Readers Respond to “Inside the Neandertal Mind”

PRIORITIZING POPULATIONA Puzzle for the Planet,” Michael E. Webber discusses the need to integrate three key factors (energy, water and food) to make it possible to meet the needs of a growing population. A critical point is that we have to stabilize that population in the first place. As long as it continues to grow, all other efforts are merely stopgaps.

AVI ORNSTEIN

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BLACK HOLE BIZARRENESSCan We Mine a Black Hole?”—that it is physically impossible to rapidly mine black holes for energy. There are many other “catches” that he does not mention, however. One is that the more massive a black hole is, the colder it is, and a black hole with a mass greater than about one tenth of that of Earth will have a temperature lower than that of the cosmic microwave background (CMB), which is about 2.73 kelvins. Any black hole with greater mass will therefore gain energy from the CMB and get more massive (and hence, oddly, colder). Only lighter, smaller black holes radiate, getting lighter and hotter as they do so, until they explode in a sudden burst of particles. So find a micron-size black hole but do not go close to it!

MICHAEL ALBROW

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OUR MURDEROUS ANCESTORSNeandertal Minds” are contrary to the known history of anatomically modern (that is, us). Her assertions that Neandertals were just outcompeted and that the 1.5 to 2.1 percent Neandertal DNA within people outside of Africa is the result of occasional “dalliances” would be historically unlikely.

The most likely scenario would involve waves of immigrating anatomically modern humans taking over land and causing death by plunder and disease, as Europeans discovering the New World did. And it would be naive to think that our Neandertal DNA was the result of consensual dalliances when rape went hand in hand with the pillage of every other civilization.

It would be wise for us to give up the notion that we are, or our ancestors before us were, a benevolent and sharing species.r

ROBERT E. MARX

NEANDERTAL SPELLING

STEVE LARIOS

MEMRISTOR NETWORKSJust Add Memory,” Massimiliano Di Ventra and Yuriy V. Pershin talk about how a network of memristors—computing components that change electrical resistance in response to the amount of current and retain that change—can solve a maze problem in one step. They fail to mention that to appropriately “wire” the memristors in the maze, so that an input is connected to an output, each square of it would need to be visited and a memristor placed where needed. Doing so may require more of the maze to be visited than a random drunkard's walk solution or the classic right-hand-to-the-wall solution.

DAVE BRUMLEY

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IS VS. OUGHTA Moral Starting Point,” by Michael Shermer [Skeptic], reminds us that although science and morality depend on each other, they are distinct. Science is about what “is”; morality is about what “ought” to be. When we make moral arguments, we act as humans equipped with a capacity for empathy toward human and nonhuman life and informed by science. We can contrast science-informed, empathy-based morality with religion-based morality, but science is not what makes us moral human beings; empathy is.

ANNE DENTON

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ERRATANeandertal Minds,” by Kate Wong, erroneously describes Gibraltar as the southernmost tip of the Iberian Peninsula. The southernmost part is Cape Tarifa.

“,” by Carl Zimmer [January 2015], incorrectly refers to penicillin grabbing onto a protein that aids in building cell membranes in bacteria. The protein helps to build bacterial cell walls.

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