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!

In a groundbreaking study published online on June 18 in iScience, researchers have found that female chimpanzees who were more socially integrated with other females before giving birth had a significantly higher chance of raising surviving offspring. This discovery sheds light on the crucial role of social connections among female chimps, particularly in the absence of close kin.

The study, led by Joseph Feldblum, assistant research professor of evolutionary anthropology at Duke University, analyzed three decades’ worth of behavioral data from 37 mothers and their 110 offspring. The researchers focused on association and grooming behavior – how often females spent time near each other or engaged in social grooming – in the year before birth.

The results showed that females who were more socially connected had a considerable better chance of raising their babies through to their first year, the period of highest infant mortality. In fact, a female with a sociality score twice the community average had a 95% chance her infant would survive the first year, while one who was halfway below average saw that chance drop to 75%. The effect persisted through age five, which is roughly the age of weaning.

Interestingly, the researchers found that having close female kin in the group – like a sister or mother – did not account for the survival benefit. Neither did having bonds with males, who could potentially offer protection. What mattered most was having social connections with other females, regardless of kinship.

“This tells us it’s not just about being born into a supportive family,” said Feldblum. “These are primarily social relationships with non-kin.”

The researchers propose several possibilities for the survival benefit, including:

* Social females receiving less harassment from other females
* More help defending food patches or protecting their young
* Offspring being less likely to be killed by another group member
* Social connections helping these females stay in better condition – maybe better fed and less stressed – through pregnancy, giving their offspring a better chance from the get-go.

Moreover, social females stayed social after their babies were born – a sign of stable relationships, not short-term alliances. “Our results don’t prove causation, but they point to the value of being surrounded by others who support you, or at least tolerate you,” said Feldblum.

This study has significant implications for understanding human evolution and cooperation. As Feldblum noted, “Human females who don’t have access to kin – for example because they moved to a new city or village – are still able to form strong bonds that can benefit them.” Studying these social dynamics in chimpanzees can help us understand how we evolved to be the social, cooperative species we are today.

The world of animal communication has long been thought to be a realm of simple signals and basic vocalizations. However, groundbreaking research from The University of Warwick is challenging this notion by revealing that wild orangutans possess a sophisticated form of communication previously believed to be uniquely human – the ability to create layered complexity through recursion.

Recursion, the repetition of language elements in an embedded way, allows for the creation of comprehensible thoughts or phrases. This complex concept has long been associated with human language, enabling us to convey intricate ideas and emotions. But research published in Annals of The New York Academy of Sciences shows that orangutans have taken this ability to a new level.

Dr. Chiara De Gregorio, Research Fellow at The University of Warwick, led the study alongside Adriano Lameira (also Warwick) and Marco Gamba (University of Torino). They analyzed the vocal data of alarm calls from female Sumatran orangutans and found that their sounds exhibit a self-embedded structure across three levels – an impressive third-order recursion. This finding challenges the long-held assumption that recursion is uniquely human.

The researchers discovered that the orangutans’ calls follow a musical-like pattern, with rhythms nested inside each other in a sophisticated multi-layered vocal structure. What’s more, they found that the orangutans adapt their vocal rhythms depending on the type of predator they encounter – faster and more urgent for real threats, slower and less regular for perceived but non-threatening stimuli.

This remarkable ability to convey meaningful information about the outside world through structured vocal recursion is a testament to the complexity and intelligence of wild orangutans. As Dr. De Gregorio notes, “This discovery shows that the roots of one of the most distinctive features of human language – recursion – was already present in our evolutionary past.”

Orangutans are helping us understand how the seeds of language structure might have started growing millions of years ago. This research presents the first empirical support for the idea that these powerful recursive capacities could have been selected for and evolved incrementally in a much earlier ancestor.

In conclusion, the hidden complexity of wild orangutans’ communication has shed new light on our understanding of animal intelligence and the evolution of language. As we continue to explore and study these remarkable creatures, we are reminded of the awe-inspiring capabilities that exist within the natural world.