A systems science of human reproduction
The Institute for Systems Demography develops a rigorous, testable science of how human reproductive systems behave.
Rather than treating fertility primarily as a single rate or outcome, systems demography examines the structures through which reproductive change occurs: how people enter parenthood, when births occur, how reproductive populations change through time, and how those changes propagate through the demographic system.
ISDEM's primary object of study is human reproduction. Mortality, migration, partnership formation, economic conditions and other demographic or social processes enter its research where they interact with reproductive systems.
Why Fertility?
Fertility has a distinctive place within population dynamics because it is recursive. Reproduction creates the future population from which subsequent reproduction occurs. Changes in reproductive timing, entry into parenthood, and family size can therefore propagate through generations, altering the structure within which future demographic change unfolds.
Biological fecundity places obvious limits on human reproduction. Emerging evidence raises a further question: whether reproductive demographic systems are also subject to structural constraints that limit the range of aggregate states and trajectories they can follow.
ISDEM investigates this possibility empirically. The objective is to identify the state variables of reproductive systems, map their feasible state space, characterise the relationships through which change propagates, and test whether those relationships hold across populations and through time.
Individual reproductive behaviour may be highly heterogeneous while the aggregate systems through which it is expressed occupy a substantially more constrained state space.
Research Program
Structure → Mechanism → Measurement → Prediction
The state variables, governing relationships and dynamic processes of reproductive demographic systems.
The mechanisms generating observed reproductive patterns, judged by predictive power rather than theoretical allegiance.
Validating demographic measures against realised outcomes and developing measures capable of distinguishing structurally different forms of fertility change.
Systems-based forecasting of reproductive change, tested prospectively against what actually happens.
The institute takes no position on whether birth rates should rise or fall. Its commitment is to the accuracy of the picture on which societies and governments decide.
Selected Research
Stephen J. Shaw, “On a microdemographic framework for decomposing contemporary fertility dynamics,” Scientific Reports, 2025.
Founding Director
Stephen J. Shaw
Demographer and data scientist
Stephen J. Shaw is a demographer and data scientist whose research examines reproductive timing, fertility measurement, childlessness and the structural dynamics of contemporary fertility. His peer-reviewed research has been published in Scientific Reports, part of Nature Portfolio.