Throughout history and across cultures elephants have amazed and perplexed us, acquiring a plethora of meanings and purposes as our interactions have developed. They have been feared and hunted as wild animals, attacked and killed as dangerous pests, while also laboring for humans as vehicles, engineering devices, and weapons of war. Elephants have also been exploited for the luxury commodity of ivory.
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Many of us know that some birds trick other host parents from a different species into rearing their young. Best known is the common cuckoo in the UK and much of mainland Europe, However, this type of deception is not only the forte of birds – many insects ‘brood parasites’ too, especially ants, wasps, and bees.
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As the days get shorter, the Netherlands, a low lying waterlogged country, becomes a safe haven for approximately five million waders, gulls, ducks, and geese, which spend the winter here resting and foraging in fresh water lakes, wetlands, and along rivers. Many of these birds travel to the Netherlands from their breeding ranges in the Arctic.
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Throughout history, the influence of the full Moon on humans and animals has featured in folklore and myths. Yet it has become increasingly apparent that many organisms really are influenced indirectly, and in some cases directly, by the lunar cycle. Here are ten things you may not know concerning the way the Moon affects life on Earth.
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By Laura Kelley and Jennifer Kelley
Visual illusions, such as the rabbit-duck (shown below) and café wall are fascinating because they remind us of the discrepancy between perception and reality. But our knowledge of such illusions has been largely limited to studying humans.
That is now changing. There is mounting evidence that other animals can fall prey to the same illusions. Understanding whether these illusions arise in different brains could help us understand how evolution shapes visual perception.
For neuroscientists and psychologists, illusions not only reveal how visual scenes are interpreted and mentally reconstructed, they also highlight constraints in our perception. They can take hundreds of different forms and can affect our perception of size, motion, colour, brightness, 3D form and much more.
Artists, architects and designers have used illusions for centuries to distort our perception. Some of the most common types of illusory percepts are those that affect the impression of size, length, or distance. For example, Ancient Greek architects designed columns for buildings so that they tapered and narrowed towards the top, creating the impression of a taller building when viewed from the ground. This type of illusion is called forced perspective, commonly used in ornamental gardens and stage design to make scenes appear larger or smaller.
As visual processing needs to be both rapid and generally accurate, the brain constantly uses shortcuts and makes assumptions about the world that can, in some cases, be misleading. For example, the brain uses assumptions and the visual information surrounding an object (such as light level and presence of shadows) to adjust the perception of colour accordingly.
Known as colour constancy, this perceptual process can be illustrated by the illusion of the coloured tiles. Both squares with asterisks are of the same colour, but the square on top of the cube in direct light appears brown whereas the square on the side in shadow appears orange, because the brain adjusts colour perception based on light conditions.
These illusions are the result of visual processes shaped by evolution. Using that process may have been once beneficial (or still is), but it also allows our brains to be tricked. If it happens to humans, then it might happen to other animals too. And, if animals are tricked by the same illusions, then perhaps revealing why a different evolutionary path leads to the same visual process might help us understand why evolution favours this development.
The idea that animal colouration might appear illusory was raised more than 100 years ago by American artist and naturalist Abbott Thayer and his son Gerald. Thayer was aware of the “optical tricks” used by artists and he argued that animal colouration could similarly create special effects, allowing animals with gaudy colouration to apparently become invisible.
In a recent review of animal illusions (and other sensory forms of manipulation), we found evidence in support of Thayer’s original ideas. Although the evidence is only recently emerging, it seems, like humans, animals can perceive and create a range of visual illusions.
Animals use visual signals (such as their colour patterns) for many purposes, including finding a mate and avoiding being eaten. Illusions can play a role in many of these scenarios.
Great bowerbirds could be the ultimate illusory artists. For example, their males construct forced perspective illusions to make them more attractive to mates. Similar to Greek architects, this illusion may affect the female’s perception of size.
Animals may also change their perceived size by changing their social surroundings. Female fiddler crabs prefer to mate with large-clawed males. When a male has two smaller clawed males on either side of him he is more attractive to a female (because he looks relatively larger) than if he was surrounded by two larger clawed males.
This effect is known as the Ebbinghaus illusion, and suggests that males may easily manipulate their perceived attractiveness by surrounding themselves with less attractive rivals. However, there is not yet any evidence that male fiddler crabs actively move to court near smaller males.
We still know very little about how non-human animals process visual information so the perceptual effects of many illusions remains untested. There is variation among species in terms of how illusions are perceived, highlighting that every species occupies its own unique perceptual world with different sets of rules and constraints. But the 19th Century physiologist Johannes Purkinje was onto something when he said: “Deceptions of the senses are the truths of perception.”
In the past 50 years, scientists have become aware that the sensory abilities of animals can be radically different from our own. Visual illusions (and those in the non-visual senses) are a crucial tool for determining what perceptual assumptions animals make about the world around them.
Laura Kelley is a research fellow at the University of Cambridge and Jennifer Kelley is a Research Associate at the University of Western Australia. They are the co-authors of the paper ‘Animal visual illusion and confusion: the importance of a perceptual perspective‘, published in the journal Behavioural Ecology.
Bringing together significant work on all aspects of the subject, Behavioral Ecology is broad-based and covers both empirical and theoretical approaches. Studies on the whole range of behaving organisms, including plants, invertebrates, vertebrates, and humans, are welcomed.
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Image credit: Duck-Rabbit illusion, by Jastrow, J. (1899). Public domain via Wikimedia Commons.<
This article was originally published on The Conversation.
Read the original article.
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To wrap up all things furry and feathered week, I have a special treat, my interview with Ethologist and author of Second Nature - Jonathan Balcombe. Check it out below.
Could you tell us a bit about yourself?
I am an Ethologist—a biologist who specializes in the study of animal behavior. I am also an advocate of animals to the fullest degree. I support efforts to protect animals and their living spaces, and I repudiate all activities that unnecessarily or gratuitously harm animals, including their use as sources of meat and dairy products, in harmful research and testing, and where they are harmed as forms of entertainment or recreation. Among my personal pleasures are painting, playing the piano, bird/nature-watching, vegan baking, and trying to understand the cats (and, I confess, the humans) I live with.
How did you become interested in animals and their behaviour?
From my earliest memories I've been fascinated by animals and what they do. How do they perceive the world? What are they thinking? How do they solve the challenges that their living environments present them with? What are their particular sources of pleasure? Etc.
How long have you been in this field?
Professionally, I've been an Ethologist since around 1978, when I decided to major in biology as an undergraduate student. Unofficially, I've been studying animal behavior since around age five, when I first began venturing into the garden to find insects and making my elbows raw by watching ants for hours on end.
Does it just become more fascinating?
The more I learn about animals and their ways, the more fascinating it becomes. The closer one looks, the more there is to discover. As much as I notice animals, I notice people often failing to notice them. I sit at an outdoor cafe and surreptitiously drop crumbs to watch the house sparrows who come foraging for them. I admire the quickness and accuracy with which they pluck tiny tidbits from the ground. I notice them glancing up at me every second or so—monitoring that big, lumbering fleshy creature up there. I can't resist twitching a foot and noticing that they flinch briefly before continuing. I notice the rusty tones on the male's neck and two ochre patches on the back and marvel at the beautiful job that that million year old artist we call “nature” did. I notice that I'm the only one watching and I think how much people are missing right at their feet.
In your opinion, if people who hunt for sport realized "the inner lives of animals" would they still be hunting?
I think that hunting, like all forms of animal abuse, requires a switching off of empathy. I suspect that few hunters lack empathy; it is just culturally and socially suppressed. I like to think that many hunters who realized the inner lives of animals would soon be hunting for a new pastime.
Most people who are intune to their pets know and believe they posse![]()
