Letters.

Help for arthritis?

I carry a gene that turns on various arthritic nightmares. Could this immune research ("Malaria disrupts the immune system," SN: 7/3/99, p. 4) carry through to find ways to disrupt the immune system beneficially?

John C Stires III Escondido, Calif.

The cause of arthritis is unknown, and research on dendritic cells is still in its early stages. However, David J. Roberts of John Radcliffe Hospital in Oxford, England, suggests that finding a mechanism for disabling dendritic cells might prove useful against autoimmune diseases, could help in suppressing transplant rejection, or may aid in combating graft-versus-host disease--in which immune cells in transplanted tissue attack the recipient's cells.

--N. Seppa

Monkeys are individuals, too

It surprises me that Sue Boinski is facing so much opposition to her observations that different squirrel monkey populations evolve different social behavior patterns ("The secret lives of squirrel monkeys," SN: 7/3/99, p. 14). It is common for isolated subpopulations to evolve mating behaviors that effectively prevent crossbreeding with partners from a different group. Only researchers' strong desire to generalize the behaviors they observe can explain the reluctance to acknowledge that a community's present social norms are profoundly affected by the historical and current interactions of the individuals that are a part of the community.

James Larkin Granger, Ind.

Bt is as Bt does

"Bt-treated crops may induce allergies" (SN: 7/3/99, p. 6) concerns human allergic response to Bt toxin in people who work with crops that have been sprayed with the material. What the article did not say is that many, many more people will be exposed to the Bt toxin and will likely be sensitized by eating crops engineered with the gene for the toxin. If, as the article stated, 70 percent of the farm workers directly exposed to the Bt toxin developed an allergic response within 3 months, what can this mean for a whole human population exposed through their food? The human population is involuntarily participating in a laboratory test on a grand scale.

Mary-Howell Martens Penn Yan, N.Y.

Dad as decoy 

The article "If Mom chooses Dad, more ducklings survive" (SN: 7/3/99, p. 6) noted that it's far from obvious why mallards form pair bonds. I can offer a suggestion. This spring, I observed pairs of both mallard ducks and Canada geese throughout the breeding season. In both species, females on their nests of brownish grass were almost invisible. The males, which normally swam on the nearby pond or conspicuously walked about, were often strikingly visible.

Many scientists have hypothesized that the male's ornaments are indications of genetic fitness. It is also possible that the ornaments are used by the female in the selection of mates because they make the male a decoy. That may divert attention away from the hen and young.

I. Scott Columbus, Ohio

MSG and type 2 diabetes 

Your article "Type 2 diabetes appearing in youths" (SN: 7/10/99, p. 31) is of special interest to me. I saw no type 2 diabetes in young people when I started medical practice in the early '60s. By the time I had retired in 1995, such patients were not uncommon in my practice. I believe monosodium glutamate (MSG) is the cause. MSG is an excitotoxin that works by overstimulating its nerve target. When MSG is fed to baby rats for the first 9 days of their lives and then discontinued, the MSG destroys the arcuate nucleus of the pituitary gland. For the rest of the life of the rat, it will be obese, hypothyroid, and lethargic when compared with controls not given MSG. Remember, MSG was released on the market in 1948. Just read your food labels.

Ian D. Murphy Toledo, Ohio

The eye of the tabby

In your July 10 issue, the article "What color is your carnivore?" (p. 26) was of interest to me, since I share my household with carnivores who usually get their prey from cans. I've noticed that tabby cats have false "eye" markings above their actual eyes, just like the tiger in the article's photo has. Because of these illusory eyes, my cats often appear to be awake when they're napping. Might these features provide an evolutionary advantage?

Yvonne Lyerla Sonoma, Calif.

Alessia Ortolani speculates that white markings under the eyes of nocturnal predators and dark muzzles on diurnal predators might have as their evolutionary purpose making it easier for other predators to read expressions and identify each other. A simpler explanation is that these markings help the predator's eyesight (almost always a plus for a carnivore). White under the eye would reflect into the eye the maximum amount of ambient light, helping nocturnal predators see in the dim light of night. Dark markings under the eye (such as on a muzzle) would help cut the glare from sunlight, useful to diurnal predators.

Lee Stevens Irving, Texas

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