- Forensic DNA Test Can Decipher Criminals’ Hair Color
- Shark Conservation Act Becomes Law
- Worms, Fractals and Mars: Top Science Image Galleries of 2010
- Spider Sex Play Speeds Up Successful Mating
Posted: 06 Jan 2011 02:55 PM PST
A new genetic test can reveal the hair color of unseen criminal suspects or unidentifiable victims.
The new analysis used a collection of recently discovered mutations linked to hair color, and it can predict the hue of an unknown person's hair with about 80 to 90 percent accuracy.
"This could be really useful in cases with no eyewitnesses, where police have no idea who to look for at all," said human geneticist Manfred Kayser at Erasmus Medical Center in the Netherlands, who led the study to be published in an upcoming issue of Human Genetics.
Forensic investigators extract DNA from blood, bones, spit, semen and other bodily stuff left at crime scenes, then check for matches in genetic databases. Until the past decade or so, unmatched samples weren't immediately helpful in crime solving. Recent genetic research, however, has buoyed DNA's forensic value by identifying markers linked to age, eye color, skin color and hair color.
Two types of melanin pigments, one light and one dark, control hair's basic shades. Most people produce only the dark melanin, resulting in black hair. But people of European descent can produce the lighter melanin and have red hair colors, or produce some combination of both for blond hair colors.
More subtle shade differences are controlled by a mutation called a single nucleotide polymorphism, or SNP, which is single change to one of 3 billion base pairs in the human genome. While many have no detectable effect on the body, some cause disease or result in visible changes such as hair coloration.
Such mutations are common in DNA but very stable, Kayser said, because the chance one will be erased is roughly one in 100 million generations. SNPs linked to hair color are even more stable because they're visible, and people tend to gravitate toward mates with specific hair colors.
Tracking down SNPs that affect physical appearance is akin to looking for needles in a haystack, but new large-scale genomic analyses have identified dozens of hair color markers.
To see if hair color could be predicted using 45 SNPs from 13 genes, Kayser and his team sampled DNA from 385 Polish volunteers and had dermatologists record their hair color. Their testing singled out 13 SNPs on 11 genes that could predict red and black hair colors with about 90 percent accuracy, as well as blond and brown colors with better than 80 percent accuracy.
"I don't see this as going-to-court kind of evidence, but as an investigative lead it's strong and could work in some scenarios really well," said forensic scientist Bruce Budowle of the University of North Texas at Fort Worth, who was not involved in the study.
In addition to helping describe mystery suspects, said Budowle, a former FBI senior scientist, the new test should help artists create better renderings of unidentifiable victims.
"A physical resemblance that's strikingly good is much better than a more abstract one. Hair color may be all it takes to push someone over the edge," Budowle said.
The new model's accuracy could be improved by testing it on bigger and different populations. Finding more SNPs linked to hair coloration with genome-wide analyses may also help, but such efforts are expensive.
"Given the complexity of hair coloration and our sample size, I'm pretty amazed at how accurate it is," Kayser said.
Image: Flickr/Jari Schroderus
Posted: 06 Jan 2011 09:54 AM PST
The Shark Conservation Act has finally become law, giving much-needed protection to some of the ocean's most magnificent creatures.
Signed by President Obama on January 4, the law closes a major loophole in an existing U.S. ban on shark finning. That gruesome practice involves fishermen cutting off sharks' fins, which are used in soup, then throwing their still-living bodies into the sea.
An estimated 73 million sharks are killed in this fashion every year. While fishing for them will continue, "I think this means less sharks will be killed," said Matt Rand, director of global shark conservation at the Pew Environment Group, who helped press Congress for the law.
While shark finning was already supposed to be illegal in U.S. waters, the previous law didn't apply to boats unequipped with fishing gear. As a result, operators of boats like the infamous King Diamond II — boarded by the Coast Guard in 2002 after a 32-ton load of fins gathered from fishing boats nearly caused it to swamp — were able to ignore the law.
Existing law also focused less on the act of finning than on fishermen's fin-to-shark weight ratio. This could be gamed by keeping the body of a large-bodied, small-finned shark, and finning several more.
The Shark Conservation Act bans finning of any sort, on any type of vessel, with one exception: North Carolina's dogfish fishery, a compromise necessary to secure the vote of Senator Richard Burr. That fishery accounts for one percent of all U.S. shark fishing.
"The exemption is not preferred," said Rand, but "if the world had 99 percent of all shark species caught with fins attached, we'd be much better off."
Because fishermen will be required to keep the bodies — which, apart from fins, are largely inedible and not valuable — they'll have less incentive to fish for sharks or keep them when accidentally caught, said Rand.
The act also allows the United States to block seafood imports from countries that permit shark finning. Similar bans helped reduce high-seas driftnet fishing, an extraordinarily destructive practice that was common in the 1970s and 1980s. (Despite pressure, however, some driftnetting still exists.)
Though the act only applies to U.S. boats and waters, it will have global consequences, said Rand. America's possession of many small Pacific islands, and the 200 miles of water around them, gives it an enormous fishing zone. Its fleet is one of the world's largest.
For those who consider any shark fishing to be unacceptable — a group that includes not just people sympathetic to animals, but scientists who point to sharks' crucial, top-predator ecological role (.pdf) — the act is just a first step toward a total ban.
In Hawaii, it's already illegal to possess or distribute shark fins. Countries like the Maldives and Honduras have outlawed shark fishing. "I hope the U.S. moves in that direction," said Rand.
Image: Allan Lee, Flickr
Posted: 06 Jan 2011 09:18 AM PST
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In addition to our most popular news stories of 2010, some of our readers' favorite Wired Science posts this year were image galleries.
Earth from space, the world's oldest trees, and painfully cute baby animals were among the year's most popular image collections.
10. Crazy-Looking New Deep-Sea CreaturesJuly 6
More than 300 hours of diving along the Mid-Atlantic Ridge contributed 10 possible new species to the Census of Marine Life. The animals are pretty weird, but also beautiful such as the scale worm pictured above.
Three of the species, which look like colorful wavy worms, belong to a group of creatures called Enteropneust, believed to be the evolutionary link between backbone and invertebrate animals. Previously only a few specimens of the group, from the Pacific Ocean, were known to science.
Image: David Shale
Posted: 06 Jan 2011 06:58 AM PST
SALT LAKE CITY — When pairs of young comb-footed spiders engage in an arachnid version of heavy petting, the males gain experience that appears to pay off later.
A male spider that repeatedly courts and mock-mates with a not-quite-mature female ends up reaping benefits later, said Jonathan Pruitt of the University of California, Davis. Speaking Jan. 4 at the annual meeting of the Society for Integrative and Comparative Biology, he proposed that such seemingly pointless spider encounters, which can't produce offspring, may resemble other young animals' racing and wrestling, by providing practice for life's future tasks.
"I thought it would sound silly if I called my talk 'Spider Sex Play,'" Pruitt said, "but that's essentially what it is." And he ranked it as the first example of any kind of play behavior demonstrated in spiders.
Among the Anelosimus studiosus spiders, which live and spin webs along rivers and under bridges from Maine to Patagonia, females don't develop an opening to their reproductive tract until their final molt. Males mature faster and hang around not-quite-mature females, often going through most of the mating routine.
During almost-sex, the male doesn't load his sex organs with sperm but performs a courtship display by drumming the female's web with his legs and sex organs. If she assumes a cooperative posture, he approximates a mating position too. He then taps her body where the reproductive tract will eventually open.
Sexual behavior even at this stage brings some risks, such as a chance that the male spider will be killed by the potentially cannibalistic female. So sex that can't possibly produce offspring remains puzzling, Pruitt said. To test the idea that such encounters might be more than wishful mistakes, he and Susan Riechert of the University of Tennessee, Knoxville set up some young spider pairs for near-matings but kept other maturing individuals isolated.
When all the spiders finally developed, the researchers observed real matings. If either spider partner had participated at least once in mock sex, a pair tended to reach the point of real mating faster than two inexperienced spiders did. The brisk proceeding wasn't a matter of knowing a particular partner, though, Pruitt said. Even pretend-sex with a different individual tended to hasten the process.
Speed should benefit the male by reducing the opportunity for some intruder to dash in and displace him, Pruitt said. Timing matters because the first male will father most of the eggs in a particular egg case.
And experienced females typically invested more in those egg cases as measured by weight, the researchers found.
The test didn't address whether females might find some benefit, too, but Pruitt speculated that they might. For example, if mock-mating turns out to be a sign of a superior male, then a female that rushes to consummate a real pairing reduces her chances of being distracted by some inferior interloper.
Spider shenanigans reminded meeting attendee Ned Place of Cornell University of chipmunks and other species of small mammals in which males emerge first from hibernation. These eager males are already waiting when the first females get moving again. Mock-mating in the spiders might confer a similar advantage by increasing the chances that a male won't miss an opportunity to mate.
Image: An Anelosimus studiosus spider. Credit: BugGuide.net/Perry Babbin
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