Readers question hominid family tree
Your comments and letters on the June 10 and June 24, 2017, issue of Science News
Hominid hubbub
In âHominid roots may go back to Europeâ (SN: 6/24/17, p. 9), Bruce Bower reported that the teeth of Graecopithecus, a chimp-sized primate that lived in southeastern Europe 7 million years ago, suggest it was a member of the human evolutionary family.
âIs it appropriate to use the terms âhominidâ and âapeâ as if the two are mutually exclusive categories?â asked online reader Tim Cliffe. âThe distinction being made is between our clade in particular and all other apes. It seems to me that âhominidsâ should be described as a subset of apes, not a separate category,â he wrote.
âYes, hominids are apes,â Bower says. âThe terminology gets pretty thick in evolutionary studies, so researchers (and journalists) use some shortcuts.â
Fossils of many ancient apes dating to between 25 million and 5 million years ago have been found, but the interest in this case is in a key transition to a particular kind of ape that walked upright and displayed various skeletal traits similar to traits unique to the human evolutionary family. âThatâs why one source in the story, Bernard Wood, wonders whether Graecopithecus was an apelike hominid or a hominid-like ape,â Bower says. âBut itâs important to remember that hominids diverged from other, ancestral apes. So did chimps.â
Science News defines âhominidâ as a member of the human evolutionary family.
Laser, camera, action
The worldâs fastest video camera films 5 trillion frames every second, Ashley Yeager reported in âA different kind of camera captures speedy actionsâ (SN: 6/24/17, p. 5). The camera works by flashing a laser at a subject and using a computer program to combine the still images into a video. Researchers tested the device by filming particles of light as the particles traveled a short distance.
Online reader JHoughton1 wondered if the researchers really filmed a light particle in their tests. âI thought light âsometimes behaves like a wave, sometimes like a particle,â but that there isnât really any particle thatâs a particle in the usual sense. Is this really a picture of a âparticleâ of light? A photon-as-ball-of-stuff?â
The camera captured the forward progression of a laser pulse, which is an ensemble of photons, Yeager says.
Photons themselves arenât âballs of stuffâ on quantum scales, says physics writer Emily Conover. All particles, including photons, are spread out in space, propagating like waves. âOnly when scientists measure or observe a photon or any other particle do they find it in one place, like the ball of stuff that people typically imagine. I think in that sense, photons are about as tangible as any other quantum particle,â Conover says.
Bringing down the mucus house
Little-known sea animals called giant larvaceans can catch a lot of carbon in disposable mucus casings called âhouses,â Susan Milius reported in â âMucus housesâ catch sea carbon fastâ (SN: 6/10/17, p. 13).
Online reader Robert Stenton wondered what happens to mucus houses as they fall to the bottom of the ocean.
What happens to discarded houses isnât yet clear, Milius says, though researchers have proposed that the houses might carry substantial portions of carbon to life on the sea bottom. And if bits of a house fall fast enough to reach great depths, the carbon could get trapped in water masses that move around the planet for centuries before surfacing. Bits drifting down slowly may be intercepted by microbes and other debris feeders and would not end up sequestered.
Correction
In âHuman noises invade wildernessâ (SN: 6/10/17, p. 14), Science News incorrectly reported that official wilderness areas in the United States do not allow livestock grazing. Grazing is permitted in protected wilderness areas at preprotection levels under the Wilderness Act of 1964, which created the National Preservation System.