The ability to sequence the entire genomes--the sequence of almost every letter of an individual's DNA--of parents and their children has for the first time allowed scientists to directly measure how fast our species is mutating. Preliminary studies are coming up with some surprising findings, including more variation than initially thought. A more accurate measure of the number of spontaneous genetic changes passed down from generation to generation will allow scientists to better estimate the timing of key events in our evolutionary history, as well as to evaluate whether some families are more likely to have children suffering from developmental disorders.

These mutations, thought to result from mistakes in DNA replication during the creation of sperm or eggs, are the basis for evolution. Some changes are benign, some are harmful--spontaneous mutations have been linked to autism and other developmental disorders--and some confer special advantages on their bearer. "Mutation is a good thing," says Don Conrad, a researcher at the Wellcome Trust Sanger Institute, in the United Kingdom. "We need to be able to respond to changes in our environment."

Last March, Leroy Hood and collaborators at the Institute for Systems Biology in Seattle, sequenced the complete genomes of a nuclear family of four, the first published example of a family having their genomes sequenced. By comparing the sequence of parents and offspring, researchers could calculate the rate of spontaneous mutations arising in the human genome from one generation to the next. The rate equates to about 70 mutations per child, lower than previous estimates.

Don Conrad has now followed up those estimates with his own analysis of family genomes, comparing mutation rates in two different nuclear families who were sequenced as part of the 1000 genomes project, an international collaboration to assess new sequencing technologies and examine genetic variability across different populations. Conrad's study confirmed Hood's figure, but it was also the first to separate out mutation rates from whole genome data based on gender. Previous indirect estimates suggest that the mutation rate is three to six times higher in men than women, a phenomena thought to be explained by the fact that sperm undergo many more cell divisions during development than do eggs. In preliminary findings presented last week at the Personal Genomes conference in Cold Spring Harbor, New York, he found that the father in a family from Utah had a mutation rate 11 times higher than the mother, higher than any previously reported figures. In the second family, from Africa, the maternal mutation rate was higher than the paternal one, which is contrary to the prevailing theory.

By simulating how mutation rates would vary had the parents in the two families switched partners, Conrad calculated that there could be as much as a tenfold difference in rates among individuals. He cautions that the work is based on data from just two families and needs to be replicated in larger samples. "I'll be exited to see what people come up with over the next six months, as they analyze sequences of more families," he says. One drawback in the study is that scientists don't know what age the parents were when they had their children; older parents tend to have more mutations in their gametes. In addition, the sequencing used DNA derived from cells from each individual, rather than direct DNA samples, though Conrad says he controlled for any errors this might have introduced.

It's not yet clear what determines an individual's mutation rates, though genetics likely play a major role. A mutation in a DNA repair enzyme, for example, could increase error rates in the replication of a genome. Environmental factors are also a possibility, however, Conrad says that no one has yet identified specific culprits. X-rays and toxic chemicals affect DNA in so-called somatic cells, or adult tissue, rather than the germline cells that go on to form eggs and sperm. It's also not yet clear what the consequences of a highly variable mutation rate would be, though it's possible that families with higher rates would be more likely to have children with sporadic disease.

Courtesy of PNAS

Researchers at the Ecole Polytechnique Fédérale de Lausanne in Switzerland have found that robots equipped with artificial neural networks and programmed to find "food" eventually learned to conceal their visual signals from other robots to keep the food for themselves. The results are detailed in an upcoming PNAS study.

The team programmed small, wheeled robots with the goal of finding food: each robot received more points the longer it stayed close to "food" (signified by a light colored ring on the floor) and lost points when it was close to "poison" (a dark-colored ring). Each robot could also flash a blue light that other robots could detect with their cameras.

"Over the first few generations, robots quickly evolved to successfully locate the food, while emitting light randomly. This resulted in a high intensity of light near food, which provided social information allowing other robots to more rapidly find the food," write the authors.

The team "evolved" new generations of robots by copying and combining the artificial neural networksof the most successful robots. The scientists also added a few random changes to their code to mimic biological mutations.

Because space is limited around the food, the bots bumped and jostled each other after spotting the blue light. By the 50th generation, some eventually learned to not flash their blue light as much when they were near the food so as to not draw the attention of other robots, according to the researchers. After a few hundred generations, the majority of the robots never flashed light when they were near the food. The robots also evolved to become either highly attracted to, slightly attracted to, or repelled by the light.

Because robots were competing for food, they were quickly selected to conceal this information," the authors add.

The researchers suggest that the study may help scientists better understand the evolution of biological communication systems.

The future of life and the origin of life are two big questions that often get intertwined. Attempts to create life from scratch could shed light on how it evolved, and on how it might be engineered in the future. Several prominent scientists, including genomics pioneers Craig Venter and George Church and biologist Jack Szostak, reflected on these questions and more at the Future of Life symposium at Harvard last weekend. Here's a sampling of interesting tidbits from their talks.

Re-creating alien life:

Harvard's Szostak has been a pioneer in attempting to re-create the origins of life. His lab has shown that lipids and RNA can spontaneously assemble under conditions resembling those of early Earth, and it's now trying to create RNA that can replicate--another prerequisite for life. Szostak's team is also thinking about what life might look like beyond Earth. "We want to see if we can make living systems by design that can live in totally different environments," he said at the conference. One of Mars's moons, for example, has a lake of liquid hydrocarbons, such as methane, rather than liquid water. So Szostak's lab is attempting to engineer life that can survive in these conditions. The researchers have so far been able to make membranes in these solvents.

Engineering long-lived rodents:

With its moist pink skin and immense buck teeth, the naked mole rat is no beauty. But what it lacks in comeliness, it makes up for in longevity. The rodent can live for nearly 30 years--more than 10 times longer than its cuter, furrier cousin, the mouse. A new project in George Church's lab will try to figure out why. Church will use novel gene transfer methods to introduce into lab mice approximately 30 genes that are thought to play a role in longevity in the naked mole rat.

Scouring the planet's genetic diversity:

According to Craig Venter, most of the world's genetic diversity has yet to be discovered. During his envious trip around the globe--spent on his yacht collecting microbes in water samples from Mexico to Nova Scotia--Venter said that 85 percent of the genome sequences he and his team collected every 200 miles were unique. While gene discovery in mammals is largely saturated (meaning that most gene families have already been discovered), "you can find new gene families from bacteria just about everywhere you look," he said.

Venter and his team haven't just been sequencing sea life: they are examining the genomes of the microbial inhabitants of our bodies as well. Case in point: the approximately 1,000 species of microbes in our mouths contribute 4,000 genes. Compared with the approximately 20,000 genes in the human genome, that's a significant contributor to genetic diversity, said Venter.