Archaeologists have found the remains of what could be Britain's oldest surviving human brain. The team, excavating a York University site, discovered a skull containing a yellow substance which scans showed to be shrunken, but brain-shaped. Brains consist of fatty tissue which microbes in the soil would absorb, so neurologists believe the find could be some kind of fossilised brain.

Fusion power is a tantalizing, but frustrating branch of alternative energy research. For years scientists have poured countless hours and money into trying to achieve the elusive goal of generating a fusion reaction that produces more power than it consumes. The sun can do it; but we just can't seem to.

With the ITER (International Thermonuclear Experimental Reactor) project ramping up, the international community's largest effort to date is about to launch, but key problems remain that could stop the project. Among the most pressing issues are containment and control of the plasma field. While critical advances in ultra-strong steels may help with the containment problems, control of the plasma -- an ultra-hot electrically charged broth of hydrogen isotopes -- remained problematic.

In September, in a circular 27-kilometre tunnel beneath the Swiss-French border, the most complex machine ever built was switched on.

It flies in the face of natural selection, yet in humans it seems fixed and universal: at around age 50, not far past the midpoint of life, normal healthy women lose their capacity to bear children. Following a decade of gentle winding down, the whole reproductive system screeches to a halt. It is as though, after a few years of wearing bifocals, all women suddenly went blind.

Menopause is a mystery. It leaves women with 20, 30, perhaps even 50 years of life - squandered time in evolutionary terms, because no further genes can be passed on. Yet the selection pressure for menopause must have been strong: there are no known pockets of women around the world who do not go through it. All the evidence suggests menopause has been around a long time, and that the age at which it hits has changed little. Increased longevity seems not to have budged our closing hours. Nor, apparently, has lifestyle; it hits hunter-gatherers at pretty much the same age as hip New Yorkers.

In an attempt to explain this phenomenon, anthropologists suggest that menopause lets women see their last child through to maturity, or that it enables them to provide for their grandchildren. Both ideas make evolutionary sense, since they allow mothers to pass on more of their genes to subsequent generations. But when the numbers are crunched, they just don't seem enough to explain why women would forgo turning out a few more babies of their own. "The sums don't add up - the benefits aren't sufficient to stop breeding," says Michael Cant from the University of Exeter at Penryn, UK. "There's a missing piece of the puzzle." As a zoologist, whose main work has been in banded mongooses and paper wasps, he had an idea about what that missing piece might be. Put bluntly, he suspects that daughters-in-law could be to blame.

Abhay Ashtekar remembers his reaction the first time he saw the universe bounce. "I was taken aback," he says. He was watching a simulation of the universe rewind towards the big bang. Mostly the universe behaved as expected, becoming smaller and denser as the galaxies converged. But then, instead of reaching the big bang "singularity", the universe bounced and started expanding again. What on earth was happening?

Ashtekar wanted to be sure of what he was seeing, so he asked his colleagues to sit on the result for six months before publishing it in 2006. And no wonder. The theory that the recycled universe was based on, called loop quantum cosmology (LQC), had managed to illuminate the very birth of the universe - something even Einstein's general theory of relativity fails to do.

Had Amin Rustom not messed up, he would not have stumbled upon one of the biggest discoveries in biology of recent times. It all began in 2000, when he saw something strange under his microscope. A very long, thin tube had formed between two of the rat cells that he was studying. It looked like nothing he had ever seen before.

His supervisor, Hans-Hermann Gerdes, asked him to repeat the experiment. Rustom did, and saw nothing unusual. When Gerdes grilled him, Rustom admitted that the first time around he had not followed the standard protocol of swapping the liquid in which the cells were growing between observations. Gerdes made him redo the experiment, mistakes and all, and there they were again: long, delicate connections between cells. This was something new - a previously unknown way in which animal cells can communicate with each other.

Gerdes and Rustom, then at Heidelberg University in Germany, called the connections tunnelling nanotubes. Aware that they might be onto something significant, the duo slogged away to produce convincing evidence and eventually published a landmark paper in 2004 (Science, vol 303, p 1007).

Half the Neanderthal genome has been decoded and the rest should be sequenced by year's end, a scientist involved in the project told a human evolution conference last week.

Researchers will roll out a rough draft of the Neanderthal nuclear genome after their sequencers have read every letter in the genome on average once - "1x coverage" in genomics speak.

However, the fragmentary state of the DNA sample - from bones recovered in Croatia - means that the first draft will offer only a tantalizing glimpse of the genome to researchers who hope to better understand Neanderthal biology and human evolution.

Some 38,000 years of decay has left the DNA in tatters and strewn with contamination from bacteria and human handlers.

"It's not like sequencing any other genome," says Adrian Briggs, a researcher at Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, who is involved in the project, along with colleagues Edward Green and Svante Pääbo.

Astronomers have crunched 16 years of data to make the most detailed observations yet of the stars orbiting the centre of our galaxy, bolstering the case that a monstrous black hole lurks there.

Black holes are invisible but can be detected by their influence on nearby stars. By observing the motion of 28 stars orbiting the Milky Way's central region, Reinhard Genzel of the Max-Planck-Institute for Extraterrestrial Physics in Germany, says his team has delivered "the best empirical evidence that supermassive black holes do really exist".

Genzel's team found that the black hole, known as Sagittarius A*, is about 4 million times as heavy as our Sun, in line with previous estimates. They also used the observations to work out that the Earth is 27,000 light years away from the centre of the Milky Way, also agreeing with previous estimates.

One star, S2, was orbiting so fast that it completed an entire revolution of the black hole over the 16-year period. Observing one complete orbit of S2 was critical to the high accuracy reached and to understanding the region, says the team.

The Sphinx in Egypt might have originally had the face of a lion, it is claimed.

And it could be much older than previously thought, investigations led by a British geologist suggest.

Egyptologists have long argued the monument outside Cairo, which has the head of a pharaoh and the body of a lion, was built soon after the first pyramid - around 4,500 years ago.

NASA's Hubble Space Telescope has discovered carbon dioxide in the atmosphere of a planet orbiting another star. This breakthrough is an important step toward finding chemical biotracers of extraterrestrial life.

The Jupiter-sized planet, called HD 189733b, is too hot for life. But the Hubble observations are a proof-of-concept demonstration that the basic chemistry for life can be measured on planets orbiting other stars. Organic compounds also can be a by-product of life processes, and their detection on an Earthlike planet someday may provide the first evidence of life beyond our planet.

Previous observations of HD 189733b by Hubble and NASA's Spitzer Space Telescope found water vapor. Earlier this year, Hubble found methane in the planet's atmosphere.