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Discounting — the last word
of a food-item by the remainder. For purely egoistic reasons, men may declare meat and, to them. other delicac!es as being ‘taboo’ t0 others’. Food taboos. however. can have numerous other explanations? and may lead to a fuller use and susiamabillty cf glve!enresources If north-west American Nootka hunt and eat the ~t~~ale. 11rllakS gOOd Sense when Tim@ of the same region regard the giant sea mammal as ‘taboo’J. If Orang-Aslr men are permitted to feast on monkey and beat, it seems ecologicaily sensible that women and children I.ave an equally good time feasting on birds and FishJ. Jewish tradition, heaven kno’vs how far that dates back, prohibits the s!aughtering of any anlmal and its young on the same day and prescribes that a parent bird has to be released before its chicks can be taken->. Once we cntrr the reallm of rellglon -. dnd aricront hunter-gatherer soclctlcs are likely to have lhad one thesltuatton hL?comes even Imore complex: to prcsont-day hunter gdlll~7::rs Oi tk Melnyan jungle ail animals have souls, Sut thos!! of smati a~lm~al:; arc too weak to take revenge on their I~iliCCS. Cwn if tlw IDtti3 happen to he mere c/i&Iron. Souls of bigger animals cdn Iiowcvcf. harm a chrld after it has killed dn ;intmal. In the logic of the Orang Ask. it follows that only older. stronger persons cdn cope vuitli avengmg so& of slain. bigger creatures”. At the end of this line of thought IS the Ilmdu religion with its belief of re-incarnation and basIcally no disttnctlon between human and antmal with regard to souls (only the ‘packaging’ is seen to differ). Obviously. to use a purely economicmaterialistic basis to explain diversity between. and wlthin. hunter-gatherer socletles IS too slmpllsbc an approach.
btlateral traits will show IntIe or no asymmetry1 5. The average of the slgned size differences in bilateral morphological traits IS supposed to be zero. However. should we realI) expect this? StuoleS on the establishment of the left-right ax15 of the three-dlmelistonal vertebrate body dunng embryonal development”~$ show that embr\(os have lrformation about left and right at a lrer); ear& stage. Such informatlon 1s crucial to normal development of, for example, the heart and viscera, which have dtrectionally asymmetrical positlons In the body. Left-nght asymmetry is essential for the correct functional juxtapositlonmg of these organs. Although left and right are not themselves significant, ambguity of the axis could have fatal consequences berause it affects the mterconnectlon of organs”. Therefore, a strong srgnal about tefl and right IS necessary I” the developing embryo. Accord@ to a recent study;. the enlbryo ,Icqttires mformntlon about left and rt:;lit from niaterni~l mRI\IA. It 1s (,lalrslble to e!q,ect IIl
unselected but common phenomenon resulting from the necessity to stgnal left-right dunng development, In humans, for example, many bilateral morphologlcal traits appenr to ex!llb~t non-functlonat DA. The congenrtai anomaly cleft lip often appears to be unilateral. w,th the clefts Imore frequently on the left sldr than on the right!!!!Suck mhercnt asymmetry could be caused by the molecular signal forth? lefl-rlght axis. In true Ilerniapllroditlsrlr in humans (1.e. ovarian and testicular tissue bemg (rrc’~crrl II\ Ill? Sili~lC Ir\divld\J.!l:, ti1r OvJri;,!, t~ssu? occurs more oftecl on the I& srde. wlltle t(‘sI~culal IISSII~ IS more ofte:: present on the rtght side”. drid IN norm1 ~~~,l~~~tmlii~n er,k+os y:ht jyn1ds .irv 171on\ ,I~l~,,inced than left iwixls”‘. Also. 111bvds 11 I\J common Mat gonxis !‘\‘!I1111 DA. iiltllOUgl~ hCIC It 15 tile Icfl gonod that IS lniore advancedI’.
Possibly. many more uf DA of bilateral structures eklst and wotlld be r?portfd If It were lcall7ed that ii could be a real phenomenon and not a case of sampling error. lt IS perhaps not necessary to discard data sets fOl the study ot I1~v~Iopm~~tRJ stability in which tlle SI@!?C!d#eleilces In bilateral traits are normally distributed around some other value than zero. Careful consfderations are necessary. Ihowever. to decide whether the devbabons 111one 01 both dIrectIons from the actual mean are appropriate measures for developmental Instablllty” Knowledge is Ineeded about the devrlopmental pathways. Furthermore. InsIght IS needed 2s 10 how the Opposmg lofces ot b&x1~0n cases
ot1 tllk?trraI
--.. _-----As witnessed by Clarke’s recent article in TREE’ and others (e.g. Refs 2.31. the discussion about fluctuabng asymmetry and Its relatton to de~e@X~~enial stabiltiy IS afcontinumg Interest to evobLtlonary biologists. In thss discussion rt ,s apparent& Pr@supposed that under optimal (envlronmenial and genetic) condibons. end in the absence of seiection davounng asymmetiy.
byrmletrv
Clarke, G.M. (1997) Trends Ecol Evol. 12, 89-91 Moller. A.P. and Thornhill. R. (1997) i Ei+ol.
Biol. 10. l-16 Pa:mer, A.R and Strobech. C. (1947) I. hoi. Eli!. 10.39-49
Palmer. A.R. and Strobeck. C. 11986) Annu. Rev. Em/. syst 17.391&4X Swaddle, J.P. ef al. (1994) Anirn. Behav. 48, 986-989 Beddlngton. R. (1996) Narure 381. 116-117 Hyatt. B.A. et al. (1996) Nature 384,62-65 Lowe, L.A. et al. (1996) Nature 381. 158-161 Mittwoch. U. (1996) Fron?iers Emkxnnoi. 16, 121-139
In thclr rcplv to my comment.
Henderson and Sutherland make two interpretations. The first IS one of theory: that my drstrust of present tlmc preferences implies narrowmg the set of preferences which count. In fact my v::,“pulnt admits d broader set of preferences those ol future people, and the future preferences of present people-and It adduces an mterpretatlon whrcti IS consistent with all these preferences. Their second Interpretation purports to be one of practice, claiming to examme my own dlscountmg preferences. via my w~ll!ngness to ~ri’pt defrrrrd payment for a book. They announce that I did not accept their terms. leaving readers to infer thal in practice I do discount, They omt to record that I did send a copy ot the book. along with my own lemis for deferred payment, trrms from wliich discounttng could /to1 be Il,lerred. Their own rejectIon of my terms can also be explained wtthout invokmg discounting on thetr part.
1 Henderson. N. and Suthcrlilnd. W.J. (19971 lrt?n& ElIOl. El/O/. 12. 194
Jllc: SctcctiOi~ 011
dcvC.~lopIl:~~~tCllS”“‘“” .O1~L~IIIII~!.ot the Ivtt
(l#l
~li\i‘?
viteract.
Correspondence i%teilI.lomg VPr%aalteiasajk(PPogis. BlniversitZt Bern, Wohlenstrasse !%a, CH-3032 Hinterkappelen. Switzerlatld
in Tf?Ei? may address
topics raised In very recent issues of TR.&Y, and shouid he sent by e-mail TREEBelsevier.co.uk
to
btlateral traits will show IntIe or no asymmetry1 5. The average of the slgned size differences in bilateral morphological traits IS supposed to be zero. However. should we realI) expect this? StuoleS on the establishment of the left-right ax15 of the three-dlmelistonal vertebrate body dunng embryonal development”~$ show that embr\(os have lrformation about left and right at a lrer); ear& stage. Such informatlon 1s crucial to normal development of, for example, the heart and viscera, which have dtrectionally asymmetrical positlons In the body. Left-nght asymmetry is essential for the correct functional juxtapositlonmg of these organs. Although left and right are not themselves significant, ambguity of the axis could have fatal consequences berause it affects the mterconnectlon of organs”. Therefore, a strong srgnal about tefl and right IS necessary I” the developing embryo. Accord@ to a recent study;. the enlbryo ,Icqttires mformntlon about left and rt:;lit from niaterni~l mRI\IA. It 1s (,lalrslble to e!q,ect IIl
unselected but common phenomenon resulting from the necessity to stgnal left-right dunng development, In humans, for example, many bilateral morphologlcal traits appenr to ex!llb~t non-functlonat DA. The congenrtai anomaly cleft lip often appears to be unilateral. w,th the clefts Imore frequently on the left sldr than on the right!!!!Suck mhercnt asymmetry could be caused by the molecular signal forth? lefl-rlght axis. In true Ilerniapllroditlsrlr in humans (1.e. ovarian and testicular tissue bemg (rrc’~crrl II\ Ill? Sili~lC Ir\divld\J.!l:, ti1r OvJri;,!, t~ssu? occurs more oftecl on the I& srde. wlltle t(‘sI~culal IISSII~ IS more ofte:: present on the rtght side”. drid IN norm1 ~~~,l~~~tmlii~n er,k+os y:ht jyn1ds .irv 171on\ ,I~l~,,inced than left iwixls”‘. Also. 111bvds 11 I\J common Mat gonxis !‘\‘!I1111 DA. iiltllOUgl~ hCIC It 15 tile Icfl gonod that IS lniore advancedI’.
Possibly. many more uf DA of bilateral structures eklst and wotlld be r?portfd If It were lcall7ed that ii could be a real phenomenon and not a case of sampling error. lt IS perhaps not necessary to discard data sets fOl the study ot I1~v~Iopm~~tRJ stability in which tlle SI@!?C!d#eleilces In bilateral traits are normally distributed around some other value than zero. Careful consfderations are necessary. Ihowever. to decide whether the devbabons 111one 01 both dIrectIons from the actual mean are appropriate measures for developmental Instablllty” Knowledge is Ineeded about the devrlopmental pathways. Furthermore. InsIght IS needed 2s 10 how the Opposmg lofces ot b&x1~0n cases
ot1 tllk?trraI
--.. _-----As witnessed by Clarke’s recent article in TREE’ and others (e.g. Refs 2.31. the discussion about fluctuabng asymmetry and Its relatton to de~e@X~~enial stabiltiy IS afcontinumg Interest to evobLtlonary biologists. In thss discussion rt ,s apparent& Pr@supposed that under optimal (envlronmenial and genetic) condibons. end in the absence of seiection davounng asymmetiy.
byrmletrv
Clarke, G.M. (1997) Trends Ecol Evol. 12, 89-91 Moller. A.P. and Thornhill. R. (1997) i Ei+ol.
Biol. 10. l-16 Pa:mer, A.R and Strobech. C. (1947) I. hoi. Eli!. 10.39-49
Palmer. A.R. and Strobeck. C. 11986) Annu. Rev. Em/. syst 17.391&4X Swaddle, J.P. ef al. (1994) Anirn. Behav. 48, 986-989 Beddlngton. R. (1996) Narure 381. 116-117 Hyatt. B.A. et al. (1996) Nature 384,62-65 Lowe, L.A. et al. (1996) Nature 381. 158-161 Mittwoch. U. (1996) Fron?iers Emkxnnoi. 16, 121-139
In thclr rcplv to my comment.
Henderson and Sutherland make two interpretations. The first IS one of theory: that my drstrust of present tlmc preferences implies narrowmg the set of preferences which count. In fact my v::,“pulnt admits d broader set of preferences those ol future people, and the future preferences of present people-and It adduces an mterpretatlon whrcti IS consistent with all these preferences. Their second Interpretation purports to be one of practice, claiming to examme my own dlscountmg preferences. via my w~ll!ngness to ~ri’pt defrrrrd payment for a book. They announce that I did not accept their terms. leaving readers to infer thal in practice I do discount, They omt to record that I did send a copy ot the book. along with my own lemis for deferred payment, trrms from wliich discounttng could /to1 be Il,lerred. Their own rejectIon of my terms can also be explained wtthout invokmg discounting on thetr part.
1 Henderson. N. and Suthcrlilnd. W.J. (19971 lrt?n& ElIOl. El/O/. 12. 194
Jllc: SctcctiOi~ 011
dcvC.~lopIl:~~~tCllS”“‘“” .O1~L~IIIII~!.ot the Ivtt
(l#l
~li\i‘?
viteract.
Correspondence i%teilI.lomg VPr%aalteiasajk(PPogis. BlniversitZt Bern, Wohlenstrasse !%a, CH-3032 Hinterkappelen. Switzerlatld
in Tf?Ei? may address
topics raised In very recent issues of TR.&Y, and shouid he sent by e-mail TREEBelsevier.co.uk
to