The vegetable food of the evolving man was drawn from the following sources :
Seeds constituted his most important vegetable food, on account of the large amount of protein they contain.
When seeds are contained in an exposed brightly coloured, fleshy envelope, they constitute fruits. In the case of most fruits these envelopes, consisting in the ripe state of little more than dilute solutions of sugar and salts, furnish a comparatively small amount of energy, while the contained seeds do not, for the most part, admit of being digested by the mammalia, unless laboriously masticated.
The term "fleshy root" may conveniently be made to include any underground part of a plant (e.g. tuber, rhizome, tap-root) serving as a storehouse of nutriment. The nutrient value of such "roots" depends chiefly upon their richness in starch.
Under this head are included leaves and the young shoots of plants. They afford little energy-yielding nutriment, and their chief food value lies in their watery and saline constituents.
These, though of little nutrient value, must also be included among the foods of the evolving man.
It is important to bear in mind that the products of the uncultivated vegetable kingdom are by themselves totally inadequate to man's nutritive needs. The popular belief to the contrary is perhaps in some measure due to the mistaken notion that fruits like the fig, the date, and the banana grow wild in abundance, and constitute even in their natural state highly nutritious foods; whereas, as a matter of fact, they are, as supplied to our markets, the finished products of a cultivation dating back into an impenetrable past and scarcely to be identified with their wild and barely edible congeners. The sugar-cane and the cocoa-nut are other instances of fruits brought to their present perfection by centuries of careful cultivation : wild, they furnish but a meagre supply of nutriment suitable to man. Even our simian and post-simian ancestors were not able to subsist entirely on the vegetable food with which nature provided them.
One's mind, influenced no doubt by the poets, is too apt to picture early man as surrounded by a profusion of luscious fruits and sweet-tasting seeds, as living in a veritable lotus-land of plenty, where an abundance of delicious food was to be had for the mere trouble of gathering it. But the reality was far otherwise, as is proved by the fact that even now no existing race of man, in spite of most elaborate methods of preparing and thus increasing the nutritive value of its vegetable food, is capable of subsisting on it alone.
As regards the animal food of the evolving man, it may safely be said that prior to the period of food culture it was acceptable to him in practically any form in which it could be procured. Some kinds would naturally be preferred before others, but there can be no doubt that, at any rate in times of dearth, all kinds were greedily devoured, from mammals, fish, birds, and birds' eggs of every description, to shell-fish, lizards, snakes, frogs, grubs, worms, snails, insects, and caterpillars.
This seems the proper place in which to mention honey, inasmuch as it is an animal product; from simian times onwards wild honey undoubtedly afforded a valuable source of nutriment to our progenitors.