Nov 15, 2012 | We are all lichens: How symbiosis research has reconstituted a new realm of individuality

Scott Gilbert (Howard A. Schneiderman Professor Swarthmore College)

UCSC Philosophy Department Colloquium

Thursday, November 15, 4 – 6 pm. Humanities 1, rm. 210

The notion of the “biological individual” is crucial to studies of genetics, immunology, evolution, development, anatomy, and physiology. Each of these biological sub-disciplines has a specific conception of individuality, which has historically provided conceptual contexts for integrating newly acquired data. During the past decade, nucleic acid analysis, especially genomic sequencing and high-throughput RNA techniques, has challenged each of these disciplinary definitions by finding significant interactions of animals and plants with symbiotic microorganisms that disrupt the boundaries which heretofore had characterized the biological individual. Animals cannot be considered individuals by anatomical, or physiological criteria, because a diversity of symbionts are both present and functional in completing metabolic pathways and serving other physiological functions.

Similarly, these new studies have shown that animal development is incomplete without symbionts. Symbionts also constitute a second mode of genetic inheritance, providing selectable genetic variation for natural selection. The immune system also develops, in part, in dialogue with symbionts, and thereby functions as a mechanism for integrating microbes into the animal-cell community. Recognizing the “holobiont”—the multicellular eukaryote plus its colonies of persistent symbionts– as a critically important unit of anatomy, development, physiology, immunology, and evolution, opens up new investigative avenues and conceptually challenges the ways in which the biological sub-disciplines have heretofore characterized living entities.


History of Consciousness Department, Center for Cultural Studies, and Science & Justice Working Group

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