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Letters from the May 27, 2006, issue of Science News

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Dig it or don't

I am rather surprised at all the attention this find is getting ("Out of the Shadows: Not all early mammals were shy and retiring," SN: 3/18/06, p. 173). Some would think that these mammals caused the downfall of the dinosaurs, but the fossil record suggests a very different scenario. There is no evidence of possum-to-coyote–size mammals for the 70-odd million years that the dinosaurs ruled the planet. The only mammals able to remain uneaten were no larger than a rat, almost too small to be noticed.

Dan Peterson
Fort Campbell, Ky.

The article mentions that "researchers analyzed the . . . skeleton of a chipmunk-size creature that lived 150 million years ago. . . . The . . . limb bones suggest that the creature spent a lot of time digging." Finally, paleontologists have discovered their own direct ancestor.

Bob Kanefsky
Mountain View, Calif.

Threes, the easy way

I refer to your article "Pigging Out Healthfully: Engineered pork has more omega-3s" (SN: 4/1/06, p. 196). Changing the diet of pigs, cows, chickens, etc., to include more omega-3 fatty acids would be a healthy alternative to genetic engineering and wouldn't require government approval. In particular, the weed purslane is higher in omega-3s than any other vegetable and is also edible by humans, although it is not generally available in markets. In addition to improving the quality of meat, purslane feed could produce healthier butter and eggs. And eggs, unlike fish, are plentiful, cheap, and free of pollutants.

Harriet Pearlman
Metuchen, N.J.

The researchers seem to be unaware that grass-finished beef has two to six times the concentration of omega-3s that grain-finished beef has. Eggs from chickens allowed to forage for part of their food average four times the omega-3s found in factory-produced eggs. There are more easily implemented methods of making animal products healthier than genetic engineering.

Virginia Brock
Rock Island, Ill.

These points about omega-3s in meat and eggs are valid, but changing an animal's feed, even by providing it more foraging space, significantly increases the price of meat, milk, and eggs, say the authors of this study. One of their study objectives was to avoid higher prices.—C. Brownlee

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