[I'm only assuming that in this section of the forum it's Ok form to start a new thread for a paper, so I'll understand if it gets moved. This is particularly long because I'm not sure how available the original paper is online.]

The basic hypothesis that this study was based on was that modern, rampant human cardiovascular disease is linked to the historically efficient conservation of cholesterol by the human body, due to an ancient diet promoting/providing very low cholesterol.

Jenkins D, Kendall C, Marchie A, Jenkins A, Connelly P, Jones P, Vuksan V, 2003. The garden of eden - plant based diets, the genetic drive to conserve cholesterol and its implications for heart disease in the 21st century. Comparative Biochemistry and Physiology-Part A: Molecular & Integrative Physiology 136(1);141-151

Abstract
It is likely that plant food consumption throughout much of human evolution shaped the dietary requirements of contemporary humans. Diets would have been high in dietary fiber, vegetable protein, plant sterols and associated phytochemicals, and low in saturated and trans-fatty acids and other substrates for cholesterol biosynthesis. To meet the body's needs for cholesterol, we believe genetic differences and polymorphisms were conserved by evolution, which tended to raise serum cholesterol levels. As a result modern human, with a radically different diet and lifestyle, especially in middle age, is now recommended to take medications to lower cholesterol and reduce the risk of cardiovascular disease. Experimental introduction of high intakes of viscous fibers, vegetable proteins and plant sterols in the form of a possible Myocene diet of leafy vegetables, fruit and nuts, lowered serum LDL-cholesterol in healthy volunteers by over 30%, equivalent to first generation statins ... We conclude that reintroduction of plant food components, which would have been present in large quantities in the plant based diets eaten throughout most of human evolution into modern diets can correct the lipid abnormalities associated with contemporary eating patterns and reduce the need for pharmacological interventions.
The important, relevant thing is that the study included three trial diets, the third of which "simulated Simian/Myocene" being, essentially, vegan (minus tubers & beans).

Hypothesis
We suggest that for most of human evolution cholesterol was virtually absent from the diet. Few foods were available from which cholesterol could be synthesized within the body, and many foods enhanced cholesterol elimination via the gut. Nevertheless, cholesterol fulfills essential functions in cell membranes, as a component of transport lipoproteins, and for bile acid and steroid hormone synthesis. Human physiology, therefore, developed mechanisms to preserve the total body pool of cholesterol through enhanced cholesterol synthetic ability and efficient retrieval in the terminal ileum of bile acids as the major metabolic end products of cholesterol metabolism. ...
Thus, human physiology, as presently constituted, along with some of its attendant SNPs for cholesterol homeostasis, is now a liability for those on a Western diet, rich in both dietary cholesterol and possibly more importantly dietary substrates for cholesterol biosynthesis, saturated and trans-fatty acids. In addition, the diet lacks ... plant sterols, viscous dietary fibers, vegetable protein, and a range of other phytochemicals.
Reconstructed diets
We selected two dietary periods to study. One was a diet that might have been eaten in the Myocene 5–7 million years ago at a time when the diet of the human ancestor was probably not very different from the range of foods eaten by contemporary great apes and when the genetic make-up was possibly no more than 2–3% different from modern humans. It consisted of large amounts of leafy vegetables, nuts (almonds and hazelnuts), and fruit. ... The second diet was an early agricultural diet, possibly representing the food supply of 10 000 years ago (Neolithic) with a major focus on the introduction of starchy foods, especially cereals and legumes.
(For some reason the Neolithic trial diet, though it didn't contain any meat, did contain dairy.)

The cholesterol reductions on the Simian diet were similar to the reductions achieved with the first generation statins. Analysis of the diet for components, which might alter cholesterol metabolism, showed that the Simian diet provided approximately 1 g of plant sterols daily, 145 g of fiber and 92 g of vegetable protein ... per day. The former two components would have reduced cholesterol and bile acid absorption and thus increased fecal steroid loss and the vegetable proteins would have reduced hepatic cholesterol synthesis, and caused up-regulation of LDL-receptors. ...
We could have studied diets closer to the chimpanzee (who also kill and eat rhesus monkeys) to which could be added molluscs and insects. Alternatively, a low saturated fat wild game diet of the Paleolithic ... However, our argument has been that our genetic differences even from the orangutan and gibbon are not great. In this respect, we believe that diets high in fiber and vegetable proteins have shaped our metabolic processes over the greater (even if not the most significant) part of our evolution and the question, therefore, was what such diets would do to risk factors for our most prevalent chronic disease, coronary heart disease.