Asian elephants have been documented deliberately burying the bodies of their calves in the first scientific report of such behaviour in this species.

Five buried calves were discovered in drainage ditches on tea-growing estates in north Bengal, India, all with their feet and legs protruding from the ground.

Footprints and dung of various sizes indicate that herd members of all ages contributed to each burial. Night guards at the estates reported loud elephant vocalisations, sometimes lasting as long as 30 to 40 minutes, before the herd left the area.

at the Indian Institute of Science Education and Research in Pune and Parveen Kaswan at the Indian Forest Service suggest that these trumpeting sounds may signify mourning and that the herds showed “helping and compassionate behaviour” during the burials.

“Calf burials are extremely rare events in nature,” says Roy.

They were surprised that the calves were buried feet up, but if the herd collectively buried each calf, this is the most accessible position to place the carcass into the drainage ditch, says Roy. As social animals, it may be most important to the elephants to bury the calf’s head, he says.

The calves’ bodies were later exhumed and examined. They ranged in age from 3 months to a year old, and a number of them were malnourished and had infections. Bruising along each calf’s back suggests they were dragged or carried long distances to the burial sites.

African bush elephants (Loxodonta africana) have been observed covering dead bodies with vegetation and returning to these locations later. However, the Asian elephants (Elephas maximus) in this study generally avoided returning to the burial sites, instead using alternative pathways.

“These observations offer impressive evidence of the social complexities of elephants,” says at the Oklahoma City Zoo and Botanical Garden. “Others have noted that elephants appear to behave in unique ways towards their deceased relatives, [but] this paper is the first to describe what appears to be methodical and deliberate burial of elephant calves after they have been carried to the burial site.”

Still, LaDue says that “we must be careful in how we interpret these results, especially as the mental and emotional lives of elephants are still largely mysterious to us”.

He isn’t convinced that the positioning of the calves was intentional. “I could envision elephants pushing a dead calf into a narrow ditch, and given the awkward shape and weight distribution, the calf landing on their back with the feet in the air,” he says. “Then, because of the shallow depth of the ditch, the feet are left unburied, not because they deliberately buried the head, but due to the unique topography of the burial site.”

The land in which elephants once roamed freely is shrinking as humans expand – especially in India, the world’s most populous country. Only about 22 per cent of the land that elephants use is within protected areas.

“Understanding how elephants behave and respond to rapid changes in human-dominated landscapes may help us develop conservation strategies that promote the coexistence of people and elephants,” says LaDue.

RNA taken from the desiccated remains of a thylacine, or Tasmanian tiger, could yield a new understanding of the species, which was declared extinct over 40 years ago. This is the first time RNA has been recovered from an extinct animal, and the technique may help our understanding of virus evolution and further controversial de-extinction efforts.

Thylacines were native to the Australian mainland and surrounding islands. While these creatures were named Tasmanian tigers by , they were actually marsupials, a group of mammals, such as kangaroos, that generally have a pouch. The last thylacine died in a zoo in 1936 and the species was .

, then at Stockholm University in Sweden, and his colleagues extracted, sequenced and analyzed RNA from a thylacine that had been kept in the collection of the Swedish Museum of Natural History for 130 years.

Before now, RNA had only been taken from living organisms and a few ancient plants. While researchers had previously extracted DNA from thylacines, many experts considered recovering RNA to be too difficult, as the molecule is more fragile than DNA and they wouldn’t normally expect it to survive in something so old unless it had been frozen.

But RNA can also tell you more about an organism than DNA alone, says Mármol Sánchez. RNA “gives you the amount, the diversity and the effectiveness of the [DNA] within the biology of the cell”, he says, because it translates, applies and regulates the genetic material in each cell. For example, DNA provides instructions on how to build muscle cells, but RNA is responsible for developing them into different muscle tissues, such as the fast-acting muscles in our limbs versus the slow-acting ones in our backs.

Extracting the thylacine’s RNA allowed the researchers to identify gaps in the previously extracted genome, and understand how its cells used the genetic traits within its DNA, including RNAs related to slow-acting muscles. They even detected remnants of RNA viruses. “This is, in a sense, impossible to do just with DNA,” says Mármol Sánchez.

Demonstrating that RNA can be extracted from such an old animal opens the door for doing the same with other museum specimens, or ones preserved in permafrost. It could also impact de-extinction efforts, controversial attempts to recreate versions of extinct species using gene-editing tools and existing organisms as hosts.

“We had previously thought only DNA remained in old museum and ancient samples,” says at the University of Melbourne, Australia, who is part of a team working to de-extinct the thylacine. “This can tell us about the function of genes in an extinct animal.”

Mármol Sánchez says that de-extinction isn’t the focus of his research, but people who want to bring species back to life will definitely need RNA to provide the full picture of how its cells actually worked.

As technology improves, “I expect we will see even more insights like this that can help us translate from genome sequence to the actual phenotype of an extinct animal”, says at University of California Santa Cruz.