How niche construction affects the carrying capacity = K of human environments

John Odling-Smee

Transcript

1. How niche construction affects the carrying capacity = K of human environments John Odling-Smee
2. Colleagues Kevin Laland School of Biology St. Andrews University John Odling-Smee School of Anthropology Oxford University Marc Feldman Biology Department Stanford University
3. Frederickson, M.E. et al., 2005. ‘Devils’ gardens’ bedevilled by ants’. Nature. 437. 495-6. Niche construction and ecological inheritance
4. Next generation t t+1 Populations of Phenotypes Populations of Phenotypes Genetic inheritance Standard evolutionary theory (SET) Et Et+1 Natural selection Natural selection Gene pool Gene pool
5. Next generation t t+1 Populations of phenotypes Populations of phenotypes Genetic inheritance Niche construction theory (NCT) Et Et+1 Natural selection Gene pool Gene pool Ecological inheritance Natural selection Niche construction Niche construction
6. Ecological inheritance: The inheritance, via an external environment, of one or more natural selection pressures previously modified by niche-constructing organisms.
7. Perturbation Organisms initiate change by physically modifying their surroundings. eg. Emission of detritus Organisms counteract change by physically modifying their surroundings eg. Thermo-regulation of nests Relocation Organisms move (or grow) into a new place eg. Invasion of a new habitat Organisms counteract change by moving to where the change is absent. eg. Seasonal migration Inceptive Counteractive The principal kinds of niche construction ( Odling-Smee et al, Niche construction, the neglected process in evolution. 2003. PUP. p.47.)
8. Sub-kinds of niche construction Positive niche construction . . . increases the fitness of the niche-constructing organisms Negative niche construction . . . decreases the fitness of the niche-constructing organisms Obligate niche construction (e.g.) a by-product of metabolism (e.g. detritus production) Facultative niche construction (e.g.) invest in an artifact (e.g. when payoff > cost)
9. Main differences between SET and NCT (i) Natural selection plus niche construction RECIPROCAL CAUSATION (ii) Genetic inheritance plus ecological inheritance NICHE INHERITANCE (iii) A DIFFERENT “MENU” SET is about the evolution of organisms in response to environments NCT is about the evolution of organisms PLUS those changes in environments that are caused by the evolution of organisms
10. The carrying capacities of environments = K Is K determined by environmental variables independently of organisms? or Do niche-constructing organisms co-determine K?
12. Schrodinger’s question - What is life? Living organisms are extremely improbable, very far from thermodynamic equilibrium systems. If it was just a matter of physics (as per the 2nd law of thermodynamics) organisms would not exist. But organisms exist. How?
13. Schrodinger’s answer “. . . the marvellous faculty of a living organism . . . . . . ‘It feeds upon negative entropy’ attracting . . . a stream of negative entropy upon itself, to compensate the entropy increase it produces by living . . .” From “What is Life?” Originally published 1944. Quote from CUP edition 1967. p. 73.
14. My question If organisms can only live by “feeding on negative entropy” (order) taken from their surrounding environments . . . . . . how can they possibly increase negative entropy, and increase eco-space . . . on earth . . . by living? . . . as has apparently happened
15. Feeding on negative entropy To stay alive organisms must . . . (i) Import energy and material resources that are relatively “rich” in free energy (e.g. food), from their environments (ii) Consume them (e.g. metabolism) (iii) Export degraded detritus, relatively “poor” in free energy (e.g. faeces), to environments Energy and matter resources = ecological resources, labelled Rp
16. Ecological resources = Rp (i) Diverse Rp exists, in the diverse habitats of diverse organisms (e.g.) nutrients = potentially limited planetary resources relative to specific organisms (ii) Radiant energy Rp from the sun = potentially unlimited solar resources relative to (e.g.) photosynthesising organisms
17. How can organisms gain negative entropy by harvesting Rp ? (i) Not by chance. (ii) Organisms must interact with their environments by active non-random work. Organisms do non-random physical work that, temporarily and locally, opposes the 2nd law of thermodynamics . . . . . . by governing their inputs and outputs selectively relative to their environments
18. More than physics – evolution too Non-random, 2nd law-opposing work depends on adaptive “know how” Organisms cannot interact with their environments selectively without being informed by algorithmic information* = “know-how” Adaptive algorithmic information is an evolutionary resource labelled . . . Ri Ri is accumulated by evolving populations, primarily by natural selection, and is transmitted to developing organisms, primarily by genetic inheritance *(Chaitin, 1987. Algorithmic information theory. CUP)
19. Rp + Ri Equipped with Rp by planetary and solar environments, and with Ri by evolution, organisms can oppose the 2nd law of thermodynamics temporally and locally . . . . . . by actively concentrating Rp = “a stream of negative entropy” on themselves . . . . . . and live
20. Beyond survival But organisms do more than live If sufficiently “fuelled” by Rp from their environments, and “informed” by evolution, organisms can produce other highly improbable systems too by their Ri -informed, 2nd law-opposing work. (i) Fit organisms reproduce (ii) Some make artefacts (iii) All emit detritus and DOM (dead organic matter) Artefacts and detritus are much less improbable than offspring organisms . . . but they are also far from thermodynamic equilibrium
21. Niche construction Each of these Rp (negentropy) generating activities of organisms . . . Reproduction* Constructing artefacts Emitting detritus and DOM$ . . . obeys the logic of NCT Each can change natural selection pressures, that feedback to populations of organisms via ecological inheritances, and select for different adaptive “know how”, or Ri *Normally we don’t think of reproduction as niche construction. But von Neumann did. He described how ‘universal construction machines’ make ‘copies’ in ‘natural automata’. (Automata Studies. 1956. PUP.) $ = by-product niche construction
22. Implications for ecospace When inserted into environments . . . each of these additional improbable products of the Ri -informed, 2nd law-opposing work of organisms . . . . . . affects ecospaces in ecosystems, temporarily and locally, by adding Rp (negentropy) to them In principle . . . it should therefore be possible for organisms to increase ecospace, and the carrying capacities (K) of environments, in ecosystems . . . . . . as well as to survive themselves . . . . . . with two provisos
23. Proviso 1 . . . from biology Adding extra Rp (negentropy) to an environment may not benefit the population that adds it (e.g.) by increasing K for “self” On the contrary, it may reduce K for “self” That raises the question: Who benefits? What populations can or cannot benefit from any extra Rp that is added to ecosystems by the Ri informed, 2nd law-opposing work of organisms? Self? Other? No one yet?
24. The “rules” (from NCT perspective) (i) Rp is relative to Ri Only organisms that carry adaptive Ri relative to the specific Rp generated by the Ri-informed work of “self” or “other”. . . can benefit from it (ii) Ri is relative to prior natural selection (iii) Prior natural selection can be changed by niche construction (iv) Rp generated by Ri-informed organisms changes selective environments (v) Changed natural selection in environments feedbacks via ecological inheritance to select for different Ri in evolving populations
25. Who benefits . . . from what? (i) Reproduction Alliances with relatives (shared Ri ) may increase K for self Competition with relatives may decrease K for self Increase in population size may increase K for others (e.g.) predators or parasites (different Ri ), but limit K for self (ii) Artefacts May increase K for self and for some other organisms (iii) Detritus Pollutes environment, and potentially decreases K for self May increases K for other organisms (e.g. detritivores) with different Ri Or . . . no one yet?
26. Self or other? In ecological successions early occupants typically impact negatively on environments relative to themselves (= inhibit self), but positively relative to succeeding taxa (= facilitate others). But early occupants may also tolerate others, or inhibit them.
27. Proviso 2 . . . from physics Ri -informed organisms can oppose the 2nd law of thermodynamics, temporarily and locally, by concentrating Rp in their environments . . . . . . but they cannot violate the 2nd law The local addition of Rp (negentropy) to environments always costs an increase in entropy somewhere else (e.g.) The construction of artefacts depends on importing “useful” Rp from somewhere . . . and dumping “not useful” detritus somewhere
30. Next generation t t+1 Populations of diverse humans Genetic inheritance Human evolution - based on genetic inheritance only, as in SET Et Et+1 Natural selection Natural selection Gene pool Culture Development Populations of diverse humans Gene pool Culture Development
32. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Jordan Egypt Sudan Uganda/ Rwanda Nigeria South Africa Milk drinkers/ pastoralists Persistence gene variant frequency Others
33. Table 1: Genes identified as having been subject to recent rapid selection with inferred culturally modified selection pressures (Laland et al. 2010. Nature Rev. Gen. 137- 148). Gene Known or likely function Known or inferred cultural selection pressure LCT (C/T-13910, G/C-14010, T/G-13915, C/G-13907) Digestion of milk and dairy products Dairy farming and milk usage G6PD Resistance to malaria Farming (e.g. fava beans) ADH Alcohol metabolism Alcohol consumption FOXP2 Language skills, vocal learning Language use, vocal learning Cytochrome P450 genes, esp. CYP3A5, CYP2E1, CYP1A2 andCYP2D6 Detoxification of plant secondary compounds Domestication of plants SLC24A5, SLC25A2, EDAR, EDA2R, SLC24A4, KITLG, TYR, 6p25.3, OCA2, MC1R, MYO5A, DTNBP1, TYRP1, RAB27A, MATP, MC2R, ATRN, TRPM1, SILV, KRTAPs The externally visible phenotype (skin pigmentation, hair follicles, eye and hair colour, freckles) Culture facilitated dispersal and local adaptation, or possibly sexual selection CDK5RAP2, CENPJ, GABRA4, PSEN1, SYT1, SLC6A4, SNTG1, GRM3, GRM1, GLRA2, OR4C13, OR2B6, RAPSN, ASPM, RNT1, SV2B, SKP1A, DAB1, APPBP2, APBA2, SKP1A, PCDH15, PHACTR1, ALG10, PREP, GPM6A, DGKI. asp , ASPM, MCPH1 Nervous system genes and genes involved in brain function and development, brain size genes Selection for complex cognition on which culture is reliant CD58, APOBEC3F, CD72, FCRL2, TSLP, RAG1, RAG2, CD226, IGJ, TJP1, VPS37C, CSF2, CCNT2, DEFB118, STAB1, SP1, Zap70, BIRC6, CUGBP1, DLG3, HMGCR, STS, XRN2, ATRN Immunity genes, pathogen response Dispersal, agriculture, domestication and aggregation exposed humans to new pathogens MAN2A1, SI, SLC27A4, PPARD, SLC25A20, NCOA1, LEPR, LEPR, ADAMTS19–20, APEH, PLAU, HDAC8, UBR1, USP26, SCP2, NKX2-2, AMY1 Genes related to the metabolism of carbohydrates, starch, protein, lipids and phosphates, including genes involved in metabolizing mannose, sucrose and fatty acids. Carbohydrate metabolism and blood-sugar regulation Culturally modified dietary preferences BMP3, BMPR2, BMP5, GDF5 Various genes involved in skeletal development Culture facilitated dispersal and local adaptation, sexual selection. MYH16 Gene deletion reduces jaw muscle fibres Invention of cooking AHSA1 Heat shock genes Culture facilitated dispersal and local adaptation
34. Next generation t t+1 Populations of diverse humans Genetic + epigenetic inheritance I Human evolution - based on genetic & ecological inheritance, as in NCT Et Et+1 Natural selection Gene pool Culture Development Populations of diverse humans Gene pool Culture Development Including “cultural knowledge” and material culture Niche construction Natural selection Niche construction Ecological inheritance
35. Alternative responses to feedback from cultural niche construction Cultural niche construction modifies environments Route 1 Route 2 Cultural processes Cultural response No cultural response Gene pool Cultural niche construction Modified environments Culturally transformed natural selection Route 2a Changed genetic influences on cultural processes
36. Logistic Growth (in biology) dN/dt = rN(1 –N/K) K = an exogenous variable= r N (1 - N/K)
37. Invention is the creation of something new and distinct Innovation occurs when inventions become economically or ecologically significant • Economic growth depends on repeated inputs of new technology K = an endogenous variable Growth in economics . . . invention & innovation Joseph Schumpeter (1883-1950) (Erwin, D.H. 2008. Macroevolution of ecosystem engineering, niche construction and diversity. TREE. 23. 304-310.)
38. Thomas Malthus (1798) “The power of population is indefinitely greater than the power of the earth to produce subsistence for man” (From: An essay on the principle of population Chp 1. p.13) Esther Boserup (1910- 1999, anti-Malthusian agricultural economist) “The power of ingenuity would always outmatch that of demand” (In a letter to TS Hueston: philosopher) Ronald Lee (1986 demographer) “Boserup observes quite plausibly that the likelihood of technological advance rises in response to increasing population density” (Malthus and Boserup: a dynamic synthesis (1986. p,100) In A.Briggs, D. Coleman & R. Schofield. The state of population theory: forward from Malthus. Blackwell)
39. HUMAN INGENUITY IN AGRICULTURE: Controlled use of fire can affect K (Smith, B.D., 2007, Evolutionary Anthropology, 16, 188–199)
41. Richerson et al’s counter-argument (i) Population growth is a consequence of technical innovation, not its cause. It does not precede it. (ii) Technical innovations generate pulses of increased resources, but human populations use up the bounty of each pulse by growing again, sometimes explosively, until . . . . . . they reach a limit set by a new K Richerson P.J. Boyd, R. and Bettinger, R.L. (2009). Cultural innovations and demographic change. Human Biology. 81. 211-235.
42. Goods vary in their degree of rivalry and excludability. (Romer, P.M. 1990. Endogenous technological change. J. Polit. Econ. 98.) Rivalrous goods (resources/products) are those that can only have one user at a time (e.g.) a bicycle Non-rivalrous goods are those that can have multiple users at any time (e.g.) computer software Excludable versus non-excludable goods differ in how easy it is for one user to exclude others (e.g.) a parking space, versus calculus Romer realised that growth in human economies ultimately depends on the invention of non-rivalrous, non-excludable goods. (e.g. the web) (Erwin, D.H. 2008. Macroevolution of ecosystem engineering, niche construction and diversity. TREE. 23. 304-310.)
43. The tragedy of the commons Hardin, G, 1968. Science 162. 1243-48 Too many people = N exploiting the same limited resource = Rp N . . . . not OK . . . . relative to K Intelligent solution ‘Cooperative’ management of the commons - seldom happens Unintelligent solution ‘Selfish’ mismanagement of the commons - often happens (e.g.) Overfished-fisheries
44. K in NCT The carrying capacity of environments, K, explicitly depends on interactions of exogenous and endogenous variables. (i) Biologists and economists are partly right. (ii) But both are partly wrong . . . and in opposing ways. For example Biologists often underestimate the capacity of endogenous variables (e.g.) niche construction, to modify K Economists often underestimate the capacity of exogenous variables to limit K
45. A better theoretical framework? Darwin* . . . “happened to read for amusement Malthus on Population” Natural selection was derived from thinking about exogenous variables NCT adds the modification of natural selection by niche construction Niche construction was derived from thinking about endogenous variables NCT provides an interdisciplinary framework for investigating the interactions of exogenous and endogenous variables . . . . . . and for investigating K * From Darwin’s autobiography
46. Power stations affect K +/-? For who? For how long? For what other species?