Was Henry David Thoreau a good naturalist?

 By Richard B. Primack

“It is not enough that we are truthful; we must cherish and carry out higher purposes to be truthful about.”  Henry David Thoreau in Early Essays and Miscellanies. 

For much of the past century-and-a-half Henry David Thoreau has been regarded as one of America’s greatest environmental philosophers. Meanwhile, his extensive observations of the natural world were largely ignored or criticized for their inaccuracy. 

An example of Thoreau’s records of plant flowering times. Primack notes are in blue.

Were Thoreau’s observations good enough for scientific use? Or were his early critics right?

In a recent article published in the journal BioScience, we present a framework for evaluating the scientific observations of historical figures using the criteria of rigor, accuracy, and utility. We apply this framework to Thoreau’s observations of flowering, leafing out, fruiting, and bird arrival times in Concord, Massachusetts. 

Not surprisingly, we find Thoreau was a good naturalist. His observations are rigorous—based on frequent and repeatable sampling. They are accurate—based on a comprehensive knowledge of species and places. And they have utility in modern ecological studies of climate change. 

The sequence of flowering of spring wildflowers that Thoreau observed is almost identical to current observations of flowering times.

This study adds to our confidence in what Thoreau has to tell us about how to observe the nature world and how we can use his observations to understand how climate change affects our world today.  

Publication: Richard Primack, Abraham Miller-Rushing, Tara K. Miller  (2022). Was Henry David Thoreau a good naturalist? An approach for assessing data from historical natural history records. BioScience.  https://doi.org/10.1093/biosci/biac063