Here is a credible idea: “We should not eat things that we are maladapted to eat.” On the face of it, this makes perfect sense: if we are maladapted to eating something (or doing anything, for that matter), then clearly it will do us harm. That’s true pretty much by definition. Let’s call this argument the adaptational health argument.
Now, let’s shift the emphasis. The meaning of the statement is actually the same, but when restated, it reveals a problem: “We should only eat things that we are adapted to eat.”
Ah. Now, the shoe is on the other foot! What exactly are we adapted to eat? We have to eat something. How do we choose? What if we have been eating things that we are not adapted to eat?
Every now and then, you can capture a snapshot of the scientific process at its worst (and paradoxically, its best, too). The trick is to look at the Letters or Perspectives section of your favorite scientific journal.
In this case, I happened to come across an argument between two sides in what I will call the Great Eukaryotic Melee (there are probably more than just two sides in this debate, but only two are reflected on these pages). Actually, the debaters seem to be rather more well-behaved than I suggested above, but it is true that these fights do sometimes turn ugly.
The central issue? How did Eukaryotes evolve. Let’s review some basics.
Well, the time has come to talk about dinosaurs. In a blog about evolution, it was inevitable. Dinosaurs are, so to speak, the elephant in the room.
It is widely believed that dinosaurs are big and go “Rawr!’. While it is certainly true that dinosaurs go “Rawr!” (of course, there’s a Santa Claus, boys and girls!), it happens that many were not very large.
Some were, of course, brain-meltingly huge. But others were the size of a chicken. In fact dinosaurs came in such a diversity of sizes and shapes, that talking about dinosaurs is a bit like talking about mammals: there are just too many of them to be able to generalize much. Mammals can be giant like an elephant – or a whale – or they can be tiny like a shrew. And they’ve changed dramatically over evolutionary time. Same thing with dinos: the first dinosaurs were quite different from the ones that got smacked down by that asteroid at the end of their reign.
But there’s one thing that seems to have remained the same over the entire age of the dinosaurs: the carnivorous ones always had a bipedal stance. From Allosaurus to Velociraptor, they all seem to have run on two beautifully engineered legs. Herbivores came in a surprising array of shapes both two-legged and four; but carnivores? Just the two-legged variety.