Enlarge (credit: Xinhua Fu)

On one level, we have fireflies figured out. We know the enzyme they use to make light (called luciferase), as well as the chemicals they use in the light-generating reaction. We know them so well that we've turned them into useful tools for studying other aspects of biology, such that lots of people who have never even seen a firefly have used firefly luciferase in the lab.

But on another level, there's a lot we don't understand. Fireflies clearly exercise a level of control over when they light up, and they do so only in specialized organs. And there's nothing like that organ in other species. So, somehow, fireflies evolved an elaborate light-producing organ, and there's no sign of any potential precursors in related species. Which makes it a bit of a mystery.

Now, a pair of researchers from Wuhan, China, (Xinhua Fu and Xinlei Zhu) have started unraveling what's going on at the level of the genes responsible. And, while they haven't produced a complete picture of how evolution built the fireflies, they've brought us a lot closer.

Enlarge / Building a bigger brain requires new genes, not a workout. (credit: OsakaWayne Studios )

On the DNA level, there's not a whole lot to distinguish us humans from our closest relatives, chimpanzees and bonobos. At stretches of DNA that line up, human and chimp sequences are well over 90 percent identical. And, for the most part, the DNA does line up at genes; there are very few genes that are either human- or chimp-specific.

That has meant most of the focus on understanding human evolution has been on small changes that can alter the timing or level of gene activity, and thus have an effect that's not proportionate to the number of bases changed.

But that's not to say that newly evolved genes are irrelevant to human evolution. A paper released this week looks into how a class of new genes evolved since our split with our simian relatives. After gaining some insight into how this class evolved, the team behind the work looked at one of these newly evolved genes and found that it plays a key role in building bigger brains.

Enlarge / The body of Ruth Marie Terry as she was found in 1974 in Provincetown, Massachusetts. (credit: Public domain )

A 12-year-old chasing after her barking dog discovered the mutilated body of a woman in the Race Point Dunes of Provincetown, Massachuestts, on July 26, 1974. Law enforcement was unable to identify the victim, who became known as the "Lady of Dunes." Nearly 50 years later, on October 31, the FBI announced it finally identified the woman as Ruth Marie Terry , a native of Tennessee who was 37 at the time of her death.

The identification was made via genetic genealogy methods: a combination of DNA testing and profiling with traditional genealogical analysis to trace family trees—the same approach used to identify the Golden State Killer (former police officer Joseph James DeAngelo) in 2018. According to the FBI, Terry was born in 1936; had "connections" to the states of California, Massachusetts, and Michigan; and was a "daughter, sister, aunt, wife, and mother." Further details have not been released out of respect for her family—and also because the murder investigation is ongoing.

“While we have identified Ruth as the victim of this horrific murder, it does not ease the pain for her family—nothing can," Joseph Bonavolonta, a special agent from the Boston branch of the FBI, said at a press conference announcing the identification. "But hopefully, they answer some questions while we continue to look for her killer. This is, without a doubt, a major break in the investigation that will hopefully bring us all closer to identifying the killer.”