The theme of the 175th Annual Meeting of the American Association for the Advancement of Science (AAAS), “Our Planet and Its Life, Origins, and Futures,” celebrated an enormous breadth of scientific accomplishments that transcends many subdisciplines of the natural and social sciences. It was intended to be both a reflection on what has been learned and a look forward to what must yet be better known if we are to make wise choices as stewards of our planet. The program committee saw this as an opportunity to examine how we have come to know and understand the coevolution of life with its interacting biological, biogeochemical, and physical environments. Further advances in this area are essential to develop scenarios that can be useful in guiding decisions to address some of society’s most pressing problems. We must work toward a future that embraces the wise application of science to improve human health and well-being and to sustain the great diversity of life on our planet.
The occasion of this annual meeting, which opened on the very day of the 200th anniversary of the birth of both Charles Darwin and President Abraham Lincoln, prompted special reflection on the significance of Darwin’s contributions to our knowledge of the coevolution of organisms and their environment and the role that President Lincoln played in the advancement of science and, in particular, its application for the benefit of societal well-being. The meeting program was rich with papers and symposia that celebrated the 150th anniversary of Darwin’s publication On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. Darwin’s thesis was the product of decades of careful observations of the natural world, which he argued could be explained by natural selection. This year he is being properly heralded for his unequaled influence on our understanding of how life on Earth is sustained and how it changes to accommodate differing conditions over time. Today, even with our far more sophisticated understanding of the processes by which evolution occurs, Darwin’s thesis remains robust. We now also know much more about how physical and chemical aspects of the environment for life have changed, and how inextricably life and its environment continue to coevolve. Regulatory aspects of feedbacks in the collective Earth system, between life and the physics and chemistry of the atmosphere, soils, and oceans, have provided a persistent habitable condition for a vast diversity of life over the past three billion-plus years.
A profound lesson from the past few decades of scientific discovery across the Earth and life sciences is that the weight of the human footprint on essential life-supporting services of the Earth system has grown dramatically since the time of Darwin. Over the past 150 years, our population has grown fivefold. Our consumption of resources has grown even more. Some of this consumption has resulted in degraded conditions in terrestrial and coastal marine ecosystems that will, under the best of circumstances, persist for generations to come. Greenhouse gases released today by anthropogenic activities will affect the heat budget of Earth’s atmosphere for tens of human generations. Some depleted aquifers will take even longer to recharge. For all intents and purposes, resources such as fossil oil have no prospect for regeneration on meaningful societal time scales. Species extinctions are irreversible.