Dual inheritance theory: Difference between revisions

Revision as of 13:12, 30 July 2024

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{{more citations needed|date=March 2023}}

'''Dual inheritance theory''' ('''DIT'''), also known as '''gene–culture coevolution''' or '''biocultural evolution''',<ref>{{cite web|last=O'Neil|first=Dennis|title=Glossary of Terms|url=http://anthro.palomar.edu/synthetic/glossary.htm#sectB|work=Modern Theories of Evolution|access-date=28 October 2012|archive-date=10 September 2017|archive-url=https://web.archive.org/web/20170910175215/http://anthro.palomar.edu/synthetic/glossary.htm#sectB|url-status=dead}}</ref> was developed in the 1960s through early 1980s to explain how [[human behavior]] is a product of two different and interacting [[evolution]]ary processes: [[genetic evolution]] and [[cultural evolution]]. Genes and culture continually interact in a feedback loop:<ref>{{Cite journal|last=Laland|first=Kevin N.|date=2008-11-12|title=Exploring gene–culture interactions: insights from handedness, sexual selection and niche-construction case studies|journal=Philosophical Transactions of the Royal Society B: Biological Sciences|language=en|volume=363|issue=1509|pages=3577–3589|doi=10.1098/rstb.2008.0132|issn=0962-8436|pmc=2607340|pmid=18799415}}</ref> changes in genes can lead to changes in culture which can then influence genetic selection, and vice versa. One of the theory's central claims is that culture evolves partly through a Darwinian selection process, which dual inheritance theorists often describe by analogy to genetic evolution.<ref>{{cite booksfn|last1=Richerson|first1= Peter J.|last2=Boyd|first2= Robert2008|titlep=Not By Genes Alone: How Culture Transformed Human Evolution|publisher=University of Chicago Press|year=2005|url=http://www.press.uchicago.edu/ucp/books/book/chicago/N/bo3615170.html{{pn}}}}</ref>

'Culture', in this context, is defined as 'socially learned behavior', and 'social learning' is defined as copying behaviors observed in others or acquiring behaviors through being taught by others. Most of the modelling done in the field relies on the first dynamic (copying), though it can be extended to teaching. [[Social learning theory|Social learning]], at its simplest, involves blind copying of behaviors from a model (someone observed behaving), though it is also understood to have many potential [[Biases in judgement and decision making|biases]], including success bias (copying from those who are perceived to be better off), status bias (copying from those with higher status), homophily (copying from those most like ourselves), conformist bias (disproportionately picking up behaviors that more people are performing), etc. Understanding social learning is a system of pattern replication, and understanding that there are different rates of survival for different socially learned cultural variants, this sets up, by definition, an evolutionary structure: cultural evolution.<ref>{{cite journal|last1=Campbell|first1=D. T.|title=Variation and selective retention in socio-cultural evolution|journal=Social Change in Developing Areas, A Reinterpretation of Evolutionary Theory|date=1965}}</ref>

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Cultural traits alter the social and physical environments under which genetic selection operates. For example, the cultural adoptions of agriculture and dairying have, in humans, caused genetic selection for the traits to digest starch and [[lactose]], respectively.<ref>{{cite journal | last1 = Simoons | first1 = F | year = 1969 | title = Primary adult lactose intolerance and the milking habit: A problem in biologic and cultural interrelations: I. Review of the medical research | journal = The American Journal of Digestive Diseases | volume = 14 | issue = 12| pages = 819–836 | doi=10.1007/bf02233204 | pmid=4902756| s2cid = 22597839 }}</ref><ref>{{cite journal | last1 = Simoons | first1 = F | year = 1970 | title = Primary adult lactose intolerance and the milking habit: A problem in biologic and cultural interrelations: II. A culture historical hypothesis | journal = The American Journal of Digestive Diseases | volume = 15 | issue = 8| pages = 695–710 | doi=10.1007/bf02235991| pmid = 5468838 | s2cid = 2140863 }}</ref><ref>Cavalli-Sforza, L., P. Menozzi and A. Piazza. 1994. ''The history and geography of human genes'' Princeton: Princeton University Press</ref><ref>{{cite journal | last1 = Holden | first1 = C. | last2 = Mace | first2 = R. | year = 1997 | title = Phylogenetic analysis of the evolution of lactose digestion in adults | journal = Human Biology | volume = 69 | issue = 5| pages = 605–628 | pmid = 9299882 }}</ref><ref>Durham, W. 1991. '' Coevolution: Genes, culture and human diversity''. Stanford: Stanford University Press. Chapter 5</ref><ref>Perry, G., N. Dominy, K. Claw, A. Lee, H>{{cite journal |last1=Perry |first1=George H |last2=Dominy |first2=Nathaniel J |last3=Claw |first3=Katrina G |last4=Lee |first4=Arthur S |last5=Fiegler |first5=Heike |last6=Redon |first6=Richard |last7=Werner |first7=John |last8=Villanea |first8=Fernando A |last9=Mountain |first9=Joanna L |last10=Misra |first10=Rajeev |last11=Carter |first11=Nigel P |last12=Lee |first12=Charles |last13=Stone |first13=Anne C |title=Diet and the evolution of human amylase gene copy number variation |journal=Nature Genetics |date=October 2007 |volume=39 |issue=10 |pages=1256–1260 |doi=10.1038/ng2123 |pmid=17828263 |pmc=2377015 }}</ref> As another example, it is likely that once culture became adaptive, genetic selection caused a refinement of the cognitive architecture that stores and transmits cultural information. This refinement may have further influenced the way culture is stored and the biases that govern its transmission.

DIT also predicts that, under certain situations, cultural evolution may select for traits that are genetically maladaptive. An example of this is the [[demographic transition]], which describes the fall of birth rates within industrialized societies. Dual inheritance theorists hypothesize that the demographic transition may be a result of a prestige bias, where individuals that forgo reproduction to gain more influence in industrial societies are more likely to be chosen as cultural models.<ref>Boyd, R. and P. J. Richerson. 1985. '' Culture and the Evolutionary Process''. Chicago: University of Chicago Press. pp. 199-202.</ref><ref>{{sfn|Richerson, P. J. and R. |Boyd. 2005. ''Not By Genes Alone: How Culture Transformed Human Evolution''. Chicago: University of Chicago Press. |2008|pp. =169-182.</ref>}}

==View of culture==

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People have defined the word "culture" to describe a large set of different phenomena.<ref>Kroeberm A. and C. Kluckhohn. 1952. ''Culture; A Critical Review of Concepts and Definitions.'' Cambridge, MA: Harvard University.{{pn|date=July 2024}}</ref><ref>Fox, R. and B. King. 2002. ''Anthropology Beyond Culture'' Oxford: Berg.{{pn|date=July 2024}}</ref> A definition that sums up what is meant by "culture" in DIT is:

{{Quotation|Culture is socially learned information stored in individuals' brains that is capable of affecting behavior.<ref>{{cite book sfn|last1=Richerson |first1=Peter J. |last2=Boyd |first2=Robert |title=Not By Genes Alone: How Culture Transformed Human Evolution |date=2008 |publisher=University of Chicago Press |isbn=978-0-226-71213-0 |pagep=6 |url=https://books.google.com/books?id=dU-KtEVgK6sC&pg=PA6 }}</ref><ref name="Boyd Richerson Memes Universal Acid">{{cite book |doi=10.1093/acprof:oso/9780192632449.003.0007

|chapter=Memes: Universal acid or a better mousetrap?

|title=Darwinizing CultureThe Status of Memetics as a Science

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}}</ref>}}

This view of culture emphasizes population thinking by focusing on the process by which culture is generated and maintained. It also views culture as a dynamic property of individuals, as opposed to a view of culture as a superorganic entity to which individuals must conform.<ref> name="Richerson, P.J. and R. Boyd. 2001. Culture is Part of Human Biology:">{{cite Whyjournal the Superorganic Concept Serves the Human Sciences Badly|doi=10. In ''Science Studies: Probing the Dynamics of Scientific Knowledge'', In S. Maasen and M. Winterhager, Ed. Bielefeld: Verlag.[http:14361//xcelab.net/rm/wp9783839400647-content/uploads/2008/08/cultureisbiology.pdf]005 }}</ref> This view's main advantage is that it connects individual-level processes to population-level outcomes.<ref>{{sfn|Richerson, P. and R. |Boyd. 2005. ''Not By Genes Alone: How Culture Transformed Human Evolution'' Chicago: University of Chicago Press. pg |2008|p=7.</ref>}}

==Genetic influence on cultural evolution==

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Two major topics of study in both [[sociology]] and [[cultural anthropology]] are human cultures and cultural variation.

However, Dual Inheritance theorists charge that both disciplines too often treat culture as a static superorganic entity that dictates human behavior.<ref name="Richerson">Richerson, P. and R. Boyd. 2001. [http://www.des.ucdavis.edu/faculty/Richerson/CultureIsBiology.pdf Culture is partPart of human biology: Why the superorganic concept serves the human sciences badly]. In M. Goodman and A. S. Moffat(Eds.) ''Probing Human Origins.'' Cambridge, Massachusetts: The American Academy of Arts & Sciences.<Biology"/ref><ref>{{cite journal |last1=Gintis |first1=Herbert |title=A framework for the unification of the behavioral sciences |journal=Behavioral and Brain Sciences |date=February 2007 |volume=30 |issue=1 |pages=1–16 |doi=10.1017/s0140525x07000581 |pmid=17475022 }}</ref> Cultures are defined by a suite of common traits shared by a large group of people. DIT theorists argue that this doesn't sufficiently explain variation in cultural traits at the individual level. By contrast, DIT models human culture at the individual level and views culture as the result of a dynamic evolutionary process at the population level.<ref name="Richerson" /><ref>Richerson, P. J. and R. Boyd. 2005. ''Not By Genes Alone: How Culture Transformedis Human Evolution''. Chicago: UniversityPart of Chicago Press. pg.Human Biology"/>{{sfn|Richerson|Boyd|2008|pp=5-8</ref>}}

===Human sociobiology and evolutionary psychology===

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*Laland, K. N. and G. R. Brown. 2002. ''Sense & Nonsense: Evolutionary Perspectives on Human Behavior.'' Oxford: Oxford University Press.

*Boyd, R. and P. J. Richerson. 2005. ''The Origin and Evolution of Cultures''. Oxford: Oxford University Press.

* {{cite book |last1=Richerson, P.|first1=Peter J. and R. |last2=Boyd. |first2=Robert 2005. ''|title=Not By Genes Alone: How Culture Transformed Human Evolution''. |date=2008 Chicago: |publisher=University of Chicago Press. |isbn=978-0-226-71213-0 }}

* {{cite book |last1=Henrich |first1=Joseph |title=The Secret of Our Success: How Culture Is Driving Human Evolution, Domesticating Our Species, and Making Us Smarter |date=2015 |publisher=Princeton University Press |isbn=978-1-4008-7329-6 }}

*Laland, K.H. 2017. ''Darwin's Unfinished Symphony: How Culture Made the Human Mind''. Princeton: Princeton University Press.