Letters

Footwear fashion

The study discussed in "Do high heels boost arthritis risk?" (SN: 6/13/98, p. 382) explains men's and women's propensity for osteoarthritis of the knee by their respective heel height.

An interesting control experiment could be performed here in the West, where both men and women frequently wear high-heeled boots.

Paul Etzler
Mountain Springs, Nev.

Confusing cohosh

How are we to reconcile the statement that black cohosh "showed no activity" in a test competing for estrogen receptors ("Medicine for Menopause," SN: 6/20/98, p. 392) with the later statement that it "spurred uterine cells to grow"?

Is it possible for such herbs to latch onto only estrogen receptors in the uterus, not elsewhere? Is it possible that black cohosh is similar to tamoxifen—which turns off estrogen receptors in the breast but nevertheless causes uterine cancer? Women trying alternative therapies need to know.

A.G. Farnell
Petaluma, Calif.

The question is a good one. Unfortunately, the researchers don't know whether black cohosh acts like tamoxifen (see p. 166). Until more is known about how such herbal remedies work, the researchers advise caution.

—K. Fackelmann

Life in miniature

In response to the discussion on the size of putative "nannobacteria" ("The Bacteria in the Stone," SN: 8/1/98, p. 75), let me set a few matters straight. When I first discovered nannobacteria in rocks, this was indeed a novel finding to geologists as well as to microbiologists, as this discovery extended the putative limit of bacterial life down to the range of 5 to 250 nanometers.

The 1996 revelation of similar objects in the Martian meteorite set off a firestorm of opposition among microbiologists, who generally consider the lower limit of bacterial life to be somewhere around 200 nm. But now, however, Nealson indeed recognizes the possibility of bacterial forms in the 50-200-nanometer range. Thus, there seems to be no longer any disagreement about there being some form of life in that size range, and the Finnish group under O. Kajander has successfully retrieved genetic material from objects that small.

More recent work by myself and colleagues has shown that small balls exist in great abundance down to sizes as small as 20 or 30 nm, about the limit of our scanning electron microscope. Whether these really minute objects are true "nannobacteria," viruses, some new form of biotic particle, nonliving organic molecules, or something inorganic, it is too early to say.

Surely, it is vitally important to resolve this question. One could say "we are certain that nothing that small can possibly be alive, so let's not even try to look for them in Martian samples." Or one could say "hmmmm . . . I wonder if life really could exist that small, let's try to solve that question first on Earth. Then we can risk returns of Martian samples carrying possible minute bionts." Not only the Martian meteorite but also carbonaceous chondrites contain 40 to 200 nm balls that resemble coccoids, staphylococcus, and streptococcus on Earth. One may question our interpretation that these were nannobacteria once living in extraterrestrial space, but one cannot question the very existence of these minute objects. This is legitimate science: first you discover what's there, then you investigate further. It is amazing what you see when you start looking.

Robert L. Folk
Professor Emeritus
Department of Geological Sciences
University of Texas at Austin
Austin, Texas

Oily sunscreen

Regarding "What was life's first sunblock?" (SN: 7/11/98, p. 31), you attribute an argument to Miller and Cleaves that many compounds in the ocean could have provided ultraviolet protection for the building blocks of life, including "a worldwide slick of naturally produced oil." Where would this oil slick have come from? I thought oil was a product of life, the geologic fermentation of plants, and was produced much later in Earth's history.

Steve Tomasko
Ashland, Wis.

Some researchers have theorized that an oil slick covering the early oceans to a depth of 1 to 10 meters could have been produced by photopolymerization of methane or by hydrocarbons delivered by meteorites.

—J. Brainard

 

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