260 Self and the Phenomenon of Life
b2726 Self and the Phenomenon of Life: A Biologist Examines Life from Molecules to Humanity “9x6”share a nest in which all the females lay their eggs. All members of the
group participate in the defense of territory, incubation of the eggs, and
feeding of the young. Adults cannot recognize their own eggs or nest-
lings so no preferential treatment is possible. In this communal breed-
ing, individual fitness of all the pairs increases. Bigger pairs are able to
defend nesting sites better than smaller pairs, and pairs attempting to
breed alone invariably fail. This is a success story of non-kin cooperation
within the same species.^2
12.3 Lessons from Microbial Communities
Bacteria are commonly viewed to be individualistic and enjoy indepen-
dent existence. More recent studies, however, revealed certain degrees
of social interaction. Quorum sensing is a decision-making process used
by bacteria to communicate to one another a change in environment,
as a result of which they switch from a nomadic life to one in a biofilm,
where they survive better en masse and become resistant to antibiotics.
Bacteria of different species can easily undergo “horizontal” gene trans-
fer through which they exchange their genetic materials to form new
species. It is believed that such genetic recombination accounts for 80%
of evolution of bacterial proteins. Different species of bacteria also form
metabolic alliances, in that the end product of one becomes the nutrient
of another, and vice versa.^3 Certain bacteria in the wild are organized
into socially cohesive units in which antagonism occurs between, but
not within, ecologically defined populations. Bacterial clusters known to
have cohesive habitat association also act as units in terms of antibiotic
production and resistance. Within a population, antibiotics produced by
a few are tolerated by all other members, suggesting cooperation among
the individuals.^4
Yeast cells respond to their environment in a collective manner.
It was reported that when food source is scarce, there is a selective pres-
sure for yeast to grow in clumps. Yeast cells normally secret the enzyme
invertase into the medium to split sucrose into glucose and fructose,