The human relationship with alcohol has long been a source of fascination, but a new study suggests that our ability to metabolize it may have originated from a behavior shared by great apes – scrumping. Led by researchers at Dartmouth and the University of St Andrews in Scotland, the study proposes that eating fermented fruit on the ground may have triggered a single amino acid change in the last common ancestor of humans and African apes, boosting their ability to metabolize alcohol by 40 times.

Scrumping, which has taken on new importance in recent years, refers to the fondness apes have for eating ripe fruit from the forest floor. While scientists had previously observed this behavior, they never bothered to differentiate fruits in trees from those on the ground, making it difficult to understand its significance for human evolution.

The researchers found that African apes “scrump” regularly, but orangutans do not. These results corroborate a 2015 gene-sequencing study, which found the primary enzyme for metabolizing ethanol is relatively inefficient in orangutans and other non-human primates.

The authors propose that metabolizing ethanol may have let African apes safely eat the ripe, fermented fruit they find on the ground, freeing them from competing with monkeys for unripe fruit in trees. This adaptation could also spare large apes the risk of climbing and possibly falling out of trees, which is so incredibly dangerous that it influenced human physiology.

The team’s analysis suggests that chimpanzees consume about 10 pounds of fruit each day, ingesting a non-trivial amount of alcohol in the process. Given that chronic low-level exposure to ethanol may be a significant component of chimpanzee life, this study provides a major force of human evolution.

Measuring levels of fermentation in fruits in the trees versus fruits on the ground will be the next step in estimating alcohol consumption in chimpanzees. The researchers also propose investigating how shared feeding on fermented fruits might influence social relationships in other apes, potentially shedding light on why humans tend to drink together.

The word scrumping has been coined to describe this behavior, and if it catches on among scientists, it may become a valuable tool for understanding the complex relationships between great apes and their environment. As Nathaniel Dominy, the Charles Hansen Professor of Anthropology at Dartmouth, notes, “If the term is useful, then it will catch on.” That’s natural selection at work!

Researchers at Swansea University have made an intriguing discovery about the behavior of wild chacma baboons on South Africa’s Cape Peninsula. By using high-resolution GPS tracking, they found that these intelligent primates walk in lines not for safety or strategy, but simply to stay close to their friends.

For a long time, scientists believed that baboons structured their travel patterns, known as “progressions,” to reduce risk and optimize access to food and water. However, the new study published in Behavioral Ecology reveals that this behavior is actually driven by social bonds rather than survival strategies.

The researchers analyzed 78 travel progressions over 36 days and found that the order in which individual baboons traveled was not random. They tested four potential explanations for this phenomenon, including strategic positioning to avoid danger or gain access to resources. However, their findings show that the consistent order of baboon movement patterns is solely driven by social relationships.

According to Dr. Andrew King, Associate Professor at Swansea University, “The baboons’ consistent order isn’t about avoiding danger like we see in prey animals or for better access to food or water. Instead, it’s driven by who they’re socially bonded with. They simply move with their friends, and this produces a consistent order.”
This discovery introduces the concept of a “social spandrel.” In biology, a spandrel refers to a trait that arises not because it was directly selected for but as a side effect of something else. The researchers found that the consistent travel patterns among baboons emerge naturally from their social affiliations with each other and not as an evolved strategy for safety or success.

The study highlights the importance of strong social bonds in baboon society, which are linked to longer lives and greater reproductive success. However, this research also shows that these bonds can lead to unintended consequences, such as consistent travel patterns, which serve no specific purpose but rather as a by-product of those relationships. The findings have implications for our understanding of collective animal behavior and the potential for social spandrels in other species.

The urban parks of Barcelona, Spain, are home to a thriving colony of tropical monk parakeets. These vibrant green birds, native to South America, have adapted well to their new European environment. As they live in large groups, they communicate with each other using an array of distinct sounds – offering scientists a unique window into understanding the intricate relationships between individual social connections and vocal variety.

For animals that live in complex societies, communication is the key that unlocks the benefits of group living. From dolphins’ clicks and whistles to primates’ calls, it’s well-known that species with more intricate social lives tend to have more diverse ways of communicating. However, a recent study on wild parrots has drilled deeper into the social and vocal lives of individual birds.

Researchers at the Max Planck Institute of Animal Behavior spent two years closely observing 337 monk parakeets in Spain, documenting their social lives and recording over 5,599 vocalizations – an astonishing number that provides a wealth of data for analysis. By examining these calls in terms of repertoire diversity (the variety of sounds a bird can make) and contact-call diversity (how unique this specific type of call is), the team was able to uncover some fascinating insights.

The study revealed that individual parakeets living in larger groups did indeed produce more variable repertoires of sounds. Interestingly, female parakeets had a more diverse repertoire than males – an unusual finding for birds. This suggests that females may be the more social sex, and their vocalizations reflect this.

Social network analysis showed that parakeets with more central positions in the social structure – those that were potentially more influential in the group – tended to have more diverse vocal repertoires. In other words, the most social individuals seemed to have a better vocabulary than less social individuals.

The researchers also found that close friends who allowed each other to approach within pecking distance sounded less like each other, as if they were trying to sound unique in their little gang. These findings offer clues about the evolution of complex communication, including human language.

As Simeon Smeele, the first author of the study, notes, “The next big step is to better understand what each of the sounds mean – a real mammoth task, since most of the social squawking happens in large groups with many individuals talking at the same time!” The study provides a crucial foundation for further research into the intricate relationships between communication and group living in animals.