Crying is known to be a symptom of pain or stress, but an evolutionary biologist from Tel Aviv University (TAU) suggests that tears are also an evolution-based mechanism to bring people closer together and make interpersonal relationships stronger.

"Crying is a highly evolved behavior," explains Dr. Oren Hasson of TAU's Department of Zoology. "Tears give clues and reliable information about submission, needs and social attachments between one another. My research is trying to answer what the evolutionary reasons are for having emotional tears."

Hasson's analysis suggests that by blurring vision, tears lower defenses and reliably function as signals of submission, a cry for help, and even in a mutual display of attachment and as a group display of cohesion.

Scientists are studying the best ways to compose messages meant for alien eyes in case we ever do get the chance to communicate with extraterrestrials.

If mankind ever does receive a signal from extraterrestrials, one of our first decisions may be what to write back.

As director of Interstellar Message Composition at the SETI Institute, psychologist Douglas Vakoch has thought a lot about this question.

"The challenge of constructing any interstellar message is trying to anticipate what you and your recipient have in common," Vakoch said. "One thing we can guarantee is they won't be native speakers of English or Swahili or Chinese."

And the same problem applies to any incoming message to Earth.

Paleontologists may have solved the mystery of how spinosaurs and tyrannosaurs - two dinosaur groups that included many large, fierce predators - could have lived in the same regions at the same time. A new study suggests that, like many pairs of surly neighbors, they simply avoided each other.