We've all had the feeling we've been somewhere before or had a feeling we've previously had a conversation. It isn't magic or mysticism, the answer is in a set of neurons called your 'place cells.'

Researchers believe these 'place cells' fire to provide a sort of blueprint for any new space we encounter. The next time we see the space, those same neurons fire. Thus we know when we've been somewhere before and don't have to relearn our way around familiar turf. But similar spaces may activate overlapping neuronal blueprints, leaving room for confusion if the neurons are not fine-tuned. Thus happens deja vu.

It used to be said that men predominantly liked salty snacks and women liked sweets. Food preference, in that sense, was related to chromosomes.

It may go deeper than that. Even your preference for fats, carbohydrates and proteins may be genetic. Researchers have found that the apolipoprotein A-II gene (APOA2) is associated with proportions of fat, carbohydrate, and protein in the diet, total calories and, therefore, with body-mass-index (BMI.

It may not sound like a great thing for your backyard festivities but scientists have figured out how to make the fruit fly live longer. Luckily, humans will get something out of the deal -namely the discovery that a single protein can inhibit aging means we might live longer to be annoyed by insects.

Though the dense humid forests of Central Africa have been regarded as among the most pristine on Earth, the expansion of industrial logging and the accompanying proliferation of road density are threatening the future of this important ecosystem.

Have you ever been trying to solve a Sudoku puzzle and been gripped by a sinking feeling that maybe you were stuck with a lemon? That maybe the puzzle you are struggling with actually has no solution at all and, if you do find a solution, how can you be sure it's the only one? What if half an hour ago you had written 5 instead of 3---would you then have gone down a path to a completely different solution?

The authors of a new study use tools from the branch of mathematics called graph theory to systematically analyze Sudoku puzzles.

The Milky Way's total mass is about 100 billion solar masses - enormous to us but average among galaxies. It spirals around a black hole that is about three million solar masses, say cosmologists.

Imagine it meeting an identical twin. Were they to merge they would produce a galaxy that's even greater. Cosmologists think that's how galaxies grow; through a complex process of continuous mergers.