If humans disappeared, what would happen to our dogs?

Shutterstock 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.

Today’s diverse dog breeds are a result of the modern approach to selective breeding. Shutterstock

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 of breeds.

Are we good for dogs?

We know certain features that appeal to people have serious impacts on health and happiness. For instance, flat-faced dogs struggle with breathing due to constricted nasal passages and shortened airways. This “air hunger” has been likened to experiencing an asthma attack. These dogs are also prone to higher rates of skin, eye and dental problems compared with dogs with longer muzzles.

Flat-faced dogs such as pugs and bulldogs often aren’t comfortable in the bodies we’ve bred them for. Shutterstock

Many modern dogs depend on human medical intervention to reproduce. For instance, French Bulldogs and Chihuahuas frequently require a caesarean section to give birth, as the puppies’ heads are very large compared with the mother’s pelvic width. This reliance on surgery to breed highlights the profound impact intensive selective breeding has on dogs.

And while domestic dogs can benefit from being part of human families, some live highly isolated and controlled lives in which they have little agency to make choices – a factor that’s important to their happiness.

Dogs without us

Now imagine a world where dogs are free from the guiding hand of human selection and care. The immediate impact would be stark. Breeds that are heavily dependent on us for basic needs such as food, shelter and healthcare wouldn’t do well. They would struggle to adapt, and many would succumb to the harsh realities of a life without human support.

That said, this would probably impact fewer than 20% of all dogs (roughly the percentage living in our homes). Most of the world’s dogs are free-ranging and prevalent across Europe, Africa and Asia.

Many dogs live independently around people, like these dogs seen on the street in India. Shutterstock

But while these dogs aren’t domesticated in a traditional sense, they still coexist with humans. As such, their survival depends almost exclusively on human-made resources such as garbage dumps and food handouts. Without people, natural selection would swiftly come into play. Dogs that lack essential survival traits such as adaptability, hunting skills, disease resistance, parental instincts and sociability would gradually decline.

Dogs that are either extremely large or extremely small would also be at a disadvantage, because a dog’s size will impact its caloric needs, body temperature regulation across environments, and susceptibility to predators.

Limited behavioural strategies, such as being too shy to explore new areas, would also be detrimental. And although sterilised dogs might have advantageous survival traits, they would be unable to pass their genes on to future generations.

Rearing puppies without human support happens successfully around the world. Shutterstock

No more designer breeds

Ultimately, a different type of dog would emerge, shaped by health and behavioural success rather than human desires.

Dogs don’t select mates based on breed, and will readily mate with others that look very different to them when given the opportunity. Over time, distinct dog breeds would fade and unrestricted mating would lead to a uniform “village dog” appearance, similar to “camp dogs” in remote Indigenous Australian communities and dogs seen in South-East Asia.

These dogs typically have a medium size, balanced build, short coats in various colours, and upright ears and tails. However, regional variations such as a shaggier coat could arise due to factors such as climate.

In the long term, dogs would return to a wild canid lifestyle. These “re-wilded” dogs would likely adopt social and dietary behaviours similar to those of their current wild counterparts, such as Australia’s dingoes. This might include living in small family units within defined territories, reverting to an annual breeding season, engaging in social hunting, and attentive parental care (especially from dads).

This transition would be more feasible for certain breeds, particularly herding types and those already living independently in the wild or as village dogs.

What makes a good life for dogs?

In their book A Dog’s World, Jessica Pierce and Marc Bekoff explore the idea of “doomsday prepping” our dogs for a future without people. They encourage us to give our dogs more agency, and consequently more happiness. This could be as simple as letting them pick which direction to walk in, or letting them take their time when sniffing a tree.

As we reflect on a possible future without dogs, an important question arises: are our actions towards dogs sustainable, in their best interests, and true to their nature? Or are they more aligned with our own desires?

By considering how dogs might live without us, perhaps we can find ways to improve their lives with us.The Conversation

Providing a good life for dogs requires thinking about their mental well-being, health and environment. Shutterstock

Bradley Smith, Senior Lecturer in Psychology, CQUniversity Australia and Mia Cobb, Research Fellow, Animal Welfare Science Centre, The University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........

What is a sonar pulse and how can it injure humans under water?

A screen labelled 'echo sounder' with a heat map

An echo sounder on a boat uses sound waves to help gauge the depth of the water. mark_vyz/Shutterstock Christine Erbe, Curtin University

Over 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, and then analyses the echoes. Depending on the timing, amplitude, phase and direction of the echoes the equipment receives, you can tell what’s under water – the seafloor, canyon walls, coral, fishes, and of course ships and submarines.

Most vessels – from small, private boats to large commercial tankers – use sonar. However, compared to your off-the-shelf sonar used for finding fish, navy sonars are stronger.


What are the effects of sonar on divers?

This is a difficult topic to study, because you don’t want to deliberately expose humans to harmful levels of sound. There are, however, anecdotes from various navies and accidental exposures. There have also been studies on what humans can hear under water, with or without neoprene suits, hoods, or helmets.

We don’t hear well under water – no surprise, since we’ve evolved to live on land. Having said that, you would hear a sonar sound under water (a mid-to-high pitch noise) and would know you’ve been exposed.

When it comes to naval sonars, human divers have rated the sound as “unpleasant to severe” at levels of roughly 150dB re 1 µPa (decibel relative to a reference pressure of one micropascal, the standard reference for underwater sound). This would be perhaps, very roughly, 10km away from a military sonar. Note that we can’t compare sound exposure under water to what we’d receive through the air, because there are too many physical differences between the two.

Human tolerance limits are roughly 180dB re 1 µPa, which would be around 500m from military sonar. At such levels, humans might experience dizziness, disorientation, temporary memory and concentration impacts, or temporary hearing loss. We don’t have information on what levels the Australian divers were exposed to, but their injuries were described as minor.

At higher received levels, closer ranges, or longer exposures, you might see more severe physiological or health impacts. In extreme cases, in particular for impulsive, sudden sound (which sonar is not), sound can cause damage to tissues and organs.

What does sonar do to marine animals?

Some of the information on what noise might do to humans under water comes from studies and observations of animals.

While they typically don’t have outer ears (except for sea lions), marine mammals have inner ears that function similarly to ours. They can receive hearing damage from noise, just like we do. This might be temporary, like the ringing ears or reduced sensitivity you might experience after a loud concert, or it can be permanent.

Marine mammals living in a dark ocean rely on sound and hearing to a greater extent than your average human. They use sound to navigate, hunt, communicate with each other and to find mates. Toothed whales and dolphins have evolved a biological echo sounder or biosonar, which sends out series of clicks and listens for echoes. So, interfering with their sounds or impacting their hearing can disrupt critical behaviours.

Finally, sound may also impact non-mammalian fauna, such as fishes, which rely on acoustics rather than vision for many of their life functions.The Conversation

Christine Erbe, Director, Centre for Marine Science & Technology, Curtin University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........