Great Tits give insight into personality

Does evolution always favour the bold and the beautiful? simondbarnes

In an Oxford woodland a soap opera plays out with the familiar plotline so loved by daytime television devotees – infidelity and the battle between bold and shy personas.

The main twist in this tale is that the lead characters are all birds and that the story is the latest piece of research into how evolution shapes personality and promiscuity, published in the Proceedings of the Royal Society B.

While we tend to think of personality as a uniquely human trait, in fact, over the past decade there has been an increasing realisation that in animal populations there is also considerable variation in the character of different individuals.

Some individuals will have a much higher propensity to explore new situations than others – they have an inherent boldness. We can learn a lot about how personality evolves by studying it in animal populations that can, in a relatively short time, be followed across generations and be subject to experimental manipulations that are simply not possible in humans.

Some of the best of this work has focused on the Great Tit, a small passerine bird about which we probably know more than any other bird in the world.

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The population of Great Tits in Wytham Wood in Oxford has been studied continuously since 1947 by researchers from the Edward Grey Institute of Ornithology, Oxford University.

The strength of studies such as this is that individuals and their offspring can be monitored for their lifetime. An extensive pedigree has been established of the birds that have lived in Wytham Wood over the past six decades allowing evolutionary biologists to study how traits are passed from one generation to another, and how a population changes over time.

In such a way the processes of evolution can be seen, almost in real time.

In their study, Dr Sam Patrick and her colleagues found bold males were more successful in cuckolding other males in the population.

But the most interesting finding was that, despite their success in gaining sneaky extrapair offspring, bold males were not more successful overall. Shy males fathered a higher number of offspring in their own nests, and together the two effects cancelled each other out.

Therefore, at the time of their study, bold males and shy males do as well as each other in evolutionary terms – on average they pass on their genes to the same number of individuals in the next generation.

This helps us to understand why there is so much variation in traits such as boldness. If one personality type consistently out-competes another, and if personality is genetically heritable then over time we would expect that personality type to dominate.

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In many animals, including humans we find a whole spectrum of variation in personality from shy retiring types to bold extroverts. Diversity is indeed the spice of life.

Personality traits such as boldness, sociability, and aggression in animals and humans are likely to influence success in many different aspects of an individuals’ life, such as acquiring resources, getting a partner and producing offspring.

The study by Dr Patrick and colleagues suggests that the relationship between these personality traits and other aspects of life will not provide straightforward answers.

There is some comfort for everyone in the message from these birds that there is more than one way to be successful in life.