In the early nineteenth century, views on the nature of living organisms were broadly divided into two categories, chemical and vitalist. The former held that life was a consequence...
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In the early nineteenth century, views on the nature of living organisms were broadly divided into two categories, chemical and vitalist. The former held that life was a consequence of complex, but ultimately knowable physicochemical processes, while the latter posited some nonnatural, perhaps unknowable, properties of living systems. Vitalism was progressively undermined by Wohler's synthesis of urea (1828) and by Pasteur's inability to demonstrate spontaneous generation (1862), as well as by Darwin's Origin of Species (1859) and Virchow's cell theory (1855). By the turn of the twentieth century the remarkable properties of living systems were more evident than ever, but vitalism was no longer invoked to explain them. The modern scientific quest for the chemical basis of life had begun in earnest. Although heredity was known as an important property of living organisms, investigations of the chemical basis of life concentrated as much on other attributes, such as metabolism and movement.
At the close of the twentieth century, genetics reigns triumphant as the central theme in biological thought. The sequence of the human genome is widely seen as the starting point for biological investigation in the next century, and the debate on the origin of life largely defines “alive” as equivalent to “accurately transmitting a genetic blueprint.” We do not question the importance of genetics, nor dispute the role of DNA as the blueprint for all the components of living systems, but we think it worth asking to what extent the “postgenomic” view of modern biology would convince a nineteenth century vitalist that the nature of life was now understood. How close are we to understanding how a single cell functions or how an embryo develops? If the answer is not so close, will true understanding of living systems come from further annotating the database of genes, or must we explore the physicochemical nature of living systems? In this essay we discuss a few personal favorite examples, starting from macromolecular assembly and increasing in complexity and scale to patterning in vertebrate embryology. Our discussion illustrates the nature of biological organization and explores the potential chemical principles behind them. Although the units we consider, proteins, cells, and embryos are manifestly the products of genes, the mechanisms that promote their function are often far removed from sequence information. In a light-hearted, millennial vein we might call research into this kind of integrated cell and organismal physiology “molecular vitalism.”