Gavin Hunt was researching his PhD in New Caledonia, looking into the plight of a flightless endemic bird called the kagu, when he first spotted the local crows. Now, four Marsden grants later, one of these clever crows has over a million hits on youtube and the research is helping us understand how early humans may have learned to make tools.
What were the birds up to that was so extraordinary?
They were making and using tools – hooked implements that would not be out of place in the toolkit of a modern human – to extract small prey from nooks and crannies in trees. Over several years I ‘stole’ tools from crows by frightening them away and retrieving their tools, which often involved climbing trees. The tools that I collected showed that the crows were actually forming refined hooks on the ends of twigs. The manufacturing of hooks in the wild is still only known in humans and New Caledonian crows, making the birds the preeminent toolmakers among nonhumans.
Are crows the smartest animals in the world?
If we look at overall intelligence then, no, New Caledonian crows are not the cleverest animals. While primates like chimpanzees do not make hook tools they are generally clever across both physical and social cognitive domains. What the New Caledonian crows excel at is solving physical problems. Our team led by Professor Russell Gray at University of Auckland has been very successful at demonstrating the crows’ skills in this area. Recently, Dr Alex Taylor extended the work for a BBC documentary when one crow named 007 solved a sequence of eight subtasks to obtain food (see video clip below).
Do New Caledonian crows have bigger brains? Why are they so clever?
New Caledonian crows seem to have a larger brain relative to their body size, but how their brain is wired is likely to be crucial. A Marsden collaboration with Dr Fabiana Kubke has revealed that New Caledonian crows have a high frequency of complex glial-neuron cell clusters throughout their forebrain, and further study will investigate if these give the species a cognitive edge. Our current Marsden project on the Genetics of Complex Cognition with Professor Neil Gemmell is looking at whether New Caledonian crows have a suite of adaptations potentially related to their tool-using lifestyle that are not seen in other crow species. This work could indicate if New Caledonian crows have special adaptations that potentially provide enhanced cognitive abilities.
As we see in humans, morphological and behavioural adaptations may also underlie a complex tool-using lifestyle. For example, New Caledonian crows have a uniquely straight plier-like bill among crow species, which facilitates the fine manipulation of tools. Our work has also shown that adults provide an extraordinarily long period of parental care to their offspring, which is consistent with the need to learn very complex foraging skills. Thus morphological, behavioural and neurological specialisation may have all combined to make New Caledonian crows clever birds.
What do New Caledonian crows tell us about the evolution of human intelligence?
Living in complex social groups is generally considered to have been a major factor in the evolution of human intelligence. It is has been problematic to investigate the role of technical intelligence, but the New Caledonian crow provides an important living model for complex tool making. Our current research should reveal if the early stages of complex tool manufacture requires wide-ranging changes to the genome or just small tweaks. It also has the potential to show whether tool making can play an important role in evolving enhanced cognitive skills, rather than the other way around.
Crows are often attacked as a common pest. Should we have more empathy for them?
Absolutely! Their relatively high level of cognitive ability and their highly opportunistic foraging lifestyles make crows crafty animals with behaviour more similar to human behaviour than that of most other animals. For some reason this seems to make humans nervous of crows, but we hope the more we learn about them the less wary we will become. Since the initial discovery that New Caledonian crows make complex tools they have featured in numerous TV documentaries and appeared on two New Caledonian postage stamps. Our research over nearly 20 years has also encouraged other researcher teams, especially in Europe, to look closely at the cognitive skills of other crow species such as rooks. The increasing awareness that crows can teach us about the evolution of higher intelligence will hopefully mean more empathy and respect for these brainy birds.
These interviews showcase researchers supported by the Marsden Fund which, since 1994, has been supporting fundamental, investigator-led research in New Zealand.