Hans Kylberg wrote:

>If we accept the theory of a (partly) scavenging past, then I think
>if you come to a carcass after the lions but before the hyenas (who
>might crack the bones) with the help of a stone or two the marrow
>could be one of the easiest parts to eat,

In "How to Carve an Elephant" at

  http://www.mc.maricopa.edu/anthro/Carve.html

some archaeologists show that a dead elephant can be carved up using the
simple tools that were available 1.5 - 1.9 million years ago. If it took
400,000 years for these simple tools to progress to the next stage (tools
that could kill animals?) then there would have been a long period where
rocks were used before any tools at all were developed. So there could
easily have been a 500,000 year period where rocks were used to break bones
for marrow, before they figured out how to fashion tools that could cut up
the meat. So one could argue that animal meat products have been eaten for
2.5 million years (other than insects, eggs and some marine life which
could go back even further).

Don.