Tag Archives: social behavior

Social behavior in mammals is as old as dinosaurs, fossil shows

Artist impression of a social group of Filikomys primaevus in a burrow. Credit: Misaki Ouchida

Virtually all mammals show some degree of social behavior, however infrequent their contact with other members of their own species. One may say this is a defining feature of our taxa, with humans being a prime example. According to a new study, mammals have mingled with one another since at least 75 million years ago, while the Earth was still dominated by the dinosaur lineage. Previously, scientists used to think mammals first exhibited social behavior after dinosaurs went extinct.

“It was crazy finishing up this paper right as the stay-at-home orders were going into effect—here we all are trying our best to socially distance and isolate, and I’m writing about how mammals were socially interacting way back when dinosaurs were still roaming the Earth!” said lead author Luke Weaver, a graduate student in biology at the University of Washington. “It is really powerful, I think, to see just how deeply rooted social interactions are in mammals. Because humans are such social animals, we tend to think that sociality is somehow unique to us, or at least to our close evolutionary relatives, but now we can see that social behavior goes way further back in the mammalian family tree.”

Weaver and colleagues at the University of Washington and Burke Museum examined the fossil skulls and skeletons of 22 individuals of Filikomys primaevus, a small, rodent-like mammal whose name aptly translates to ‘youthful, friendly mouse.’  F. primaevus belonged to the extinct taxon of rodent-like mammals known as multituberculata, which existed from about 178 million to 50 million years ago.

“Multituberculates are one of the most ancient mammal groups, and they’ve been extinct for 35 million years, yet in the Late Cretaceous they were apparently interacting in groups similar to what you would see in modern-day ground squirrels.”

Credit: Credit: Misaki Ouchida.

The fossils were found clustered together in groups of two to five individuals, with at least 13 individuals found within a 30 square-meter area in the same rock layer at Egg Mountain, a famous dinosaur nesting site in western Montana. The ancient mammals were found in a mixture of multiple mature adults and young adults, suggesting that these groups weren’t simply parents raising their young but rather the social members of a pack.

A block of Filikomys primaevus fossils analyzed from the Egg Mountain Formation in western Montana. Credit: Luke Weaver.

Strong shoulders and elbows suggest that F. primaevus were likely burrowing animals that nested together in the caverns they built.

Up until now, scientists used to think that social behavior in mammals first emerged long after the dinosaurs went extinct, and mostly in animals in the Placentalia group —  a rather diverse group, with nearly 4000 described species alive today including such diverse forms as whales, elephants, shrews, and humans.

However, the new findings show that social behavior was likely present well within the age of dinosaurs, and in an entirely different, more ancient group of mammals to boot.

“These fossils are game changers,” said senior author Gregory Wilson Mantilla, a University of Washington professor of biology and curator of vertebrate paleontology at the Burke Museum. “As paleontologists working to reconstruct the biology of mammals from this time period, we’re usually stuck staring at individual teeth and maybe a jaw that rolled down a river, but here we have multiple, near-complete skulls and skeletons preserved in the exact place where the animals lived. We can now credibly look at how mammals really interacted with dinosaurs and other animals that lived at this time.”

The findings appeared in the journal Nature Ecology & Evolution.


Worn money spent easier than crisp banknotes


The reason why we don’t trade with gold, diamonds or cheese is because these do no offer the exact interchangeable value. Money the other hands, does. If you loaned someone with $50, and the other person returned the money all in coins for instance, you’d still have the same exact value back in your hands. A new study, however, shows that money in its physical form, banknotes or coins, is not all the same, after it found the people spend old or filthy bank-notes more freely than freshly-minted ones.

“The physical appearance of money can alter spending behavior. Consumers tend to infer that worn bills are used and contaminated, whereas crisp bills give them a sense of pride in owning bills that can be spent around others,” write authors Fabrizio Di Muro (University of Winnipeg) and Theodore J. Noseworthy (University of Guelph).

The researchers believe this behavior has something to do with the fact that we generally do not like touching things already touched by many other unknown people. This is magnified when a bank-note is dirty, worn or crumpled because we can see evidence this cash has passed through a lot of hands before getting to ours, they said. Thing is, money really is dirty; a separate study found 26% of bank notes and 47% of credit cards are covered in germs, while 80% of notes and 78% of credit cards had some traces of bacteria.

The researchers enlisted participants which they either offered worn or crisp banknotes for shopping related activities – yes, it’s one of those studies. They found that the consumers tended to spend more with worn bills than with crisp bills. They were also more likely to break a worn larger bill than pay the exact amount in crisp lower denominations.

“Consumers may value a crisp banknote more than a worn bank-note because they believe the latter is disgusting and thus want to be rid of it,” the scientists note.

Awkwardly enough, when consumers thought they were being socially monitored, they tended to spend crisp bills more than worn bills.

The researchers said: “Money may be as much a vehicle for social utility as it is for economic utility.

“We tend to regard currency as a means to consumption and not as a product itself, but money is actually subject to the same inferences and biases as the products it can buy.”

What this says is that we’re proud about our brand new, minted money and value banknotes which are clean and crisp more. The major takeaway here is: always ask for new money at the bank if you’re looking to save cash.

Findings appeared in the Journal of Consumer Research.


Dolphins hang out in cliques

It seems we keep finding out more and more interesting facts about dolphins, the fantastic creatures highlighting a not-so-pleasant but rather human behavior: much like sassy highschool girls, dolphins hang out in cliques.

Discriminating dolphins

Dolphins have figured out how to use sea sponges as hunting tools – which is an absolutely remarkable feat in itself. Mothers who develop this technique teach youngsters and this method seems to have more and more success throughout the dolphin population. What researchers found was that female dolphins (and not males) which use sea sponges spend much more time with other females also using sea sponges, and less time with the ones that don’t.

However, as researchers note, things are more subtle than they might seem at a first glance: it’s not the fact that some use a hunting technique and some don’t, dolphins also discriminate based on “enduring traits such as sex, kinship, age, and geography”, much like humans do too.

Cultural behavior

There’s a rather heated debate around what exactly defines a cultural behavior. While researchers are still arguing about all the aspects, the general belief is that any such behavior has two central components: it must be socially learned, meaning that animals learn it from observing and interacting with others, and it must lead to identifiable groups – some which exhibit the behavior, and some which don’t. In other words – it has to produce social cliques – and for dolphins, it does.

Researchers from Georgetown University used a social network analysis technique to examine a trait called “homophily,” or in this case, how likely dolphins were to associate with other dolphins who hunted the way they did. The analysis was greatly complicated by the fact that dolphins, like humans, spend varying amounts of time with other dolphins. Researchers explained that judging by how clearly dolphins act on this matter, sponging cliques are probably just the tip of the iceberg, and they expect to see much more such behaviors in the future.