Bob Avery said
>
> Is there any proof that all or most of the Earth was ever covered in ice?
>

Is there any doubt? When there was so much water stored in ice that sea
levels were low enough for animals and humans to walk between what is now
mainland Europe and the British Isles, then I submit that the whole globe
must have been considerably cooler than it is today.

I thank Melissa Darby for the information about Sagittari latifolia
(wapato). This is a plant I don't know. I would like to know more: what is
its amino acid profile, for example? Could it have been used as a staple
source of the nutrients the body needs for any length of time?

I take Don's point about ratios -- if the plant foods are cooked. The
question now is: when did cooking become universal?

Homo erectus began to appreciate the value of fire around 350,000 years ago.
Although hearths have been discovered that are 100,000 years old, these are
very rare. European Neanderthal coprolites from around 50,000 years ago,
before their use of fire, contain no plant material. (Bryant V M,
Williams-Dean G. The Coprolites of Man. Scientific American, January 1975.)

It seems that it was not until Cro-Magnon's colonisation of Europe, some
35,000 years ago, that hearths became universal. Even then the evidence
suggests that they were not used for cooking plants but merely for warmth.
This is really too recent in our history for any big change in genetic
makeup, surely?

Yes, Dana, we in Europe do eat grass-fed ruminants, although there may be
some grain based feed introduced during winter months. We wouldn't give you
a thank-you for wholly grain-fed animals.

Barry Groves
http://www.second-opinions.co.uk