Measuring animal intelligence is challenging, but many researchers are dedicated to exploring this question, often with surprising results. A notable recent example is the common cuttlefish, which can pass tests designed for human children.
Intelligent invertebrates. In an experiment published in the journal Proceedings of the Royal Society B, a group of scientists found that common cuttlefish (Sepia officinalis) can succeed in the “marshmallow test.” This test is designed to assess the ability to delay gratification, but it can also be used to measure animal intelligence.
The marshmallow test. In the original version of the test, a child is given a piece of candy and told that if they don’t eat it, they’ll receive a larger reward later. Those who can resist the immediate temptation to wait for the better reward are considered to have passed the test.
For their study, researchers modified this test for cephalopods. Cuttlefish were presented with two types of food: a less appealing snack and a more desirable one. The food was placed behind transparent doors marked with simple shapes (like circles and squares). The animals were trained to understand that the shapes indicated whether the doors would open in a short or a long time.
Experiment details. Researchers removed the second, more appetizing option after the cuttlefish consumed the first piece of prey. Interestingly, the cephalopods quickly learned that waiting led to a better reward and exhibited patience.
Hunting habits. In the paper, researchers speculated about the reasons behind the hunting abilities of cuttlefish. They hypothesized that these abilities might stem from the hunting strategies the animals employ.
Cuttlefish tend to camouflage themselves and wait for their prey to approach, allowing them to ambush it effectively. However, when they attack, they lose their camouflage, which not only scares off other nearby prey but also makes them vulnerable to predators. This ability to wait for the right moment to strike may be an evolutionary strategy developed by cuttlefish.
The smartest invertebrates. Among invertebrates, cephalopods possess the most complex and advanced nervous systems. The recent study shows a correlation between their brain development and their intelligence.
Increasing awareness. Animal intelligence is an area of interest for many researchers. They conduct experiments like the one with the cephalopods and explore the evolutionary circumstances that gave rise to the cognitive abilities typically associated with intelligence.
Another recent study, which was also published in Proceedings of the Royal Society B, identified five key moments in evolutionary history related to the development of intelligence, including human intelligence. Although invertebrates diverged from other evolutionary lines after the first of these critical points, resulting in their unique nervous systems, this hasn’t hindered them from solving simple problems like those examined in the study.
Intelligent beings. Many of the best examples of animal intelligence are found among mammals and birds. For instance, birds like crows have demonstrated impressive abilities in problem-solving and memory. Within the mammalian group, species such as primates, dolphins, pigs, and others also exhibit notable capacity to solve problems. Naturally, humans represent the pinnacle of intelligence.
Image | Heidi Bruce
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