Dual inheritance theory: Difference between revisions

Revision as of 23:44, 9 April 2023

Revision as of 02:08, 13 April 2023

Line 48:

'''Food processing'''

Culture has driven changes to the human digestive systems making many digestive organs, such as teeth or stomach, smaller than expected for primates of a similar size,<ref name=":2">{{Cite journal|last1=Aiello|first1=Leslie C.|last2=Wheeler|first2=Peter|date=1995-01-01|title=The Expensive-Tissue Hypothesis: The Brain and the Digestive System in Human and Primate Evolution|jstor=2744104|journal=Current Anthropology|volume=36|issue=2|pages=199–221|doi=10.1086/204350|s2cid=144317407}}</ref> and has been attributed to one of the reasons why humans have such large brains compared to other great apes.<ref name="Fonseca-Azevedo 18571–18576">{{Cite journal|last1=Fonseca-Azevedo|first1=Karina|last2=Herculano-Houzel|first2=Suzana|date=2012-11-06|title=Metabolic constraint imposes tradeoff between body size and number of brain neurons in human evolution|journal=Proceedings of the National Academy of Sciences|language=en|volume=109|issue=45|pages=18571–18576|doi=10.1073/pnas.1206390109|issn=0027-8424| pmc=3494886 |pmid=23090991|bibcode=2012PNAS..10918571F|doi-access=free}}</ref><ref>{{Cite journal|last=Gorman|first=Rachael Moeller|title=Cooking Up Bigger Brains|journal=Scientific American|language=en|volume=298|issue=1|pages=102–105|doi=10.1038/scientificamerican0108-102|pmid=18225702|year=2008|bibcode=2008SciAm.298a.102G}}</ref> This is due to food processing. Early examples of food processing include pounding, marinating and most notably cooking. Pounding meat breaks down the muscle fibres, hence taking away some of the job from the mouth, teeth and jaw.<ref>{{Cite journal|last=Farrell|first=J. H.|date=1956-05-01|title=The effect on digestibility of methods commonly used to increase the tenderness of lean meat|journal=British Journal of Nutrition|volume=10|issue=2|pages=111–115|doi=10.1079/BJN19560019|pmid=13315930|issn=1475-2662|doi-access=free}}</ref><ref>{{Cite book|title=The Secret of Our Success: How Culture Is Driving Human Evolution, Domesticating Our Species, and Making Us Smarter|last=Henrich|first=Joseph|publisher=Princeton University Press|year=2015|isbn=9780691166858|___location=Princeton|pages=66}}</ref> Marinating emulates the action of the stomach with high acid levels. Cooking partially breaks down food making it more easily digestible. Food enters the body effectively partly digested, and as such food processing reduces the work that the digestive system has to do. This means that there is selection for smaller digestive organs as the tissue is energetically expensive,<ref name=":2" /> those with smaller digestive organs can process their food but at a lower energetic cost than those with larger organs.<ref name=":3">{{Cite book|title=Catching Fire How Cooking Made Us Human|last=Wrangham|first=Richard|publisher=Profile Books|year=2009|isbn=9781846682865|___location=London|pages=40}}</ref> Cooking is notable because the energy available from food increases when cooked and this also means less time is spent looking for food.<ref name="Fonseca-Azevedo 18571–18576" /><ref name=":8">{{Cite journal|last1=Carmody|first1=Rachel N.|last2=Wrangham|first2=Richard W.|date=2009-10-01|title=The energetic significance of cooking|journal=Journal of Human Evolution|volume=57|issue=4|pages=379–391|doi=10.1016/j.jhevol.2009.02.011|issn=1095-8606|pmid=19732938|s2cid=15255649 |url=http://nrs.harvard.edu/urn-3:HUL.InstRepos:5283945}}</ref><ref>{{Cite journal|last1=Carmody|first1=Rachel N.|last2=Weintraub|first2=Gil S.|last3=Wrangham|first3=Richard W.|date=2011-11-29|title=Energetic consequences of thermal and nonthermal food processing|journal=Proceedings of the National Academy of Sciences of the United States of America|volume=108|issue=48|pages=19199–19203|doi=10.1073/pnas.1112128108|issn=1091-6490| pmc=3228431 |pmid=22065771|bibcode=2011PNAS..10819199C|doi-access=free}}</ref>

Humans living on cooked diets spend only a fraction of their day chewing compared to other extant primates living on raw diets. American girls and boys spent on average 7 to 8 percent of their day chewing respectively (1.68 to 1.92 hours per day), compared to chimpanzees, who spend more than 6 hours a day chewing.<ref>{{Cite book|url=https://www.amazon.co.uk/dp/B003F5NSVK/ref=dp-kindle-redirect?_encoding=UTF8&btkr=1|title=Catching Fire: How Cooking Made Us Human|last=Wrangham|first=Richard|date=2010-08-06|publisher=Profile Books|edition=Main|pages=140|language=en}}</ref> This frees up time which can be used for hunting. A raw diet means hunting is constrained since time spent hunting is time not spent eating and chewing plant material, but cooking reduces the time required to get the day's energy requirements, allowing for more subsistence activities.<ref>{{Cite book|title=Catching Fire: How Cooking Made Us Human|last=Wrangham|first=Richard|date=2010-05-27|publisher=Profile Books|isbn=9781846682865|edition=Main|___location=London|pages=142|language=en}}</ref> Digestibility of cooked carbohydrates is approximately on average 30% higher than digestibility of non-cooked carbohydrates.<ref name=":8" /><ref>{{Citation|last=University of California Television (UCTV)|title=CARTA: The Evolution of Human Nutrition -- Richard Wrangham: Fire Starch Meat and Honey|date=2013-03-21|url=https://www.youtube.com/watch?v=VnN-QeMgJ_U |archive-url=https://ghostarchive.org/varchive/youtube/20211219/VnN-QeMgJ_U |archive-date=2021-12-19 |url-status=live|access-date=2017-03-27}}{{cbignore}}</ref> This increased energy intake, more free time and savings made on tissue used in the digestive system allowed for the selection of genes for larger brain size.

Line 65:

===Cultural drift===

[[Cultural drift]] is a process roughly analogous to [[genetic drift]] in evolutionary biology.<ref>{{cite journal | last1 = Koerper | first1 = H. | last2 = Stickel | first2 = E. | year = 1980 | title = Cultural Drift: A Primary Process of Culture Change | journal = Journal of Anthropological Research | volume = 36 | issue = 4| pages = 463–469 | doi = 10.1086/jar.36.4.3629615 | s2cid = 163932368 }}</ref><ref name="CavalliSfornza">Cavalli-Sfornza, L. and M. Feldman. 1981. ''Cultural Transmission and Evolution: A Quantitative Approach''. Princeton, New Jersey: Princeton University Press.</ref><ref name="artsci.wustl">{{cite journal | last1 = Bentley | first1 = R.A. | last2 = Hahn | first2 = M.W. | last3 = Shennan | first3 = S.J. | year = 2004 | title = Random drift and culture change | url = http://artsci.wustl.edu/~pboyer/CEwebsite/Archive/ShennanRandomDrift.pdf | journal = Proceedings of the Royal Society B | volume = 271 | issue = 1547 | pages = 1443–1450 | doi = 10.1098/rspb.2004.2746 | pmid = 15306315 | pmc = 1691747 | access-date = 2008-05-05 | archive-url = https://web.archive.org/web/20110928021713/http://artsci.wustl.edu/~pboyer/CEwebsite/Archive/ShennanRandomDrift.pdf | archive-date = 2011-09-28 | url-status = dead }}</ref> In cultural drift, the frequency of cultural traits in a population may be subject to random fluctuations due to chance variations in which traits are observed and transmitted (sometimes called "sampling error").<ref name="duke">{{cite journal | last1 = Hahn | first1 = M.W. | last2 = Bentley | first2 = R. A. | year = 2003 | title = Drift as a mechanism for cultural change: An example from baby names | url = http://www.duke.edu/~mwh3/BabyNames.pdf | journal = Proceedings of the Royal Society B | volume = 270 | issue = Suppl 1 | pages = S120–S123 |doi=10.1098/rsbl.2003.0045 | pmid=12952655 | pmc=1698036}}</ref> These fluctuations might cause cultural variants to disappear from a population. This effect should be especially strong in small populations.<ref>Boyd, R. and P. J. Richerson. 1985. '' Culture and the Evolutionary Process''. Chicago: University of Chicago Press. pp.9, 69</ref> A model by Hahn and Bentley shows that cultural drift gives a reasonably good approximation to changes in the popularity of American baby names.<ref name="duke" /> Drift processes have also been suggested to explain changes in archaeological pottery and technology patent applications.<ref name="artsci.wustl" /> Changes in the songs of song birds are also thought to arise from drift processes, where distinct dialects in different groups occur due to errors in songbird singing and acquisition by successive generations.<ref>P.J.B. Slater, V.M. Janik. Vocal Learning. In "Encyclopedia of Animal Behavior", 2010, Pages 551-557. http://www.sciencedirect.com/science/referenceworks/9780080453378</ref> Cultural drift is also observed in an early computer model of cultural evolution.<ref>Gabora, L. (1995). [http://www.vub.ac.be/CLEA/liane/papers/mav.htm Meme and variations: A computer model of cultural evolution]. In (L. Nadel & D. Stein, Eds.) ''1993 Lectures in Complex Systems'', Addison-Wesley, 471-486.</ref>

===Guided variation===

Line 104:

The idea that human cultures undergo a similar evolutionary process as genetic evolution goes back at least to [[Charles Darwin|Darwin]].<ref>Darwin, C. 1874. ''The descent of man and selection in relation to sex.'' 2nd ed. 2 vols. New York: American Home Library.</ref> In the 1960s, [[Donald T. Campbell]] published some of the first theoretical work that adapted principles of evolutionary theory to the evolution of cultures.<ref>Campbell, D. 1965. Variation and selective retention in socio-cultural evolution. In ''Social change in developing areas: A reinterpretation of evolutionary theory'', ed. H. Barringer, G. Blanksten, and R. Mack, 19-49. Cambridge, MA: Schenkman Publishing Company.</ref> In 1976, two developments in cultural evolutionary theory set the stage for DIT. In that year [[Richard Dawkins|Richard Dawkins's]] ''[[The Selfish Gene]]'' introduced ideas of cultural evolution to a popular audience. Although one of the best-selling science books of all time, because of its lack of mathematical rigor, it had little effect on the development of DIT. Also in 1976, geneticists [[Marcus Feldman]] and [[Luigi Luca Cavalli-Sforza]] published the first dynamic models of gene–culture coevolution.<ref>{{cite journal | last1 = Feldman | first1 = M. | last2 = Cavalli-Sforna | first2 = L. | year = 1976 | title = Cultural and biological evolutionary processes, selection for a trait under complex transmission | journal = Theoretical Population Biology | volume = 9 | issue = 2| pages = 238–59 | doi=10.1016/0040-5809(76)90047-2 | pmid=1273802}}</ref> These models were to form the basis for subsequent work on DIT, heralded by the publication of three seminal books in the 1980s.

The first was Charles Lumsden and [[E. O. Wilson|E.O. Wilson's]] ''Genes, Mind and Culture''.<ref>Lumsden C., and E. Wilson. 1981. ''Genes, Mind and Culture: The Coevolutionary Process.'' Cambridge, MA: Harvard University Press.</ref> This book outlined a series of mathematical models of how genetic evolution might favor the selection of cultural traits and how cultural traits might, in turn, affect the speed of genetic evolution. While it was the first book published describing how genes and culture might coevolve, it had relatively little effect on the further development of DIT.<ref name="Laland">Laland K. and G. Brown. 2002. ''Sense and Nonsense: Evolutionary Perspectives on Human Behavior''. Oxford: Oxford University Press.</ref> Some critics felt that their models depended too heavily on genetic mechanisms at the expense of cultural mechanisms.<ref>{{cite journal | last1 = Boyd | first1 = R. | last2 = Richerson | first2 = P. | year = 1983 | title = The cultural transmission of acquired variation: effects on genetic fitness | journal = Journal of Theoretical Biology | volume = 100 | issue = 4| pages = 567–96 | doi=10.1016/0022-5193(83)90324-7| pmid = 6876815 | bibcode = 1983JThBi.100..567B }}</ref> Controversy surrounding Wilson's [[Sociobiology#Controversy|sociobiological theories]] may also have decreased the lasting effect of this book.<ref name="Laland" />

The second 1981 book was [[Luigi Luca Cavalli-Sforza|Cavalli-Sforza]] and Feldman's ''Cultural Transmission and Evolution: A Quantitative Approach''.<ref name="CavalliSfornza" /> Borrowing heavily from [[population genetics]] and [[epidemiology]], this book built a mathematical theory concerning the spread of cultural traits. It describes the evolutionary implications of [[vertical transmission]], passing cultural traits from parents to offspring; oblique transmission, passing cultural traits from any member of an older generation to a younger generation; and [[horizontal transmission]], passing traits between members of the same population.

Line 122:

{{Quotation|"In many ways the most complex and potentially rewarding of all approaches, [DIT], with its multiple processes and cerebral onslaught of sigmas and deltas, may appear too abstract to all but the most enthusiastic reader. Until such a time as the theoretical hieroglyphics can be translated into a respectable empirical science most observers will remain immune to its message."<ref>Laland, K. N. and G. R. Brown. 2002. ''Sense & Nonsense: Evolutionary Perspectives on Human Behavior.'' Oxford: Oxford University Press. p. 290.</ref>}}

Economist [[Herbert Gintis]] disagrees with this critique, citing empirical work as well as more recent work using techniques from [[behavioral economics]].<ref>Herb Gintis Amazon.com review: https://www.amazon.com/review/product/0198508840/</ref> These behavioral economic techniques have been adapted to test predictions of cultural evolutionary models in laboratory settings<ref>McElreath, R., M. Lubell, P. J. Richerson, T. M. Waring, W. Baum, E. Edsten, C. Efferson, and B. Paciotti. 2005. [http://www.des.ucdavis.edu/faculty/Richerson/WheatPotatoes.pdf Applying formal models to the laboratory study of social learning: The effect of task difficulty and environmental fluctuation.] Evolution and Human Behavior 26: 483-508.</ref><ref>{{cite journal |author=Efferson, C. |author2=R. Lalive |author3=P. J. Richerson |author4=R. McElreath |author5=M. Lubell |year=2008 |title=Conformists and mavericks: the empirics of frequency-dependent cultural transmission |journal=[[Evolution and Human Behavior]] |volume=29 |issue=1 |pages=56–64 |doi=10.1016/j.evolhumbehav.2007.08.003|citeseerx=10.1.1.606.1789 |s2cid=2107499 }}</ref><ref>{{cite journal | last1 = Baum | first1 = W. M. | last2 = Richerson | first2 = P. J. | last3 = Efferson | first3 = C. M. | last4 = Paciotti | first4 = B. M. | year = 2004 | title = Cultural evolution in laboratory micro-societies including traditions of rule-giving and rule-following | url = http://www.des.ucdavis.edu/faculty/Richerson/Baumetalprinted.pdf | journal = Evolution and Human Behavior | volume = 25 | issue = 5| pages = 305–326 | doi=10.1016/j.evolhumbehav.2004.05.003| citeseerx = 10.1.1.404.8710 }}</ref> as well as studying differences in cooperation in fifteen small-scale societies in the field.<ref name="Henrich_a">Henrich, J., R. Boyd, S. Bowles, C. Camerer, E. Fehr, H. Gintis (Eds). 2004. ''Foundations of Human Sociality: Economic Experiments and Ethnographic Evidence from Fifteen Small-Scale Societies'' Oxford: Oxford University Press.</ref>

Since one of the goals of DIT is to explain the distribution of human cultural traits, [[ethnography|ethnographic]] and [[ethnology|ethnologic]] techniques may also be useful for testing hypothesis stemming from DIT. Although findings from traditional ethnologic studies have been used to buttress DIT arguments,<ref>Cavalli-Sfornza, L. L. and M. Feldman. 1981. ''Cultural Transmission and Evolution: A Quantitative Approach.'' Princeton, New Jersey: Princeton University Press.</ref><ref>Boyd, R. and P. J. Richerson. 1985. '' Culture and the Evolutionary Process''. Chicago: University of Chicago Press.</ref> thus far there have been little ethnographic fieldwork designed to explicitly test these hypotheses.<ref name="Soltis" /><ref name="Henrich_a" /><ref>{{cite journal | last1 = McElreath | first1 = R | year = 2004 | title = Social learning and the maintenance of cultural variation: An evolutionary model and data from East Africa | url = http://arbeit.ucdavis.edu/mcelreath/files/mcelreath%20AA%202004.pdf | journal = American Anthropologist | volume = 106 | issue = 2 | pages = 308–321 | doi = 10.1525/aa.2004.106.2.308 | access-date = 2008-03-27 | archive-url = https://web.archive.org/web/20070717022400/http://arbeit.ucdavis.edu/mcelreath/files/mcelreath%20AA%202004.pdf | archive-date = 2007-07-17 | url-status = dead }}</ref>