The article delves into the fascinating world of elephant brains, highlighting the distinct differences between their Asian and African counterparts. Despite being separated by millions of years of evolution, research has revealed that Asian elephants possess a 20% heavier brain than their larger African relatives. This groundbreaking finding, published in the scientific journal “PNAS Nexus,” sheds light on potential explanations for behavioral differences between the two species, as well as their remarkable youth and long lifespan.

Elephants are renowned for their exceptional social and intelligent nature, yet surprisingly little is known about their brains. A team of international researchers, led by Malav Shah and Michael Brecht from Humboldt-Universität zu Berlin, has analyzed the weight and structure of Asian elephant (Elephas maximus) and African elephant (Loxodonta africana) brains based on dissections of wild and zoo animals, as well as literature data and MRI scans. Their findings show that adult female Asian elephants have significantly heavier brains, weighing an average of 5,300 grams, compared to their African counterparts, which weigh around 4,400 grams.

Moreover, the cerebellum is proportionally heavier in African elephants (22% of total brain weight) than in Asian elephants (19%). The researchers attribute this difference to the more complex motor function of the trunk in African elephants, which can perform diverse movements with their two trunk fingers. This is also reflected in a higher number of neurons in the trunk’s control center in the brain.

The study further reveals that elephant brains grow almost as much as human brains after birth, tripling in weight by adulthood. This remarkable postnatal brain growth exceeds that of all primates, except humans, where the brain at birth weighs only around a fifth of its final weight. The researchers emphasize that this finding is significant for understanding motor skills and social behavior in elephants.

The study’s authors highlight the challenges involved in acquiring elephant brains for research, as extracting them from skulls is a complex veterinary procedure rarely performed. Nevertheless, they were able to analyze 19 brains extracted from deceased zoo animals or wild elephants, including those obtained from dissections of wild elephants that had died. The inclusion of data from an earlier study by another research team further strengthened their analysis.

The implications of these findings are profound, suggesting that the difference in brain weight could explain important behavioral differences between Asian and African elephants. For instance, while both species interact with humans differently, Asian elephants have been partially domesticated over thousands of years and are used as work animals in various cultures and regions. In contrast, there are only a few cases where domestication was even partially successful for African elephants.

The study’s authors conclude that social factors and learning processes could explain the strong brain growth after birth, as elephants live in complex social structures and have an outstanding memory. The experience and accumulated knowledge of adult elephants, especially matriarchs, is central to group behavior in elephants and young animals are closely cared for over a long period of childhood and adolescence.

Ultimately, this research highlights the need for further investigation into the brains of Asian and African elephants and their significance for motor skills and social behavior. As the authors note, there are many unanswered questions in researching these fascinating, intelligent animals and their “control centers.”

The researchers at the Francis Crick Institute have made a groundbreaking discovery: mice use chemical cues, including odors, to sense the social hierarchy of unfamiliar mice and compare it to their own. This remarkable phenomenon has been shown to influence the behavior of mice in confrontations with other mice.

Unlike previous suggestions that mice may display fixed behavior regardless of who they interact with, or that physical properties can give cues about social ranking, the new research published in Current Biology reveals that mice instead infer an unfamiliar mouse’s rank through chemical cues transmitted in the air (odors) or through direct contact (non-volatile scent cues).

The Crick team conducted a series of experiments to demonstrate this remarkable ability. They created a test where male mice entered a transparent tube at opposite ends, meeting in the middle. In this type of confrontation, a more submissive animal will typically retreat. The researchers first observed interactions between mice who shared the same cage, ranking each mouse on a hierarchy before observing how the mice responded to a set of unfamiliar opponents.

The results showed that the strangers could recognize each other’s rank, compare it to their own, and either retreat or force the other mouse to retreat. To further investigate this phenomenon, the team tested the mice in the dark, finding that this did not affect rank recognition, suggesting that cues like physical size or behavior don’t determine recognition of a more aggressive opponent.

The researchers then experimentally blocked the two chemosensory systems that mice use – one for odors in the air (olfactory system) and one for chemical signals transmitted by physical contact (vomeronasal system). They found no effect when just one of these systems was removed; both needed to be ablated before the mice couldn’t recognize opponent rank. This showed that mice use both olfactory and vomeronasal systems to recognize rank and can compensate if one is missing.

Like humans, mice are able to infer the social status of others around them relative to their own, using sensory cues such as language, facial expression, or clothing. The next step for the researchers is to investigate which areas of the brain process the information on opponent rank and own rank and initiate a decision to retreat or advance.

This remarkable phenomenon offers an interesting perspective on social mobility: humans, like mice, can enter a new group of people but still maintain understanding of our own social rank and gauge the social status of unfamiliar people. The State-Dependent Neural Processing Laboratory studies how processes within the brain are impacted by the state of the body, with the hope of advancing a more integrative view of brain physiology in health and disease.

Now, here’s the rewritten article:

Capuchin monkeys have developed a bizarre social tradition on Jicarón Island in Coiba National Park, Panama. The primates, known for using stone tools, have started abducting baby howler monkeys and carrying them for days at a time. This behavior has been observed in five young male capuchins over the course of 15 months, with 11 different howler infants being carried.

The researchers, led by Zoë Goldsborough, discovered this unusual tradition while analyzing camera trap footage from the island. They initially thought it might be adoption, but soon realized that the behavior had spread to multiple individuals and was not just a one-off event.

The capuchins don’t seem to have any clear benefit or reason for carrying the baby howlers. They don’t eat them, play with them, or receive more attention from their group mates while carrying an infant. However, the tradition does have destructive outcomes for the world around them, as four of the baby howler monkeys were observed to have perished.

The researchers suggest that this social tradition might be a result of boredom and free time in the safe environment of Jicarón Island. The white-faced capuchins on the island have developed a unique culture, using stone tools to crack open hard foods like nuts and shellfish. Interestingly, only males use these tools, hinting that the two socially learned traditions might spring from the same source: boredom.

The study offers the first known documentation of a social tradition in which animals repeatedly abduct and carry infants of another species without any clear benefit to themselves. It highlights the ways in which animal culture can parallel our own and raises questions about why this tradition arose and why it persists.

As one researcher notes, “The more interesting question is not ‘why did this tradition arise?’ but rather ‘why here?'” The study’s findings have profound implications for conservation efforts in Coiba National Park, where the endangered howler monkey population might be impacted by this bizarre social tradition.