Healthy foods in prehistory?

My day has been a lot about health and nutrition. Though I wouldn’t say I’m a health freak, I do enjoy healthy eating and exercising. We all know that eating healthily equals to eating vegetables and fruits more than anything else, while a broad and varied diet is essential. Human society provides a fantastic array of food varieties, at least in the developed countries.

But what would it have been like in prehistoric times? I do not only mean just before humans, but way back in the history of our planet.

I don’t really have anything figured out, only that question resonating in my head, and I am keen to find some answers, but do not have the time tonight. So, here I will present only a few ideas that have popped in my head at the moment.

A key fact to note is that the angiosperms (flowering plants), which produce all vegetables, fruits and seeds we find most of our nutrition in, were only present in significant abundance for the last 100 million years. The flowering plants provide such nutritious foods because they use it to attract animals to help spread their seeds or pollen; that is the sole reason they present such rich, juicy rewards. Before that, there were few, if any, organisms that would do such a thing – they would not display parts of them to be eaten!

So, this poses the question of where the nutrients would have been found before the angiosperms evolved. It may very well be that other plants had plenty of nutrients in them, but not as concentrated in specific parts, but rather more spread out. As a result, the herbivores would have needed to eat more of the plant in order to obtain sufficient levels of nutrients. I have no support for this idea, however.

Remembering an interesting side note from a lecture in soils – that most of the nutrients in modern rainforests are locked in the high canopies, while the soils are poor – made me think about the Carboniferous period, where the forests, restricted to humid, swampy coastal areas, were dominated by humongous ferns, club mosses and horsetails that had evolved tree-like forms. In our rainforests, the trees grow extremely quickly, shooting their leaves high up in a race to get to the sunlight. Because they grow so fast, they quickly absorb and assimilate most of the nutrients that are released to the soil by decay of dead organic matter, leaving the soils virtually depleted of nutrients. The same spatial arrangement of nutrients probably also occurred in the Carboniferous forests.

It is curious then how animals could thrive in these primitive forests. It is typically said that plants had to colonise land before animals, because they provide the base of the food chain. However, (if I am not completely mistaken), there were no large or even medium-sized herbivores until much later, in the Permian period. It seems the animals did not feed primarily on these plants. In that case, what did they eat? Other animals? Quite likely, but what did the animals that were eaten by those other animals eat in the first place? (Surely, there must have been low-growing vegetation around, but enough to feed entire ecosystems? Maybe, maybe not.) Did they perhaps eat fungi and other degraders? Would they have been nutritious enough?

Finally, I should mention, as a side note, that these questions relate mostly to land-based ecosystems. In the oceans and lakes, the story is different, since nutrients may be freely available floating around with the currents; many animals filter these directly from the water. Moreover, planktonic primary producers (i.e. organisms that produce organic food by photosynthesis, floating around in the water column) have probably been around since the dawn of life, first as cyanobacteria, and later as various other forms. So, in aquatic ecosystems, most nutrients will either be at the bottom, where decomposers release them from dead organisms that have sunk down, or suspended in the water.