They may seem awfully vegetative in their habits, and the university researchers who study them may often be counted as members of the botany department, but fungi are turning out to be far more closely related to animals than to plants, scientists say.

In a new analysis of genetic relationships among organisms with complex cells, including sponges, protozoa, algae, plants and animals, researchers have concluded that animals and fungi share a common evolutionary history and that their limb of the genealogical tree branched away from plants perhaps 1.1 billion years ago. Fungi and animals then went their own way some undetermined time after that.

The new findings, which appear today in the journal Science, suggest that the common ancestor of animals and fungi was a so-called protist, a single-celled creature that very likely possessed both animal and fungal characteristics -- perhaps spending part of its early life cycle in a membranous and mobile form resembling a human sperm, and at a different stage growing a stiff cell wall similar to that seen in today's fungi. Evolution Study by Genes

The new report did not look at fossil data or physical traits of organisms, as more traditional taxonomic studies have done, but rather took the currently popular approach of studying evolution by examining genes. Through analyzing the same genes in many different species and tracking how many mutational changes have occurred in the genes from one organism to the next, scientists are able to calculate kinships based on complex mathematical models rather than on an eyeball appraisal of how species look.