The biology behind Facebook.

I developed the following piece at Carl Zimmer's Science Writing Workshop at Yale in February 2012.

It only takes a few minutes on Facebook and a few mindless clicks to get lost in a digital morass of vacation photos, party invitations, and wall posts. No longer is Facebook simply a tool for managing real-life social groups. It has become a platform for a new kind of socializing, where coworkers, acquaintances, and childhood playmates are lumped together in one group of ‘friends.’ These online social networks differ from real-life social networks in more ways than just the definition of friendship. They may actually utilize different social skills. In fact, a team of scientists led by Dr. Ryota Kanai of University College London discovered that this new brand of online socializing taps into different areas of the brain.

The human brain is specially adapted to navigate life in social groups. Scientists even know which brain regions are important for face recognition, empathy, and other social skills because of a recurring pattern between brain size and use. The brain controls the body with cells called neurons, which send rapid chemical signals to other neurons through a web of fibrous connections. Like wires on a switchboard, more connections arise among neurons that signal more often. A brain region that manages a particular skill will actually get larger the more that skill is practiced, because those neurons must form more connections to handle the increased signaling traffic. For instance, as real-life social networks get larger, so does an almond-shaped structure buried in the front of the brain. This structure, the amygdala, allows us to experience and perceive emotions, serving a critical role in managing complex social groups.

While scientists understand the relationship between the brain and real-life social networks, the biological basis behind online social networks remains unknown. Dr. Kanai and his team set out to solve this mystery, asking if differences in online network size can be explained by the size of known social brain regions, such as the amygdala. They predicted that if online and real-life socializing use the same skills, they would see similar trends in brain structure.

More than one hundred UCL students volunteered for the study. Each volunteer provided an MRI brain scan and reported his or her number of Facebook friends, which the scientists call the Facebook number. About half of the volunteers also answered a questionnaire about the size of their real-life social networks.

Using high-tech imaging tools, the scientists manipulated the brain scans, isolating the outer layer of the brain that is used in cognition and information processing – the grey matter. Just like any body part, individual brains are different sizes. The scientists accounted for these differences by adjusting the scale of the images, making every brain the same size. Then they spotted differences in the amount of grey matter found in each of the social brain regions. When they compared these amounts to the volunteers’ Facebook numbers, the results were eye-opening.

The scientists found that social brain regions do indeed get larger as online social networks get larger, but surprisingly, these are not the same regions that help us manage real-life networks. Three regions of the brain, each linked to socialization or memory, were larger in volunteers with larger Facebook numbers. However, the size of other social brain regions, including the amygdala, did not have a strong tie to the Facebook number. As expected, the amygdala was larger in volunteers with larger real-life networks, but the three regions that corresponded to Facebook number were not.

The team’s results suggest that the brain functions differently for online socializing than for real-life socializing. “There is a certain skill for online socializing that these areas subserve,” says Dr. Robert Ross, head of the Laboratory of Neurobiology at Fordham University. But without a strong link to the amygdala, online socializing could be missing the emotional dimension that we experience in real-life. “This may mean that you have developed the facility to distinguish truth from fiction, nuanced expression, all of that. But it doesn’t require any feeling,” says Ross. Dr. Kanai’s research demonstrates for the first time that online socializing is unique on a neurological level, and while it may complement real-life socializing, it’s no substitute for the real thing.


Kanai, R., B. Bahrami, R. Roylance, and G. Rees. 2011. Online social network size is reflected in human brain structure Proc. R. Soc. B April 7, 2012 279 (1732) 1327-1334
Image: detraveler.blogspot.com

The ocean's most exclusive community.

The great thing about science is that questions lead to answers. The bad thing is that through this process, a subject that was once novel and strange slowly loses its mystique. When the thrill is gone and the mysterious becomes mundane, the jaded biologist longing for that delicious scientific buzz need only look down - way way down. And, oh my GOODNESS, a really thrilling bit of science was just pulled up from the uncharted ocean depths and published in PLoS Biology.

Deep-sea hydrothermal vents! Is there anything more amazing? They are remote like outerspace but with thriving communities of freaky biota. And as a team of researchers, led by Dr. Alex Rogers of Oxford University, recently found – if you’ve seen one you have NOT seen them all.

These ecosystems are so mystifying because they are fundamentally different from the ecosystems we are used to seeing. Whether you are in tropical rainforest, arctic tundra, or open ocean, nearly all food webs are built upon the plants and algae that harness sunlight to transform carbon dioxide into organic molecules. Photosynthesis is incredible, but also pedestrian. Things get really strange when you look into the darkness and find bizarre organisms that have capitalized on a different energy source – poisonous, smelly hydrogen sulfide gas.

Deep-sea hydrothermal vents, found at an average depth of 2100 meters, spew plumes of hot water from the earth’s crust. This water can be as hot as 400˚C and contains high concentrations of hydrogen sulfide. The surrounding water is nearly freezing and dark as night with pressures so great it keeps the hot plumes from boiling. Still some organisms have managed to thrive in this oppressive environment. Not surprisingly, it all comes down to the microbes. Bacteria and archaea living in and around the vent utilize the energy stored in the bonds of hydrogen sulfide to fix carbon dioxide into organic molecules. This process, known as chemosynthesis, was only a theory until it was observed in action at the hydrothermal vents of the Galapagos Ridge in 1977.

The unusual properties at the base of the vent food web radiate up through all the animals it supports. The giant tube worm that hosts chemosynthetic bacteria within its body is the most familiar image. In many ways it has assumed the role of the community’s iconic species. That is until Dr. Rogers and his team restored the mystique of the hydrothermal vent ecosystem.

Departing from the vents of the tropics and subtropics that are relatively easy to access, the team examined the communities on the East Scotia Ridge (ESR), 500 km to the east of Cape Horn between South America and Antarctica. At a depth of more than 3000 meters in the Southern Ocean, the ESR has two ridge segments with hydrothermal activity, E2 and E9. A deep-sea drive by the remotely operated vehicle Isis revealed that these areas are completely devoid of the tubeworms, polychaetes, clams, and shrimp that we’ve come to expect in hydrothermal vent communities. Rather, they host a complex community of endemic organisms – organisms that haven’t been seen anywhere else – notably a new species of crab, stalked barnacles, limpets, snails, sea anemones, and a seven-armed starfish.

The biological diversity of these areas is built upon the diverse landscape. In some spots chimneys as tall as 15 meters release concentrated plumes of mineral-rich water from the Earth’s crust. This water emerges at temperatures exceeding 300˚ C, and when it hits the near-freezing water of the ocean floor, the minerals fall out of solution and create that black smoker appearance. In other areas there is more diffuse vent flow with temperatures closer to the surroundings. Even between the two sites there is variation in the chemical composition of the vented liquid. These differences could affect the microorganism populations at the two sites which would have cascading affects up the food web.

The truly thrilling thing about the ESR discovery is not the strange biota, because, let’s be honest – finding new species in a remote habitat is old hat. The amazing thing is WHY the species are so strange and why the ESR community is different from the ones we see in similar ecosystems. While they seem inhospitable to us, hydrothermal vents are the only suitable habitat for these organisms. In that way they are just like islands out at sea or parks in an urban landscape. Biogeography is the study of species distributions across space – the traits of an organism that lead it to new areas and the barriers that stand in its way. And remarkably, when you consider all the geologic, hydrologic, and biologic pieces of the puzzle, it appears that hydrothermal vent communities suggest the same patterns of biogeography that govern terrestrial communities.

Deep ocean organisms face unimaginable hurdles to dispersal. Larvae might catch a ride on an ocean current, but many of them won’t last long before passing by another hydrothermal vent. These vents are found only at the boundaries of tectonic plates, which would serve as a great dispersal corridor if they corresponded with the currents. They don’t. Even more daunting is the surface to sea-bed Polar Front, which encloses the Southern Ocean and effectively blocks the entry of outside organisms. At the Polar Front water temperatures and salinity levels change abruptly, creating an insurmountable physiological challenge to most organisms attempting to cross. Knowing this it’s really no shock that the ESR has so many endemic species and so few of the usual suspects. With these barriers preventing migration, the populations of the ESR have been held in reproductive isolation for millions of years with the forces of evolution at work.

However, over geologic time scales ocean currents and plate movements are not even constant, which adds a whole new twist to the story! The hydrothermal vents appeared when the ESR began to spread – around 15 million years ago. That period corresponded with climatic conditions that made the Polar Front less intense, meaning that organisms dispersing from other vent communities actually had a chance to colonize this brand new environment. But the gates closed around 13.8 million years ago when the climate changed and the Polar Front strengthened.

Even more interesting is the phylogenetic history of one of the ESR endemics, which seems to corroborate the geologic and climatic stories. A new species of Kiwa crab, found in the vents of the ESR, is closely related to K. hirsuta of the nearby Pacific Antarctic Ridge. By looking at differences in their genetic markers, researchers loosely estimated that the two species diverged around 12.2 million years ago. Other ESR animals show similarity to species found in hydrothermal vents in the lower latitudes of both the Atlantic and Pacific. The dispersal of organisms from two oceans was likely aided by the Antarctic Circumpolar Current, which circulates around Antarctica, linking the Atlantic, Pacific, and Indian Oceans.

Dr. Rogers' team’s research adds another layer of complexity to the biogeography of vent ecosystems, even suggesting that the Antarctic vents comprise a new biogeographic province. For scientists and non-scientists alike it represents a whole new world of mysteries to be revealed, recharging our hope for big, exciting discoveries.

Rogers AD, Tyler PA, Connelly DP, Copley JT, James R, et al. (2012) The Discovery of New Deep-Sea Hydrothermal Vent Communities in the Southern Ocean and Implications for Biogeography. PLoS Biol 10(1): e1001234. doi:10.1371/journal.pbio.1001234

She's baaaack...

Recent reports by NOAA revealed that la Nina has returned to the tropical Pacific and strengthened over the month of August. The sister of el Nino, La Nina is the cool phase of the ocean warming phenomenon, during which surface temperatures of the equatorial east-central Pacific change by at least 0.5 degrees Celsius. Last month, temperatures dropped by 1.3 - 1.8 degrees. It seems like this chilly little girl is back, and she may be sticking around into 2011.

By some oceanic and climatic mystery that remains unsolved, el Nino and la Nina have a powerful influence over the weather conditions in many parts of the world. These events, which tend to alternate in cycles of 3-6 years, can alter seasons, upset fisheries, and increase the occurrence of extreme weather such as floods, droughts, hurricanes, and cyclones. Over the past two years in California, el Nino played a role in everything from nerve-wracking drought to vanishing Chinook salmon. As a result, it was easy to blame el Nino for anything that was at least slightly annoying. Rain on my birthday? Hot temperatures on the day that I decided to wear lined wool pants? Flight delays at SFO? Damn you el Nino.

Will la Nina be as good a scapegoat as her brother? Nature News has some answers.

Shocking marine invertebrate news...

The Diasan Shinsho-maru, a Japanese fishing trawler, will certainly regret this bycatch. The ten ton vessel capsized, sending its three crew members into the drink, while trying to haul out a net full of Nomura's jellies off the coast of Chiba, Japan. The crew members were thankfully rescued by another vessel, but this incident marks another bout of trouble with the giant Nomura's (Nemopilema nomurai). The largest jellies in the world, Nomura's can grow as large as two meters in diameter. Although some years bring virtually no sightings, this year has seen massive blooms of the monsters in the Yellow and South China Seas. Their unwelcome presence, promoted by climatic conditions and a decline in predators, has come at an enmorous cost to the commercial fishing industry. To learn more about the jellies that sank a ship, read the article in The Telegraph.

Photo: The giant Nomura's jelly, Environmental News Network