BRISTOL, England — We may be among the smartest species on the planet, but some humans still behave quite similarly to birds and mammals around them, suggests a new study. Some humans find food, reproduce, share parenting, and even organize their social groups in a way that is similar to their animal neighbors. This applies to people who obtain most of their food through foraging, and similarities can depend on where they live in the world.
Scientists say that environmental factors are a key influence on how foraging human populations and non-human species behave, despite their very different backgrounds. Similarities can include whether they hunt or fish for food, how many partners they have, and even at what age they have their first child.
In the study, researchers looked at data from more than 300 locations around the world, observing the behaviors of foraging human populations alongside other species of mammals and birds living in the same place. For 14 of the 15 behaviors investigated, humans were more likely to behave similarly to the majority of other non-human species living in the same place than those elsewhere.
“We were surprised these associations appeared across humans, mammals, and birds,” says study author Dr. Dieter Lukas of the Max Planck Institute for Evolutionary Anthropology in Germany in a statement. “Different species could be expected to sense and interact with their environments in very different ways. Even if they end up with the same behavior, they might have gotten there through different paths. In particular, the flexibility that allows humans to adapt behavior to environments around the world is probably facilitated by relying on learning from other people and building on this information over generations.”
Which behaviors are most similar between humans and other species?
When obtaining food, humans in certain environments get a significant proportion of their calories from hunting. Researchers found these locations also have much higher numbers of carnivorous mammals and birds than elsewhere in the world.
Similar links were found for reliance on fishing, how far to travel to gather food, whether or not to store food, and whether or not to migrate between seasons. Each behavior was found to be more common in humans, other mammals, and birds in some locations than in others.
For reproductive behavior, researchers found larger differences across populations in regards to when individuals first give birth. In some human populations, men, on average, have their first child at age 30 or older, while in other populations men might be younger than 20. In areas where humans have children later, the local mammals and birds are, on average, also older when they first reproduce, compared to the mammals and birds living in places where humans reproduce early.
The study also shows other variables across species, including the number of individuals having multiple partners, how far individuals move to live with new partners, and how likely couples are to divorce. Regarding social interactions, in some places in the world offspring care is more equally shared between parents than in others. In some places, group sizes are larger, and in some places, social hierarchies (meaning some individuals are more dominant) are more common in humans and non-human species.
Surroundings make a difference in how humans, mammals, birds behave
Findings strongly indicate that these behavioral similarities are linked with the local environment.
“Previous research has explored how environmental conditions shape the behavior of closely related species. This is the first time a broad comparative perspective has been used to systematically compare very different species – humans, [other] mammals, and birds – across a wide range of behaviors,” says study co-author Dr. Toman Barsbai from the University of Bristol, England, and the Kiel Institute for the World Economy in Germany.
“Our evidence shows how remarkably pervasive and consistent the effect of the local environment is on behavior,” Barsbai adds. “The similarities are not only present for behaviors directly relating to the environment, such as finding food, where we might expect a clear correlation, but also for reproductive and social behaviors, which might seem less dependent on the local environment.”
Knowing the environmental conditions of a place meant the researchers could predict what behaviors to expect there. But it is not yet clear which environmental factors are of particular importance for specific behaviors, or which mechanisms are linking them.
“It would be interesting to see how many of these environmental restrictions shape other societies where individuals get food through agricultural specialization and trading,” adds study co-author Dr. Andreas Pondorfer, from the University of Bonn and the Technical University of Munich. “Agricultural intensification is often thought to buffer humans from the environment. Nevertheless, individuals in these populations might not be as buffered as we think and behaviors might still reflect adaptations that occurred before the adoption of agriculture.”
The findings are published in the journal Science.
SWNS writer Laura Sharman contributed to this report.