I know that Eaton started out in 1985 with Paleolithic Nutrition with a very low protein estimate. And he continued with this low estimate in Paleolithic Nutrition Revisited in 1997. However, you can see him here bending slowly away from this opinion. For one thing, he had to. The Paleontological community had just accepted the Expensive Tissue Hypothesis of Aiello Wheeler in 1995. Now it is in all text books and required reading at all universities. This Expensive Tissue Hypothesis says that the human brain could not have increased to that of modern man without the addition of a lot of meat and animal fat. Man and primates' basal metabolic rates are similar, but it takes more fuel for a larger brain, therefore our intestines became smaller which meant we could no longer eat bark and had to eat high quality/high energy foods like animal products to get enough calories and nutrients and fats (brain needs fats) to evolve a larger brain. Eaton had to relent and re-arrange his thinking which this 1998 essay shows his trend toward doing. You will also note in his conclusion a plea from him that more research needs to be done as he says that it is possible with more research to reconstruct a better picture of Paleolithic Nutrition (He obviously wasn't satisfied with his previously published views.)

Then in 2000 Eaton collaborated with Cordain on re-examining the basis for reconstructing Paleolithic Nutrition. (see Hunter-Gatherer, Dr. Eades unlisted PPLP references here on this forum). As Dr. Eades says in PPLP, the studies were all based on present day hunter-gatherers according to Lee's interpretation of the Ethnographic Atlas. However, as Dr. Eades points out, Lee was wrong. He included hunter-gatherers eating of shellfish as gathering and then Eaton concluded in 1985 that gathering was plant based and everyone has gone by this since. Cordain saw the error and Eaton himself got in on the study. Cordain and Eaton together proved by re-examining the Ethnographic Atlas that (and I quote:)



So Eaton wrote the definitive work on Paleolithic Nutrition in 1985 based on the definitive work by Lee done earlier which was wrong. Eaton (or I should say the Eatons who work together) have changed their tune.