A new study from the University of Cambridge reviews the history of human embryology and development research, highlighting the “cycles of attention” that led to significant breakthroughs.
Professor Nick Hopwood from the Department of History and Philosophy of Science explains the recent resurgence in human development research by analyzing the past. Published in the Journal of the History of Biology, the study covers the boom in human embryology a century ago, its decline after World War II, and its revival since the late 20th century.
Most articles and news stories on human development include some history. However, it often needs to be more accurate and accurate. I wanted to see the bigger picture and understand the reasons behind the renewed Interest. Being in Cambridge helped a lot.
The University has led innovation from the first test-tube baby to advanced embryo culture, organoids, and stem-cell models. Through Cambridge Reproduction, experts in science, medicine, humanities, and social sciences helped Hopwood trace these advancements—this involved library research, archives, interviews, document sharing, conferences, and talks.
Studying human development is challenging due to the hidden nature of embryos in pregnant bodies. Historically, researchers either studied other animals, hoping results would transfer (an indirect approach), or worked with the limited human specimens available (a direct approach). This article examines how the focus on human material grew and how human studies still relied on animal research.
Evolution debates increased Interest in human embryos in the late 19th century. Darwinists highlighted early similarities between humans and animals as evidence of common descent. Critical anatomists formed networks to collect materials, mostly from pregnancy losses. New techniques like serial sectioning and wax modeling made 3-D views of internal structures possible.
This led to a significant milestone: the Carnegie Institution of Washington established the first embryology research department at Johns Hopkins University in 1914. Focusing on human embryos, researchers made vital discoveries, such as the timing of ovulation and descriptions of embryos in the first two weeks after fertilization.
After World War II, human embryology lost momentum. Developmental biology became prominent, focusing on model organisms like flies, frogs, chicks, and mice due to more accessible research capabilities involving micromanipulation, biochemical studies, and genetic tools.
This approach revealed similarities in development mechanisms across animals in the 1980s, sparking renewed Interest in human material. Research on human development fluctuated throughout the 20th century due to shifting opportunities and politics.
The rise of human in-vitro fertilization in 1978 and the UK Human Fertilisation and Embryology Act 1990 allowed better access to embryos for research despite opposition and limited donations. New technologies in digital communication, molecular analysis, and imaging have transformed the field, making the study of human embryos more accessible and accurate.
Researchers needed to justify studying human embryos by highlighting that mouse models alone weren’t enough, as understanding human-specific details is crucial for clinical applications like fertility treatments. Funders supported this for its medical benefits.
Over the past fifteen years, stem-cell-based embryo models have transformed the field, enabling new experiments on human development and suggesting these human systems as the new standard for vertebrate development. This shift created the sub-field of human developmental biology, marked by conferences and significant research programs.
Hopwood’s research, focused on the USA and the UK, suggests exploring other countries’ histories due to differing reproductive politics. He believes understanding history can help maintain public support for research. He also questions whether current Interest in human development will persist or shift back to animal models and how present actions will shape future species choices in research.
Journal reference :
- Hopwood, N. Species Choice and Model Use: Reviving Research on Human Development. Journal of History of Biology. DOI:10.1007/s10739-024-09775-7.