After Cuvier’s death, Agassiz became a professor at the Lyceum of Neuchatel in Switzerland, where for thirteen years he worked on many projects in paleontology, systematics, and glaciology. Agassiz began studying glaciers in 1836 as something of a sideline, but his contributions made him known as the “Father of Glaciology.”
In 1848, Agassiz became a professor at Harvard University. He immediately set about establishing a great museum of natural history. In 1859, his dream came true with the founding of the Museum of Comparative Zoology, which opened its doors in 1860. Agassiz labored for support of science in his adopted homeland; he and his colleagues urged the creation of a National Academy of Sciences, and Agassiz became a founding member in 1863. Agassiz was also appointed a regent of the Smithsonian Institution in 1863.
The cornerstone of Agassiz’s biological thought was his belief that the ranking from low to high forms, in any taxon, paralleled the order of appearance in the fossil record, the order of stages in the organisms’ development, and the distribution and ecology of the taxon. The “lowest” forms were found lowest in the rock record, earliest in embryonic development, and at the highest latitudes. Agassiz summed up his thought in his Essay on Classification, first published in 1851:
…the phenomena of animal life correspond to one another, whether we compare their rank as determined by structural complication with the phases of their growth, or with their succession in past geological ages; whether we compare this succession with their relative growth, or all these different relations with each other and with the geographical distribution of animals upon the earth. The same series everywhere!
Darwin, and many others after him, accepted these parallelisms as providing evidence for evolution. Darwin wrote in The Origin of Species that “this doctrine of Agassiz accords well with the theory of natural selection.” But Agassiz was no evolutionist; in fact, he was probably the last reputable scientist to reject evolution outright for any length of time after the publication of The Origin of Species. Agassiz saw the Divine Plan of God everywhere in nature, and could not reconcile himself to a theory that did not invoke design. He defined a species as “a thought of God.” As he wrote in his Essay on Classification:
The combination in time and space of all these thoughtful conceptions exhibits not only thought, it shows also premeditation, power, wisdom, greatness, prescience, omniscience, providence. In one word, all these facts in their natural connection proclaim aloud the One God, whom man may know, adore, and love; and Natural History must in good time become the analysis of the thoughts of the Creator of the Universe…
Natural theology had once inspired countless scientists, including Darwin and his forerunners, but by the time of publication of the Origin of Species it had largely run out of steam, unable to offer any real explanation for natural phenomena except “God made it that way.” Within Agassiz’s lifetime, and much to his grief, most of his students — including his son Alexander, a well-known naturalist in his own right — became evolutionists, though not necessarily Darwinians.
Yet Agassiz still made lasting contributions to evolutionary biology and systematics. Perhaps Agassiz’s greatest lasting insight was the realization that paleontology, embryology, ecology, and biogeography had to contribute to any classification that purported to show the true relationships of organisms — even if those relationships, to Agassiz, existed only in the mind of God. As he wrote in his Essay on Classification:
Classification seems to me to rest upon too narrow a foundation when it is chiefly based on structure. Animals are linked together as closely by their mode of development, by their relative standing in their respective classes, by the order in which they have made their appearance upon earth, by their geographical distribution, and generally by their connection with the world in which they live, as by their anatomy. All these relations should, therefore, be fully expressed in a natural classification; and though structure furnishes the most direct indication of some of these relations, always appreciable under every circumstance, other considerations should not be neglected which may complete our insight into the general plan of creation.