Biggest is not always best as far as primate brains are concerned, new research suggests.
Scientists found the brain sizes of some lemurs and monkeys shrank during the course of evolution.
The same may also be true for one kind of human.
The findings of a new study challenge the widely accepted view that as primates evolved, their brains got bigger.
They add to the controversy surrounding the three-foot tall hobbits discovered on the Indonesian island of Flores.
Experts disagree over the classification of the diminutive Homo floresiensis as a new human species.
The creatures lived on the island until 13,000 years ago, along with dwarf elephants and giant lizards.
Some scientists maintain their small heads and brains were probably the result of disease rather than evolution.
The new evidence indicates there is no reason why the Lilliputian humans could not have evolved with limited food resources where small size may have been an advantage, as body and brain size were subject to separate natural selection pressures.
Study leader Dr Nick Mundy, from Cambridge University in the UK, said: "It is likely that reductions in brain size occurred to meet demands of the species' changing ecological needs meaning some individuals with smaller brains are favoured by natural selection."
The findings are published in the journal BMC Biology.