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

Is iridescent fur wasted on the blind golden mole?

Despite human demand for fur coats, mammals are still the dowdiest members of the animal kingdom. While many birds, insects, and mollusks have iridescent coloration that gives off a metallic, shimmering appearance, mammals rely on pigments to imbue their fur with a single, matte color. Biologists think that iridescent animals use their flashy coloration to lure mates. However, a recent discovery of iridescent mammalian fur throws a wrench into the sexual display hypothesis. The iridescent coloration is possessed by a mammal that cannot even see – the blind golden mole.

The golden mole (Family: Chrysochloridae) is a burrowing animal that lives underground in sub-Saharan Africa. It has no need for sight, and its eyes are covered by skin and fur. Despite living in darkness, its dense coat shimmers with green, blue, and violet highlights. Dr. Matthew Shawkey of the University of Akron examined the microscopic, physical qualities of golden mole hairs and found that they are specially constructed to produce an iridescent sheen.

Whether it’s the rainbow shine of a soap bubble or a hummingbird’s shimmering throat feathers, iridescence occurs when light hitting different surfaces is reflected at different angles – a process known as thin-film interference. For these surfaces to shine though, their thickness must be just right. When Dr. Shawkey looked at a golden mole hair under an electron microscope, he found that its outer layer was composed of alternating layers of electron-dense and electron-lucent material. These layers happen to be the perfect thickness to reflect light at angles that produce iridescence through thin-film interference.

Other characteristics of the golden mole hair enhance the iridescent coloration. Instead of a continuous, tubular shape like most mammalian hairs, golden mole hairs become flat towards the ends. This flattened shape, also seen in iridescent bird feathers, provides more surface area for light reflection. Also, the golden mole hairs are smoother than typical mammalian hairs. Most mammalian hairs are covered by rough, cuticular scales that diffuse light. However, the cuticular scales of the iridescent golden mole hairs are compressed and smooth, which focuses more light on the reflective layers.

Like all mammals, the golden mole’s coat is actually composed of two hair types. The iridescent hairs are the protective, outer guard hairs. Golden moles also possess non-iridescent down hairs, which are dense, curly, and provide insulation for the animal. Dr. Shawkey observed that, in contrast to the iridescent guard hairs, the down hairs of the golden mole are thin and tubular with large cuticular scales. While they did not have the layered substructure of the iridescent hairs, their cells had many pigment organelles called melanosomes. The iridescent guard hairs on the other hand contained very few melanosomes.

While iridescence in mammalian fur is an amazing discovery, the reason behind such a trait, especially in a blind animal, remains unclear. Dr. Shawkey hypothesizes that the structure of the iridescent hairs is actually conducive to the mole’s underground lifestyle. Flattened guard hairs may help the moles move through the dirt. Also, the small, compressed cuticular scales likely reduce friction. It just so happens that these adaptations also give the golden mole guard hairs the perfect structure for iridescent coloration. For a mammal that never sees the light of day and couldn’t if it tried, the golden mole’s iridescent fur gives new meaning to ‘beauty is in the eye of the beholder.’

Holly K. Snyder, Rafael Maia, Liliana D'Alba, Allison J. Shultz, Karen M. C. Rowe, Kevin C. Rowe, and Matthew D. Shawkey. Iridescent colour production in hairs of blind golden moles (Chrysochloridae. Biol Lett 2012 : rsbl.2011.1168v1-rsbl20111168. 

Photo: Namib Desert Golden Mole, Eremitalpa granti namibensis. By G. Rathbun, Afrotheria.net

Wetland restoration: Is it worth the effort?

If forests are the lungs of our planet, then wetlands are surely the liver. Wetlands filter overland runoff through a unique suite of plants and soil microorganisms that break down harmful compounds, ensuring that waters reaching streams and coastlines are contaminant-free. Wetlands also store a massive amount of carbon in their soils, serve as a nursery ground for many fisheries, and protect shorelines from floods and storm surges.

Despite these benefits and more, humans allowed worldwide wetland degradation to continue unchecked for two hundred years. Instead of protecting existing wetlands, we gamble on restoration efforts, investing over $70 billion to bring back functional wetlands in North America alone. Until now the overall outcome remained unclear. But after investigating 621 wetland restoration projects around the world, a team of scientists led by Dr. David Moreno-Mateos and renowned ecologist Dr. Mary Power of the University of California Berkeley determined that wetland restoration is generally a losing bet. They published their results last month in PLoS Biology.

The team combed the scientific literature for studies that compare restored and newly created wetlands to adjacent undisturbed wetlands. They compiled all the data from these studies to find out how three characteristics of the restored or created wetlands recover over time: hydrology, biological community, and biogeochemistry.

Wetland hydrology includes water level, flooding patterns, and water storage. It recovers quickly because it depends on the surface features engineered by restoration teams. Before they place a single plant in the ground, restoration teams manipulate soil levels and permeability to achieve ideal patterns of wetland hydrology. The biological community, however, is much harder to recreate. Even after 100 years, biological communities in restored wetlands only recovered to 77% of their undisturbed counterparts. Moreover, plant communities recovered more slowly than animals.

Biogeochemistry, the movement and transformation of nutrients in a system, only recovered to 74% after 50 to 100 years. A healthy, functioning wetland stores large amounts of carbon and organic matter, because their flooded soils deprive decomposing microorganisms of necessary oxygen. If wetlands dry out during a disturbance, oxygen reaches decomposers, allowing them to break-down carbon compounds and larger pieces of organic matter. The decomposers eventually release carbon dioxide to the atmosphere as a byproduct of this process. Once restoration teams restore the proper wetland hydrology, decomposition shuts down and carbon begins to build up in the soil once again. However, even after twenty years, the amount of carbon and organic matter stored in wetland soils remains significantly less than levels in undisturbed wetlands.

Dr. Power's team suggests that restored wetlands do not resemble their original condition because they have shifted to alternative states. Much like building a house, successful ecosystem restoration requires that all the right pieces come together in the correct order. If a construction crew lays out the wrong foundation or neglects to build the second floor, the house will look completely different from the blueprints. The result of this botched construction project is like an alternative state. In ecosystems, the presence or absence of certain organisms determines which organisms come next. If a restoration team fails to introduce an important organism, or does so at the wrong time, a restored wetland may give rise to an alternative state that differs from the goal.

When it comes to wetland restoration, we may know which plant species to add, but the proper foundation remains unknown. Wetland plant communities and biogeochemistry depend on soil microorganisms. If the microorganism community shifts during wetland degradation, or if restoration requires imported soils, the soils may lack the microorganisms necessary for native wetland plants to grow. These unseen changes underground have cascading effects through the wetland ecosystem, producing an alternative state. Alternative states often host different organisms, function at reduced levels, and cannot confer the ecosystem benefits we depend on. Unfortunately, the only way to fix it is to start again from scratch.

Moreno-Mateos D, Power ME, Comı´n FA, Yockteng R (2012) Structural and Functional Loss in Restored Wetland Ecosystems. PLoS Biol 10(1): e1001247. doi:10.1371/journal.pbio.1001247

Photo: Vermont Department of Forests, Parks and Recreation