Orphaned chimpanzee infants given special ''mothering'' by humans are more advanced than the average human child at nine months of age, Hampshire scientists said today.

Psychology expert Professor Kim Bard found that young chimpanzees, like humans, need emotional support as well as physical support to become ''well-adjusted'' adults.

Her study found that chimpanzees who were given extra emotionally-based care were more cognitively advanced than human infants.

However, humans overtake chimpanzees in development terms as they grow older, Prof Bard, of the University of Portsmouth, said.

But she added that the study acted as a ''stark warning'' that looking after just an infant's physical needs was likely to result in a child who was maladjusted, unhappy and under-achieving.

She said: ''The attachment system of infant chimpanzees appears surprisingly similar to that found in human infants.

''Early experiences, either of warm, responsive care-giving or of extreme deprivation, have a dramatic impact on emotional and cognitive outcomes in both chimpanzees and humans.

''Parental sensitivity is an important factor in human infant development, contributing to emotionally and cognitively strong children, and it would seem the same is true for great apes as well.''

Professor Bard studied 46 chimpanzees in the Great Ape Nursery at the Yerkes National Primate Research Centre in Atlanta, USA, in the 1980s and 1990s.

The chimpanzees were in the nursery because their mothers' maternal skills were so inadequate the infants were at risk of dying.

She found that chimpanzees given 20 hours a week of responsive care - which looks after the emotional and physical development - were happier, more advanced and better adjusted than chimpanzees given standard institutionalised care which meets just their physical needs.

She explained: ''Those given responsive care were less easily stressed, less often attached to 'comfort blankets', had healthier relationships with their caregivers and were less likely to develop stereotypic rocking.

''They were also more advanced intellectually than chimpanzees reared with standard institutionalised care.''