Foster care for chimpanzees successful

In a unique experiment at the Yerkes primate centre in Atlanta Leiden education specialists Rien van IJzendoorn and Marian Bakermans-Kranenburg and colleagues from the University of Portsmouth have demonstrated that young chimpanzees benefit from four hours a day personal attention from a human carer. They form a more secure attachment to the caregiver and also show improved development of their cognitive abilities. The researchers expect the same effect in children. 

An article on these research resuts will appear this week on the website of the journal Developmental Psychobiology.


The research was conducted on 46 chimpanzee babies whose mothers were unable to care for them.  In the Yerkes primate centre in Atlanta (USA) baby chimpanzees are taken away from their mothers if they are at risk of dying from neglect or physical abuse. Some of the new-born chimpanzees in the research received standard care from caregivers who fed them and cleaned their living quarters, but without any personal attention.  These young chimps grew up in a group with others in similar circumstances.  A further random group of chimps also received extra care and attention from their personal caregiver four hours a day, five days a week during their first year.  

IQ test

At nine months the chimps were tested for their cognitive development.  The same method was applied as with human babies, using games and puzzles which are also used in IQ tests for children.  The quality of the bonding with the human carers was measured, also in the same way as with human babies.  This had never previously been done with primates, but demonstrated surprising similarities in patterns of behaviour during the procedure.  

More trust

What were the results of almost a year of responsive, personal care in comparison with the usual more detached type of care?  The young chimpanzees were less anxious in their attachment to their caregiver.  They also had less need of a surrogate such as a comfort blanket as a substitute when the caregiver was absent.  The young chimpanzees in the enriched social environment with greater personal attention had more trust in their carer and experienced less panic if they had to remain in a strange environment or with an unknown person.  There were also positive benefits for their cognitive development. The chimps which had been given more personal care performed much better in the cognitive tests than their counterparts who were not given extra one-to-one care.

Importance of environment

The researchers conclude that development is strongly influenced by the environment, even in primates.  Attachment and cognitive development can improve enormously if there is personal, responsive care.  The Leiden researchers believe that the tens of thousands of young children throughout the world who are forced to grow up in orphanages could also benefit from such extra attention.

Residential institutions and orphanages

Young children in residential institutions and orphanages have to manage without this personal attention. They suffer from structural neglect of the most basic human need for safety and protection in times of stress and anxiety. The enormous advances made by children once they are adopted or taken into foster families can probably be ascribed to this need for personal attention.  If it is not possible to avoid children being brought up in institutions or orphanages, as is the case in many East European and African countries, the researchers argue that the care received in these institutions has to be drastically improved.  More stable, personal care is a crucial ingredient, as the experiment with the young chimpanzees demonstrated. 

Marinus H. van IJzendoorn, Kim A. Bard, Marian J. Bakermans-Kranenburg and Krisztina Ivan (2008). Enhancement of Attachment and Cognitive Development of Young Nursery-Reared Chimpanzees in Responsive versus Standard Care. Developmental Psychobiology December 2008  

Last Modified: 20-11-2008