immunity: key immunological processes occur at the level of each cell (for
example, any cell of the organism infected by a virus will respond by triggering
a diversity of protective mechanisms, including the production of interferons
and other cytokines–a phenomenon often referred to as cell intrinsic immu-
nity –which can alter neighboring cells about the presence of the virus)
(Goubau et al. 2013) and at the level of each tissue. Most of the time, one can
distinguish degrees of immunological responses: in most multicellular organ-
isms, for instance, cell and tissue immunological responses are strongly con-
trolled and coordinated at the systemic level, so the systemic level seems to be
the level at which the highest degree of immunological integration is realized.
Interestingly, in some cases, the highest degree of immunological integration is
realized at the level of a colony rather than intuitively defined individuals. For
example, some data in a number of social insects such as termites and honey
bees suggest that key immunological processes occur at the colony level, which
has led to the concept of“social immunity”(Cremer et al. 2007; Jones et al.
2018) and has sometimes been used to support the superorganism hypothesis.
The conclusion of this discussion is that recent immunological research has
seen extensive revisions of its core concepts (particularly“self,”“tolerance,”
and“microbe”), which in turn have led to a significant reassessment of our
traditional understanding of biological individuality insofar as a living thing can
be seen as an immunologically unified chimera (Gill et al. 2006; Eberl 2010;
Bosch and McFall-Ngai 2011; Pradeu 2012). But do these changes have any
practical consequences? The short answer is that they have many practical
consequences, particularly from a therapeutic point of view. Let’s take two
Figure 3.2Rejection between two colonies ofBotryllus schlosseri.
When two colonies ofBotryllus schlosserimeet, they can reject (panel A) or
fuse (not shown). This occurs at the colony level. The brown zones show the
starting point of rejection. Panel B shows rejection at the more precise level of
ampullae. (Photographs courtesy of Tony De Tomaso, UCSB)
26 Elements in the Philosophy of Biology