Accumulative Error

What is accumulative error? The concept is simple. Lets say you need to measure one mile. If you have a tape measure that is one mile long, you will be quite accurate perhaps within 1/8 th of an inch or so, not to shabby. But lets say you only have a 12 inch ruler. One mile is 5,280 feet long, so you take the ruler lay it down, draw a line at the end and then move the ruler to the line and draw another line. If you do this 5,280 times you will be one mile, right.....Problem is, when you pick up that ruler and move it to the line , the line may be 1/16th of an inch thick, so do you go to the middle of the line, the outside of the line, the inside? You may be off up to 1/16th of an inch each time you move the ruler. Doesn't sound like much, does it? By the time you do this 5,280 times you could be off 27.5 feet. So if you were to use this method to find someone's house, you may end up knocking on the wrong door.
In the world of science, accumulative error is rarely accounted for. I was watching Discovery channel, and they were showing the evolution of the horse. They carefully mapped out the family tree 55 million years back to a creature called hyractherium. I thought to myself, what if just one of those ancestors is wrong. The whole thing could be wrong. We don't actually have the DNA, so decisions about ancestors are made on appearance alone. So we could be compounding accumulative error. It took us almost 50 years to figure out that T-Rex didn't drag its tail, so do we really know that much about appearances of fossils. I am not saying that the trail of equuis ancestors is wrong. I'm just saying that we should never accept it as fact. Always be skeptical. If one of those ancestors in the horse tree is wrong and perhaps belongs in another group, then the accumulative error compounds even more. Not just for the horse group but for whatever group it really belongs. Even more, if evolution doesn't happen The way we think it does, the error could be even higher. Every scientist has a preconceived notion of what he expects is correct, its human nature.
I once watched a show on the T-rex, where two well known paleontologist debated over the behavior of T-rex. One (I think it was Bob Barker) felt that T-Rex was a fast moving hunter, quick and agile. The other, felt that he was a slow moving scavenger. They both used the size of the upper leg bone verses the size of the lower leg bone to justify how fast he could run. One said that the lower leg bone was larger than the upper leg bone. Other animals that posses this quality such as ostriges run very fast. The other said the upper leg bone was longer than the lower leg bone, and animals that posses this quality such as iguanas, move very slow. I'M watching this thinking to my self. They are measuring the same damn animal. How in the hell can they get different measurements. I think one was including the knee (which isn't even there) in the upper bone measurement and the other was counting it in the lower (or perhaps ankle was included). Point being they both have a preconceived idea of what they expect to find and manipulate the data to their favor. Sometimes an unproven idea gets kicked around so much it becomes fact. Such as the Big Bang theory. And others build on that unproven fact. Hence, more accumlitive error.I know people that think the DaVinci code is real!
As Ben Franklin said "We don't know 1/10th of one percent, about anything"