Knocking on wood is a common superstition in Western culture, mostly used to prevent bad luck after talking about good fortune, but sometimes to reverse bad fortune or undo a "jinx."

Other cultures maintain similar practices, like spitting or throwing salt, after someone has tempted fate. Even people who aren't superstitious often participate in these practices.  And since this baseball playoffs start today, don't even get one of them going about their crazy superstitions and rituals. 

Because an uninterrupted sequence of fossilized pollen from flowers begins in the Early Cretaceous, approximately 140 million years ago, it is generally assumed that flowering plants first evolved around that time. 

A new study documents flowering plant-like pollen that is 100 million years older, implying that flowering plants may have originated in the Early Triassic (between 252 to 247 million years ago) or even earlier.  Flowering plants evolved from extinct plants related to conifers, ginkgos, cycads, and seed ferns.  

In Antarctica's Vestfold Hills, Deep Lake has been isolated from the ocean for the last 3,500 years ago, a result of Antarctic continent rising that has left a saltwater ecosystem that remains liquid, even in extreme cold.

Concerns about the negative effects of mercury on fetal development have led to
the US National Research Council
warning against eating too much fish during pregnancy, but those guidelines may need to be reviewed.

New research instead found that fish accounts for only seven percent of mercury levels in the human body. Further, an analysis of 103 food and drink items consumed by 4,484 women during pregnancy found that the 103 items together accounted for less than 17 percent of total mercury levels in the body. 

Disrupted sleep patterns have been linked to autism but the quality of the evidence accumulated to date has often been compromised by small sample size, lack of agreed definitions, and poor comparability of study participants.

Some data also suggest that production of the sleep hormone melatonin may be impaired in some children with autistic spectrum disorders, which may explain disturbed sleep patterns, say the authors of a new paper.

But it's unclear just what impact this shortened sleep pattern may have, they acknowledge, though other researchers have suggested that sleep loss may have impact on neuronal development.

Fiber-optic sensors running along a 36-km stretch of high-speed commuter railroad lines connecting Hong Kong to mainland China have taken more than 10 million measurements over the past few years, a demonstration that the system can help safeguard commuter trains and freight cars against accidents.

Attuned to the contact between trains and tracks, the sensors can detect potential problems like excessive vibrations, mechanical defects or speed and temperature anomalies. The system is wired to warn train operators immediately of such problems so that they can avoid derailments or other accidents.