Palaeolithic man, stone tool bearing, social, hunter gatherers from between 2 million to 20 thousand years ago learned to spot patterns in the world about them. They could recognise the changes in the season; they knew when plants would bear fruit; the migratory patterns of their prey became markers for their hunting expeditions; and subtle changes in the weather were signs of storms to come. This ability to spot patterns is an essential part of our evolution but it maybe leads to some strange anomalies in modern humans.
Those of us alive today are the ancestors of survivors from the past, we carry their survival traits in our genes passed on through countless generations. Imagine this scenario. It is 20,000 years ago and a huntsman is making his way through the long dry grass of the plain stalking a tasty looking glyptodon. Out of the corner of his eye he spots a slight movement and the vague outline of something cat-like. It might be a predator or it could be just a gust of wind and a fallen branch. If our hero assumes the worst and dashes for cover without waiting to check he might miss lunch, if he ignores his intuition he may become lunch for a hungry predator.
A type 1 error (false positive) is believing a pattern is real when it is not; a type 2 error (false negative) means not believing a pattern that is genuine. If our hunter commits a type 1 error then he may go hungry but if his error is of type 2 then he will probably be killed. Natural selection has therefore favoured those early humans who saw patterns when none existed over those that ignored patterns that indicated danger. If you have ever jumped at a shadow that you briefly thought was alive, seen a face in the clouds or heard a noise in the dark that made your skin crawl you were probably experiencing a type 1 error.
Through the generations this trait has been preserved in us and as a result most of us see patterns in all sorts of random information. (You may see some faces and other familiar shapes in this post Global Warning as examples of pareidolia.) This pattern spotting is called apophenia and includes gamblers thinking they can see a pattern in the random movements of a roulette wheel; it is evident in the behaviour of people playing Deal or No Deal on TV; it accounts for the success of fortune tellers, psychics and alternative medicine; it plays havoc with science when over enthusiastic researchers find meaning in random data; and it causes people to trust their gut feeling rather than to look at the evidence. The brilliant satirist Stephen Colbert sums it up nicely…
“That’s where the truth lies, right down here in the gut. Do you know you have more nerve endings in your gut than you have in your head? You can look it up. Now, I know some of you are going to say, “I did look it up, and that’s not true.” That’s ’cause you looked it up in a book. Next time, look it up in your gut. I did. My gut tells me that’s how our nervous system works.”
Whilst humans have developed pattern recognition other organisms have developed amazing ways to break up their outline and disrupt a pattern that predators or prey might identify. Pictures earlier showed an owl and a tiger but I think the leaf-tailed gecko above (Uroplatus phantasticus) has taken its disguise to extremes. It has co-evolved with its environment acquiring remarkable strategies to survive; not only does it closely mimic its habitat but it also opens its jaws wide in a threatening display and the end of its tail can be shed if it is being pursued by a predator.
But there are more dynamic options. This magnificent invertebrate, an octopus, takes it to a whole new level. This is not CGI but genuine film footage of a real animal in its natural environment.
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It is easy to appreciate how this ability to completely blend into the environment is a terrific tool for hunting and to avoid predation – assuming that the predators rely largely on sight. Other organisms have evolved other ways to avoid being attacked by predators such as being poisonous or looking like something that is poisonous. Can you think of any other examples? If so leave a comment, perhaps with a picture of the organism.
Questions…
- Suggest two ways in which a human is a typical mammal.
- Name two characteristics of a bird such as an owl.
- To which class of vertebrates do geckos belong?
- Of which phylum is the octopus a member?
- What structures are responsible for passing on heritable characteristics?
- Where in the cell are they found?
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