  In recent years it has become evident the need of understanding how failure
of coordination imposes constraints on the size of stable groups that highly
social mammals can live in. We examine here the forces that keep animals
together as a herd and others that drive them apart. Different phenotypes (e.g.
genders) have different rates of gut fill, causing them to spend different
amounts of time performing activities. By modeling a group as a set of
semi-coupled oscillators on a disc, we show that the members of the group may
become less and less coupled until the group dissolves and breaks apart. We
show that when social bonding creates a stickiness, or gravitational pull,
between pairs of individuals, fragmentation is reduced.
