Light Friday: Why Do Humans Kiss?

June 28, 2013


MIT Develops Cheap Hologram Technology

A Triplet of Possible Life-Supporting Planets

How Throwing Stones Is Tied to Human Evolution

If you think about it, kissing seems like an odd activity. Why would two members of a species place their lips (and sometimes tongue) together in such a way? What is the evolutionary advantage?

Research shows that kissing likely evolved from mouth-feeding - when a mother places pre-chewed food directly into her child's mouth. Birds are famous for this, but the behavior has been seen in other animals, including primates.

Other scientists say that a person's saliva carries information about their health, which helped in mate selection. The video below from Vsauce explains more.


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MIT Develops Cheap Hologram Technology

Holograms are not a mysterious technology. We know how to make them. There are no theoretical obstacles. And yet here you are, reading on a two-dimensional screen. What gives?

The answer, of course, is money. But thanks to new developments at MIT's Media Lab, holographic displays might become much less expensive. In a paper recently published in Nature, Daniel Smalley outlines his idea for a standard-definition, full-color, holographic video display.

Key to Smalley's invention is a $10 optical chip that he developed at the Media Lab. The chief breakthrough is the way it directs light through the crystal that propagates the display's holographic image -- in Smalley's display, a tiny lithium niobate crystal sits at the center of the operation. Its underside is stippled with microscopic channels called waveguides, which are used to confine and direct the light that will eventually make up the display's image. They are also embedded with an electrode that provides an acoustic wave.

As beams of red, green, and blue light travel through the crystal's waveguides, the electrodes embedded within them create an audio wave that filters out the colors that aren't needed in the image. In the end, the binary channeling done by both the surface of the waveguides and the audio frequency sounded within them allows Smalley to produce a quality holographic video signal, all for roughly the same price as my lunch yesterday.

Impressively, Smalley's display could become even cheaper. "Everything else in there costs more than the chip," says Smalley's thesis advisor, Michael Bove, "The power supplies in there cost more than the chip. The plastic costs more than the chip."

Currently, a number of companies are actively pursuing holographic technology

, and in the coming years, we'll likely see holographic TVs pop up in R&D labs across the globe. Coupled with MIT's new holographic technology, those first models might turn into cheap consumer displays.

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A Triplet of Possible Life-Supporting Planets

Astronomers have discovered several planets that might support life in a star system not too far away. Dr. Guillem Anglada-Escude of the University of Göttingen, Germany, discovered seven planets orbiting a star known as Gliese 667C, about 22 light-years away. Three of the planets, known as "super-Earths" because they are between four and eight times the mass of our own planet, lie within the region that could support life, known as the habitable zone. As CNN explains

, the habitable zone is a band around a star that could support life and theoretically hold water. Our own solar system's habitable zone runs from Venus, through Earth, and ends at Mars.

The Gliese 667C star is the third in a triple-star system called Gliese 667. These three stars provide as much light to the three possibly habitable planets as our sun and moon provide Earth. The three planets are either rocky or water-covered planets, and are "tidally locked," meaning the same side of each planet faces its sun at all times.

This finding follows a similar discovery in April concerning planets in the Kepler-62 system. Scientists are finding more planets that could support life as technology develops and opens the skies to deeper investigation.

"As soon as our telescopes and data analysis tools have become sophisticated enough to find them, habitable planets are popping up everywhere," Sara Seager, professor of planetary science at Massachusetts Institute of Technology, told CNN. "It's simply exhilarating to know that potentially habitable planets are ubiquitous."

How Throwing Stones Is Tied to Human Evolution

These days, preparing a meal doesn't require as much exertion as our ancestors, whose ability to throw stones in order to hunt game factored into our evolution. One post-doctorate fellow is researching how changes in anatomy shaped hunting behaviors, which can be traced back nearly 2 million years to Homo erectus ancestors.

Neil Thomas Roach

, a biological anthropologist and fellow at The George Washington University is investigating the tie between changes in upper body anatomy during human evolution and throwing performance, which ultimately factored into the tools hominins used for hunting game. Roach and his colleagues, Harvard University researchers, also looked into energy storage in our shoulder muscles and examined 20 young men with good throwing ability. They were able to use a 3D camera system to analyze throwing movements.

The team found that a powerful throw is linked to the amount or energy stored in shoulder muscles. Human shoulders are different from our scavenger ancestors (whose sockets faced forward instead of projecting from the sides like us), yet we still have strong throwing ability: a 12-year-old boy can throw three times faster than chimpanzees, our closest evolutionary relative, New Scientist reported


Diet also influenced our throwing ability, Roach contends. "Eating more calorie-rich meat and fat would have allowed our ancestors to grow larger brains and bodies and expand into new regions of the world, all of which helped make us who we are today," he said. Next, Roach and his team will trace evolution to investigate the types of objects that were used for hunting. Something to think about as you eat your sandwich at work today.


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