A molar tooth from Southeast Asia probably belonged to a member of a cryptic group of Stone Age hominids called Denisovans, researchers say.

If so, this relatively large tooth joins only a handful of fossils from Denisovans, who are known from ancient DNA pegging them as close Neandertal relatives.

Analyses of the tooth’s internal structure and protein makeup indicate that the molar came from a girl in the Homo genus. She died between the ages of 3½ and 8½, paleoanthropologist Fabrice Demeter of the University of Copenhagen and colleagues say.
A Denisovan molar that dates to at least 160,000 years ago was previously found on the Tibetan Plateau (SN: 12/16/19). The newly discovered tooth strongly resembles that other molar, indicating that the new find is probably Denisovan too, the team reports May 17 in Nature Communications. Before the Tibetan Plateau tooth, all known fossils from the mysterious hominids had been found in Siberia.

Estimated ages of sediment and fossil animal bones in Tam Ngu Hao 2, or Cobra Cave, in Laos place the tooth found there between 164,000 and 131,000 years old.

It’s possible that the Cobra Cave tooth represents a Neandertal or someone with Denisovan and Neandertal ancestry (SN: 8/22/18), Demeter says. His group hopes to extract DNA from the fossil, which could clarify its evolutionary status.

It now appears that at least five Homo species, including Denisovans, inhabited Southeast Asia between roughly 150,000 and 40,000 years ago, Demeter says. Others include Homo sapiens, Homo erectus (SN: 12/18/19), Homo luzonensis (SN: 4/10/19) and Homo floresiensis (SN: 3/30/16), also known as hobbits, he contends.

Still, some researchers regard Denisovans as one of several closely related, ancient Homo populations rather than a distinct species (SN: 6/25/21). Whatever evolutionary ID Denisovans actually held, the Cobra Cave tooth adds to suspicions that the hominids inhabited Southeast Asia’s tropical forests as well as Central Asia’s cold mountain ranges and Siberia.

A speck of gold dancing to a pipe organ’s tune has helped solve a long-standing mystery: why certain wind instruments violate a mathematical formula that should describe their sound.

In 1860, physicist Hermann von Helmholtz — famous for his law of the conservation of energy — devised an equation relating the wavelength of a pipe’s fundamental tone (the lowest frequency at which it resonates) to pipe length (SN: 3/31/28). Generally, the longer a pipe is, the lower its fundamental tone will be.

But the equation doesn’t work in practice. A pipe’s fundamental tone always sounds lower than the pipe’s length suggests it should according to Helmholtz’s formula. Fixing this problem requires adding an “end correction” to the equation. In the case of open-ended pipes such as flutes and those of organs, the end correction is 0.6 times the radius of the pipe. Why this was, nobody could figure out.

A break in the case came in 2010. Instrument builder and restorer Bernhardt Edskes of Wohlen, Switzerland was tuning an organ when he spotted a piece of gold that had come loose from a pipe’s gilded lip. Air pumping through the pipe should have carried away the gold. Instead, it seemed to be trapped in a vortex just above the pipe’s upper rim.

Edskes told his friend, physicist Leo van Hemmen of the Technical University of Munich, about the observation. Together with colleagues from Munich and Wageningen University in the Netherlands, they studied how air moves through playing organ pipes using cigarette smoke.

When an organ pipe sounds, a vortex indeed forms over the pipe’s rim, the team reported March 14 in Chicago at a meeting of the American Physical Society. What’s more, this vortex is capped by a hemisphere of resonating air.
This vibrating air cap, van Hemmen says, is the long-sought explanation for the “end correction.” The cap effectively lengthens the organ pipe by the exact amount that must be tacked on to Helmholtz’s formula to explain the pipe’s fundamental tone.