"The cones [of Araucaria bidwilli, the 'Bunya Bunya' pine of Australia] shed their seeds which are....sweet before being perfectly ripe, and after that, resemble roasted chestnuts in taste. They are plentiful once in three years, and when the ripening season arrives...the aborigines assemble in large numbers from a great distance around, and feast upon them. Each tribe has it's own particular set of trees, and of these, each family has a certain number allotted, which are handed down from generation to generation with great exactness...The food seems to have a fattening effect on the aborigines, and they eat large quantities of it after roasting it at the fire.. Contrary to their usual habits, they sometimes store up the Bunya nuts, hiding them in a water - hole for a month or two." -  J. Maiden in 'Forest Flora of New South Wales' 1889.

The greatest advantage of nut trees is that, unlike animals, they don't run away! The energy expended in gathering and preparing nuts is much less than the time and energy spent obtaining the same calorie value from hunting.

Nuts are about the most calorically dense foods found in the natural environment nature (apart from animal fat). A small number of nuts provides a large part of the daily energy requirements. They are also low glycemic, which means they 'burn slow' and don't cause a surge in insulin levels which can result in a crash in blood sugars.

Nuts are not just a European temperate crop-Africa has many edible seeded trees and vines. On the riverine alluvium and Kalahari sands of Botswana and South West Africa, an extremely valuable fruit and nut tree grows.. The Manketti nut (Ricinodendron rautanenii) is covered by a sweet flesh that can be dried and stored. The kernel itself has a protein content of about 25%, and a fat content of  about 50% (40% of which is linoleic acid, an 'omega 6' essential fatty acid, 18% the monounsaturated oleic acid, and the rest saturated fats) It has an extraordinarily high vitamin e content - around 560mg per 100 grams of kernel! The tree is not only found scattered in open woodlands-in some areas there are large stands, up to 60,000 hectares in extent. One such forest was estimated to produce (in a good year) a crop of 1 ton of nuts to the hectare! It is estimated that one hundred of these small (about 5 gram) dried fruits, with the kernel, would provide 71% of the daily energy requirement for an adult and 115% of the daily protein requirement. Examples of other African tree seeds that are used for food are the African Breadnut (Treculia africana) found from coastal west Africa to Sudan, and the African Brazilnut (Poga oleosa) an abundant forest tree in equatorial West Africa which also easily yeilds an oil similar to olive oil.

Tree seeds are not necessarily benign. Some contain bitter tannins, some contain chemicals that can cause anything from a guts ache through to death. But humans have learned two strategies to deal with even these unpromising food items- leaching the poisons out in running water, and inactivating them by cooking. Humans millenia ago were essentially no different (genetically) to us today. Then, as now, there would have been the hierachy of preferred foods. Some tree seeds would have been avidly sought after, and others used only if food was in short supply.

There is no doubt that we could live on tree seeds alone. When we radiated out of Africa, we sought and exploited tree seeds wherever we went - hazels in Europe, the tropical almond, Terminalia catappa, in India, the very buttery okari nut, Terminalia kaernbachii of Papaua New Guinea, the souari nut of tropical America-and found them in abundance. Some of the tropical species crop twice a year, and many have very hard woody or fibrous shells that lend themselves to limited storage, even in tropical conditions. Some seeds are superb eating (the souari nut, along with two other species of tree seed, has been described as "the most popular articles of food in the Amazon region"), and very many are rich with oils of all kinds.

With the abundance of seeds came the harvesters. Humans camped in the groves for the season. Rodents foraging for their share, wild pigs too. And in some areas, rodent eating snakes lay in wait for the rodents. We, of course, ate them all.

There is no doubt that we could live on tree seeds alone-and there is no doubt that we didn't. We ate everything. In the west, however, nuts have been regarded as little more than snacks. They have been reviled as 'fattening'. In fact, they are an excellent primary food for the human animal. Excess calories are stored as fat. We have evolved to be able to do that. It is a store against hard times, it is the nutritional bank account that allows ovulation, growth of a foetus, and milk production. Curiously, trials under way (on obese people who have difficulty dieting) are suggesting that far from being fattening, people who consume nuts as a component of their diet compensate quite unconsciously by reducing calories from other sources. Weights remain stable, or even reduce slightly. Presumably this is because nuts are 'slow burners', and therefore keep you from feeling constantly hungry for calory laden sugar.

As Western scientist probe tree seed consumption they discover that 'This is astonishing! Nuts are a food very fit for human consumption!'. In experiments where the standard unnatural western diet was 'enriched' with macadamia nuts, the blood cholesterol level dropped 5%, and the level of harmful triglycerides in the blood also dropped. A similar result was found when pecans were added to the standard diet. Studying the effects of a diet rich (39% of calories derived from fats) in fats derived predominantly from almonds, scientists found, again, blood cholesterol dropped by around 11%, and the dangerous LDL cholesterol fell by a very healthy 17%. (Part of this effect may well be from eliminating high omega-6 polyunsaturated oils, and displacing hydrogenated oils, as much as including nuts high in monounsaturates.) Other studies have shown those people who include nuts in the diet are at significantly lower risk from coronary disease.

Interestingly, they have also shown that when the whole nut is eaten, rather than just the pressed oil, the oil component of the nut enters the bloodstream more slowly compared to eating the expressed oil (as in a salad dressing). It takes about an hour for the lipids to peak in the bloodstream, and then they dropped away more rapidly as well. The fat from whole nuts is delivered in a different way in comparison with the pressed oil. It is 'encapsulated' and delivered slowly, like a time release tablet. It doesn't 'flood' the bloodstream. Scientists suspect the 'encapsulation' effect holds true for most, if not all, tree seeds.
 
Evolutionarily speaking, we have had only a limited ability to press oil from nuts. We probably only did it when there was a superabundance, and where the oil naturally forms a soapy or fatty solid that could be stored in gourds or the like. The seeds of a Brazilian coastal nut tree, Caryocar brasiliensis, for example, has a kernel that is cold pressed by the native people. "The fat is of excellent taste and solid like butter" as one observer commented.

Most of these large tropical trees with nutritious seeds have never been brought into cultivation outside their ecosystem. Even brazil nuts, Bertholettia excelsa, are still gathered soley from the wild. The wild, the woodland, the jungle, the forest margin, is where we evolved, remember. The forest is our supermarket. And the tree seed section is well stacked. Almost all these trees will probably never be cultivated, and a fair proportion of them will become rare, very rare, or extinct as the human animal both alters and destroys the complex natural ecosytems of the world. Not only have we left our natural supermarket, we've lit a match and casually thrown it down as we walked out the door.

Perhaps the grasses have discovered and unleashed a new terrorist-the human, Homo sapiens-to become their agents in their age old war with woodland and forest for control of the land! A cunning plot, and it may just work!
 
These notes are a look at the tree seeds we eat, but from a hunter-gatherer evolutionary perspective. It is not so much a 'guide to' as a 'guided tour' of what we evolved to eat, and what we now eat due to urbanisation.  The guide is divided into two parts.

First, those tree seeds we eat regularly, or on occasion.
 
Second, those tree seeds  a Western person is unlikely to eat in their lifetime - a normal human food, perhaps eaten by many people, but screened out by cultural conditioning, the historical circumstances of the politico/industrio/heirachical urbanisation of our Western society. And because some tree seeds are difficult to grow outside their specific environment, and some may require more preparation to get at the edible part (or to remove bitter or dangerous toxins) than Westerners have time to for. (under construction - one day, when I have time....)
 
Links
Protective and weight loss benefits of almonds An interesting article detailing how almonds protect against colon cancer, and how a diet that includes almonds as a fat source helps take weight off and also keeps it off. At the California Almond Board site.
http://www.almond.org/growers/releases/18.htm
 
Paper Reading-list of books & scientific papers to buy or find at the library (links to internet sources of the book or paper are included where available)

The author rejects any responsibility for any decisions about life, diet, or anything else other than his own. Any action you take after reading the material here is solely your responsibility - seek advice from others, read critically and widely, don't accept everything you read here. You have been warned! Question everything.
 
Form your own opinion on these matters after reading widely and consulting appropriate professional advice, including advice of medical practitioners and professional nutritionists.