Bradley Smith, CQUniversity Australia and Mia Cobb, The University of MelbourneFor many of us, dogs are our best friends. But have you wondered what would happen to your dog if we suddenly disappeared? Can domestic dogs make do without people?
At least 80% of the world’s one billion or so dogs actually live independent, free-ranging lives – and they offer some clues. Who would our dogs be if we weren’t around to influence and care for them?
What are dogs?
Dogs hold the title of the most successful domesticated species on Earth. For millennia they have evolved under our watchful eye. More recently, selective breeding has led to people-driven diversity, resulting in unique breeds ranging from the towering Great Dane to the tiny Chihuahua.
Humanity’s quest for the perfect canine companion has resulted in more than 400 modern dog breeds with unique blends of physical and behavioural traits. Initially, dogs were bred primarily for functional roles that benefited us, such as herding, hunting and guarding. This practice only emerged prominently over the past 200 years.
Some experts suggest companionship is just another type of work humans selected dogs for, while placing a greater emphasis on looks. Breeders play a crucial role in this, making deliberate choices about which traits are desirable, thereby influencing the future direction...
If humans disappeared, what would happen to our dogs?
Read More........ Categories: Animal,Australia,Dog,Matter-Of-Fact,University
What is a sonar pulse and how can it injure humans under water?
Christine Erbe, Curtin UniversityOver the weekend, the Australian government revealed that last Tuesday its navy divers had sustained “minor injuries”, likely due to sonar pulses from a Chinese navy vessel.
The divers had been clearing fishing nets from the propellers of HMAS Toowoomba while in international waters off the coast of Japan. According to a statement from deputy prime minister Richard Marles, despite HMAS Toowoomba communicating with internationally recognised signals, the Chinese vessel approached the Australian ship and turned on its sonar, forcing the Australian divers to exit the water.
The incident prompted a response from the Australian government, who labelled the incident “unsafe and unprofessional”. But what exactly is a sonar pulse, and what kinds of injuries can sonar cause to divers?
What is sonar?
Light doesn’t travel well under water – even in clear waters, you can see perhaps some tens of metres. Sound, however, travels very well and far under water. This is because water is much denser than air, and so can respond faster and better to acoustic pressure waves – sound waves.
Because of these properties, ships use sonar to navigate through the ocean and to “see” under water. The word “sonar” stands for sound navigation and ranging.
Sonar equipment sends out short acoustic (sound) pulses or pings,...
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