Natural reward and macroevolution
Explaining the advancement of life through innovation, ecological expansion, and incumbent advantage.
Why has life expanded into new resource zones and acquired increasing command over free energy? The theory of natural reward addresses these macroevolutionary questions by distinguishing two evolutionary struggles and the non-random processes that act within them.
The question: adaptation and advancement
Natural selection explains how organisms become adapted to the conditions in which they live. It does not, by itself, predict that they will evolve the capacity to exploit new resources or enter new environments. Adaptation can produce specialization in a narrow way of life, leaving organisms vulnerable when their environment changes.
My research asks how evolutionary theory can explain the broader history of life: the appearance and spread of major innovations, the expansion of cellular, multicellular, and colonial forms, and progressive increases in the capacity to innovate. The theory of natural reward distinguishes this problem of advancement from the problem of adaptation.
The struggle for existence
Darwin’s struggle for existence includes the checks that limit population increase. These checks can arise from resource limitation, predators, parasites, and other ecological constraints. Within this struggle, heritable differences affect which variants leave more descendants.
The forms favored by natural selection need not have the greatest potential for ecological expansion. In social evolution, for example, a selfish action can be selectively favored even while reducing mean reproductive success. Conversely, a beneficial action can increase mean reproductive success without that total increase being captured by the effect responsible for its spread.
This distinction between relative success within a population and the capacity for population growth provides a starting point for asking what happens when an innovation permits escape from existing checks to increase.
The struggle for supremacy
An innovation can allow a lineage to exploit a previously inaccessible resource or environment. A form that reaches this opportunity first may expand and diversify before competitors arrive, gaining an incumbent advantage that makes subsequent invasion more difficult.
This struggle differs from competition among alternative variants within an established population. Its outcome depends on the discovery and occupation of ecological opportunities, and on the advantages acquired by being first.
Natural reward
I use natural reward to identify the evolutionary force associated with this incumbent advantage. Natural selection produces inventions adapted to existing conditions, without foresight about their potential in a broader ecological setting. Natural reward favors the dissemination of inventions that happen to permit expansion into new resource zones.
In an economic analogy, natural selection acts as nature’s inventor, while natural reward acts as nature’s entrepreneur. The analogy distinguishes the production of an invention from its expansion into a new market; both processes contribute to innovation.
Two processes in the history of life
Invention–conquest macroevolution
Through invention–conquest macroevolution, natural selection generates an innovation and natural reward promotes its expansion into ecological opportunities. The resulting incumbent advantage helps the innovators persist and diversify.
Extinction–replacement megaevolution
Incumbent advantage is also a constraint: established forms can prevent alternatives from gaining a foothold. Extinction can release these constraints, creating opportunities for replacement by new forms. Across long time frames, extinction–replacement megaevolution can increase life’s innovative capacity.
The theory therefore treats innovation and constraint together. Being first can enable expansion, but the success of an incumbent can also obstruct subsequent innovation.
The success of the innovative
The theory of natural reward proposes that the broad-scale history of life is characterized by the success of the innovative. This complements the role of natural selection in determining which heritable variants succeed within a population.
Advancement here concerns expansion into new resource zones and increased capacity to innovate. It is not a claim that every lineage becomes more complex, or that evolution follows a predetermined route. The central question is how the history of invention, expansion, incumbency, extinction, and replacement produces broad directional trends.
Connections to social evolution
My work on kin recognition shows how a complex trait can evolve through a historical sequence of cause and effect, while the final product has incidental consequences distinct from the selective pressures responsible for its origin. Kin recognition used for association preference may originate as a means of avoiding discriminatory conflicts, yet incidentally help protect complex social systems against the spread of intraspecific and interspecific parasites. From this perspective, the protective role emphasized by Buss may be better understood as a long-term consequence of kin recognition than as the adaptive explanation for its origin. This provides a connection to natural reward: a trait produced by selection in one context may incidentally enable persistence or expansion in another.
Innovation in science
Scientific theories and research programs can also acquire incumbent advantages. Established programs accumulate specialized models, evidence, expertise, and institutional support, while a new approach must demonstrate its promise before comparable resources become available.
I apply ideas from evolutionary theory and economics to ask how scientific institutions can support intellectual risk and entrepreneurship. This work examines how funding systems might create opportunities for new explanatory frameworks while preserving rigorous evaluation.
Publications and continuing work
Natural reward drives the advancement of life
Owen M. Gilbert · 2020 · Rethinking Ecology 5: 1–35
The published account of natural reward and its implications for the history of life.
Natural reward as the fundamental macroevolutionary force
Owen M. Gilbert · 2019 · arXiv preprint
An earlier, extended treatment of the theoretical framework.
The Advancement of Life
How Natural Reward Gives Evolution the Power to Innovate
My developing book project brings together evolutionary theory, the history of ideas, and the mechanisms underlying life’s capacity to innovate.