At Darwin’s Table

Did hunter gatherers eat starchy tubers? Most websites and books on paleo diets say that our paleolithic ancestors ate a diet high in lean protein and non-starchy vegetables. It is the protein part that anthropologists today argue that permitted us, as a species, to evolve our huge brain and fuel it with the required energy. On vegetables alone, such as the apes, there simply would not have been enough energy to fuel the human brain. However, controversy has arisen and his name is Dr Nathanial Dominy.

His latest findings published in Nature Genetics in October 2007, and his earlier work, challenge this viewpoint.  His research took a novel approach and rather than basing his finding on more typical techniques, such as dental structure and archeological findings, he used genetics and chemistry to answer the question. He recently weighed in on a contentious issue that developed eight years ago when isotopic evidence gathered from fossilized hominin teeth suggested that our early ancestors subsisted on a diet primarily of grasses and sedges. This was in contrast to the morphological work on dentition which suggested that our early ancestors flat teeth appear better adapted for chewing on anything but tough grass.

Dr Nathanial Dominy further investigated this dilemma using stable isotope analysis, which tests the chemical signature on tooth enamel and is able to inform the researcher what type of food that chemical originally came from. He tested the tooth enamel of early hominins, todays mole rats which feed exclusively on bulbs and tubers (underground storage organs such as onions and potatoes) and fossils of mole rats, which were taken from sites where hominins were also discovered. The enamel of both rat samples matched that of the human sample providing strong evidence that early humans consumed tubers and bulbs.  His research published in Nature further tested this hypothesis using molecular genetics. In this research they focused on the gene for salivary amylase, an enzyme in saliva that digests starch. Plants use starch to protect their fuel stores making them difficult to digest. He found through his research that chimpanzees, which subside mainly on fruit, had only two copies of this gene whereas humans have several copies of this gene. Having several copies allows more salivary amylaze to be made thus more easily breaking down starches. Thus, at some stage between the evolution of humans and chimpanzees, the duplication of these genes occurred, allowing humans to more easily subsist on tubers.

This study could help explain how humans grew such big brains. Becoming the brainiest primate, as our ancestors did, required a reliable supply of sugar. Some scientists have doubted whether meat alone could have fueled brain growth, since very early humans probably ate meat sporadically (their words not mine). With efficient methods for digesting starchy plant parts hidden underground, pre-humans tapped an unused energy source with an abundant supply.  Certainly examples exist where starchy vegetables are consumed by todays hunter-gatherer populations. The Hadza people of Tanzania, among the world’s last hunter-gatherers, rely on starchy tubers for up to 50 percent of their diet. Another study on Aborigine hunter-gatherers in Australia showed that they also typically consumed a wide variety of plants but mostly roots and starchy vegetables as well as seeds, nuts and fruits. Although this supports this hypothesis this group consumed predominantly meat. I personally do not believe that either hypothesis is mutually exclusive. I certainly think there is more evidence that most hunter gatherer groups today consume predominantly meats. This was likely to be the case for our ancestors also but perhaps starchy tubers were able to supplement this diet providing the extra energy, or glucose, needed for brain growth. 

Food

Well after yesterdays melt down, I woke up this morning thinking I might continue giving the whole grains and saturated fats a try. I think there is a grey area here. Certainly it would have been very difficult for hunter gatherers to feed on grains. But certainly there are cases of traditional tribes growing and eating them – the American Indians, the Massai, and the Dinkas, for example. But then by definition does this mean that these groups are not strictly hunter gatherers? Do you have to solely hunt and gather food for this title? Regardless, these groups certainly showed remarkable health, with no signs of the modern diseases we have today. In fact, Dr Weston Price said that the Dinkas were the healthiest tribe he had observed and he had travelled the world visiting many strictly hunter gatherer tribes. So I will explore this grey area further over the next couple of weeks and come to a conclusion at the end. Sorry guys you must think Im so flippant.

So what did I eat? Well this morning for breakfast I had two oranges and an avocado. Then I baked a very small amount of whole wheat bread (50g). The whole wheat is stone milled and organic. Short of milling wheat myself this is the best alternative available. I cooked the remaining chicken stock from the other day and added some carrots and red peppers.    

Chicken soup with Whole Wheat Bread

I was hungry around late afternoon so I had a glass of non-homogenised milk. Then I put a huge pork roast in the oven with some carrots and asparagus. This is supposed to last me for a few days. But I loved making it. It tasted really good too.

Roast Shoulder Pork with Carrots and Asparagus

My flatmate then came home and wanted to have some celebratory drinks because it was his last day. I managed to only have one beer. 

Nutrition

Exercise

Sprint/Walking – 20mins