evolution

Wise elk learn to outsmart hunters and tell apart their weapons

As female elk get older, they also get wiser: they learn how to avoid getting shot by hunters, and appear to adapt their behaviour to the types of weapon the hunters carry.

Hunting by humans is known to affect how elk behave, selecting for more cautious behaviours by killing more of the bolder animals. But ecologist Henrik Thurfjell at the University of Alberta, Canada, wondered whether the animals might also learn how to stay safe as they age. Read more in New Scientist.

Competition Pressured Killer Whales Into Menopause

Selfish daughters, not altruistic grandmothers, could explain the evolution of menopause.

Surviving beyond the end of your reproductive life is a rare trait: only female humans, killer whales, and short-finned pilot whales are known to do it. The question is why?

If the purpose of life is to pass on your genes, as evolutionary biologists suggest, then an end to reproductive ability—menopause—really just makes no sense. Read more in Hakai Magazine.

Rattlesnakes silently shook their tails before evolving rattles

Shake, rattle and strike. It is possibly one of the most terrifying sounds in the animal kingdom, but how the rattlesnake evolved its chilling warning signal is a mystery. Now a study suggests the rattle evolved long after the tail-shaking behaviour.

The evolution of the rattle has baffled scientists because, unlike other complex physical traits like eyes or feathers, it has no obvious precursor or intermediate stage.

“There is no half-rattle,” says David Pfennig at the University of North Carolina at Chapel Hill. Read more in New Scientist.

Hawaiian crows can use sticks as tools but are nearly extinct

It’s certainly something to crow about. New Caledonian crows are known for their ingenious use of tools to get at hard-to-reach food. Now it turns out that their Hawaiian cousins are adept tool-users as well.

Christian Rutz at the University of St Andrews in the UK has spent 10 years studying the New Caledonian crow and wondered whether any other crow species are disposed to use tools.

So he looked for crows that have similar features to the New Caledonian crow – a straight bill and large, mobile eyes that allow it to manipulate tools, much as archaeologists use opposable thumbs as an evolutionary signature for tool use in early humans.

“The Hawaiian crow really stood out,” he says. “They look quite similar.” Read more in New Scientist.

Smallest perching bird’s long-lost family revealed by genetics

The pygmy bushtit’s diminutive size makes it a superlative species, and it has a genus all to itself. But now genetics is showing that it’s not so special after all.

The pygmy bushtit isn’t much to look at. It’s an inconspicuous dull grey, but it is absolutely tiny. So small in fact, that it is the smallest member of the Passeriformes, or perching birds, an order that encompasses more than half of all bird species including sparrows, finches and chickadees. Read more in New Scientist.

Wild gorillas compose happy songs that they hum during meals

Gorillas sing and hum when eating, a discovery that could help shed light on how language evolved in early humans.

Singing seems to be a way for gorillas to express contentment with their meal, as well as for the head of the family to communicate to others that it is dinner time. Read more in New Scientist.

Development Of Airplanes Is Like Biological Evolution, Engineer Says

Airplanes and birds may have followed similar pattern to increase efficiency.

The development of passenger aircraft over the past century mirrors the evolution of flying animals, and shows that evolution is not just a biological phenomenon, according to a paper published today in the Journal of Applied Physics.

Adrian Bejan, a mechanical engineer at Duke University in Durham, North Carolina, argues that evolution is a physical phenomenon, with changes in animals driven by physical laws. In the case of birds, the factors include aerodynamics.

“I want to persuade people that evolution – that is the change in [body shape] over time – recognizes no distinction between the two camps of biology and physics,” he said. Read more in Inside Science.

Fungi borrowed bacterial gene again and again

Multiple independent gene transfers gave fungi ability to colonize plant roots.

A single gene from bacteria has been donated to fungi on at least 15 occasions. The discovery shows that an evolutionary shortcut once thought to be restricted to bacteria is surprisingly common in more complex, eukaryotic life.

Bacteria frequently trade genes back and forth with their neighbours, gaining abilities and traits that enable them to adapt quickly to new environments. More complex organisms, by contrast, generally have to make do with the slow process of gene duplication and mutation. Read more in Nature.

Smelly microbes help hyenas to communicate

Bacteria in scent glands give information about hosts’ species, sex and reproductive state.

The hordes of microbes that inhabit every nook and cranny of every animal are not just passive hitchhikers: they actively shape their hosts’ well-being and even behaviour. Now, researchers have found evidence that bacteria living in the scent glands of hyenas help to produce the smells that the animals use to identify group members and tell when females are ready to mate.

Kevin Theis, a microbial ecologist at Michigan State University in East Lansing, had been studying hyena scent communication for several years when, after he gave a talk on the subject, someone asked him what part the bacteria might play. “I just said, ‘I don’t know’,” he says. He started investigating. Read more in Nature.

Amorous insects predict the weather

Changes in atmospheric pressure reduce mating in beetles, moths and aphids.

People have long claimed that animals can predict the weather, for examply by curtailing their activity when rain threatens. Such theories have had little evidence to support them, but now, a team of scientists has found a concrete example: insects shy away from sex in response to the drop in atmospheric pressure that presages rain. Read more in Nature.