Virtually all mammals wisely choose to avoid eating chilli peppers and other foods that taste ‘hot’. New research shows that Chinese tree shrews have evolved to eat large quantities of chillies in their diet by tuning down their taste buds to the chemical that makes these foods spicy.
Ticks feed on the blood of vertebrates, but this diet is low in B vitamins, which are vital for cellular metabolism. A study published earlier this year shows that African soft ticks (Ornithodoros moubata) supplement their diet with vitamin B from bacterial symbionts.
Parasites are thought to diversify with their host species, but the theory has rarely been tested. Kevin Johnson at the University of Illinois and his colleagues sequenced the genomes of 46 species of lice that parasitise birds or mammals, and two non-parasitic bark lice, and constructed an evolutionary tree. They estimated that parasitic lice first emerged between 90 and 100 million years ago, but didn’t begin to diversify until 66 million years ago – around the time of the dinosaurs’ extinction.
As I’ve mentioned before, living in a large densely-packed social group, like a city or an ant colony, comes with some drawbacks – perhaps worst of which is the risk of catching a contagious diseases. Earlier this year I wrote about research showing that raider ants treat injured workers’ wounds, helping them to heal. Now, a new study shows that the queen can pass on resistance to diseases she’s encountered, arming her workers against pathogens.
Infant mongooses rely on adults to escort them as they learn to forage. A new study from the University of Exeter reports that adult mongooses show no preference for their own offspring when choosing a pup to escort, and the authors suggest they may not be able to tell their own kin apart.
House mice outcompeted their wild relatives to become domesticated as soon as long-term human settlements appeared, some 5000 years before agriculture took hold.
The advent of farming marks a huge change in human populations – a change in diet, social structure and a switch to a more sedentary lifestyle. Agriculture also had a profound impact on wild animals, and is thought to have led to the domestication of many species, from wolves to cattle and chickens. But other species became domesticated accidentally – as humans started storing grain for lengthy periods of time, the house mouse adapted to thrive in this new ecosystem. Now, a new study shows that it was our sedentary lifestyle, not agriculture, that domesticated one of our most prolific pests.
The first skeletons evolved multiple times independently because of unusually chalky seas, later becoming essential for survival even when chalk became scarce.
Calcium-based skeletons appeared suddenly in the fossil record around 550 million years ago, fundamentally changing the global carbon cycle and introducing a wealth of new predatory strategies to the sea.