Teaching with Evaluation in Ants

Abstract

Tandem running in ants is a form of recruitment in which a single well-informed worker guides a naive nestmate to a goal [1-8]. The ant Temnothorax albipennis recently satisfied a strict set of predefined criteria for teaching in nonhuman animals [9, 10]. These criteria do not include evaluation as a prerequisite for teaching [10]. However, some authors claim that true teaching is always evaluative, i.e., sensitive to the competence or quality of the pupil [11-13]. They then assume, on the premise that only humans are capable of making such necessarily complex cognitive evaluations, that teaching must be unique to humans. We conducted experiments to test whether evaluation occurs during tandem running, in which a knowledgeable ant physically guides a naive follower to a goal. In each experiment, we interrupted the tandem run by removing the tandem follower. The response of the leader was to stand still at the point where the tandem run was interrupted. We then measured how long the leader waited for the missing follower before giving up. Our results demonstrate T. albipennis performs three different kinds of evaluation. First, the longer the tandem has proceeded the longer the leader will wait for the follower to re-establish contact. Second, ant teachers modulate their giving-up time depending on the value of the goal. Finally, leaders have shorter giving-up times after unusually slow tandem runs.

On optimal decision-making in brains and social insect colonies

“…We argue that the interaction patterns between populations are the crucial part of the decision-making process at both these levels of biological complexity, organismal and super-organismal. Notwithstanding their impressive individual abilities (Koch 1999), neurons are simple in comparison with individually sophisticated social insects (Giurfa et al 2001;Chittka et al 2003;Franks et al 2003b;Franks & Richardson 2006;Richardson et al 2007). Simple interaction patterns in both these systems, however, may implement robust, efficient decision-making regardless of how sophisticated their individual components are.…”

“…In T. albipennis, scouts recruit nest-mates to a site they have discovered by tandem running, teaching others the route (Möglich & Hölldobler 1974;Möglich 1978;Franks & Richardson 2006;Richardson et al 2007). The recruiters pause for longer before recruiting to poor nests than they do for good nests (Mallon et al 2001).…”

Identifying teaching in wild animals

“…Moreover, teachers may have evolved mechanisms allowing sensitivity to current circumstances. Richardson, Houston, and Franks (2007), for example, showed that T. albipennis leaders' investment in a bout of teaching (a tandem run to or from a nest site) is responsive to the time already invested in that bout, the quality of the goal (poor or good quality nests), and the speed of the follower. Richardson et al's techniques of interrupting bouts of teaching and altering the quality of goals may be of great use in assessing the degree of sensitivity shown by teachers in other species as well.…”

“…Richardson et al's techniques of interrupting bouts of teaching and altering the quality of goals may be of great use in assessing the degree of sensitivity shown by teachers in other species as well. Further manipulations, such as experimentally reducing pupils' ability to learn (e.g., Richardson et al, 2007), may also prove helpful in analyzing teaching in vertebrate species but should be given careful ethical consideration.…”

Do ants need to be old and experienced to teach?

“…First, in T. albipennis tandem running has a pivotal role in new nest choice (Pratt et al, 2002); such decisions are likely to influence the inclusive fitness of all colony members, so it would benefit the colony to have the most able individuals performing this task. Second, tandem running is such a sophisticated form of communication that it actually qualifies as a form of teaching (Franks and Richardson, 2006;Richardson et al, 2007). Indeed, it trains other recruiters because followers of tandem runs often become leaders of subsequent tandem runs (Möglich et al, 1974;Franks and Richardson, 2006;Richardson et al, 2007).…”