Brain size matters for intellectual ability and bigger is better, McMaster University researchers have found.

Evolution has been the foundation and guiding theory of biology since Darwin gave the theory its proper scientific debut in 1859. But Darwin probably never dreamed that researchers in 2005 would still be uncovering new details about the nuts and bolts of his theory -- how does evolution actually work in the world of influenza genes and chimpanzee genes and stickleback fish armor? Studies that follow evolution in action claim top honors as the Breakthrough of the Year, named by Science and its publisher AAAS, the nonprofit science society.

Using functional magnetic resonance imaging, or fMRI, researchers at the University of Pennsylvania and Princeton University have provided evidence that the act of recalling a memory is a bit like mental time travel. Their study, presented in the Dec. 23 edition of the journal Science, demonstrates that the same areas of the brain that are active during an event are activated when a person attempts to recall that event – seconds before the memory surfaces.

The presence of only five tiny strands of RNA is enough to clearly distinguish cancerous thyroid tissue from otherwise normal tissue, scientists say.

Like a wolf in sheep's clothing, a protein from a disease-causing bacterium slips into plant cells and imitates a key host protein in order to cripple the plant's defenses. This discovery, reported in this week's Science Express by researchers at the Boyce Thompson Institute (BTI) for Plant Research, advances the understanding of a disease mechanism common to plants, animals, and people.

Totipotent stem cells allow plants to build new organs throughout their whole life. But it has been unclear how hormones and genetic factors work together to prevent plants from having growth that is either stunted, or uncontrolled and tumor-like. Scientists from the Max Planck Institute for Developmental Biology have now uncovered a feedback mechanism, involving a growth-enhancing hormone and a regulatory protein, which controls the number of stem cells the plant produces. (Nature, December 22, 2005). The results are of great importance for all of stem cell research.

One year after a tsunami devastated South Asian communities, global fisheries experts say habitat restoration, retraining and education programs are much needed to revive severely exhausted fisheries and steer survivors into more sustainable livelihoods than fishing.