Thursday, 27 October 2011

Origin of Us

More great output from the BBC.  The 'Origin of Us' is available on iPlayer (until 7:59PM Mon, 7 Nov 2011):
  • In this second episode Dr Alice Roberts charts how our ancestors’ hunt for food has driven the way we look and behave today – from the shape of our face, to the way we see and even the way we attract the opposite sex. Clues to our ancestor’s diet can be found in some surprising places. Alice goes in search of a lion kill to find out how the tape worms in lion’s food reveal our ancestors were eating the same diet of big game 1.7 million years ago. She puts her teeth to the test to reveal that our teeth have evolved to shear through meat. But by comparing her saliva with that of chimpanzees she demonstrates that our body is as much designed to eat starch as it is to eat meat.

    And visiting a tribe of hunter gatherers in Tanzania, who still gather food in a similar way to our ancestors, Alice discovers that starchy tubers are crucial to survival when meat is scarce. The latest research suggests that the way the different sexes found food throughout our evolution has shaped the way we relate to each other today. The way the Hadza tribe share food and form long-term couples is thought to be the origin of love and marriage in all of us. And a fun experiment with Britain’s best skateboarders shows they take more risks when women are present – it seems men are designed to show off to attract a mate.
Some very interesting points are raised including:
  • Human and lion tape worms are genetically almost identical which suggests we caught the parasite from a common source, and most likely from eating the same food - big game.  Genetic research on the tape worm points this to some time between 800k and 1.7 m.y.a.
  • Early tools found in Africa suggest they were used for butchering.
  • As covered elsewhere on this blog, our teeth have become smaller and sharper, with thicker enamel which are quite specific to tearing flesh.  However, pits and scratches on the teeth of Homo Erectus suggest an omnivorous diet.
  • Human saliva contains 6-8 times more amylase than in the saliva of chimps.  Amylase breaks down starch in to sugars.
  • An argument is made that it was cooking, not necessarily meat-eating that fuelled the growth of our brains (again something I covered here).  The remains of ancient fires show the remains of charred bones and hazelnut shells!  But specifically, if you eat 100 calories of for example, carrot, 25% of your calories go in to digesting it.  If you cook that carrot, you can get 35% more energy out of it.
The program follows the totally unjacked Hadza.  In Hadza society the women forage and the men hunt.  Hunting is unreliable as a food source, but women highly prize a good hunter - rating men more for their hunting than their looks.  In Hadza society the most successful hunters tend to be in their 40s and 50s.

Although the program used the Hadza as basis for recommending we eat an omnivorous diet, looking at them I saw a population surviving in a harsh environment - but perhaps not thriving.  Given the tapeworm point above, and given the overhead of specialisation in evolution (the cost of adaption of our teeth towards a  specialisation for tearing meat), suggests to me that meat eating was VERY important to our ancestral diet.

No comments: