The sleeping Coptotermes snored louder than he chewed.
Illustrated by Mike McRae
Next time you’re taking a walk through the bush, stop and listen. It might sound peaceful, but don’t let that fool you. There’s a war going on in those trees. And it’s not pretty.
In a battle for resources, the species getting the most with the least effort will usually succeed while its competitors will struggle to keep up.
At first glance, the drywood termite Cryptotermes secundus seems rather underprepared for battle. Its colonies number little more than about 200 individuals and have no more than one or two soldier termites for protection. Even then, they can do little more than block tunnels with their massive heads while the workers flee from an attack.
These puny termites are no match for Coptotermes acinaciformis. They can have colonies of millions with soldiers that can shred the strongest Crytpotermes with a single chomp of their mandibles. In a fight, there’s no doubt who would win. Fortunately, survival isn’t always about who is the strongest, fastest, or biggest. In this war, being sneaky can be enough to save your skin.
Entomologists at CSIRO and the University of New South Wales have discovered that the Cryptotermes termite has an ear for the chewing sounds made by its competitors. When the researchers played recordings of Coptotermes feasting on some splinters, their weaker relatives looked to a quieter block of wood. Faced with such powerful competition, the drywood termite has learned to forage as much food as it can while still keeping a healthy distance from its enemy’s jaws.
For Australians, the drywood termite is less of a problem than the fearless Coptotermes. However, this research could eventually lead to methods for pest control that don’t rely on spraying nasty chemicals. Perhaps it only takes the right tune to send the big ones packing as well?
We often hear the term ‘survival of the fittest’ to describe how natural selection works. In a competition for survival, fitness is simply about finding the best way to get lunch into your belly while avoiding being lunch in somebody else’s.
For each volunteer, write a number on a piece of paper (starting at ‘1’), fold it up and place it in the bowl.
Give everybody two polystyrene cups. If the cups have raised edges, cut these off.
Instruct them to use the marker to write their name on one. The other should be left blank.
Ask the volunteers to bite (not all the way through) by placing the lip of each cup as far inside their mouth as they can and clamping down firmly with their teeth, leaving a light impression.
Collect the cups with their names on them and place them at one end of the table.
Before collecting the blank cups, ask the volunteers to pull a number from the hat, memorise it, and then place it into their unlabelled cup. Place all these unlabelled cups with the others.
Invite everybody to match the named cups with the numbers using just the teeth marks.
What’s happening?
By biting the cups, volunteers left behind an impression of their teeth. Just like our fingerprints, our dental patterns are all rather different.
Although they are white and made from similar chemicals, teeth are not bones. Rather, they are made from several different types of tissue that range from a soft dentine to an extremely hard material called enamel. Their shape and position are related to our diverse diet of meat, soft fruit and tough vegetables.
On average, humans have 20 primary or ‘milk’ teeth that fall out before adolescence and are replaced by 32 permanent teeth – half in the lower jaw (mandible) and half in the upper jaw (maxilla). They are divided into three groups – incisors for cutting, canines for piercing and grasping, and molars for grinding. Adults have a group of teeth called ‘pre molars’ that grow beneath the molar milk teeth, and can have even more molars at the very back called ‘wisdom teeth’.
The shape and growth pattern of teeth depends on a range of factors such as the size of the jaw, original positioning of the teeth, dental problems and dental work that has occurred over time. They also change rather slowly over time, meaning it’s possible to match a bite mark with a person, even if a long period of time has passed.
Applications
Forensic odontology is the term used to describe the field of study where bite marks are matched with people. Bite marks have been used as evidence since the late 19th century where a victim has been bitten or where an object – such as a piece of fruit – has tooth impressions. One of the first published cases involving forensic odontology occurred in Texas in the 1950s, when a lump of cheese was used to link a suspect to a burglary.
Some argue that although bite marks differ between most people, there isn’t much evidence showing our mouths are all completely unique, leading to the possibility of false convictions. It might also be possible to misread impressions where the material has stretched or changed shape.
Because of the tough coating of enamel on our teeth, they often survive a fire where bones don’t. If the teeth can be matched to a dental record, it’s possible to identify a victim this way.
That reminds me – it’s time I booked my next dental appointment. THis could be an interesting hobby for you, find more hobbies on www.myhobbyport.com
Did you know?
Termites prefer soft timbers, such as pine, over hardwoods. One in three houses in Victoria will be affected by termites at some point, with an average of $25 000 damage done to the structure.
On seeing a human, Bo-bo found it hard to believe that they were just as evolved as chimpanzees.
Illustrated by Mike McRae
‘Is it through your grandmother or your grandfather that you consider yourself descended from a monkey?’ the bishop ‘Soapy’ Sam Wilberforce once asked the naturalist Thomas Huxley during a rather heated debate on the topic of evolution.
Following Darwin’s book ‘On the Origin of Species’, a number of people mistakenly believed that the ancestors of modern humans were apes and monkeys. Of course, this makes as much sense as saying your cousins are also your great, great grandparents. Darwin’s argument was that humans and primates are more like very distant cousins – we both share a common ancestor.
Like humans, our closest living relative - the chimpanzee - has also evolved quite a bit over the past few million years. But finding fossils that describe precisely what our shared ancestor may have looked like is a little tricky.
A recent find has come quite close, and has palaeontologists rather excited. At four and a half million years old, Ardipithecus ramidus (Ardi for short) would have walked the Earth only a few hundred thousand years after the ancestors of chimpanzees and humans went their separate ways.
Ardi’s bones tell an interesting tale. It seems this species walked upright, just as we do, yet had hands and feet that were capable of grasping branches with ease. Importantly, their pointy canine teeth were smaller than those of other apes, indicating a change in how often males fought one another. This tells us a little about their behaviour.
Such clues hint at what a common ancestor of humans and chimpanzees might have looked like. While it’s tempting to picture them with rather chimp-ish characteristics, it seems nothing could be further from the truth.
It’s easy to consider the great apes as ‘primitive’ or ‘unevolved humans’. Using Ardi’s bones to give us a snapshot of our family album, it’s clear that chimpanzees have come just as far in five million years as we humans.
