PD Dr. Michael Griesser

My research investigates the evolution of cooperation, language-like adaptations and cognition in birds. I combine diverse methods, including longitudinal studies, field experiments and comparative work to do my research. Our current research investigates the ecological and proximate drivers of social relationships among unrelated individuals.

The evolution of family living and cooperative breeding in birds

Cooperative breeding is an extreme form of cooperation that evolved in a range of lineages, but the factors favouring its evolution remain debated. Based on an analysis of about 3000 bird species, we showed that this behaviour evolved in two steps (Griesser et al 2017 PLoS Biology). First, families formed by prolonging parent-offspring associations, and second, these offspring began helping at the nest. We then showed that although the formation of families is associated with productive environments, the subsequent evolution of cooperative breeding is linked instead to low environmental productivity. These findings are consistent with patterns in insects and mammals (including humans), and clarify current disagreements on the role of environmental forces in the evolution of cooperation.

The adaptive value of family living: a safe haven to acquire vital life skills

I use my long-term study system, the Siberian jay (Perisoreus infaustus), to investigate the mechanisms and fitness consequences of family living. In this bird species, groups include a breeding pair, offspring that remain beyond independence in the family group, and unrelated non-breeders. This provides a natural experiment to assess the role of kinship in social interactions among group members. Experiments demonstrated that family living is highly adaptive as parents provide their independent offspring with nepotistic access to food and protection from predators (Ekman & Griesser 2016). Moreover, parents provide their offspring with opportunities to learn vital skills, such as predator recognition (Griesser & Suzuki 2017), boosting their survival and chances to become breeder in a high-quality territory. Ongoing work demonstrates that quick learning non-breeders have a higher survival probability and therefore do much better later on in life.

The evolution of language-like features in animals

Language is a defining feature of humans, but given its uniqueness, it is difficult to study the factors that ultimately drove the evolution of language. Thus, language evolution has been suggested to be one of the most difficult question to answer in science. Its power arises from our ability to combine meaningless vocal elements (phonemes) into words, which in turn are combined into meaningful phrases based on grammatical rules (syntax). My past and ongoing research (in collaboration with Ass. Prof Suzuki, Kyoto University, David Wheatcroft Stockholm University) demonstrates that birds have evolved several features that are also critical elements of language: referentiality (Griesser 2008) and syntactic combinations (Suzuki et al 2016, 2017, 2019) where elements with meaning are combined into more complex messages. Thus, language-like features also evolved in birds, but it remains open how widespread these adaptations occur.