About Development
A Big Picture View of Development
About Development
A Big Picture View of Development
When people think about development, they often think of childhood. But childhood is only one especially visible part of a much larger process. About Development does not focus on findings and methods in any particular area of developmental science. Instead, it steps back to ask what development itself involves, and how we should think about change in living individuals. Below are links to a set of readings that outline this broader view.
Development is remarkably reliable, yet living form is not simply present in miniature at the beginning. How does organized form arise so dependably without assuming that the outcome was already specified in advance? That question leads to the role of DNA, but also to the activity of the developing organism and to the conditions through which a life cycle is reconstructed.
The same problem appears in the development of bodies and brains. A brain is not built first and then handed over to an organism that begins using it. Neural development occurs within a living body that is already active, and what develops at one point changes the possibilities available later. Throughout the resource, the aim is not to replace one master cause with another, but to ask what developmental process actually needs to explain.
The readings are written for students and for other readers interested in development across psychology, neuroscience, and biology. They are connected, but each is intended to stand on its own. You can follow the numbered sequence from the beginning or enter through a topic that interests you and use the surrounding readings to go further.
This resource originates in work by Peter J. Marshall at Temple University in Philadelphia (USA). For background on this open educational resource (OER) as well as reading tips and information on licensing and attribution, see this page.
Part 1 begins by asking what counts as development, how developmental questions change when we look across different timescales, and what it means to say that development has direction. It then widens the view to the evolutionary origins of development in the context of multicellular bodies.
Development is often identified with childhood, growth, or change with age. This reading begins by asking what should actually count as development and why development matters for understanding living individuals across the lifespan.
1.2 The Big Picture of Development
Development can be examined at many timescales, from changes unfolding over moments to the history of an individual life and the much longer histories of generations and species. This reading introduces explanatory frames as a way of asking how these different processes and histories fit together.
1.3 Life Cycles and Developmental Direction
Development has direction, but that does not mean that its endpoint was specified in advance. This reading considers life cycles, Aristotle’s idea of telos, and how a developing individual can move through an organized sequence without simply executing a preexisting plan.
1.4 The Origins of Multicellular Development
Multicellular bodies were not always part of life on Earth. This reading asks how multicellular development arose and what became possible once cells began developing together as parts of a larger living individual.
The second set of readings turns to the problem of how living form is made. It revisits preformationism and epigenesis, asks what form and organization mean, examines DNA as a developmental resource, and discusses the implications of Developmental Systems Theory for the relation between development and evolution.
If the adult organism is not already present in miniature at the beginning, where does its organized form come from? This reading revisits the historical debate between preformationism and epigenesis as a problem that developmental explanation still has to solve.
2.2 The Riddle of Form and Matter
What makes a living thing the kind of thing it is cannot be found simply by listing what it is made of. Beginning with Aristotle’s distinction between form and matter, this reading asks how organization can arise without being stored as a complete plan.
2.3 DNA as a Developmental Resource
DNA matters enormously for development, but what exactly does it do? This reading distinguishes the real molecular functions of DNA from the stronger idea that DNA contains a blueprint or program for the organism.
2.4 Developmental Systems Theory
Development draws on many resources, including genes, cells, bodies, activity, and environmental conditions. Developmental Systems Theory asks what follows if these are treated as parts of a developing system rather than as separate contributions from nature and nurture.
Evolution does not merely produce traits that development later expresses. Development generates variation in form and activity, and evolutionary change can involve changes in the developmental processes through which life cycles are reconstructed.
The final part turns to the developing body and brain. It begins with the evolution of nervous systems within active bodies, then shifts to the development of the cerebral cortex to illustrate how plasticity operates within constraints as organisms develop.
3.1 The Evolution of Bodies and Brains
Brains did not evolve on their own. They emerged within bodies that were already organized for movement, sensing, and activity, and changes in the development of bodies helped make new kinds of nervous systems possible.
This reading focuses on the development of the mammalian cortex as an area of study. This reading examines how neural activity, bodily organization, movement, sensory systems, and surrounding conditions participate in the reliable development of cortical organization.
The developing cortex is plastic, but plasticity does not mean unlimited malleability. This reading asks how developmental possibilities are opened and narrowed through the history and organization of the developing system.
Drawing together the themes of About Development, the Coda considers what a developmental perspective changes about how we explain living systems, brains, and human lives.