I'm glad they're doing some research into the digestive acids and what-not to show that paleos would have eaten mostly meat, but to me, the biggest proof that humans ate mostly meat is that no matter what part of the world you live in, there are seasons to the year. It doesn't matter where you are - naturally occurring edible matter (including fruit and nuts) is either not growing at all, or extremely limited at least part of the year, whether it's the dry season or the winter. They had to eat something other than vegetation, or they would have never survived until vegetation started to grow again in the spring. With no preservation methods available, that "something" had to be animal matter.

Besides, I look around right now, and where I live (PA), it may be spring, but there's very little edible vegetation growing yet, just some onion grass and dandelions.

It'll be at least a couple more weeks before any local spinach, asparagus, strawberries, and rhubarb are available - and none of those ever grow wild in sufficient quantities to stave of starvation until more caloric and filling fruits and vegetables are available locally.