Discovered: We may come microscopic worms after all; men and women tell stories differently; having fewer children tied to living longer; we feel in 3D.

Humans descended from a microscopic worm. For awhile now scientists have contested the claim that Xenoturbella bocki, a species of microscopic worm, is the organism from which humanity descended. But new research performed by a pair of Swedish scientists lends credence that human beings descended from the tiny creature. "Even though the worm does not particularly resemble man, development biologists have referred to the fact that the early embryonic development of the worm may display similarities with the group to which man belongs. But the problem has been that no one has previously been able to see the development of the creature." Having isolated newborn Xenoturbella bocki, the researchers found no reason to disqualify the worm as man's first ancestor. [Nature Communications]

Men and women tell stories differently. You can usually tell apart men's and women's voices. But can you distinguish the way they tell stories? Two professors, one in Florida and the other in Georgia, found that men and women — in particular, mothers and fathers — tell stories to their children in different way. "Mothers elaborated more when reminiscing with their children than fathers," the pair found. "Contrary to previous research, however, [the professors] found no differences in the extent to which either parent elaborated on a story depending on the sex of the child. Mothers tended to include more emotional terms in the story than fathers, which they then discussed and explained to the child." [Sex Roles]

Having fewer children tied to living longer. Having fewer children entails having less stress — which in turn means living longer, a (different) group of Swedish scientists studying geese populations recently learned. Stress erodes telomeres, a kind of protective cap on the ends of DNA strands. The faster they wear away, the faster the body ages. It's unclear if this research is applicable to human beings, though: "Among barnacle geese, the telomeres thus shorten more quickly in females, which in birds is the sex with two different gender chromosomes. Interestingly, it is the exacte opposite in humans." [BMC Evolutionary Biology]

We express ourselves in 3D. A group of researchers at Columbia University are phrasing their latest discovery in the terms of the latest film trend. According to a survey of individuals who underwent brain scans while expressing their emotions, the human brain reports feelings in three dimensions: "one system that directs attention to affective states ("I feel"), a second system that categorizes these states into words ("good", "bad", etc.); and a third system that relates the intensity of affective responses ("bad" or "awful"?)." Beyond the 3D metaphor, this means that the way we report our own emotions, far from being simplistic reflection of our internal state, is in fact a complex expression of several kinds of feeling. "Self-reports of emotion ... are supported by a network of brain regions that together take us from an affecting event to the words that make our feelings known to ourselves and others." [Biological Psychiatry]