Darwinius masillae -- the missing link?

Recently in the popular press there has been reports of new fossil. Claims have been made that it is "the missing link". But is it? I'm not going to tell you --- instead I am going to tell you why that is a damn poor question to ask.

First off here is the fossil:

It has been given the name Darwinius masillae and dates back 47 million years. It is certainly an important fossil. I think it is a shame that it has been so overhyped.

First of all it is not "THE missing link". Each of us have our own ancestors. I have traced one lineage of my ancestry back to the 1400's. Theoretically everybody before that are "missing links" in my evolutionary history. Species categories are somewhat artificial terms. There are numerous missing links. So a better question might be: Is Darwinius masillae A missing link? Unfortunately, it too is a damn poor question ask.

If I were Richard Dawkins or some other prominent evolutionist I would hate writing what I am about to write because I know I would be quote-mined by creationists for decades to come. But I'm just little old me ... I have the luxury of being able to explain things without being quoted out of context. Let me emphasize this next bit of text:

Now let me explain it.

The evidence for evolution is overwhelming. We evolved. But from what? Well the textbook answer at the moment is Homo erectus.

Did we evolve from them or not? Well, first of all there are technical problems. We have a lot of fossils that are presently labelled as Homo erectus. The person who finds the original fossil of a new species gets the honor of giving it its species name. The original fossil becomes what is called the "type specimen". Theoretically any new fossil found needs to be compared to the type specimen in order for it to be considered the same species. The original fossil of Homo erectus was found by Eugene DuBois in 1895. It was not a complete skeleton by any means. It was a skull-cap, a tooth, and a femur:

Not too much, is it? But it is even worse. We are no longer sure that the skull-cap, tooth, and femur come from the same individual. Furthermore, DuBois found those fossils in Indonesia, and they date to about 1.2 million years ago. The Out-of-Africa hypothesis is dominant now in human evolution. That hypothesis says that the modern human lineage left Africa between 100,000 and 200,000 years ago. So DuBois' fossil is certainly NOT an ancestor to us.

But, this is a picture of the "Turkana Boy" fossil that dates back to 1.5 million years ago:

It is much more complete. It was found in Africa. It too is classified as Homo erectus. It is certainly human-like. It could be our ancestor. There are two questions we must ask though. The less important one (in my mind) is: Is it REALLY a Homo erectus?

The reason it is not that important is that giving a fossil a name is arbitrary. My guess is that it probably is not the same species as DuBois' Homo erectus. They were separated by hundreds of thousands of years and by 1/2 a world. They come from very different environments and a lot of evolution could take place between them. I suspect that if we could see the specimens as they were in life we would classify them as different species. Perhaps DNA analysis will answer this question someday. There has been a push to classify Turkana Boy as a different species ... Homo antecessor. If that becomes fashionable then I suspect that science will change their putative human ancestor to Homo antecessor. But even if they do that, we cannot possibly claim that we actually evolved from Homo antecessor. The reason for that brings us to the second and more important of the two questions we need to ask. What are the alternatives to Homo erectus/antecessor being our ancestors? In other words, if we didn't evolve from them, who did we evolve from?

From all the possible alternatives we have at the moment, a Turkana Boy-like individual is our best guess. But Turkana Boy was found in 1984. Prior to that we would have said something different. The alternative at that time would have been a fossil specimen that hadn't yet been found, and ouila -- Turkana Boy would have shown up proving it to be correct. Well, guess what ... that is the alternative now to Turkana Boy-like fossils. And if we happen to in the future find a fossil that seems to fit the data better than a Turkana Boy-like specimen the alternative will still be a fossil specimen that has yet to be found. NO MATTER WHAT WE FIND, THERE WILL ALWAYS BE THE ALTERNATIVE OF A FOSSIL SPECIMEN THAT HAS YET TO BE FOUND. We can never rule that out. And since we can never rule that possibility out, we can never say with absolute certainty that any fossil specimen is ancestral to any other.

That is why I hate the term "missing link". Since we cannot possibly determine ancestry, we cannot possibly call anything a link to anything else. But if fossils cannot determine ancestry, does that mean that they are useless? NO, NO, NO!!! They are very important and they are EXCELLENT evidence that evolution has occurred. And they shed a great deal of light on our ancestry.

Let's look at Darwinius masillae as an example of what fossils CAN tell us. Here is what we knew. Primates are an order of mammals that includes tarsiers, lemurs, monkeys, apes and humans. The fossil record and genomic analysis tell us that humans and chimps split from the rest of the apes about 5 to 7 million years ago. Apes split from the monkey lineage about 30 to 35 million years ago. But the origin of the monkey lineage is not certain. It must have happened sometime earlier. Furthermore it is not certain whether or not they branched from the lineage that led to Tarsiers or from the lineage that led to Lemurs.

Prior to Darwinius masillae we had no good fossil specimen that covered the important time period. Based on the anatomy of living organisms scientists made arguments for both Tarsiers and Lemurs as being more closely related to the monkey lineage. The dominant argument was for Tarsiers, but no one would be especially surprised if it were the other way.

Darwinius comes in at 47 million years ago. It is excellently preserved. Modern evolutionary theory predicts that any such specimen we should see at that time should have characteristics of both lemurs and tarsiers. There is no apriori reason that the fossil has to be that way. If modern evolutionary theory is wrong it could have been very human-like. It could have been very ape-like, it could have had a full set of characteristics like modern monkeys. It didn't, it had just what modern evolutionary theory predicted such a specimen should have.But it also has some primitive characteristics of modern monkeys. So even if we cannot say that it is our direct ancestor, we can say that it branched from the lineage that leads to monkeys (and hence us).

So the question then is ... is it more like a lemur or is it more like a tarsier? The answer is it is more like a lemur. So the importance of it is that it tells us that most likely our line branched off from the lineage that led to lemurs than it did from the lineage that led to tarsiers. We deduce that because this is better and more reliable data than comparing the anatomy of existing animals. Now that is important and is hype enough. There is no reason to be labelling it something that we cannot possibly claim it to be.