:p.3,l.38-42.Thisalcoholicsapisanthropogenicallymanipulatedandmaintained,
soisnotanaturalsystem.
Ourresponse:Weacknowledgethetruthofthiscomment,andwehavemodifiedourtext
toreflectthispoint:"Thisbehaviourismarginallyunnatural(thechimpanzeescapitalise
onthepresenceofsap-collectingplasticcontainers[8]),butitindicatesaproclivityfor
alcoholandisthereforecompatiblewiththeadaptivehypothesisofCarriganetal.[11]."
6.Comment:p.4,l.20."likelyaspuriousmutation";why?Isn'titsconsequenceswhat'sbeing
evaluatedhere?
Ourresponse:Reviewer1isquitecorrect.Thisstatementwasintendedasanarrative
device,astrawmanofconvenience.Wehavemodifiedourtexttobetterreflectourgoal
ofbuildingnarrativesuspense:“Giventhatlarvaeareanimprobablesourceofalcohol,it
istemptingtointerprettheA294Vtransitionofaye-ayesasaspuriousmutation.”
7.Comment:p.4,l.33.Thesucrosecontentdatavarydramaticallyfromthe"lowsugarreward
of2.8%";pleaseclarify.Possiblyeffectsoffermentation?
Ourresponse:TheliquidsubstanceinthebractsofR.madagascariensisanditslow
sucrosecontentareratherpuzzling,andReviewer1isastutetosuggestfermentation.To
clarifyourviewsontheuncertainorigin,composition,andecologicalimportanceofthis
substance,weelaboratedwiththefollowingtext:"Thisdescriptionresemblesaccountsof
fermentednectar[32],buttheextraflorallocationandlowsugarcontentispuzzling,
suggestingadistinctexudate.Alternatively,thebractsmayaccumulateexcessorspilled
nectar,thesugarofwhichisdilutedbyrainorconsumedbyyeastduringfermentation.
Accesstooneorbothliquidsraisesthepossibilitythataye-ayesconsumenontrivial
quantitiesofalcoholonaseasonalbasis."
8.Comment:p.5,l.3....areunknown…
Ourresponse:editaccepted
9.Comment:p.5,l.23.Whatisthecaptivediet?Howcanalcoholexposure(e.g.,withinripe
fruits)necessarilybeexcluded?
Ourresponse:commentaccepted,withthefollowingtextadded:“Thedietsofboth
speciescontainchowgruel,mealworms,andamedleyofripefruit,whichisexpectedto
containtraceamountsofalcohol.Lifetimeexposuretoalcoholisthereforelimited.”
10.Comment:p.6,l.5.99.5%ethanolisnotpure100%;pleaserecalculatethepresented
ethanollevelsaccordingly.Also,ifstocksolutionsofsucroseandethanolweremadeatthe
indicatedconcentrations,thenhowcouldthesucrosepercentageremainconstant(l.13)if
aqueousethanolisthenaddedtoit?Moredetailsonthemethodsarerequiredhere.
Ourresponse:Reviewer1makesanimportantpointhere,andwemustadmitoversight.
Tofullyaddressthisissueoftransparencyandreproducibility,wehaveaddedthe
followingtext:"Tosimulatefermentednectars,weusedthesestocksolutionstocreate
serialdilutionsofpure(99.5%)ethanol(Fishercatalogueno.BP2818500).Thisprotocol
simplifiedthedailyon-siteproductionoffreshsolutions,butithasthedisadvantageof
systematicimprecision.Forinstance,ourserialdilutionsof1.0%,3.0%,and5.0%ethanol
2
Downloaded from http://rsos.royalsocietypublishing.org/ on June 16, 2017
inasolutionof14%sucroseareinfactdilutionsof0.995%,2.985%,and4.975%ethanol
insolutionsof13.86%,13.58%,and13.30%sucrose,respectively.Similarly,ourserial
dilutionsof1.0%,2.0%,and4.0%ethanolinasolutionof10%sucroseareinfactdilutions
of0.995%,1.990%,and3.980%ethanolinsolutionsof9.9%,9.8%,and9.6%sucrose,
respectively."
11.Comment:p.7,l.24.nodifferentialconsumptionamongsolutions[notvariables]
Ourresponse:editaccepted
12.Comment:p.7,l.28.Theaprioricharacterizationof1%ethanolaslowseems
inappropriate;whynotsimplytreatalcoholconcentrationasacontinuousvariable?Forthe
slowloris,categoricaldesignationof1%aslowand2%ashighseemsparticularlyarbitrary.
Lumping0%and1%isalsoproblematical.Iencouragetheauthorstorethinkthestatistical
analysis;Figure3iskeyhereasthismaybewidelyreplicatedasevidenceofprimateattraction
toalcohol,butembedstheaforementionedproblems.
Ourresponse:thiscommentraisesastatisticalpredicament.Reviewer1isquitecorrectin
untitled: Fithis/herviews,butsuchananalysiswiththeslowlorisdata[which,recall,isbasedonfive
Y by X of proportion mass consumed by solution
Page 1 of 6
trialsonly]istoounderpoweredandrisksatypeIIerror.Athresholdbetween1%and2%
isnotquiteasarbitraryasitseemsonthesurface,assuggestedinthisplot:
Oneway Analysis of proportion mass consumed By solution
proportion mass consumed
0.5
0.4
0.3
0.2
0.1
0
0%
1%
2%
4%
solution
All Pairs
Tukey-Kramer
0.05
Itwasonthebasisofthisplotthatwebinned0%and1%as"lowconcentrations"and2%
Oneway Anova
and4%as"highconcentrations",whichwehavesinceeditedto"lower"and"higher"
concentrationstobetterreflectthegrammarofrelativedifferences.Topreserve
Summary of Fit
analyticalandgraphicalsymmetry,asimilarapproachwasappliedtotheaye-ayedata.
Rsquare
0.427563
Insum,werespectandacknowledgethiscommentbyReviewer1,andwehavedefinitely
Adj Rsquare
0.320231
thoughtcarefullyabouttheanalyses,asrequested.Inthiscase,however,wewould
Root Mean Square Error
0.089687
prefertokeepourbinnedcategoriesandthecorrespondingstatisticalsignificance.
Mean of Response
0.25
Observations (or Sum Wgts)
20
13.Comment:p.7,lines47-57.Thisparagraphbelongsinthemethods,notresults.
Analysis of Variance
Source
solution
Error
C. Total
Sum of
DF
Squares Mean Square
3 0.09612867
0.032043
3
16 0.12870056
0.008044
19 0.22482922
F Ratio Prob > F
3.9836 0.0269*
Downloaded from http://rsos.royalsocietypublishing.org/ on June 16, 2017
Ourresponse:weagreethatthefirstsentenceisredundantwithtextinthepreceding
methodssection,anditisdeleted.However,theensuingsentencewaseditedforclarity
andretainedasaformalresult.“Covariationofthetwomeasures,digital-probe-tomouth-events(DPMEs)andmassconsumed,wasnonlinearbuthighlypredictiveacross
30trials(R2=0.96;electronicsupplementarymaterial,figureS2),indicatingthaterror
fromspillageormiscountedDPMEswasdistributedevenlythroughtheexperiment.”
14.Comment:p.9,l.24.Thissentenceisprobablyunnecessarygivenrestrictionsdetailedinthe
followingsentences.
Ourresponse:editaccepted,thesentenceisdeleted
15.Comment:p.9,l.34."samplebias";vague,betterdrawattentionjusttotheneedformore
phylogeneticsampling,bothatmolecularandbehaviorallevels.
Ourresponse:weareinagreement,andwehavemodifiedthesentenceaccordingly:
"Third,ourexperimentsuffersfromlimitedsamplingwithintheprimatephylogeny,both
atthemolecularandbehaviorallevels.Itisunknownwhether..."
16.Comment:p.9,l.41,andelsewhere.ADH4isonlyoneofmanyenzymesinvolvedinethanol
metabolism,sotheabsenceoftheA294Vmutationmaybeirrelevantifthereiscompensation
elsewhereinthepathway.AfewsentencesaboutthevariousADH'sandALDH'sknowntooccur
inprimateswouldbeuseful.
Ourresponse:Thesesuggestionsareexcellent,andwehavecompliedwithaneconomyof
text.Thissentencenowreads:"Asimilarpreferenceforalcoholisperhapslikelygiven
thatseveralspeciesofmonkeyareattractedtoalcoholdespitelackingtheA294V
mutation(e.g.,baboons,vervets,macaques[review:6]),suggestingthattheA294V
mutationcouldbeirrelevantifcompensationexistselsewhereinthealcoholmetabolic
pathway.ADH4ismerelyoneofmanyenzymesinvolvedinalcoholmetabolism.
17.Comment:p.9,l.52.Notsomuchpreservationaspresenceofthemutationthatis
evidence.
Ourresponse:editaccepted,thesentencenowreads:"Apreferenceforalcoholamong
aye-ayesiscompatiblewiththehypothesisadvancedbyCarriganetal.[11],i.e.,thatthe
presenceoftheA294Vmutationinalineageisplausibleevidenceoffermentedfoodsin
thediet."
18.Comment:Figure2c;thereappearstobeaninsectinthephoto;perhapsworthpointingout
thatinvertebratesmayalsobeattractedtofermentingnectar!
Ourresponse:Weagree!andthecaptionnowincludesthisadditionalsentence:The
presenceofanitidulidbeetledemonstratestheattractionofinsectstofermentednectar;
itisalsoapotentialvectorofinoculationwithyeast[32](photographbyAnnette
Zitzmann,reproducedwithpermission).
19.Comment:Figure3.formassdesignation(intheupperrightcorner),betterethanolmass,or
consumedmass
Ourresponse:editaccepted
Reviewer2
4
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1.Comment:InthesecondparagraphintheBackgroundSection,Istronglysuggestthatyou
clearlydefineRobertDudley's"DrunkenMonkeyHypothesis"-asthisreallywasthefirst
hypothesistogenerateresearchonthistopic,andmakeitclearthathishypothesisisNOTabout
theanimalsgettingdrunk,butchronicallyconsumingandseekingoutlowlevelsofethanol.
Ourresponse:weareinstrongagreementwithReviewer2-RobertDudley'sDrunken
MonkeyHypothesisisoftenmisunderstood.Theproblem,however,isthatthisparticular
paragraphisverymuchfocusedonthehypothesisofCarriganetal.inPNAS,andthe
distinctionbetweenfermentedfruitsandexudates,which,inturn,enablesasmooth
seguetothetopicofexudatesandaye-ayes.Weareconcernedaboutderailingthis
paragraphforthesolepurposeofprovidingclarifyingtextaboutanother,albeitrelated
hypothesis.So,wearerespectfullydecliningtoacceptthissuggestionatthispointinthe
paper.
2.Comment:Onthepage4,line39-thisisthefirsttimeyoumentiontheslowlorisinthemain
textandsoyoushouldincludethescientificnamehere.
Ourresponse:editaccepted
3.Comment:Inthemethodssection-pleasediscusswhythevolumesofsolutionsaredifferent
forthetwospecies.
Ourresponse:ThisdifferencewasmandatedbytheveterinarystaffoftheDukeLemur
Center,andthereforetheIACUCofDukeUniversity.Theinstitutionalrationalewasthat
thevolumeofsolutionshouldvaryinproportiontobodymass,andaslowlorisisabout
one-thirdthemassofanaye-aye.Bywayofexplanation,weaddedthistext:"Weheld
thevolumeofsolutionineachcontainerconstantat25ml(aye-ayes)or10ml(slowloris),
adifferencethatisproportionaltothebodymassesofourstudyanimals."
4.Comment:Inamoregeneralstatement,Iwouldlikeyoutotonedowntheimportanceofthe
Miltonpaper-itistheonlyrealarticlethatrefutesthiswholeideaanditisseriouslyflawedfor
tworeasons-oneitisbasedonaquestionnaireandnotactualdata,and2.thequestionnaire
onlyaskedpeopletotalkaboutsignsofobviousintoxication-whichisNOTwhatmostofus
whostudythissubjectthinkisimportant.Indeedweallthinktheovertintoxicationisavery
rareeventandirrelevanttoDudley'shypothesis.
Ourresponse:weareinstrongagreementwithReviewer2-theMiltonsurveyisgliband
counterproductive.Ourcitationstothisstudyserveastructuralpurpose,tocallattention
toscholarlydebate,evenifflawed.Wehaveeditedoursecondcitationtosubtlyreveal
thegistandsubjectivityofthepaperwithoutanyovertdenigration:Webelievethiswill
helptonedownthevalueoftheMiltonstudy,whichisref10:"Thisadaptivehypothesisis
alluring[13]butsomehumanobservershaveinferredorimputedaprimateaversionto
fermentedresources[10].Atthesametime,chimpanzeesareknowntoingestthe
fermentedexudatesofsomeplants[8,14]."
Inaddition,andinresponsetocomment#1ofReviewer2,weaddedthistextinthe
discussion:"Aproblemwithanyoftheseideasisthatsystematicdataarescarce,inpart
becausealcoholwasonceviewedasadeterrenttovertebratefrugivores[39]and
becausewildprimatesshowfewoutwardsignsofintoxication[10].Inconsequence,the
chronicconsumptionofalcoholatlowlevelsinripeandoverripefruits,asoriginally
emphasizedbyDudley[1],remainsanunderappreciatedfactorintheforagingecologyof
primates,andalcoholisseldommeasuredinprimatefoods."
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Lastly,weassertthatworkhasnotbeenpublishedoracceptedforpublication,andisnotunder
considerationforpublication,inanotherjournalorbook;thatitssubmissionforpublicationin
RoyalSocietyOpenSciencehasbeenapprovedbyallrelevantauthorsandinstitutions;andthat
allpersonsentitledtoauthorshiphavebeensonamed.Additionally,weaffirmthattherelevant
InstitutionalAnimalCareandUseCommitteesapprovedthemethodsandprotocolsdescribed
andthatalldataareaccessionedinDryad.
Sincerely,yours,
SamuelR.Gochman
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