Longer childhoods help young birds become more intelligent, study finds

Study of corvid populations highlights ‘vital role’ parents play in allowing young minds to develop

Carrion crow. Scientists tracked two species of corvid to find out how their chick-rearing techniques affected their success (Getty )

Even among primates, humans’ lengthy “extended childhood” is unusual. But could it be the key to the success of our species?

Scientists have long believed the years of childhood and adolescence, in which parents provide and care for their offspring, and give us the time and opportunity to explore, create and learn, allows us to learn complicated skills we otherwise would not be able to develop.

Across the animal kingdom, such extended childhoods are not common. But there are other species who take longer to reach maturity, including elephants, dolphins, whales, some bats, and a few species of birds, notably corvids – the crow family.

But does this extra time result in more mentally nimble offspring too? And if so, then how do parenting techniques alter the results?

Focusing on two species of corvid – the Siberian jay and the New Caledonian Crow – researchers spent years observing the species in the wild to understand how young birds’ learning is related to parenting received during adolescence and survival in adulthood.

They found that due to this parenting technique, similar to humans, the birds had greater opportunity to learn complex tasks, grew bigger brains, and allowed them to access larger quantities of food. This resulted in higher rates of survival and possibly allowed the birds to spread into new environments.

The authors, made up of scientists from the Max Planck Institute for the Science of Human History and the University of Konstanz in Germany, said the work “offers a groundbreaking new view on the evolution of intelligence, where parenting takes centre stage”.

In order to assess the birds, at a study site in Sweden the researchers used field experiments to test the ability of young Siberian jays to learn crucial life skills: recognising a dangerous predator and opening a puzzle box to access food.

Across Europe, north Africa and Asia, Siberian jays live in family groups which can include not only the young of a breeding pair, but also young that were born in other groups. These young can stay with the family group for up to four years.

The birds that stayed with their parents longest appeared to benefit from being with their parents: they learned faster by watching their parents and received more food from their parents.

As a consequence, they were more likely to live longer and to start their own family.

Meanwhile, at a study site in New Caledonia in the south Pacific, east of Australia, researchers tracked New Caledonian crows to find out how juveniles learn a key survival skill: making tools for food retrieval.

This population of crows has developed a cunning technique of using twigs as tools to push into logs to better reach their prey. What’s more, previous research has revealed the birds carefully select their twigs and either choose hooked twigs, or carved a hook into twigs themselves.

Using a hooked twig is up to ten times more effective than the straight tool, the scientists found, indicating not only are New Caledonian crows tweaking and improving their old designs, but are also possibly sharing their knowledge with other members of their species, according to the research, reported in the National Geographic.

The new study found it takes about a year for young New Caledonian crows to learn how to use tools – a costly time investment for the parents who still have to feed the young. But these crows can stay with their parents for up to three years, allowing for a much longer “childhood” than most other crows.

The scientists observed that parents and other adults are extremely tolerant to young crows. While adults are using a tool to get food, they feed the juveniles, let them watch closely, and even tolerate tool theft and physical contact by juveniles.

As a result of this tolerant learning environment, New Caledonian crows have the largest brain size for their body size of all corvids.

The authors argue the role of parenting on the evolution of cognition has been overlooked so far.

They said that while it has often been regarded as merely an “inevitable chore”, parental care is the reason children can spend their childhood learning and making mistakes.

“Extended parenting has profound consequences for learning and intelligence,” said Michael Griesser of the University of Konstanz.

“Learning opportunities arise from the interplay between extended childhood and extended parenting. The safe haven provided by extended parenting is critical for learning opportunities. It creates extended developmental periods that feed back into the extended childhood.”

Looking at the key evolutionary differences between corvids and all other passerines (a large group mostly made up of smaller perching birds), the scientists found corvids have much larger brains relative to their body size, like humans. They also have prolonged developmental periods, both in the nest and after they leave – another characteristic of humans.

“Both humans and corvids spend their youth learning vital skills, surrounded by tolerant adults which support their long learning process,” said Natalie Uomini of the Max Planck Institute.

She added: “Moreover, corvids and humans have the ability for lifelong learning – a flexible kind of intelligence which allows individuals to adapt to changing environments throughout their lifetime.”

The scientists said their study brings the importance of parenting into even sharper focus, and shows how a nurturing and supportive environment is needed to allow brains to reach their potential.

The study is published in Philosophical Transactions of the Royal Society B.