About 175 million years ago, the ancestors of today's snakes and lizards probably gave birth to live young, researchers reported last week in Ecology Letters.

The finding counters a long-held belief that the 2,000 or so species of snakes and lizards that give live birth evolved only recently, said Alex Pyron, a biologist at George Washington University.

Pyron and Frank T. Burbrink of the City University of New York used DNA sequencing to create an evolutionary tree of more than 4,000 snake and lizard species. They discovered that today's live-bearing snakes and lizards belong to earlier, more ancient branches of the evolutionary tree.

Over the millennia, the researchers also found, many species have vacillated between laying eggs and giving live birth, and climate has been important in driving the switch. In colder times, snakes and lizards seem to favor live birth. "Eggs don't do so well in colder climates," Pyron said.

Crime-spotting through victims' eyes

Can the eyes of photographed crime victims help authorities spot the perpetrators?

According to new research published last week in the journal PLOS One, high-resolution photographs can be "mined" for hidden information. Specifically, the authors said that photographs of faces can reveal enough visual information on bystanders to identify them.

In a small sampling of 32 study participants, test subjects were able to spot familiar faces reflected in the pupils of someone who was photographed 84 percent of the time, researchers said. When the reflected images were of unfamiliar people, observers were able to match the person to a second mug shot with 71 percent accuracy.

Among worms, sex kills the female

The presence of male sperm and seminal fluid causes female worms to shrivel and die after giving birth, researchers at Princeton University found. The demise of the female after delivering hundreds of progeny appears to benefit the male worm by removing her from the mating pool for other males.

The researchers found that male sperm and seminal fluid trigger pathways that cause females to dehydrate, prematurely age and die. "Their life spans are cut by about a third to a half," said senior author Coleen Murphy, an associate professor of molecular biology.

Bats have to work harder if it's warmer

As the planet warms, some bats will find it harder to locate and track their airborne prey, a new study suggests. The distance that sound travels before it becomes too weak to hear depends on a number of factors, including its frequency and the temperature and humidity of the air: In general, higher frequencies are more quickly stifled in warmer air.

If air temperature rises 4 degrees Celsius — an increase within the range estimated by some climate models during the 21st century — the volume of space in which tropical bats can effectively find and track prey may decrease as much as 10 percent, researchers reported online this month in the Journal of the Royal Society Interface.

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