Readers react to surfing protons, the origins of humans and more

Cover of September 25, 2021 issue

Surf’s up

A laser experiment suggests that protons in outer space can accelerate by surfing shock waves within plasma, Emily Conover reported in “Shock waves give protons a boost” (SN: 9/25/21, p. 7).

Reader Norma Frank wanted to know why the protons surf shock waves at all.

Protons in the presence of such cosmic shock waves don’t have much choice, Conover says. “The electric and magnetic fields in the vicinity of the shock wave create forces that push and pull the protons, according to the laws of physics,” she says. “That’s what causes the particles to surf.”

Mind the map

Humans tend to arrange abstract ideas such as numbers or time spatially, but we don’t all use the same directions, Sujata Gupta reported in “Culture shapes humans’ mental maps” (SN: 9/25/21, p. 8).

Reader John Strand asked whether native languages influence the direction in which people map objects.

Written language may influence directionality, Gupta says. A study published in 2005 in the Journal of Cognition and Culture examined how Arabic speakers, who read from right to left, arrange numbers in a line. That study revealed that people who read only in Arabic tend to place lower magnitude items on the right — the opposite of native English speakers. This tendency was weaker for people who could read in both Arabic and English, and was not observed in Arabic speakers who couldn’t read, the researchers found.

Reckoning with racism in science

Some everyday names for animals and plants contain racist or offensive connotations. A movement to change those monikers is growing within the scientific community, Jaime Chambers reported in “Racist legacies lurk in common names” (SN: 9/25/21, p. 12).

“Bravo to this initiative!” wrote reader Fatimah L.C. Jackson, a biologist at Howard University in Washington, D.C. “This is an important step to making the world a better place.”

Bidding brows adieu

The last century of paleoanthropology has sketched out a rough timeline of how human evolution played out, centering its early roots in Africa, Erin Wayman reported in “Tracing the origins of humans” (SN: 9/25/21, p. 20).

Reader Elizabeth Hatcher wondered when and why humans lost the prominent brow ridges sported by many early human ancestors.

“No one knows for sure why humans lost big, heavy brow ridges,” Wayman says. One recent idea is that the loss was a consequence of human “self-domestication” (SN: 1/18/20, p. 16). Sometime over the last few hundred thousand years, the theory goes, humans became more cooperative and peaceful, favoring the friendly over the aggressive. Selecting for “tameness” among each other also resulted in genetic changes that affected our appearance, leading to small, flatter faces — akin to how selecting for tame wolves as our companions tens of thousands of years ago led to the floppy-eared, curly-tailed dogs we know today.

An offshoot of this idea suggests that smaller brow ridges allowed for the development of mobile eyebrows that could express a range of emotions, Wayman says. Being able to communicate even subtle feelings and intentions may have been advantageous at a time when human social relationships were becoming increasingly complex. “Of course, like many things in human evolution, these ideas are controversial,” she says.

Reader Rick Doughty praised how Wayman’s story put into perspective the last century of efforts to understand human origins. “I remember reading in Science News about the ‘latest news and findings’ that were coming to light in the 1960s and 1970s,” Doughty wrote. “I now have a better understanding of the field and also an appreciation for how far we have come in 100 years (and also how much still remains unresolved).”