How do slow people behave

Similar to humans, chimpanzees develop slowly

Chimpanzees take more than five years to acquire key skills

Many primates, especially humans, develop slowly because the key skills needed to survive and reproduce successfully must first be acquired. There is surprisingly little data on developmental processes in chimpanzees, one of the closest living relatives of humans. Researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig have now systematically examined development milestones in free-living chimpanzees in the Taï National Park (Ivory Coast) and found that they too develop slowly and take more than five years to develop important motor, communicative and social skills Reaching milestones. This timeframe is similar to that of humans and indicates slow maturation of the brain.

Few species evolve as slowly as humans, both in terms of adult skill development and in terms of brain development. Human toddlers are born so underdeveloped that they cannot survive for several years after birth without adult care and nutrition. Children have to learn basic skills like walking, eating, speaking, using tools and much more. When these developmental milestones first appear, doctors can determine whether children and children's brains are developing normally. Little is known about the age at which other long-lived, closely related species, such as chimpanzees, reach motor and social development milestones and what this means for their brain development. For example, when do chimpanzees start walking, self-feeding, social grooming, and using tools? Comparative studies of important developmental steps in chimpanzees and other species help to understand the evolutionary basis of extended developmental periods.

Researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig have now systematically documented a wide range of behaviors in free-living chimpanzees and examined when they are first exercised. For this study, the researchers observed 19 chimpanzee children (eight females and eleven males) from Taï National Park, Ivory Coast, from the first month after birth up to the age of five. The results showed that gross motor skills develop at around four months, communicative skills at twelve months, social interaction skills at 14 months, and fine motor skills at 15 months. "Not only the time frame, but also the order of acquisition are similar in chimpanzees and humans, which reflects our common evolutionary history," says first author Aisha Bründl the acquisition of adult skills is necessary. "

"Such development milestones can provide us with valuable information about the maturation of the brain," says senior author Catherine Crockford, one of the heads of the Evolution of Brain Connectivity (EBC) project of the Max Planck Society. “Our results indicate that some parts of the chimpanzee brain develop as slowly as in humans.” However, this still has to be investigated as part of the new EBC project, a collaboration between the Leipzig Max Planck Institutes for Evolutionary Anthropology and for Cognitive and Neurosciences, for the researcher post mortem Scan and analyze the brains of great apes and correlate the results with the behavior of the animals.

The researchers also found that more complex skills, such as tool use and social interactions, emerge later in development. In addition, the point in time when these skills first appear differs more between individual chimpanzees than is the case with less complex skills. “This variation can be caused by fundamental differences in the social environment in which a chimpanzee grows up, but also by other factors such as diet and needs to be investigated further,” explains co-author Patrick Tkaczynski.

"Such a development study requires long-term data, since chimpanzees have a similarly slow life history as humans," emphasizes Roman Wittig, another senior author of the study and head of the Taï chimpanzee project. "We are fortunate that we have observation data on wild chimpanzees over a period of 40 years." Overall, this study is the most comprehensive description of developmental milestones in chimpanzees to date and advances research on common developmental processes in different great ape species.

SJ / AB, RW