The metamorphosis of biology into a science offering numerically precise descriptions of nature has taken a leap forward with a Princeton team's elucidation of a key step in the development of fruit fly embryos - discoveries that could change how scientists think not just about flies, but about life in general.

Investigators from the Institute of Research in Biomedicine (IRB Barcelona) have identified a new signalling mechanism among cells in the fruit fly, Drosophila melanogaster. The researchers found that two independent groups of cells generate the same signal by different pathways and that these cells subsequently act together to send the signal to the target cell.

In a triumph for pests, scientists have figured out how to make the fruit fly live longer.

Forthcoming in Physiological and Biochemical Zoology, a fascinating new selection of papers collects leading experimental research in evolution and artificial selection, providing insight into how organisms adapt to changing environmental conditions and fluctuations.

The planarian is not as well known as other, more widely used subjects of scientific study - model creatures such as the fruit fly, nematode or mouse. But University of Illinois cell and developmental biology professor Phillip Newmark thinks it should be. As it turns out, the tiny, seemingly cross-eyed flatworm is an ideal subject for the study of germ cells, precursors of eggs and sperm in all sexually reproducing species.

Serotonin is a major signaling chemical in the brain, and it has long been thought to be involved in aggressive behavior in a wide variety of animals as well as in humans. Another brain chemical signal, neuropeptide Y (known as neuropeptide F in invertebrates), is also known to affect an array of behaviors in many species, including territoriality in mice.