Archive | October 2013

Yangtze River Dolphin’s Genes Indicate Humans Caused Its Extinction

 

 

river dolphin baiji

A free-ranging baiji swims in China’s Yangtze River in this undated photo. Credit: Kaiya Zhou

The verdict is in regarding the recent extinction of a Chinese river dolphin: humans, not a glitch in the animal’s genes, were responsible.

Researchers reconstructed the entire genome of a baiji (Lipotes vexillifer), or Yangtze River dolphin, using tissue remains from a specimen frozen since 1985. The baiji, poetically known as the “Goddess of the Yangtze,” is a symbol of the challenge of marine conservation in the face of expanding human activity.

 

 

As recently as the 1950s, there were an estimated 5,000 baiji living in China’s Yangtze River. The country’s rapid industrialization, however, resulted in habitat loss and water pollution. That coincided with a rapid decline in the dolphin’s numbers. The last confirmed baiji sighting was in 2004. Two years later, after a broad survey failed to find a single animal, the species was declared “functionally extinct.”

A research team has now sequenced the genome of a male baiji and then resequenced the genomes of three additional specimens to create a broader understanding of the species’ evolution. The findings appear today in Nature Communications.

Dolphin Genetics

Researchers found evidence for a genetic bottleneck that reduced diversity in the species some 10,000 years ago, coinciding with a rapid decrease in global and local temperatures. However they concluded there was no genetic reason for the animals to go extinct, and that human activity alone was to blame.

Although the researchers who sequenced the baiji’s genome focused on reconstructing the species’ past to understand its evolution, the results of their work could one day be used to resurrect “the Goddess of the Yangtze” through de-extinction.

Facebook Algorithm Predicts If Your Relationship Will Fail

 

 

couple on facebook in relationship

If you tell Facebook you’re in a relationship, but don’t say with whom, then you might think you’ve got some privacy. But think again: A newly developed algorithm can identify which “friend” you’re dating and predict whether or not that relationship will last.

The number-crunching was conducted by a computer scientist and a Facebook engineer, using a dataset of 1.3 million Facebook users who met three criteria. Each was 1) at least 20 years old, 2) listed their relationship status as married, engaged or dating and 3) had at least 50 friends. The researchers used the data to come up with a new metric they call dispersion—the extent to which two people’s mutual friends overlap.

Facebook as Fortune-Teller

In a relationship with high dispersion, a woman would be connected to all of her boyfriends’ closest friends, and he to hers, but those friends would not be friends with one another. In a relationship with low dispersion, by contrast, those mutual friends are more connected to each other.

People tend to have highest dispersion with their family members and with romantic partners, the researchers found. And by taking into account factors like age, gender and where users live, the algorithm could narrow this down to the most likely boyfriend/girlfriend with 60 percent accuracy. That may not seem like great odds, but keep in mind that with the minimum number of friends (50), the chances of a random correct guess would only be 2 percent.

One Failure Leads to Another

Even the algorithm’s incorrect guesses were surprisingly informative, as The New York Times describes,

Particularly intriguing is that when the algorithm fails, it looks as if the relationship is in trouble. A couple in a declared relationship and without a high dispersion on the site are 50 percent more likely to break up over the next two months than a couple with a high dispersion, the researchers found. (Their research tracked the users every two months for two years.)

The paper, published in ArXiv this week, argues that the most successful relationships are those with high dispersion, where romantic partners widen each other’s social worlds while maintaining their own circle of friends. This makes sense. What may be more surprising is if and how Facebook decides to put this metric to use. Keep that in mind next time you consider changing your relationship status on the FB.