HOW much is that doggy in the window? Waggly tail or not, owning a pet comes at a far higher cost than you might imagine. As you watch a large dog bounding out of the back of an SUV, you might mentally reprimand the owner for their choice of vehicle. You would do better to save your indignation for their choice of pet. Because, as we report on page 46, the ecological footprint of our companion animals can dwarf that of even the most gas-guzzling cars. Man’s best friend, it turns out, is the planet’s enemy.

According to the authors of the new book Time to Eat the Dog, it takes 0.84 hectares of land to keep a medium-sized dog fed. In contrast, running a 4.6-litre Toyota Land Cruiser, including the energy required to construct the thing and drive it 10,000 kilometres a year, requires 0.41 hectares. Dogs are not the only environmental sinners. The eco-footprint of a cat equates to that of a Volkswagen Golf.

If that’s troubling, there is an even more shocking comparison. In 2004, the average citizen of Vietnam had an ecological footprint of 0.76 hectares. For an Ethiopian, it was just 0.67 hectares. In a world where scarce resources are already hogged by the rich, can we really justify keeping pets that take more than some people?

Cute, fluffy and horribly greedy

EDITORIAL

Most consumers have come to accept the scale of the ecological crisis facing humanity. We grudgingly put out the recycling and use low-energy light bulbs. Giving up our pets in the name of sustainability may seem like a sacrifice too far, but if we are going to continue to keep animals purely for our enjoyment then we have to face uncomfortable choices.

The authors’ suggestion – that we should recycle our pets by eating them or turning them into pet food at the end of their lives – is surely a non-starter. The prospect of keeping chickens instead of dogs and cats is also unlikely to appeal.

But there are more acceptable ways to reduce your pet’s impact. Feeding the cat or dog leftovers will have an immediate effect – and also help do something about the scandal of food waste. Consumer power could also be brought to bear. A trip to any supermarket will tell you that there is a large and growing demand for “green” products, whether less-polluting washing powder or locally sourced food. There’s no reason why the pet-food industry shouldn’t get in on the act.

At the moment, pet-food manufacturers thrive by selling us the idea that only the best will do for our beloved animals, but once owners become more aware, what they demand from the industry is likely to change. The first manufacturer to offer a green, eco-friendly pet food could be onto a winner. Sustainable lifestyles require sacrifices, and even cats and dogs can be made to do their bit. ■

If you really want to make a sacrifice to sustainability, consider ditching your pet

What’s hot on NewScientist.com

MODERN medicine is sometimes said to have freed humans from the constraints of evolution because vaccines, drugs and surgery allow weaker genes and individuals to survive and reproduce instead of being culled by natural selection. This is a long-standing concern with important social implications: similar worries about the survival of the unfittest helped usher in the eugenics movement in the early 20th century.

So it is good to see yet more evidence that we are still evolving (see page 14). In fact, researchers have made the first scientific prediction of what humanity – or at least half of it – will look like in 400 years: women will become stouter, healthier and fertile for longer. This is evolution at work. Darwin is still in charge. ■

It’s hubris to say we’ve outgrown evolution

I, Robopathologist

FROM Isaac Asimov’s “three laws of robotics” to RoboCop, science fiction has repeatedly warned us of the dangers of handing robots autonomy. That is why surgical robots have never been more than large, complex instruments wielded by human hands: an autonomous robot with a scalpel is too much of a risk. But replace that scalpel with a scanner, and the patient with a corpse, and medical robots can finally break free (see page 22). Until one goes on the rampage around the pathology lab, of course… ■

“In a world of scarce resources, can we justify keeping pets that consume more than some people?”

24 October 2009 | NewScientist | 5

ENVIRONMENT California’s

undersea landfill The first

survey of trash off the coast of

California has found a seascape awash

with fishing detritus, kitchen sinks and

artillery debris. Much of it is colonised

by marine life, as our video reveals

ARCHIVES What should

museums throw out? What

are the least important objects from

an archive including NASA photos,

a 19th-century surgical mask and a

hippo skull? View our gallery to decide

SPACE Elusive lunar plume caught

on camera after all A spacecraft

trailing behind NASA’s LCROSS moon

impactor did manage to snap photos

of a faint plume of ejected material.

Researchers are searching the data

for signs of water

GALLERY Prize-winning

medical imagery Look at our

gallery of pics from the Wellcome

Image Awards for a new perspective

on human bones and to discover how

even aspirin crystals can be beautiful

NEUROSCIENCE Inside the brains

of the big cats The social brain

hypothesis predicts that increased

brain size is related to increased social

complexity, and it has been borne out

by studies in primates. Now for the

first time it is tested in nine species

of big cats, including lions and tigers

TECH Necklace camera to capture

your life It takes a picture every

30 seconds, or when someone

steps near or you enter a new

environment. Originally developed

to help people with memory problems,

it will also be marketed to general

consumers who don’t want to forget

a single thing

SPACE FLIGHT Where should

NASA send astronauts next?

New Scientist adds up “scores” for

the five options NASA could pursue

in human space flight. The winner?

Deep space, here we come

For video, comment and online

debate, visit www.newscientist.com