For humans, deception is a part of everyday life. The word ‘deceive’ has connotations of malevolence, selfishness and strategy – deliberate lying for personal gain. We think of manipulative politicians, fraudulent businessmen or cunning criminals attempting to bend the truth at the expense of others. But often we deceive in less cynical ways, such as pretending not to see an ex in the street or feigning confidence when speaking in public. Arguably, deception is vital for self-preservation. As we learn to be more effective deceivers, we also learn to be cautious to avoid being deceived by others, resulting in a classic arms race.
Animals deceive each other with the same complexity and nuance as humans. Evidently, deception confers an evolutionary advantage. This brings up the question: to what extent is this deception intentional? Deceptive behaviours that seem deliberate may be the result of associative learning and fine-tuning by natural selection. We can look at several examples throughout the animal kingdom to try and understand their origin.
In a predator-prey relationship, both parties generally benefit from remaining undetected by the other and therefore have strategies for evading detection. Some are physical, such as camouflage, which can be achieved through several means.
Cryptic colouration allows the animal to blend in with its background. This may be achieved by an active colour change, most famously seen in chameleons and cuttlefish, or through being the same colour as their predominant background.
Disruptive colouration and shape scrambling serve to create a shape that does not fit the image of the prey in the predator’s mind. The plains viscacha, a South American rodent, has a dark stripe which obscures its eyes, eyes being a common feature predators look for and lock onto. The leafy seadragon has a strange morphology that makes it look like floating seaweed. This means that even if it is spotted, the predator will classify it as something else. This is known as special resemblance, or ‘masquerade’.
Whilst these techniques are certainly deceptive, this kind of deception is a product of evolution, not an intentional, conscious action made by the animal. Can the same be said for camouflaging behaviour?
Some animals hide from predators, others freeze to avoid motion detection, or ‘play dead’ so the predator doesn’t pursue them. Certain moths will choose to settle on backgrounds that more closely resemble their own colouration. Are these animals consciously modifying their behaviour because they understand that the other animal may see them?
Let’s use an example to explore this problem: the Grote’s Bertholdia moth conceals itself from predatory brown bats by emitting high frequency clicks of up to 4,500 per second to jam echolocation – a unique defensive adaptation that is extraordinarily similar to radar jamming techniques used by the military. Does the moth know that it is jamming the bat’s echolocation and therefore giving itself a fighting chance at escaping? Has it learned to click when in the presence of a brown bat? Or has natural selection resulted in this automatic, reflexive behaviour?
Defensive Advertisement & Mimicry
Instead of avoiding detection, some animals are confusingly conspicuous, such as brightly coloured poison dart frogs. They advertise that they are unpalatable, dangerous, and that the predator will suffer some sort of cost by choosing to eat them. This is called aposematism.
Some animals will display the aposematic warning signal, but lack the dangerous feature. These animals are known as Batesian mimics and essentially deceive the predator by making it think they are dangerous, for example hoverflies that are harmless but look like wasps or bees. In a similar way, the bright leaves of the venus fly trap attract insects which mistake it for a nectar-bearing plant. It feigns harmlessness whilst actually being deadly; this is known as aggressive mimicry.
Again, this kind of deception is not intentional. Let’s look at a situation where an animal modifies its behaviour in order to mislead another.
When a predator is in close proximity to a nest, a parent Killdeer bird will feign having a broken wing and hop around in front the predator, so as to divert its attention from the nest and protect its offspring. Despite not actually being injured, the behaviour is so convincing she is often successful. This behaviour is flexible, in that if the fox returns to pursuing the nest, the broken wing behaviour will intensify.
Whilst effective, it is hard to tell whether the bird is intending to deceive the fox, i.e. whether she knows that the fox will interpret the wrong signal, or if she has adopted this behaviour because when she did it in the past, it protected her young. The latter explanation relies on associative learning, which does not require higher level cognition. Alternatively, the behaviour could be a reflexive response which has been created by many years of natural selection.
An experiment looking at chimpanzee behaviour in a competitive feeding paradigm provided interesting results. A dominant and subordinate chimp would be placed on either side of a feeding cage and food was “hidden” inside. Two conditions were applied: (1) food was placed where both chimps could see it, and (2) some food was placed where only subordinate could see it, and other food placed where both could see it. In the second condition, subordinates would go to the food hidden from the dominant in 73% of trials, therefore avoiding conflict and obtaining more food. It seems that the subordinate is aware the dominant can’t see the hidden food. But perhaps the subordinate was simply monitoring the dominants behaviour and chose to go to the hidden food when it saw the dominant approaching the open food.
Scrounging Scrub Jays
Wild scrub jays hide food and store it for later (caching). Sometimes jays will pilfer the stores of others – a deceptive act. It was noticed that sometimes jays would re-cache their own food in a different location. This happened more frequently when they had originally hidden food in front of others. Perhaps they understand that if others can see where they are hiding food, they may steal it, and thus are protecting themselves from pilferers. To test this idea, two groups of hand-reared jays were allowed to cache food in the presence of others. One group had never pilfered; the other frequently did so. It was found that only the pilfering group recached their food. Does this suggest that they have insight into their own actions and can project this experience onto others? In other words, are the pilferers self-aware, such that they understand that their food may be pilfered by other deceitful individuals?
Perhaps. This study is promising, but it needs replicating. It is still possible that a behaviour reading artefact is at play: suspicious subjects may cause differences in observer behaviour to which they react. This illustrates the difficulty of distinguishing between cognitive and sophisticated behaviouristic explanations!
Intentionality is hard to prove
Trying to deconstruct the cognition behind animal behaviour is extremely challenging, in the same way that testing for consciousness is. Nonetheless, the field is fascinating and a reminder not to attribute anthropomorphic explanations to the rest of the natural world.
Madeleine Hurry is an MRes Student studying Experimental Neuroscience